Archive for the ‘Mechanical Systems’ Category

What goes out must come in

December 5, 2010

On my Linked In page, I passed on a link to an article titled, “Makeup Air for Range Hoods” (  The author, Martin Holladay, digs into the details of adding a larger range hood to a home.  In particular, he investigated whether consumers were warned about what could be the impact of adding such a hood to a home.  Mr. Holladay’s blog is a fair warning to consumers that they might not be warned about products that could have a negative impact on your home’s environment, and that impact could be hazardous.

In this post, as I promised on my LI page, I am going to dig into more detail about the impact the fan or other devices that change home pressurization could have on the home and potentially its occupants.  Let me start the same way.  Consider your home–or any building for that matter–as a box.  When air is removed from that box, replacement air has to come into the box to replace the air that is removed.  This replacement air is normally called makeup air by building professionals.  The issue is from where that makeup air comes.

If the home is air leaky, makeup air will come through openings in the building’s exterior shell, i.e. walls, roof, windows, doors, etc.  Leaks are usually a major issue because the air can come from many places.  Rehabbing older homes cuts down on the leaks, but usually cannot totally eliminate them.  But, even newer, so-called tight, buildings have air leaks.  The problem with air leaks in all buildings is mainly a thermal comfort issue because leaks cause drafts, and few people enjoy the feeling of a cold air stream inside the home on a cold day.  Another just as important issue is that if air can come in through a leak, it can go out through a leak, which translates into loss of heated or cooled air.  But, air streams flowing past hoods, fireplaces, ventless heaters, etc. can impact their operation.

Air is a lot like most people in that it takes the path of least resistance.  So, air coming through leaks can mess with the home’s return air system.  For a heating and air conditioning system to work properly, adequate air of a certain temperature has to be supplied to an area to compensate for the heat gain or loss from that area.  What may no be known is that air has to also be removed from the area to help the supply air side of the system work right.  In buildings with poor return air systems, large temperature differences could exist from one area to another even if the supply air flow is ideally designed and installed.  What can happen is that air entering through leaks has the path of least resistance to the air handler.  That air, then, prevents the return air system from returning air back to the air handler from some (or all) of the building’s areas.  Those areas that do not have proper air return will be hotter or colder, depending on whether the air handling system is in the cooling or heating mode, respectively.  Alternatively, those areas through which the leak air is traveling could be too hot or too cold.

What about buildings that are pretty well sealed?  If the exhaust fans in the home do not have adequate makeup air, they will either not move as much air as designed or makeup air will come from wherever it can, which might be from undesirable places, such as through flues or chimneys.  The condition of air flowing in the reverse direction from which it is intended is called backdrafting.  When backdrafting occurs in flues and chimneys, combustion gases, including carbon monoxide, could be pulled into the home.  When wood is not being burnt in the fireplace, backdrafting air can pull creosote emissions into the home, which believe me is not a desirable fragrance. Backdrafting can also impact combustion of some appliances, making them less efficient.

What if a combustion appliance, such as a water heater or furnace, have flue booster fans that are supposed to push the exhaust gases outdoors.  If the appliance is a closed system, such as many of the higher efficiency furnaces, no impact should be expected because closed systems pull air directly from outdoors.  Appliances that pull air from the general building air, as do the water heaters with flue fans, may be affected, depending on which fan in the building moves more air or other characteristics.

The impact that exhaust fans could have on other combustion appliances is not unknown to building professionals, though.  Some homes with furnaces that used general home air for combustion have a duct that runs from outdoors to somewhere in the vicinity of the furnace.  That is all.  This duct is not connected to any fans or any other devices.  This duct is simply a path for air to travel from outdoors to indoors to makeup air removed from the home.  Do they work?  Maybe.  But, as I said earlier, air takes the path of least resistance and, if the duct is not the path of least resistance, it will not work.

The concern as stated in the blog post cited at the beginning of this blog in particular was discussing the installation of large kitchen exhaust fans that move over 1000 cubic feet per minute (cfm) of air.  That is an extraordinarily large fan for a home.  Will the usual kitchen exhaust fan cause the same issues?  If it doesn’t exhaust air outdoors, which is normal for these fans, the answer is most likely no.  If the fan exhausts air outdoors, the answer is maybe.  By itself, the fan likely will not cause backdrafting at the least.  That fan in combination with other fans might cause backdrafting.  Again, if the home is air leaky, any exhaust fan can pull air through leaks, causing thermal comfort and/or heating or cooling efficiency issues.

Are exhaust fans the only things that can cause air leakage or backdrafting issues?  Well, no.  All buildings have a chimney effect where heated air rises within the building.  As this air rises, air is pulled into the building at lower levels.  The chimney effect is for the usual home is definitely not as great as that for a high rise building.  In most homes, backdrafting due to the chimney effect is likely not an issue; but the chimney effect can cause drafts in lower parts of the home.  The only way to know whether a backdrafting or draft issue exists is through investigation.  A homeowner might be able to investigate the issue using smoke from an incense stick or other air flow indicator.   However, a professional will know more about the conditions to which to test under and will have more sophisticated instruments than a homeowner.

So, if you have this favorite nook in your home that sometimes feels comfortable and then other times feels drafty, consider that the reason could be an exhaust fan or the home’s air handler pulling air through a leak.  What to do about it from there is up to you.

Sump Pump Systems Revisited

November 21, 2010

I recently came across a sump pump installation during a home inspection that caught me by surprise–and that takes some doing.  Below is a picture of the pit.  So, what was wrong with this sump pump pit installation in the following photo:

A sump pump pit in a home that I was inspecting.  What is wrong with this installation?

Hopefully, your answer is that the pit was constructed of cardboard.  More accurately, the pit was constructed using a concrete form tube, such as Sonoco’s Sonotube brand ( or Quikrete’s Quik-Tube brand (  For those unfamiliar with form tubes, they are thick-walled, multi-layered cardboard tubes that are used for rapidly constructing concrete forms primarily for column piers or foundations.  They have been a boon for structural construction in that, when a pier is needed, say to support a deck column, the installer only needs to dig a hole large enough for the form tube, (hopefully) install a footing or compacted base material, place the tube in the hole with rebar if needed, and pour concrete into the tube.  (I have also heard that form tubes make a wicked impromptu drum.)

For the installation in the photo, the form tube was used as a sump pump pit.  It appeared to have been installed a number of years after the home was built.  The basement in which the pit was installed had apparent moisture intrusion issues, which I concluded were  partially due to the water drainage for several adjacent properties being run within 20 feet of the basement.  The installation indicated that a hole had been made in the basement’s concrete floor and the sub-slab soil removed to a couple of feet.  Then, gravel appeared to have been put in the bottom of the hole and the form tube installed and concreted in place.  As the photo shows, a drain line is run through the side of the form tube, although from where it came could not be determined.

So what is wrong with using a cardboard tube for the pit.  The darker tube area deeper in the pit is the clue.  This part of the tube is saturated with moisture, even though a number of weeks had passed since the area received measurable rain.  I was able to stick a screwdriver blade through the darkened area of the tube, verifying that it was wet and degrading.  Over time, the cardboard will likely completely degrade.  As that happens, soil around the pit will erode into the pit decreasing the pit’s depth.  Erosion of the soil will also create a void under the slab and quite possibly under the nearby foundation.  And then, the home has great risk of structural issues that will be expensive to fix.

But, degradation of the pit and potential structural issues are not the only problems.  Water flowing into the pit is also likely not contained within the pit.  Instead, it is flowing out of the pit into the soil under the basement slab.   The lower part of the tube still being wet despite no rain for awhile shows that the soil at that level is also wet, which was verified by the mud on the screwdriver blade when I withdrew it.  Water in the soil below the slab will wick throughout the soil up to the slab.  If an adequate vapor barrier was not installed below the slab, water vapor from the soil can flow through the slab and into the home, causing moisture issues inside the home. Even if the sump pump removes the loose water under the slab, as the cardboard shows, the soil will still hold water because that is what soil does.  This moisture will eventually evaporate to water vapor, which could flow into the home through the slab if an adequate vapor barrier is not present.

And what happens if a LOT of water is flowing into the sump pit through the drain line in the photo?  In this home, cracks in the slab had been sealed, which may have been precautionary.  On the other hand, water could have percolated up through the slab already.  A large volume of water flowing into the sump pit and under the slab could lead to water flowing up through cracks in the slab, even if a vapor barrier were present.  Water could flow out of cracks in the slab without coming out of the sump–water seeks its own level and the top of the slab around the cracks could be lower than the top of the slab around the sump pit.  If this drain line is carrying water from around the exterior of the basement foundation, there could be a LOT of water, especially if water from nearby properties is being channeled near that basement wall.

Water flowing into the sump pit will also be carrying small soil particles.  Although soil particles being present in groundwater is normal, if that water is flowing from an area prone to soil erosion, the amount of soil particles could be greater than normal.  These soil particles are sucked into the sump pump with the water.  In turn, these soil particles erode the pump’s impeller, the part of the pump that moves the water .  Erosion of a pump’s impeller shortens the pump’s life, meaning that the pump would need replacing more often than normal.  (Note that for most pumps, replacement is cheaper than trying to rebuild them.)  Erosion of other materials inside the pump likely also occurs, decreasing the pump’s efficiency.  That is, the same amount of electricity is being used to run the pump; but the pump is not moving as much water for the amount of electricity used.  You pay the same amount for the electricity, but get less for it.  BTW, if you have not priced a sump pump lately,  they start at about $125 just for the pump–plumbers, if needed, are much more expensive.

For the sump pump system in the photo, it will need replacing.  Hopefully, a proper durable sump pit and pump will be used.  I also hope that the person who installed this sump pump system is not the one hired for the replacement job.  The homeowner assured me that person will NOT be the one they hire.  I just hope that no one else has hired him/her for their plumbing work.  Sump pump systems seem like such simple things, and they are to an extent.  However, they are very important systems for keeping a home high and dry.  They should be given the priority they deserve.

Central vs. Portable Humidification Systems

November 14, 2010

In previous posts, I discussed how humidification systems work and how effective a central humidification system might be.  In that post, I hinted at differences between central (whole house) humidification systems and portable (local) humidification systems.  In this post, I want to discuss more about the differences between the two systems.

If you have not realized yet from previous posts, I am biased–I am not a fan of central humidification systems.  I see them often in the homes I inspect; but I suspect that most do not work as intended.  Yet, there they are.  I have to wonder if the installation company actually analyzed the need for a humidification system or was just selling a product that is quite profitable for the company.  Simply asking the homeowner whether he and/or she wanted a humidification system is not the analysis about which I am talking, by the way.

Following are the reasons that I believe a PHS is better than a central humidification system.  For simplification, CHS is used for central humidification system, while PHS is used for PHS.

First is the big picture.  Why try to humidify a whole home when all of the home occupants are not in all of the home’s areas at once?  Let me put is bluntly, injecting a gallon of water into a room is going to be more effective at raising the humidity than injecting a gallon of water into the whole home.

Second is effectiveness.  I believe that a portable humidification system providing spot moisture would likely work better than a CHS.  With a PHS, moisture from a judicially placed unit can be directed into the air around a person’s head (the area that industrial hygienist types call the breathing zone or when they really want to be cool—the BZ).  Even if the PHS cannot be aimed to direct moisture into the occupant’s breathing zone, it can be located close enough to elevate the moisture in the air people are breathing.  If the room can be closed up, such as a bedroom, humidification will likely be more successful than trying to humidify an entire home.  In fact, in the previous blog where I discussed virus and humidification, a portable humidifier was used in that research.  As my previous blog post showed,, CHSs are probably not effective at significantly elevating humidity levels in some homes, particularly air leaky homes.

Home leakiness leads to the third reason portable is better than CHSs—losses.  Moisture in the air is in the form of water vapor, which behaves like the other gases in air.  As such, if the amount of airborne moisture in one area is greater than in another area, moisture in the first area will travel to the second area as long as the two areas are connected.  On cold winter days, the amount of moisture in the outdoor air is usually lower than the amount in indoor air (a subject for another post).  In air leaky homes, indoor moisture will likely move outdoors, even if outdoor air is moving in the opposite direction.  So, most of the water a CHS is putting into the air could be traveling directly outdoors, barely elevating the indoor humidity levels.  Over an entire home, the total area of the air leaks is less than those in a single room.  Therefore, the amount of moisture being lost from one area will be less than throughout all areas.  If a PHS is supplying more moisture to a given area than the central system is supplying to the entire home area, moisture levels in the area with the PHS will be greater.  Even if the moisture from the PHS is also traveling outdoors, it has a better chance of being effective as it travels through people’s breathing zones on it trip outdoors.

A fourth reason is condensation areas.  Most homes have cold surfaces in the winter where condensation can occur.  The chances that condensation surfaces are in the same room with a PHS are less than the chances of moisture from a CHS seeing a condensation surface.

A fifth reason is better humidity control.  Some PHSs now come with their own humidistats.  Basically, the portable unit is sensing the humidity right in the space where the person is.  CHS humidistats are installed in the return air duct in an effort to sense the “average” humidity in the home.  What happens if the return air system is pulling more air from some areas of the home than others, meaning that it is not sensing the true average humidity levels?  That issue is more common than you might think.  Some central system humidistats are placed on a wall in the home; but those also have the same issues as far as sensing the “average” humidity levels.

A sixth reason is operation.  CHSs, if they are working right, only humidify air when the air handling system is working.  During the rest of the time, the CHS is at the mercy of the thermostat.  The central humidification control system has to wait until the thermostat calls for heat before it can work.  Just in case someone is thinking that the CHS can be set to operate without the furnace, remember that the CHS needs air moving through it to work.  Someone is likely also thinking that the thermostat can be set to ON so that the fan is operating all the time.  Then, if the humidistat calls for humidification, air will be flowing through the CHS.  It could; but, the reason air downstream of the furnace is passed through the CHS is because heated air can hold more moisture than cooler air. So, more water will be lost with the CHS if unheated air is passed through it than heated air.  With PHSs, the unit is always injecting moisture into the air without the need for moving air to transport the moisture.

A seventh reason is maintenance.  If a valve on the CHS sticks open, water will be dumped right down the drain when air is not moving through it.  In some cases, the CHS drain is plugged up, and water is dumped into the air handler and then ultimately onto the floor outside the unit.  If that water travels to nearby furnished areas, moisture-related damage can occur.  Sometimes, the damage is extensive, such as shown in the photos below.  The fact is that CHSs are usually not inspected very often and problems may not found until a serious malfunction occurs.  If a PHS malfunctions, it is usually right in the same room with the home’s occupants, who can then see that a problem is occurring.  Maintenance of a PHS is usually so easy that the home owner can do it.  For most homeowners, a HVAC technician is needed to service the CHS.  Remember too, that the more debris that collects on the media inside a CHS, the less air can get through the CHS and the less effective it will be.  The PHS, on the other hand, can be kept clean of debris.


Water damage caused by a malfunctioning CHS



An eighth is bioaerosols.  One of the more well-known cases with PHSs is humidifier fever caused by a PHS that was not properly cleaned and reservoir water was allowed to sit in the unit and grow yuck.  When the unit was operated, the yuck was injected into the air that people were breathing.  But, CHSs are not without the same problems.  In fact, they are essentially operating as a back-up filter to air handler filter.  The debris collected on the media inside the CHS stays there until the media is replaced and that debris contains bioaerosols that may find the conditions inside the CHS a very nice place to grow.  Nowadays, most PHSs are made so that the owner can readily clean the unit and all of them recommend using fresh water every time the unit is operated.

A ninth reason is cost.  A homeowner can buy a lot of PHSs for the cost of one CHS.  For sure, the initial cost of a CHS is much more than a PHS.  But, consider also that if you are not happy with the operation of the humidification system, replacing a PHS is a lot cheaper than replacing a CHS.  I have found cases where homes had unused or disabled CHSs along with PHSs that were being used.

A tenth and final reason is choice.  For residences, homeowners are mainly stuck with one option—the wetted media CHS.  Although residential steam injection CHSs are available, they are even more expensive than the wetted media CHSs.  With PHSs, the owner has not only choice of the method of humidification, as explained in a previous post, a number of manufacturers produce the various types of PHSs.  Having a range of options also means more competition with PHSs than with CHSs, which further means price and feature competition.  I have seen several CHSs and they appear to be amazingly similar, while I have seen a range of PHS designs and those designs continue to evolve.

I guess I could be faulted in this post for not finding more advantages of CHSs over PHSs.  The truth is, none comes to my mind other than the fact that water is supplied to the CHS, while the owner has to carry water to the PHS.  Even though that difference could be considered an advantage of a CHS over a PHS, I think it can also be considered a disadvantage because when changing water, the owner actually is inspecting the PHS and likely keeping it clean.

If you have another opinion, let me know.

How effective are central humidification systems?

October 19, 2010

I am currently working on a post discussing central versus portable humidification systems.  In the midst of it, I realized that I was discussing a lot of issues that might be too much to take in one post.  In other words, it was getting kinda long.  So, I decided to break out part of it for this post.  Well, that and the fact I am beginning to get brain fog in composing the post.

So, for this post, I am going to discuss just how effective a central humidification system might be.  Warning to those who glaze at the use of calculations, they are in here.  If you cannot dig through it, just go to the conclusions.

So, you have a central humidification system that is dumping moisture into the air.  Just how effective is that humidification system at raising the humidity level of the air flowing through the air handler?  Consider this point—to raise the humidity 1% will require about 0.00004 gallons of water for every cubic foot of air (assuming I did my psychrometrics right).  That doesn’t seem like a lot, right?  But, a typical air handler fan pushes around 1200 cubic feet of air per minute.  That means 0.046 gallons (or about 0.7 pints) of water is needed every minute just to raise the humidity in the air flowing through a typical furnace 1%.  Want to try to raise that humidity from 10 to 50%?  That would be nearly 2 gallons of water per minute.  Do you think your humidifier can do that?

Now, consider this point.  Most central humidification systems work by evaporating water into the air passing through the humidification system.  That evaporation process is not 100%.  If you want proof and have one of these systems, check for water coming out of the overfill tube when the system is operating.  Now, the water flowing through the humidification system is not pure–it contains minerals.  As the water evaporates, it leaves those minerals behind to coat the media, as shown in the photo below.  As the media becomes coating, it is less able to absorb the moisture and the surface area of the media that is available for evaporation decreases.  Water that is not evaporated into the air passes through the humidification system to the overfill tube and is wasted.  Whether the water goes into the air or down the drain, you are paying for it.


Mineral encrustation on a wetable media inside a central humidification system.

Mineral encrustations on the humidification system as shown in the photo can also channel water down through only part of the media.  That further decreases the wetted area of the media from which moisture can evaporate.  Less areas from which water can evaporate means lower efficiency.

One more issue I would like to mention.  As the temperature of the water being supplied to the humidification system drops, less water evaporates into the air.  Basically, some of the water flowing over the media is absorbing heat without evaporating into the air.  That means that less water is entering the air.  I don’t know about your water system, but mine sure seems colder in the winter than the summer.  Per my previous post, the water valve supplying water to the humidification system only allows one flow rate.  During the winter, if you water supply temperature is colder, not only is water potentially being wasted, it could also be carrying some of the heat you are supplying to the air down the drain.

In my next (or maybe the one after that or after that or . . . ) post, I am going to get more into central versus portable humidification systems.  I promise.  Stay tuned.

What is the purpose of humidifying air?

October 11, 2010

In the last post, I said my next post would be to compare central to portable humidification systems.  Well, I got well into writing that post–which will be more than one post, as I found out–when the thought came to me that maybe I should explain some of the reason I have heard for humidifying our homes.  That last post indicated one reason based on more recent research and that is to control virus. We shall see if future research supports the findings.

Another common reason I heard is to protect the wood in a home.  I am not so convinced, at least for more modern homes that use a lot of manufactured wood products rather than the real McCoy (do people still use that phrase?).  All wood expands and contracts as the wood’s moisture content changes, and the content does change with the amount of moisture in the air.  Cracks form in the wood when it is constrained from moving either by the way it is installed or by its own natural structure.


Based on a little research (and note I said a LITTLE research) I believe that most wood in homes expands less than 1/4″ and more likely the amount is around 1/8″.  In a short article published on-line (, The University of Georgia Cooperative Extension Agency published results of a little study on the amount of moisture in wood in 20 homes or offices for oak and maple.  The authors found that the average maple moisture content 7.9 to 10.3% and for oak the average was 6.3 to 8.1%.  In another article published on-line  (, Mr. Carl Hagstrom gives this rule of thumb:  for every 4% increase in wood moisture content, the wood expands 1% (for “flat gain material”).  (Mr. Hagstrom also very nicely provides a link to an on-line shrinkage calculator at  Putting these two bits of information together, wood inside homes will likely expand about 1% during a typical change in winter conditions.

Mr. Hagstrom further states that wider boards expand more than narrower boards, as you would expect based on his rule of thumb.  However, not a lot of wider boards are used in new construction.  Not that many old big trees are still around these days, and those that are usually are used for veneers.   But, craftsman builders know how to account for wood expansion–both back then and now.   Having inspected a large number of older homes, I have not seen a lot of cracks in finish wood.  I have seen plenty in structural wood, although not many I would consider bad enough to be structural issues.  At that, I have to wonder if the cracks were not caused by the wood not being adequately dried or being exposed to the more extreme variations in moisture and temperature of outdoor air.

I also do not hear many homeowners saying that they humidify because of concerns about the wood.  Instead, the issues are usually that pesky static shocks from walking across carpets in dry environments and physiological issues such as stuffy head and dry skin.  WikiHow has a list of things a homeowner can do to reduce static shock (  Apparently, some carpets are also now manufactured to reduce shock.

I have my own theories about the physiological effects of dry air.  I believe that the dry air dries out the mucous membranes of the nasal system.   To prevent drying, the the mucous membranes swell to increase humidification of the air going into our lungs.  Swelling of the membranes causes little fissures in the mucous membranes that cause slight bleeding, which some people see when they blow their nose during this time.  The nasal stuffiness causes some people to use decongestant sprays that can also irritate the mucous membranes and some have rebound effects that make the stuffiness worse.  Decongestants , particularly the ones combined with antihistamines, can also cause a drying effect of the membranes.  Moisturizing sprays can help relieve the drying effects; but, the effect, for me at least, is relatively short-term.

I have one other alternative to help reduce the physiological effects of dry air that most people will not find attractive.  That is, reduce the air temperature of the home.  Doing so will effectively increase the relative humidity of the air.  I confess that during the winter, I keep my home at around 65 degrees.  Even though this temperature is noticeably lower than the 75 to 85 degrees most people keep their homes at during the winter.  I have found over the years, that our bodies are amazingly adaptive.  One other lesson I have learned is that I can always put on more clothes and putting a heating pad under my butt during the coldest days can go a far way toward keeping me warm enough.

The basics of humidification systems

October 6, 2010

In a previous post on virus and humidification, I promised to discuss more about humidification systems.  In this post, I am going to discuss the basics of humidification systems.  Humidity is a measure of the moisture in the air.  Technically, the humidity that everyone is usually talking about, including the weather guys is relative humidity.  Every so often, the term absolute humidity sneaks out of the scientific and engineering circles into the public.  This is a different measurement of moisture in the air; but that is a subject for another day when I pretty much run out of other topics—and I do have a list.

Humidification systems are simply devices for putting moisture into the air.  In our area, we only want to put moisture in the air during the winter.  In the summer, we are more concerned with getting out of the air.  The reason that people want to humidify air is that the air in our homes is extremely dry during the winter.  Even though outdoor air during the winter may have what seems like a normal humidity level, when that air comes indoors and is heated, the relative humidity levels drop to levels seen in a desert—somewhere around 10%.

For homes, a homeowner has really two basic choices in humidification systems:  central and portable.  A central humidification system supplies water to the air going into or coming from the air handler.  The humidified air is then distributed to all areas of the home.

Central humidification systems typically are recognized as a plastic box mounted on a return air duct near the air handler as seen in the photo below.  However, I recently saw on system mounted on the supply air duct, which may have been the work of an installation instruction-challenged installer.

A typical central humidification system

Inside the box is a web-like media through which air flows.  The air that flows through this media usually comes from the supply air duct just downstream from the air handler (the duct coming into the side of the humidifier in the above photo).  A humidistat connected to a sensor normally in the return air duct upstream of the humidification system (the little white box above the humidifier in the above photo) operates an electronic water valve that controls the water flowing onto the media (the valve can be seen alongside the humidifier in the photo above).  The humidistat is a control system for sensing moisture in the air similar to the way a thermostat senses temperature.  The water valve is connected to the home’s water supply.

When the humidistat senses that the moisture level of the air is too low, it opens the valve to let water flow over the media.  When the humidistat is satisfied, it closes the valve.  Air flowing through the media is supposed to pick up the moisture through evaporation and carry it into the return air stream.  Water flowing across the media that is not absorbed by the air is supposed to flow into an overflow that has a drain line to a nearby drain (the black tubing below the humidifier in the photo above).  In a few cases, the humidistat is located in a living area of the home, usually next to the thermostat.  Some humidistats are incorporated into the thermostat.

Most people will be more familiar with the portable humidification system, particularly since they are sold pretty much everywhere.  These units are self-contained humidifiers that have a water reservoir and a means for converting the water into a mist.  Some units also have a small fan to power air through the unit.  Portable humidifiers have three methods for turning the water into a mist.

The first method for turning water into a mist is a nebulizer that is simply a vibrating plate onto which the water dribbles.  The vibration breaks the water into a mist that is usually carried into the air by a fan-powered air stream.  These units are pretty simple devices that use the electric current to generate the vibrations in the plate.

The second method for turning water into a mist is a rotating disk that slings water at a comb-like device, which is supposed to break the water up into a mist.  The spinning disk operates both as a kind of pump to pull water up out of the reservoir and a means of slinging the water at the comb and a fan to push the mist out of the unit.  This method tends to generate larger water droplets than the other methods, which can lead to water falling on surfaces around the unit.  But, they are also commonly the cheapest units.

The third method for turning water into a mist is the old tried and true method from many of us boomers child-hoods is steam generation.  These humidifiers have a electrical resistance element that heats up when electricity runs through it, similar to the elements on an electric stove.  Water in contact with the heated element boils and is converted into steam.  The steam literally is forced out of the unit because of the energy it absorbs as it turns to steam.  This method of humidification is also used in most commercial and higher-end home humidification systems.

So, in summary, humidifiers convert water into water vapor through three methods; but all of them ultimately work through evaporation.  Central humidification systems use direct evaporation of the moisture into the air as it passes through a wet media, similar to the way that we evaporate water from our skin.  The other methods generate a mist with the intent to get it into the room air where the water will evaporate into the surrounding air.  For these mist generators, the smaller the size of the droplets in the mist, the better the water evaporates.  That doesn’t mean that central systems are more effective humidifiers than the others.  Steam systems are actually the most effective method, but take more energy to do the humidification.

I will end this part of the discussion there.  In the next post on humidification, I will discuss the pros and cons of central and portable humidification systems.

Some more links I believe are useful

September 15, 2010

The following article, 10 Things Your Plumber Won’t Tell You, came in an e-letter I received today:

I recommend that you also check out the other 10 Things articles  that Smart Money has posted on-line at:

BTW, one of those articles are about home inspectors, on which I hope to comment in the near future.  That is one article, with which I don’t totally agree–at least for my firm.

A potential Freon fiasco

March 8, 2010

One of the inspector message boards recently posted a letter from one of the home warranty companies to realtors about Freon.  The parts of the letter related to most homeowners are duplicated below:

Starting January 1, 2010, a new Environmental Protection Agency (EPA) mandate will change the way your clients’ home

air conditioners are serviced and repaired. At that time, manufacturing HVAC equipment that primarily utilizes Freon®

(also known as R-22 and HCFC-22) will be banned, and the nation will begin using products such as Puron® (also known

as R-410A) as the standard refrigerant for air conditioners. This change will affect your buyers and sellers in many ways.

Costs will increase

A variety of factors will lead to increased costs:

  • R-22 parts may no longer be available.
  • Since R-410A parts are not always interchangeable with R-22 parts, replacement of the entire system might be necessary.
  • Physical changes to your system may be needed to accommodate the larger equipment required in air conditioners using R-410A refrigerant.
  • The supply of R-22 refrigerant will be limited, causing the price to increase.
  • Repairs may take longer because you may want to explore your options and wait for less expensive parts, if they are available.
  • New HVAC equipment may be more expensive to purchase and install.

Manufacturers’ warranties may not provide full coverage

Typical manufacturers’ warranties only cover parts for one year, in most cases. Labor is a significant part of any repair.

Each manufacturer may take a different position if an R-22 system cannot be repaired or parts are not available.

System and appliance warranties/ service contracts typically exclude coverage resulting from government mandated changes

Most system and appliance home service contracts/warranties contain language that effectively excludes the additional

costs resulting from this government-mandated change. Each home service contract may deal with this situation


Visit to answer all your questions concerning the impact of this new government mandate to you and your clients or call 877-777-3188 to deliver real time answers to agents and homeowners.
Even though the letter was originally written to realtors, it contains information that is important to homeowners, particularly the parts about prices of the Freon alternative.  But, one other part of the letter, which I did not include here, was that homeowners who are selling will likely now have to disclose any Freon systems.  As home buyers get wise to the Freon system problems, sellers will likely end up reducing their selling price because of the Freon problems.  Likewise, if you are in the market for a home, you may want to ask about whether the air conditioning system uses Freon.  Most likely it does or it will (depending on which side of the sell you are on).  That means in turn that older air conditioning systems that need repair might end up being cheaper to replace than repair.

Plants as indoor air cleaners

December 9, 2009

Here we go again.  WebMD reported this week that HortScience had an article in August about research on using house plants to remove indoor air pollution.  Interestingly, the article did not report anything about been there, done that.  Well, not me personally.  But, a few years ago, NASA was doing similar research.  At that time, a bunch of people were proposing that plants could be used to clean indoor air.

The research seems to be clear.  Yes, some plants appear to be able to remove some indoor pollutants.  The truth is in the practicality.  Usually, these studies are designed using injection of an initial concentration of a chemical inside an airtight container that contains the plant.  The chemical’s concentrations are then monitored over time to determine how well the plant removes the compound.  The first possible problem with this kind of research is that some of the compound could be lost to surfaces inside the container.  If this research is like most of this kind of research, such losses are not included in the study details.  Another problem is that, over time, chemicals can also break down, depending on the environment and the chemical.  Again, study details don’t usually describe how this loss is accounted for.  And a final detail about the study methodology is sometimes overlooked, and that is loss of chemical to the study.  Each time a sample is removed, the chemical concentration inside the container decreases.

Those facts were about the practicality of the study design.  Reality is probably the least practical aspect of the study results.  We don’t usually have only one chemical floating around in the air.  Does that mean if a whole bunch of plants would be needed if they each have their own chemical they like to dine on?   Realistically, chemicals are not put into the environment in one squirt and then left to decline over time.  Some chemicals are emitted into the air over time, such as those from building materials.  Even more complicating is the fact that chemical concentrations can vary over time because the emissions from materials vary over time, depending on a range of environmental factors.  I have collected this kind of sample data myself, as have many other researchers.  The changes in chemicals floating around a building are pretty amazing to study, actually.

In our buildings, air is constantly being exchanged–moving in and out.  No building is airtight like the containers used for most plant studies.  Air coming in also can carry chemicals into a space and air leaving can taken them out, which is also another reason why chemicals and their concentrations can vary dramatically over time.  Changes in the rate that air enters and leaves a space can be controlled by factors inside and outside the building.  Wind direction and speed, house design, sun and many other factors can influence air movement inside a home.  Operation of the air handler, people movement, heat sources, interior design and many other factors can influence air movement inside a home.  As vapors, chemicals are also influenced by the Ideal Gas Laws, in particular the part about partial pressures which says that vapor pressure of any one chemical in one area will equilibriate with vapor pressure of the same chemical in an adjoining space if the chemical can move between them.  So, chemicals at a higher concentration inside compared to outside a building will eventually equilibriate with concentrations in the outside air.

Materials inside a building also absorb and re-emit chemicals.  Ever smell cigarette odor on non-smoker who has been in a smokey bar?  The fixed things in buildings, the things of which the building is constructed, as well as the solid materials floating around in the air and the other things moving through the building, such as people, pets and their related materials, all absorb and re-emit chemicals.  The researchers call things that absorb sinks and the things that emit sources.  A dynamic exchange is going on between these things all the time.  Further, something that is a sink at this time can become a source when a chemicals concentration changes.  So, what is a plant to do?  Then again, how many plants should a person have when the emission rates could be constantly changing?

But, let’s dig into that question a little more.  How many plants would be needed.  Past research has shown that plants absorb a definable, but minute amount.  Such research predicted that a small forest would be needed to make a significant dent in the chemical concentrations.  Again, we are talking about static chemical concentrations, whereas most buildings have dynamic concentrations.  That brings me to another subject that seems to often overlooked.

Past “Plants Eat Chemical Compounds” researchers also took a lot of criticism for one major overlooked factor.  Plants grow in soil.  Soil contains–dare I say that M word–yes, mold!  In fact, many plants have a symbiotic relationship with certain molds to help them absorb nutrients.  But, many molds themselves emit chemicals into the air.  So, a person has to ask, is it practical to use plants to absorb one chemical when the soil in which they grow could be emitting a whole bunch of other ones?  Probably not.

NASA had a good reason to research whether plants absorbed chemicals or not.  NASA was interested in using plants on spaceships making long journeys where plants might be used for food and to help control the air quality inside the ship.  Currently, NASA uses chemical filters to control chemicals emitted into their ships.  On a long journey, those filters could become saturated, and in some cases then start re-emitting chemicals back into the air.  Having something that absorbs and holds the chemicals would be nice.  Having something that absorbs those chemicals and then turns them into a product that the spaceship residents can use would be great.  Now, given we are kind of like astronauts flying along on this great ship Mother Earth, we still have enough air to take care of plants, chemicals and us.  The amount of air around us is currently adequate to support a recycling system that maintains a reasonably (although I admit debatably) healthy air quality.  Other systems inside out buildings do a better job than plants.

For solid materials floating around in our building air, particle filters do a very good job–as long as air is moving from the building through the filter.  For gaseous materials, chemical absorption filters can work well; but in most cases, they are impractical for many buildings.  More effective, though, is dilution where outside air is brought indoors to reduce chemical concentrations.  And that is where I am going to leave things for right now.  I promise to cover more about control of gaseous chemicals in a future blog.  Suffice to end this blog this way:  use plants to make you feel good mentally; but use dilution or filters to make you breathe well.

A sobering reminder

December 2, 2009

The following news item was released on December 1, 2009:

3-Year-Old Ind. Girl Drowns In Basement

FORT WAYNE, Ind. (AP) — Authorities say a 3-year-old Fort Wayne girl drowned after she fell into a sump pit pump pit in her family’s basement.

The Allen County coroner says Alexis Stark-Bork was pronounced dead at a hospital soon after she was found in the pit about 2 a.m. Saturday.

Police say Alexis was last seen watching television in the home’s living room. About 20 minutes later, the girl’s parents noticed she was missing and she was found face down in the pit.

An officer reported finding the pit’s cover about 6 feet away underneath a futon.

(Copyright 2009 by The Associated Press. All Rights Reserved.)

What a sobering reminder.  I have heard of drownings where a toddler has fallen head first into a regular 5-gallon bucket.  I never thought about a sump pit system, even though a sump pit is a bucket of sorts.  In fact, I have seen cases where a regular 5-gallon bucket was used for one.  A sump pit holds water like a bucket; but, unlike a bucket, when enough water builds up in the sump pit, a float switch is supposed to activate a pump that empties the water.  Even though the lid not being on the sump pit appears to have been the reason this child drowned, other issues could be involved.  For example, even though the toddler would have raised the water level in the sump pit, why didn’t the float switch activate the pump and lower the water to a safe level.  Likewise, I have also experienced many other cases of problematic sump pit systems, which before I would have only considered as potential moisture problems. Now, I see them as potential safety problems too.

First and foremost, sump pits are supposed to have lids.  That point is pretty obvious in this toddler’s case where the lid was not used.  The obvious lesson is to make sure that if the sump pit has a lid, USE IT.  Sump pits can be deceiving.  When water is not flowing into the pit, seeing the water in the pit can be difficult for an adult–and probably impossible for a toddler.  In fact, in my own sump pit, I have to check the position of the float switch sometimes to determine whether water is in it.  One particular time stands out in my mind when the float switch failed to activate the pump.  The sump was filled to the brim and I could not notice it until the area around the put got wet.

Furthermore, I know of at least three sump pit designs and I would be very safe in assuming many others exist.  The various sump pits do not have interchangeable lids.  Therefore, make sure to use the right lid for the sump pit.

That is not the end of the discussion, however.  Manufactured sump pits have a rim specifically made for a lid.  Homemade sump pit systems, such as 5-gallon buckets or plastic barrels, don’t.  Someone will likely argue that the latter have lids.  However, when their lids are cut to allow access for the plumbing, they are likely not structurally able to bear the same weight as the manufactured lid.  I have seen a variety of lids that were well constructed and possibly could work as well as the lid manufactured for the sump pit.  More often, I have seen lids that are not well constructed.

But, let’s assume that the lid is well-constructed, the most common material I have seen used is plywood.  So, let’s see, a wood product being used over a sump pit that contains water or is in a moist environment.  Over time, the wood can rot (and I have also witnessed that), rendering the lid useless as a safety device.

The bottom line is that homemade sump pit lids do not meet safety codes—so, just don’t use them.  Likewise, manufactured sump pit lids are not made to be used on homemade sump pits.  So, don’t use homemade sump pits.

Someone will likely argue that if sump pit is not located in basement where a child can find it, why use a manufactured sump pit, right?  Any parent or other person who knows kids will tell you that kids don’t always go only where they should.  Again, just use the right sump pit and lid for the job.  If that argument is not reason enough for some people consider this point.  If a person does use a lid that is designed for the sump pit or uses a sump pit that was not designed for safety, although I am not a lawyer, I can see where that person probably has just surrendered pretty much any legal defense.

Assuming that the correct manufactured lid was used for the correct manufactured sump pit, another factor to consider is that manufactured lids have a locking mechanism on them.  The more expensive sump pits, particularly those used with radon mitigation systems, have lids that have fasteners, such as screws.  The most common, and generally least costly, types of sump systems have a lid that twist-locks on the sump pit.  With these types of sump systems, the lid and sump pit rim have tabs.  The lid is inserted into the rim of the sump pit with the lid’s tabs misaligned with the sump pit’s tabs.  The lid is then twisted so that its tabs slide under the sump pit’s tabs, locking the lid in place. If the sump pit does not have a locking lid, get another system that does have one.

Even with sump pits that have locking lids, many times I have found the sump pit lid only sitting inside the rim and not locked.  In some cases, twisting the lid to lock it is not possible because the concrete around the sump pit lid had pushed the rim inward; making the lid/pit fit so tight the lid cannot be turned.  The lid should be set in the sump pit rim when the concrete is put around the sump pit during the pit installation.  Further, before the concrete sets, the lid should be twisted back and forth to assure that is will work properly.

Even if the lid fits and can be twisted, I have found many cases where the pipe from the sump pump prevents the lid from being fully locked.  For twist-lock sump systems, the pipe is usually supposed to be installed so that it is centered in the sump pit.  Manufactured lids have a slot that fits around the pipe, so that the lid can be set in place around the pipe.  When installed properly, the pipe is at the end of the slot in the lid, and the lid can be twisted and locked.  If the pipe is not centered in the sump pit, but is installed more toward the rim, the lid can only be twisted with difficulty or not at all.  Therefore, be sure to test the pipe installation to make sure the lid works before the pipe parts are glued or cemented together.  Check twice, glue once.

Speaking of plumbing, somewhere in the plumbing system, a check valve should be installed to prevent water in the pipe from re-entering the sump pit.  In most basement sump pump installations, the pipe runs vertically a number of feet before it turns horizontally to exit through the foundation wall to points thereon.  When the sump pump empties water from the pit and then turns off, all of the water in the vertical pipe can flow back into the sump pit due to gravity.  As the water in the vertical section flows back down the pipe, the water can also siphon water back from horizontal pipe sections.  A check valve allows the water to only flow in one direction–up the pipe.  With a check valve in the plumbing system, when the pump shuts off, water cannot flow back into the sump pit.

Without a check valve, a sump pit can partially, and in some cases fully, refilling after the pump shuts off.  Least case, the pump constantly cycles trying to empty the sump pit because the pit refills as soon as the pump shuts off.  The worst case is where a potential drowning situation could occur if the sump pit only refills so that several inches of water are in the pit, but not enough for the pump to be actuated.

Even if a check valve is installed, they sometimes fail, such as when grit in the water causes the valve to get stuck open.  So, first, make sure that a check valve is installed in the plumbing.  Usually, one is installed right at the pump or within a few feet of it.  In most cases, the check valve must be in a vertical position to work correctly.  For those who are not sure what a sump system check valve looks like, I recommend taking a trip to the ol’ Home Depot to see what one looks like.  Although they may vary in appearance, they normally have the same shape or markings.  If a check valve is installed, do not fully trust that it is or always will be working.  Periodically, operate the sump pump to the point where it shuts off.  When the pump stops, check to see if water is flowing back into the sump pit.  A little likely will back flow; but a lot indicates a check valve problem.

On the other hand, another problem I have found is where the float switch or pump is not working properly.  Float switches do fail, and one could fail so that the sump has adequate water in the sump to drown a child.  Usually, people do not discover that a float switch has failed until a basement floods or other moisture problems occur.  The lesson here is to periodically check the sump pump float switch by elevating it to the point where it activates the pump.  Check to make sure that the pump continues to operate until the sump pit is nearly empty.  By the way, be sure to use a non-conducting material, such as wood, to lift the switch, just in case an electrical “leak” has energized the water.

When the float switch fails, a person has three alternatives to fix it.  The first one is to replace the pump and float switch as a unit, which is how they are usually sold.  The second alternative is to replace the switch, which is tricky for most home owners because the switch needs to be watertight to prevent an electrical short or worse an electrical leak that energizes the water.  If the home owner is not extremely handy, the pros should replace the switch.

The final alternative is to install a float switch parallel to the one that is not working.  The problem that occurs with this installation is that the float switch might not be adjusted properly.  Manufacturers of pump/switch assemblies preset the distance of travel for the switch relative to the pump.  When installing a replacement float switch in parallel with the old one, the installer needs to manually set this distance.  That setting can vary widely depending on how the switch is installed.  The problem is that if the switch has too much travel, the sump could have more than enough water to drown a toddler.

Just as likely as float switch failure, though, sump pumps also fail.  I had one case of a basement flooding where the sump pump was literally encased in minerals from the water.  In areas like southern Ohio, which has high mineral content in the water, concretions like this case can occur.

Grit carried into the sump pit with the water will also eventually doom most pumps.  The impellers on most pumps are normally plastic, and the grit can chew them up.  In some cases, the grit or even pieces of plastic from a degrading impeller can jamb the impeller, causing the pump to fail.  I recommend that the sump pit pump be set up off the floor of the sump pit a couple of inches to provide a grit settlement area.  A brick laid flat provides just about the right distance above the sump pit floor for this purpose.  The grit in the settlement area should be cleaned out ever year or so because this area can fill with grit where it can once again get into the pump.

Another electrical problem that can occur with sump pumps is that some codes require that they be installed on a ground fault circuit interrupter (GFCI) outlet or circuit.  Based on personal experience, a GFCI can kick out for some unknown reasons that have nothing to do with a short.  Most people do not discover that the pump is not working, again, until a basement floods or other moisture problems occur.  I recommend that most people install a battery-backup sump pump.  Until now, that recommendation was based merely on the threat of a basement flooding.  I now have another reason for that recommendation.

Even when a float switch or pump has failed, water can back up and pool below a basement slab, hiding for a time the fact that the sump system is not working.  Further, for most homes, periods can occur where the sump pump does not work frequently, leaving the sump pit with adequate water to drown a toddler.  In most cases, home owners treat sump systems as an out of sight, out of mind item.  They should not be.

The sad fact in the case of this toddler’s downing is that a thing as simple as the lid may have been the most important factor in saving her life.  Even if the float switch and sump pump were operating as intended, the toddler could have fallen into the sump on top of the float switch.  In which case, she could have submerged the switch, preventing it from actuating the pump.  If she had fallen in such a way that the sump’s water level was raised enough to allow the float switch to activate the pump, the water might have been lowered enough for her to survive.  No matter what, a lid would have prevented her falling into the sump.  And, I have seen my share of sumps that did not have a lid installed.

Even if the sump pit has a lid, if it is located in a room or closet away from the rest of the basement, make sure that room or closet has a door with hardware that a toddler cannot operate.  If the sump is located in a crawlspace, make sure the crawlspace is not accessible to any children.

Up to this point, I have covered all of the mechanical aspects of how problems with a sump pit system could have contributed this toddler losing her life.  Now, I will put on my other hat as a father (whose kids are now all grown) and a former volunteer EMT.  A toddler can drown in less than four minutes and in only a few inches of water.  If they fall head first into a bucket, or in this case, a sump pit filled with water, they do not have the upper body strength, or even know how, to get out of the situation.  A toddler’s weight distribution is different than an older child in that they have more weight distributed toward their upper bodies.  In effect, they are top-heavy.  Once head down in the water, they would have a very difficult time getting out of it and definitely not able to call for help.

This leads to the most important lessons of all.  A parent should constantly be evaluating the home for potential safety problems for kids.  I encourage all parents to take available kid safety classes when they are offered and freely exchange kid safety issues whenever they hear them.  While some aspects of homes remain fairly constant, designs, materials and systems are constantly changing.  My grandparents began their lives in homes that did not have electricity–now, it is all around us in our homes.  If you do not know about child safety in the home, here is a good place to start:

I will close this final lesson, and it is one that most parents have heard before.  Always know where your kids are.  For toddlers, always have them within sight or hearing range.  Train yourself to listen for when they are not within site.  Most parents do; but the important skill is to make sure you keep attentive.  Drowning can occur in less time than a phone call.  If you don’t hear your child and you know they are not napping, then check up on them.  Always be in touch with them somehow.  Remember, less than four minutes can be the difference between you watching your child grow up or your having a lifetime of regret and guilt.

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