Archive for November, 2010

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 (http://www.sonotube.com/sonotube.html) or Quikrete’s Quik-Tube brand (http://www.quikrete.com/productlines/QuikTubeBuildingForm.asp).  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.

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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.


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