One Source, Real Estate Inspection: Water Heater Expansion Tanks

One Source, Real Estate Inspection: Water Heater Expansion Tanks: Water Heater Expansion Tanks by Nestor Garcia, One Source Real Estate Inspection   What is an expansion tank?   An expansion t...

Water Heater Expansion Tanks

by Nestor Garcia, One Source Real Estate Inspection

 

What is an expansion tank?

 

An expansion tank is a metal tank connected to a building’s water heating appliance designed to accommodate fluctuations in the volume of a building’s hot water supply system. These fluctuations occur because water expands in volume as it gets hot and loses volume as it cools.

 

Expanding water volume in a closed system can create dangerously high water pressure. As water is forced into the tank by expansion, it compresses air contained inside of a rubber bladder. Air is used as a cushion because it exerts less force on its container than water, which cannot be compressed.

 

The function of this bladder is to prevent air from becoming absorbed into the water, a process that could cause the expansion tank to lose its ability to act as a sort of shock absorber. If, over time, the bladder begins to leak some air, a Schrader valve, identical to the fill valve found on bicycle and car tires, can be used to add more air.

 

What does it look like, inside and out?

 

Expansion tanks are considerably smaller than water heaters, usually holding about two gallons in residential systems, although tank sizes vary in relation to the water volume of the hot water supply system they serve. The design pressure for which a tank is rated is marked on a label on the tank, commonly 150 pounds per square inch (PSI) for a residential tank.

 

InterNACHI inspectors should check that tanks are positioned high enough above the water heater that water will easily drain back down into the water heater tank.  It is best positioned near the water heater and may be installed vertically, either above or below the horizontal supply pipe, but can also be positioned horizontally. Horizontally-hung tanks will need additional support to reduce the stress on the copper piping.

 

The expansion tank should be inspected for proper location and support, corrosion and leakage. Although many jurisdictions now require an expansion tank to be installed at the same time that a water heater is installed, an expansion tank has not always been required in the past and may still not be required in some regions.

Not a Substitute for a Temperature Pressure Relief (TPR) Valve

If water heater controls fail and pressure in the system exceeds 150 PSI, or temperature exceeds 210° F, a temperature and pressure relief valve (TPR valve) installed on the side of the water heater tank will open, safely discharging water from the system. TPR valves are capable of reducing water pressure at a rate greater than the capacity of the water heater to raise it, thus eliminating the possibility that water will become superheated (greater than 212 degrees) and pose a serious threat. The importance of this valve cannot be overstated, and it is crucial that it is examined periodically for rust or corrosion, and the release lever should be exercised monthly by the homeowner, not by the inspector.

 

If a TPR valve fails to operate when it’s needed, the result can be catastrophic. Pressure will continue to build in the water heater tank as water temperature rises past the boiling point and water becomes superheated. Eventually, pressure in the tank will exceed the ability of the weakest part of the water heater to contain it and the tank will rupture, exposing the superheated water to air and causing an instantaneous and explosive expansion of steam. This situation can propel the water heater like a rocket or make it explode like a bomb, causing extensive property damage, personal injury or death.

 

In summary, the expansion tank should be inspected for proper location and support, corrosion and leakage. Although not required in every jurisdiction, they are quite crucial to the successful and safe operation of residential potable water systems.

 

 One Source Real Estate Inspection @ www.onesourceinspection.com.

One Source, Real Estate Inspection: Air Sampling for Mold Inspections

One Source, Real Estate Inspection: Air Sampling for Mold Inspections: Air Sampling for Mold Inspections by Nestor Garcia, One Source Real Estate Inspection.     Taking air samples during a mold inspect...

Air Sampling for Mold Inspections

by Nestor Garcia, One Source Real Estate Inspection.

 

 

Taking air samples during a mold inspection is important for several reasons.  Mold spores are not visible to the naked eye, and the types of mold present can often be determined through laboratory analysis of the air samples.  Having samples analyzed can also help provide evidence of the scope and severity of a mold problem, as well as aid in assessing human exposure to mold spores.  After remediation, new samples are typically taken to help ensure that all mold has been successfully removed.

 

Air samples can be used to gather data about mold spores present in the interior of a house.  These samples are taken by using a pump that forces air through a collection device which catches mold spores.  The sample is then sent off to a laboratory to be analyzed.  InterNACHI inspectors who perform mold inspections often utilize air sampling to collect data, which has become commonplace.

Air-Sampling Devices

There are several types of devices used to collect air samples that can be analyzed for mold.  Some common examples include:

• impaction samplers that use a calibrated air pump to impact spores onto a prepared microscope slide;
• cassette samplers, which may be of the disposable or one-time-use type, and also employ forced air to impact spores onto a collection media; and
• airborne-particle collectors that trap spores directly on a culture dish.  These may be utilized to identify the species of mold that has been found.

When and When Not to Sample

Samples are generally best taken if visual, non-invasive examination reveals apparent mold growth or conditions that could lead to growth, such as moisture intrusion or water damage.  Musty odors can also be a sign of mold growth.  If no sign of mold or potential for mold is apparent, one or two indoor air samples can still be taken, at the discretion of the inspector and client, in the most lived-in room of the house and at the HVAC unit.  

Outdoor air samples are also typically taken as a control for comparison to indoor samples.  Two samples -- one from the windward side and one from the leeward side of the house -- will help provide a more complete picture of what is in the air that may be entering the house through windows and doors at times when they are open.  It is best to take the outdoor samples as close together in time as possible to the indoor samples that they will be compared with.

InterNACHI inspectors should avoid taking samples if a resident of the house is under a physician’s care for mold exposure, if there is litigation in progress related to mold on the premises, or if the inspector’s health or safety could be compromised in obtaining the sample.  Residential home inspectors also should not take samples in a commercial or public building.

Where to Sample and Ideal Conditions

In any areas of a house suspected or confirmed to have mold growth, air samples can be taken to help verify and gather more information.  Moisture intrusion, water damage, musty odors, apparent mold growth, or conditions conducive to mold growth are all common reasons to gather an air sample.  Samples should be taken near the center of the room, with the collection device positioned 3 to 6 feet off the ground.

Ten minutes is an adequate amount of time for the air pump to run while taking samples, but this can be reduced to around five minutes if there is a concern that air movement from a lot of indoor activity could alter the results.  The sampling time can be reduced further if there is an active source of dust, such as from ongoing construction.

Sampling should take place in livable spaces within the house under closed conditions in order to help stabilize the air and allow for reproducibility of the sampling and measurement.  While the sample is being collected, windows and exterior doors should be kept shut other than for normal entry and exit from the home.  It is best to have air exchangers (other than a furnace) or fans that exchange indoor-outdoor air switched off during sampling.

Weather conditions can be an important factor in gathering accurate data. Severe thunderstorms or unusually high winds can affect the sampling and analysis results.  High winds or rapid changes in barometric pressure increase the difference in air pressure between the interior and exterior, which can increase the variability of airborne mold-spore concentration.  Large differences in air pressure between the interior and exterior can cause more airborne spores to be sucked inside, skewing the results of the sample. 

Difficulties and Practicality of Air Sampling

It is helpful to think of air sampling as just one tool in the tool belt when inspecting a house for mold problems.  An air sample alone is not enough to confirm or refute the existence of a problem, and such testing needs to be accompanied by visual inspection and other methods of data collection, such as a surface sample.  Indoor airborne spore levels can vary according to several factors, and this can lead to skewed results if care is not taken to set up the sampling correctly.  Also, since only spores are collected with an air sample and may actually be damaged during collection, identification of the mold type can be more difficult than with a sample collected with tape or a cultured sample.

Air samples are good for use as a background screen to ensure that there isn’t a large source of mold not yet found somewhere in a home.  This is because they can detect long chains of spores that are still intact.  These chains normally break apart quickly as they travel through the air, so a sample that reveals intact chains can indicate that there is mold nearby, possibly undiscovered during other tests and visual examination. 

In summary, when taken under controlled conditions and properly analyzed, air samples for mold are helpful in comparing relative particle levels between a problem and a control area.  They can also be crucial for comparing particle levels and air quality in an area before and after mold remediation.  

 

Air Sampling for Mold Inspections @ www.onesourceinspection.com.