This ERV-equipped condominium in Naples, FL is only one of many sad cases for homeowners and one-time tenants. What the ERV "salesman/expert" does not want you to know (But then, he may not even know it himself):
For photos taken today, August 28, 2010 CLICK HERE The home is not rented, it is empty and for sale. Note the lockbox on the door handle. Apparently, the owner finally decided that the ERV was causing his moisture and mold problems. SO HE BLOCKED OFF THE AIR INTAKE with a nearly invisible material. More than likely, he now has elevated radon levels. This will be a tough property to sell or rent except at a distress price. This ERV installation represents radon and mold promises broken. Shame on the smooth talking ERV salesman who got the owner into this terrible mess.
Many months ago, when I was called to address a moisture and mold problem in this home, the owner assured me and insisted that his ERV would control moisture and prevent mold. "The ERV is not the cause of my mold problems," he said. After all, the salesman had told him that it would prevent mold and reduce radon. The owner would not listen to me, and he had mold professionals clean up and chemically treat the home at considerable cost. They were experts at tearing out drywall, washing studs with bleach, replacing drywall and spraying chemicals. No changes were made on the ERV installation. The mold returned, as chemicals are not a permanent solution. Building scientists know that the permanent solution is to keep the home so DRY that mold and bacteria cannot survive. Experience has shown that ERVs are often incapable of keeping homes in hot, humid climates dry enough to prevent mold. And they cannot pressurize a home to reduce radon, eliminate moldy odors or to prevent mold growth in exterior wall cavities.
Photo Gallery
Photos of mold-damaged, stinky clothes, shoes, etc. in this condo about five months after ERV installation
Condo Mold Nightmare (stinky, moldy clothes) not long after an ERV installation to reduce radon (in a hot, humid climate, SW Florida)
The Culprit: Energy Recovery Ventilator
Why is the Energy Recovery Ventilator a poor choice for radon mitigation in a hot, humid climate? What the ERV salesman does not want you to know and will not tell you if you are in a hot, humid climate (like Florida):
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By their design, ERVs cannot pressurize a building in which they are installed unless they are run out of balance which defeats their energy-saving purpose.
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All radon mitigators know that pressurization is an excellent way to reduce radon levels. ERVs cannot do it. Unless they are intentionally run out of balance...so they have to blow much more air and water vapor to compensate
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ERVs blow the same amount of air into a building that they blow out = no pressurization.
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ERVs depend upon low indoor relative humidity in the air blown out (exhaust) to dry the air coming in.
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RESULT? when your indoor relative humidity is high, (mold prone) an ERV will not not be able to dry the incoming air effectively.
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So when you need to keep your home as dry as possible to prevent mold, the ERV does not help, but instead, it makes things worse
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ERVs generally over ventilate
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In most cases, ERVs cannot be efficiently tuned to deliver the correct amount of air to produce precisely correct radon levels.
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Because of this, an ERV may deliver two to six times too much air (and water vapor) to deliver the necessary radon reduction.
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Over ventilation delivers excess moisture to a home that will soak into the home and its furnishing as long as the ERV is running. Moisture = Mold. The more moisture, the more mold.
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There are several other highly technical reasons that ERVs are a poor choice for radon mitigation in hot, humid climates, but they are beyond the scope of this discussion. Information available upon request from scientist@condomold.info
SouthWest Florida, a hot, humid climate:
This upside down Energy Recovery Ventilator has been spotlessly cleaned of mold by its owner. The home had experienced major mold problems not long after the ERV was installed. The tenants had been ready to move out as mold covered their clothes, shoes, handbags and furniture. Operation of this ERV to reduce radon was the cause of moisture saturation of the condo and its contents despite claims by the radon mitigator that it would prevent moisture and mold problems. The home has not been dried out, and it will not take much additional moisture from ERV operation before the mold will again reappear. Because this home is mitigated using an ERV, it will likely also need a full time, heavy duty dehumidifier too.
ERVs work extremely well in northern states during cold outdoor temperatures. Almost all ERV manufacturers are located in Canada, Minnesota and Wisconsin. And that is where most of them are installed successfully.
In hot, humid climates, the Radon Mitigators who install ERVs have turned to ERV technology because experience has revealed to them that most radon mitigation by mechanical ventilation increases indoor humidity and often causes mold problems. A single radon mitigator in Florida has conducted radon R&D to develop successful technology to prevent moisture and mold problems and at much lower cost than installation of ERVs, and without the need for a dehumidifier. That firm is the only one that will guarantee that reducing radon will not cause new mold problems.
Note the orange extension cord that was used to plug the ERV into a wall outlet. Unplugging the extension cord turned the system OFF and plugging it in turned it ON. There were no instructions as to how to operate the ERV or to clean it.
You can see that the owner had spent a great deal of time spotlessly cleaning this fairly new unit. The two blue "hog's hair" or spun polyester filters can be seen at the far right in immediate contact with the rectangular energy exchange core. The triangular shaped area in the right upper corner collects dead moths, wasps, gnats, chameleons, flies, pollen, dust, dirt, etc. that are strained out just before they reach the square energy exchange core. Their dead bodies grow both bacteria and mold inside the ERV. In the lower right, you can see how the owner had installed a wooden "T-splint" in an effort to hold the filter in place and to prevent it from sagging down. Imagine having to clean the filters and the entire interior of this unit every 30 to 60 days. Sponges, soapy water, bleach, vacuum cleaner, crevice tool, drying towels. Result? These ERVs are rarely cleaned and as a result, they act as reservoirs for mold and bacteria colonies. It may be necessary for the homeowner to clean the filters and the entire interior of these ERVs every 60 days or so. The installers do not provide owners any instructions as to cleaning nor how often the units must be scrubbed clean and sanitized. Especially before the ERVs are completely installed and the installation fee is paid in full. The energy cores in these units are expensive. If they become contaminated from dirty air, bacteria and mold, they may need to be replaced at a cost of approximately $700.00 for the core alone, not including labor.
In this writer's opinion, if an ERV is not causing moisture and mold problems in a hot, humid climate, it is likely a very new installation and it has not yet brought in enough moisture to reach 70% moisture saturation by weight, or it is because the filters and core are clogged with dirt and little or no outdoor air is passing through the ERV and into the home.
This ERV installation to solve radon problems cost the condo owner over $6,000.00, six thousand dollars...before he had to pay mold remediators to clean up the mold. Now the owner needs a heavy duty dehumidifier too!
IMPORTANT: In a hot, humid climate, ERVs control moisture best when indoor relative humidity is low. ERVs control moisture worst when indoor relative humidity is high. In other words, in a hot, humid climate, ERVs work worst when they are needed most. In a cool, dry climate, they work very well almost all the time.
In a hot, humid climate, a much better choice exists.
You can see this 8 inch air intake has no filter, but if you look very closely, you will see that it has been totally blocked off with a clear plastic film. Likely, the owner finally decided that the ERV created his problems, closed the air intake off so that buyers would not see that the ERV had been disabled, and decided to sell this nightmare property.
Would a home inspector recognize that this ERV system had been disabled? The transparent film blocking off the intake is almost invisible. The owner may be desperate to sell. I believe it to be unlikely that any home inspector would recognize this serious concealment/clue.
VERY IMPORTANT AND VERY DANGEROUS: by blocking off this intake, whenever the ERV is operated, it will immediately and powerfully depressurize the home which will almost certainly cause radon levels to increase dramatically. Negative pressures suck radon and moisture out of the soil and out of the concrete and deliver them directly into the breathing zone. A most unfortunate, dangerous and unintended consequence of a simple act. If there were combustion appliances in the home, the resulting negative pressure could prevent the combustion products including carbon monoxide from rising up the exhaust stack, and the occupants could suffer illness or death from carbon monoxide poisoning. And even more remarkably, depressurization makes it even more likely that carbon monoxide will be generated by furnaces and water heaters. When personal injury attorneys finally learn about this they will pay close attention to the fee generating opportunities of such a simple, "innocent" act.
Note the key lockbox on the door to allow real estate professionals to show the property. It did not appear to have been disturbed in some time.
Maybe the million dollar insurance policy of the radon mitigator would pay for the homeowner's losses of rental income and property destruction and repair. But then again, maybe the insurance carrier denied coverage on this claim. It is unlikely that radon installation insurance will cover mold damage without a special mold rider. An inconvenient fact unlikely to be revealed by radon mitigators who boast of their million dollar insurance policies.
This knob-adjusted timer above the thermostat can be set to turn the ERV on and off from time to time in an effort to prevent mold and moisture problems. Instead of a timer, the ERV system should have a "Moisture Smart" controller that will know when the home becomes humid enough to grow mold and bacteria. Later and more expensive ERV controls are operated by pushbutton with multiple LED lights to indicate system operation. (see below)THEY ARE NO BETTER AT PREVENTING MOLD. ERVS GIVE A FALSE SENSE OF SECURITY.
A very attractive but "Moisture Dumb" ERV controller. Anyone in a hot,
humid climate who relies on this control may experience serious moisture
and mold problems six to 60 months after ERV installation. Usually, the
air conditioner is wrongfully blamed. RadonMan has developed an
effective "Moisture Smart" electronic controller retrofit for ERVs.
(Patent protection anticipated) Just because the mold did not show up
for some time after installation is no indication that the ERV was not
to blame.