Thermastor

[amyc]

I live in a shady spot in Georgia, and my HVAC system can't provide adequate dehumidifcation especially in the spring and fall when we have no need for heating or cooling. When my son developed allergies and I realized I needed to get the humidity down to below 50%, I spent a small fortune on the Thermastor Ultra-Aire (I did my homework). It has been on full-blast for two weeks but we aren't getting any dehumidification (it stays above 60%, same as during a normal winter before the unit was put in). Before they installed this thing the HVAC company guaranteed humidity below 50% (not in writing of course). But now, every time I call them I get a different guy who gives a different reason why I should not expect good dehumidification. Apparently I should not expect to dehumidify my home if I open the door a couple of times a day to come and go, run the heat when it's cold out, or do other things that normal people do. Is this right? I feel really ripped off because this thing cost thousands and apparently doesn't do squat. Any advice? My house is about 1800 square feet on waterproofed crawl.
Thanks!

[cxagent]

Something is definately wrong. It sounds like the UltraAire is not dehumidifying at all. Maybe the fan is running but not the compressor. Is there anyway you can post the temperature of the air leaving the UltraAire? That would tell a lot about how it is running.

The second option is to call Thermastor and see if they have a contractor in your area they would recommend to check it. You can get their phone number form their web site at http://www.thermastor.com.

[amyc]

Thanks. This company was recommended by Thermastor and they have a great reputation in my area, which makes this all the more strange. I will see about measuring the temperature of the air going out.

[teddy bear]

Appreciate your bussiness. Call 800 533 7533 ext 7803 to give me the details and contractors name. Thanks TB

[dash]

Originally posted by amyc
Thanks. This company was recommended by Thermastor and they have a great reputation in my area, which makes this all the more strange. I will see about measuring the temperature of the air going out.


Can you post digital pictures of the installation??

[amyc]

A rep from the HVAC company came today with his own hygrometer and measured 39% RH inside our house, so they say the problem is with our hygrometer, not the dehumidifier. We have a laboratory-grade hygrometer from Fisher Scientific (about $70) and so we feel pretty good about its accuracy. After the rep left, we ran out and bought two more hygrometers from our local hardware store. They are the cheapo kind but they more or less agree with the Fisher. Right now, the three hygrometers say 61%, 62%, and 63% RH inside the house next to where the Thermastor controller is. The Fisher is the lowest of the three readings.

We could not figure out how to measure the temperature of the air coming out of the Thermastor without taking it apart. I'm not sure I want to monkey with it because I have no clue what I'm doing. I'm happy to send photos but I don't want to post them on the web. Ya never know when my HVAC guys might log on and see their own work.

Basically I was just looking for validation of my expectations for this unit. I was frustrated that after installation they told me I should not have expected so much. If anyone has recommendations for accurately measuring RH let me know and I can go from there. Thanks.

[cxagent]

First and foremost - talk to teddy bear. He has a way of making things work ;-)

You should be able to measure the discharge temperature without taking anything apart. If your unit discharges into the A/C ducts then turn the A/C off and the UltraAire on for 20 - 30 minutes and measure the temperature at the closest supply register. It will not be a perfect measurement, but it will give some idea of what is happening.

Measuring relative humidity is not as accurate as some people think If two readings are within 5%, that is pretty good agreement. It sounds like the three readings from your hygrometers show very good agreement. I suspect the contractor didn't wait long enough for his hygrometer to get a good reading.

I wouldn't be concerned about the HVAC guys seeing the pictures on the web. They should be proud of their work and want everyone to see their work. If they don't take pride in their work, I don't think they should be doing HVAC work. Just my opinion though.

[teddy bear]

To calibrate your %RH meters, place a cup with 2 tablespoons of salt and 1 tablespoon of water into a plastic bag along with your meters. Seal the bag and wait an hour in 70-75^F air temperature. The correct %RH is 75%RH. If they are off, mark +-% on the meter and use the adjustment. Measure the temp-%RH is a couple parts of your home. Keep in mind the absolute humidity is generally uniform throughout open space. But the %RH is affected by temperature. The %RH is 2% higher or lower per degree of higher or lower temperature. The cooler parts of the home should be <55%RH while warmer parts 50%RH or lower. If higher RH, lower the setting of the control to operate the dehumidifier. Water from the condensate drain and warm air from the air output duct will be observed. Also registering your warranty gets you an accurate %RH meter N.C. to monitor the Ultra-Aire's operation. Sizing the Ultra-Aire to match your home's size. You can talk to me without me calling your contractor or posting on the web. This time of year in your climate, humidity control is not difficult because of the low outdoor dew points. If you have high humidity with a properly operating dehumidifier, additional investigation may be required to find the moisture source. You mentioned a water proofed crawlspace. Critical for humidity control in the home is to cover all the earth in the crawlspace. What about the vents in the crawlspace? Plastic on all earth and vents should be closed. Keep me posted, I'm very concerned about your high humidity. TB

[amyc]

TB-

Our humidity readings continued to climb slowly over the weekend and have been at above 65% for a couple of days. We are having a warm spell here and the humidity outside has been 80 - 90%.

I calibrated all of our hygrometers as you suggested, and after two hours in the bag with the salt mixture and at 73 degrees ambient temperature, the Fisher read exactly 75% while the two cheaper versions read 74% The Thermastor is still cranked up to the maximum setting and as far as we can tell, never shuts off.

I taped an indoor/outdoor thermometer to the supply register closest to the Thermastor and turned on the fan blower without the AC or heat. After 45 min, the thermometer read 78 degrees. Then I turned off the fan blower and after a half hour it read 80 degrees. The house remained constant at 73 degrees the whole time.

I have been using my HOBO data recorder from my lab at work to make a log of our humidity over the last several days. For about 8 hours yesterday the humidity was oscillating up and down by one degree with a very regular period of about 20 minutes. After that, the humidity started to climb abruptly. I don't know if those oscillations represent anything do to with the Thermastor but I found it remarkable.

When our crawl was waterproofed by B-dry last year they did put down a vapor barrier but it's not complete and our crawl vents are open. We are going to try to address this problem as soon as possible.

One more question: when you say "lower the setting" on the dehumidifier, you mean turn it up (clockwise), right? We have the thing turned all the way to the right as far as it will go, and if we turn it counter clockwise we can hear it shut off and back on as we turn it clockwise again. I just want to check, because if we are in fact turning it off, that might explain the problem!

Amy

[teddy bear]

Originally posted by amyc
TB-

Our humidity readings continued to climb slowly over the weekend and have been at above 65% for a couple of days. We are having a warm spell here and the humidity outside has been 80 - 90%.

I taped an indoor/outdoor thermometer to the supply register closest to the Thermastor and turned on the fan blower without the AC or heat. After 45 min, the thermometer read 78 degrees. Then I turned off the fan blower and after a half hour it read 80 degrees. The house remained constant at 73 degrees the whole time.

When our crawl was waterproofed by B-dry last year they did put down a vapor barrier but it's not complete and our crawl vents are open. We are going to try to address this problem as soon as possible.

One more question: when you say "lower the setting" on the dehumidifier, you mean turn it up (clockwise), right? We have the thing turned all the way to the right as far as it will go, and if we turn it counter clockwise we can hear it shut off and back on as we turn it clockwise again. I just want to check, because if we are in fact turning it off, that might explain the problem!


You are trying to maintain <50%RH inside your home which is <50^F dew point. Outdoor %RH always approachs 100%RH as the air cools overnight. Use the outdoor dew point as reference for humidity load. The outdoor dew point in Atlanta rose to +60^F this week. This means that air infiltrating your home humidifies your home above 50%RH. Uncovered earth in the crawlspace is also adding moisture to the air. The a/c is not operating or removing any moisture. Minimize the moisture entering your home covering all the earth and blocking the vents. If you operate your a/c fan continuously with normal duct leaks in an attic/crawl, expect +100 cfm increased of outside moist air which could exceed the dehumidifiers capacity. 100 cfm of outside +60^F DP air has 60 pints per day of excess moisture. 3-4 occupants also generate 24 pints/day. This is roughly the capacity of the small Ultra-Aire @73^F, 50%RH. Chech the dehumidification rate of the dehumidifier by measuring amount of water being removed per hour. At 73^F, 60%RH, 3-4 pints per hour or 7-10 gals/day. Also measuring discharge temperature of the dehumidifier discharge indicates the proper function. Expect a 15^F increase, so 73+15 = 88^F discharge at the unit. Your 80^F at the supply maybe ok.
With minimal air leaks and crawlspace prevention measures,
Rotation to the right decrease the %RH. Extreme right is constant "on". The dehumidifier clicking spot indicates the current %RH.
The last issue is duct connections to the home. Ideal is an independent return connect from the open part of the home to the return of the dehum. The supply from the dehu is connected to the supply of the a/c. This allows operation of the dehu indepent of the a/c AH. Other options may require constant a/c fan operation and should be discussed. Many of our contractor's techs have not had experience solving resolving these minor issues. I can help your contractor do a better job of servicing you. Hope this helps. Thanks for seeing this through. Call. TB

[teddy bear]

Factory service tech passing through Atlanta on Nov 11-12. 800 533 7533 ext 7803 TB

[ek]

Sounds like you have one hell of a return air leak or a supply duct has come loose causing the home to go very negative. We have installed many Thermastor's in the past and have never had a problem like you are describing. Especially on an 1800 Sqft home.

I Recommend taking a good look at your ductwork.