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View Full Version : Munters DryCool vs. Ultra Aire xt150?



Tony Corazza
04-25-2011, 03:09 PM
I need advice on which high efficiency dehumidifier to go with in the basement. It is a relatively small house 11,000 sq. ft. one level with 3/4 basement and crawlspace. It was designed as a passive solar double envelope home here in SW Virginia but they included cool tubes to vent the basement which unfortunately brought in moisture and did not cool in the hot summertime. I shortened the cool tubes so I now have two ten foot long 6 inch tubes that go from the basement out and up to air at groundlevel. I am torn between the Munters which works with a dessicant wheel and would not introduce fresh air in to the basement but is designed so that the REACT ducts are only supposed to be reduced to 8inch round duct runs. The company says this may just make it run up to two degrees hotter due to loss of cfm's. I was going with the more expensive Munters because it is advertised to not add much heat to the space if any. The most humid time is also the hottest so the basement could go from 80 to 90 degrees with a regular system (I was told) and the heat would rise through the wooden floors into the house.
We do not have any forced air ducts or AC. We heat with wood in the winter (humidity is not a problem from November to March). The UltraAire xt 150 or 155 has slightly higher efficiency rating and is designed to allow you to add fresh air from outside by way of a 6inch duct (so I would only need to use one of them) and has a motorized damper so you can manually adjust the amount of fresh air. It would be cool if the damper could be controlled by a humidistat to only allow air in up to a certain humidity level and then close more so wet air isn't coming in reducing efficiency. Does anyone know if this can be done?
The Munters has optional 13 MERV and the Ultra Aire has 14 MERV standard. With the extras the Munters is coming close to $ and the Ultra Aire closer to $. I am interested in the highest efficiency since we are supplyiing electricity from a photovoltaic system, but I also am not keen on raising the temperature more than necessary in the basement. Before running two small dehumidifiers (high electr. cost) the humidity can top out near 90% in the summer even though I have put in a sealed vapor barrier over the earthen crawlspace and concrete floor with plastic vapor barrier beneath where there was not before. It is time to make the decision because the dehumidifying season is here and I just finished digging down to the cool tubes and putting in the short runs to the surface. Can anyone give me advice on which system to buy? I read an earlier thread on this forum but it was for an island location. I am in the mountains of SW Virginia. I appreciate anyone willing to write on this topic with knowledge of these systems and how they might work in my application.

teddy bear
04-25-2011, 07:54 PM
I assume that you have a 1,100 sqft basement not 11,000 sqft?
I suggest a Ultra-Aire 90 H instead of the the Ultra-Aire 150H. I would expect a 3^F rise in a basement space with Ultra-Aire dehumidfiers. A 3^F rise in basement temperature will help decrease the %RH by about 7%RH. Using an oversized dehumidifier increase the operating cost while decreasing the efficiency. the U-As are simplier devices for long term maintaince.
If you go with the other dehu, let us know how it works.
We have tested the unit that mention. It worked but had a couple draw backs. It will take me couple days the dig up the details of results of the test.
Regards TB

Tony Corazza
04-26-2011, 10:26 AM
Thanks Teddy Bear,
Yes, its 1,100. I was trying to look for the highest efficiency units and did have a couple of guys from Basement Specialists (I think) come and look at the space. They said that unit (comparable to both the Ultra Aire 150 and the Munters DryCool HD) was just right for the amount of dehumidifying being that it is alot of humidity down there and infiltrating up (put an earth colored rust on the walls, when we moved in needed to paint all walls and ceilings. Did you mean you have stats on the Munters and/or 150? I have the Munters guy waiting (he offered to bring the unit with him on his trip to visit his daughter at college- to save me some shipping money). I was really worried about restricting the REACT inlet and outlet down to the 6inch 10-15 ft runs (two 90 degree elbows). But if the UltrAire will really only raise it a few degrees then I think I'll go with that one and introduce the amount of fresh air you suggested. I will also look into the smaller UltraAire now; I started from only looking at Energy Star models. I appreciate you checking on me for any further info or more advice since I need to get back with Munters soon so he can plan his trip or not. Thanks again, Tony

teddy bear
04-26-2011, 05:19 PM
Munters is a Swedish co that makes large commercial units. We tested the their unit. Worked ok. It is complicated. It have a extra fan motor and a rotating dehu wheel that also has a motor. The efficiency of the wheel depends on the moisture level in the process air. Cool damp air removes less moisture that warm dry air.
Expensive, complicated, oversized, and expensive, but maybe ok?
Regards TB