Will one Aprilaire Dehumidifier cover my whole home? If humid air rises why install in downstairs? Wouldn't it be better to install upstairs.

Friday, February 18, 2011 by Aprilaire Team
Consumer question:

Will one Aprilaire Dehumidifier cover my whole home?  If humid air rises why install in downstairs? Wouldn't it be better to install upstairs.


Aprilaires' response:

Thank you for contacting us about your dehumidifier questions. Your logic does make sense in wanting to add a dehumidifier upstairs. However, humidity starts in areas that are darker and with less air movement which are usually basements. If the unit is put upstairs than we are simply containing the humidity level upstairs and not at the root source down stairs. If you can keep the humidity contained downstairs than the upstairs levels will not "see" this humidity.


Consumer follow up question:

Ah yes for Basements that makes sense. I live in Texas and have a two story home on slab. Upstairs is two bedrooms and a full bath. Down stairs is master bed, master bath, kitchen, living room, and dining room. Upstairs is about 800 sq ft and down stairs is about 2000 sq ft, probably about 300 sq ft of conditioned attic space. I have a sealed attic that has been foamed in. I need to install a dehumidifier before summertime or I will have moisture issues. If I install a dehumidifier downstairs it will have to be a stand alone unit, probably in living room or dining room. If I install ,either whole house system or stand alone, upstairs I can install in sealed attic and duct it to the two upstairs bedrooms. I cannot run any new duct work to the down stairs due to the layout of the two story home.

My only other option is a whole house system ducted into my central HVAC system. The HVAC is installed in the sealed attic. The main return from downstairs and the two from upstairs, one in each bedroom, all connected from duct work to into a plenum on the air handler. The outlet plenum is connected to the opposite side of the air handler and runs duct work all back through the house. If I connect the inlet from the whole house system into the return and the outlet into the main side how does the system no just cycle air around the shortest path through the air handler when it is not on? Path of least resistance! Also when the air handler is on wouldn't the pressure from the outlet side of the HVAC try to cycle air backwards in the dehumidifier?

That is the reason for the moist air rising question. any suggestions would be grateful.

Aprilaires' follow up response:

In your situation, you only option will be to install a dehumidifier to the central HVAC system. By doing this, you will dehumidify any humid air that raises from the basement area. This will still dehumidify the basement area too. The way this will be done will be a result of how the upper level are being dehumidified. By lowering the humidity levels in the upper levels this will allow the basement humidity to raise quicker because humidity is displaced to areas that are less humid. In this case, the dehumidified upper levels.

With the dehumidifier ducted to the HVAC system and tied into the fan, the issue of "path of least resistance" is not a factor. Reason being is because the force of the air will push the air around the home at a certain CFM. Some area's may receive air that is dryer than others but this air will even out over time.

Comments for Will one Aprilaire Dehumidifier cover my whole home? If humid air rises why install in downstairs? Wouldn't it be better to install upstairs.

Monday, October 28, 2013 by clarence christian:
Good day to you.Very informative site!Q:have a 600 AAbypass installed .,controlled by #60 h/stat h water is connected from a tankless heater.flow rate from humidifier not enough to trigger tankless heater-so water is cold.Any suggestion to get hot water.W/H Iis non recirc.Thanks
Wednesday, November 27, 2013 by Brett:
Thank you for contacting us with regards to your Aprilaire Model 600 Humidifier. As tankless water heaters usually require a demand that’s much higher than what the humidifier uses, it won’t provide the humidifier with hot water. Another option would be to invest in a low-volume water heater that has a tank. You may find relatively inexpensive 2.5-5 gallon units that will operate on gas or electricity. This should provide more than enough capacity for the humidifier.
We appreciate the opportunity to be of assistance.

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