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Managing humidity without ducts

I am playing around with possible scenarios for my HVAC setup in the house I am planning to build. One possibility I am really looking into is that of not using any ducts. I'm not certain why I am so opposed to having ducts, but I think it has to do with the idea of blowing dust around, having drafts, and general complications - even if the ducts are straightforward, it seems like equipment connected to ducts tends to be complicated.

What I am thinking about is radiant heating (and possibly cooling) combined with Lunos ventilation fans to handle our ventilating requirements. Neither of these systems requires forced air ductwork, which I very much like. (One side question I have, if anyone can provide some insight, is whether a Lunos fan running on the lowest setting would be louder, quieter or equivalent to a vent connected to one of the less noisy central HRV systems.)

My main concern with this configuration is controlling humidity. We are planning to install 5" wide solid wood flooring, and are concerned about cupping - they recommend staying within the 35-60% relative humidity range. We would be building in Kelowna, BC, which looks like Zone 6, and although I've always thought of it being dry there, the mean RH during part of the year does get up to 85%. With the above configuration we wouldn't have any real way to dehumidify incoming air during the part of the year when outdoor humidity is too high.

We are planning for 2 stories (about 1250 sq ft each) plus a basement, so it seems like it would be tricky to get everywhere with a stand-alone unit located somewhere in the house. Also, we have a fairly open main level, and I don't even know where we would put a stand-alone unit there. We are planning to have plaster walls, which may help to buffer the humidity levels by absorbing some moisture from the air and releasing it when it gets drier, but I'm not sure how much difference it will really make.

My question is this: Is there an effective way to manage humidity throughout the whole house without ducts? Should I just embrace ducting and get a whole house HRV with de-humidifier? How much dehumidification should I really need to keep the indoor humidity below 65%?

Thanks for the insight!

Asked by Stephen Youngquist
Posted Jun 30, 2014 10:47 AM ET


6 Answers

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Q. "Is there an effective way to manage humidity throughout the whole house without ducts?"

A. Yes. There are at least two options: ductless miniplit units (which provide cooling and dehumidification) and stand-alone dehumidifiers.

Every option involves compromises. If you don't want ducts, you have to be willing to look at the equipment. Of course, if you want, you could disguise your dehumidifer(s) by building a cabinet with louvered sides.

Answered by Martin Holladay
Posted Jun 30, 2014 11:10 AM ET
Edited Jun 30, 2014 11:11 AM ET.


I'm not convinced that you necessarily need dehumidifiers. I live in a home that is unconditioned during the summer, and I have never had any problems with my hardwood floors.

Hardwood floors were installed for two hundred years, at least, before air conditioners and dehumidifiers were invented.

Answered by Martin Holladay
Posted Jun 30, 2014 11:49 AM ET


The LUNOS e2 we distribute at www.foursevenfive.com is rated at 16.5db at low and 19.5db - 15cfm. This means that sound generated by the fan is so quiet at both settings that it is as quiet as rural nighttime (a href="http://trace.wisc.edu/docs/2004-About-dB/">dB eq. Wisc.edu. Meaning it is practically inaudible. On the low setting you will have to put your hand at the register to tell it is on (feel airflow).

Let us know if you have any other questions,

Answered by floris keverling buisman
Posted Jun 30, 2014 12:55 PM ET


Floris - do you happen to know how much noise one would hear at the vent opening when using a central HRV, in db?

Martin - I tend to agree with you on potentially not needing a dehumidifier, and there is a big part of me that wants to just try without and see how it goes. The scary thing about that is that it's a lot harder to add ducts back in after construction if it turns out I need one.

I'm not a fan of ductless minis, simply on aesthetic grounds. Do you think I would need a stand alone dehumidifier for each floor? I like your louvered cabinet suggestion - I'm thinking about possible planning a space where I could do that if necessary, and then just waiting to see what moisture is like after the first year before deciding to install the dehumidifiers or not.

Answered by Stephen Youngquist
Posted Jun 30, 2014 1:30 PM ET


That depends on the unit and length of duct run, if mufflers are installed etc. It should be in the same range ideally, but is not a given if duct are short, metal ducts are used, no mufflers are installed.
To many variable to give you a correct answer for your situation.


Answered by floris keverling buisman
Posted Jun 30, 2014 2:19 PM ET


Hi Floris - I have one more question about the Lunos fans. Is it not recommended to install a pair of fans in two rooms separated by a door (or two, and a hallway)? Perhaps with a bit of a gap under the doors?

Answered by Stephen Youngquist
Posted Aug 26, 2014 3:07 AM ET

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