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PATHChat
| SUBJECT: |
RE: HRV's
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| FROM: |
TED HICKS, HOMEBASE SERVICES
thicks@nahbrc.org
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| DATE: |
3/19/1999 4:25:00 PM |
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For general information on dealing with interior
moisture, I'd suggest reading the article that appeared
in the Fall 1997 issue of HOMBASE News: "Dealing with
Interior Moisture"
http://www.nahbrc.org/homebase/newslttr/dealing.htm).
Since you are in Canada, I'd suggest contacting the
Canadian Housing and Mortgage Corporation
(www.cmhc.ca) for relevant publications and assistance.
In short, control moisture generation and remove
moisture as necessary, either by exhaust-only systems
(be aware this strategy may cause backdrafting),
balanced exhaust/intake systems, or HRV's. HRV's make
the incoming air warmer, and are the most energy
efficient option but also the most expensive initially.
HRV's can be controlled using humidistats but specific
control strategies should be discussed with
manufacturers to make sure condensation in the unit is
either avoided or that defrost cycles are used. Bear
in mind that with an outside temperature of -30 deg. F,
interior relative humidity would have to be 30% or less
(which is toward the low end of what might be seen in a
house) in order to prevent center-of-glass condensation
on air-filled, double-paned windows (edge-of-glass
would be colder yet, so condensation might still
occur). This just points out the difficulty of
preventing condensation in that environment. One part
of the solution, which is more economical for new
construction, is to install windows that provide better
insulation than double-pane units - triple glazing,
gas-fills, low-e coatings, etc. With the same outdoor
temperature, double-glazed, low-e, argon-filled windows
would not form condensation at center-of-glass until
the RH reached 50%. See the chart at:
http://www.efficientwindows.org./condensation.html or
in the book "Residential Windows":
http://www.efficientwindows.org./rwbook.html
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Partnership for Advancing
Technology in Housing (PATH)
451 7th Street, SW, Rm. 8134
Washington, DC 20410-0001
Telephone: 202 708-4277 Fax: 202 708-4250
E-mail: pathnet@pathnet.org |
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