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Fred Bloggs
Guest
Tue Jan 31, 2012 7:14 pm
On Jan 30, 3:05 pm, mike <spam...@gmail.com> wrote:
Quote:
On 1/30/2012 9:42 AM, Fred Bloggs wrote:
On Jan 29, 7:22 pm, "Dave M"<dgminala4...@mediacombb.net> wrote:
I have a Honeywell H600A humidistat (http://www.longviewweb.com/h600a.pdf)
that I'd like to use in the crawl space of my house. I know that this
controller is intended for indoor use, but I want to use it to control a
couple of powered foundation vents.
Is there any reason why it would be harmed or come to an early demise if I
mounted it in the crawl space (away from any possibility of rain contact, of
course)?
--
Dave M
A woman has the last word in any argument. Anything a man says after that is
the beginning of a new argument.
It is completely unsuitable for crawl space humidity control- wrong
component, wrong algorithm.
More words please.
What's the algorithm and how does it differ from one designed for use in
the crawl space?- Hide quoted text -
- Show quoted text -
The crawl space ventilation controllers inhibit activation when
outside humidity is higher than the crawl space humidity. The indoor
application doesn't have this because the air is juts being circulated
through a mechanical dehumidifier, but the crawl space humidifier is
drawing air in from the outside and therefore must measure its
humidity.
mike
Guest
Tue Jan 31, 2012 7:30 pm
On 1/31/2012 9:14 AM, Fred Bloggs wrote:
Quote:
On Jan 30, 3:05 pm, mike<spam...@gmail.com> wrote:
On 1/30/2012 9:42 AM, Fred Bloggs wrote:
On Jan 29, 7:22 pm, "Dave M"<dgminala4...@mediacombb.net> wrote:
I have a Honeywell H600A humidistat (http://www.longviewweb.com/h600a.pdf)
that I'd like to use in the crawl space of my house. I know that this
controller is intended for indoor use, but I want to use it to control a
couple of powered foundation vents.
Is there any reason why it would be harmed or come to an early demise if I
mounted it in the crawl space (away from any possibility of rain contact, of
course)?
--
Dave M
A woman has the last word in any argument. Anything a man says after that is
the beginning of a new argument.
It is completely unsuitable for crawl space humidity control- wrong
component, wrong algorithm.
More words please.
What's the algorithm and how does it differ from one designed for use in
the crawl space?- Hide quoted text -
- Show quoted text -
The crawl space ventilation controllers inhibit activation when
outside humidity is higher than the crawl space humidity. The indoor
application doesn't have this because the air is juts being circulated
through a mechanical dehumidifier, but the crawl space humidifier is
drawing air in from the outside and therefore must measure its
humidity.
Thanks.
Could you elaborate more on RH as it applies to structural damage?
Virtually everything I read talks about RH. Is that what we really care
about?
For example, shouldn't the crawl space humidistat inhibit activation
when the dew point outside exceeds the dew point in the crawl space?
My crawl space is 55F year round. Outside temperature varies between
20F and 100F. So the crawl space RH change due to ventilation should
track differences in dew point of the inside/outside air?????
Fred Bloggs
Guest
Tue Jan 31, 2012 9:20 pm
On Jan 31, 1:30 pm, mike <spam...@gmail.com> wrote:
Quote:
On 1/31/2012 9:14 AM, Fred Bloggs wrote:
On Jan 30, 3:05 pm, mike<spam...@gmail.com> wrote:
On 1/30/2012 9:42 AM, Fred Bloggs wrote:
On Jan 29, 7:22 pm, "Dave M"<dgminala4...@mediacombb.net> wrote:
I have a Honeywell H600A humidistat (http://www.longviewweb.com/h600a.pdf)
that I'd like to use in the crawl space of my house. I know that this
controller is intended for indoor use, but I want to use it to control a
couple of powered foundation vents.
Is there any reason why it would be harmed or come to an early demise if I
mounted it in the crawl space (away from any possibility of rain contact, of
course)?
--
Dave M
A woman has the last word in any argument. Anything a man says after that is
the beginning of a new argument.
It is completely unsuitable for crawl space humidity control- wrong
component, wrong algorithm.
More words please.
What's the algorithm and how does it differ from one designed for use in
the crawl space?- Hide quoted text -
- Show quoted text -
The crawl space ventilation controllers inhibit activation when
outside humidity is higher than the crawl space humidity. The indoor
application doesn't have this because the air is juts being circulated
through a mechanical dehumidifier, but the crawl space humidifier is
drawing air in from the outside and therefore must measure its
humidity.
Thanks.
Could you elaborate more on RH as it applies to structural damage?
Virtually everything I read talks about RH. Is that what we really care
about?
For example, shouldn't the crawl space humidistat inhibit activation
when the dew point outside exceeds the dew point in the crawl space?
My crawl space is 55F year round. Outside temperature varies between
20F and 100F. So the crawl space RH change due to ventilation should
track differences in dew point of the inside/outside air?????- Hide quoted text -
- Show quoted text -
I do not know that any of them do. You would be better off closing off
the vents during warm weather, and circulating conditioned air from
the interior of the house through the space. It does not require much,
the nominal design flow rate is 2 CFM per 100 sf of crawl space. This
assumes you have taken steps to seal the space. See
http://www.crawlspaces.org/
for some science.
Winston
Guest
Tue Jan 31, 2012 10:30 pm
Fred Bloggs wrote:
Quote:
On Jan 31, 10:46 am, Winston<Wins...@Bigbrother.net> wrote:
Dave M wrote:
(...)
Quote:
Perhaps a French drain would work. but installing powered vents would be
much less expensive and much easier to install. I already have the
humidistat, and the powered vents are relatively cheap and easy to install.
The majority of the work to be done will be to run power to the crawl space.
That will be fairly straightforward as well.
Thanks for all the comments.
We had a serious 'standing water' problem in our crawlspace
after every rain. After installation of the French Drain
and clearing a few obstructed foundation vents, the crawlspace
remains quite dry during all but the very worst downpours.
(Even during power failures.) :)
--Winston- Hide quoted text -
- Show quoted text -
French drain should be required by the local building code.
Yes. It *should*. :)
Code inspection is done on behalf of the seller in
my area, not the buyer. Our present house sure
showed that to be the case! None of the houses in
my area have peripheral drainage. Water in the
crawlspace and cracks due to erosion is a chronic
problem for many of my neighbors.
(...)
Quote:
Lastly, regardless of the drainage, a 6-mil vapor
barrier is used to cover the ground inside the crawl space, plastic is
staked in place, seams overlapped by minimum 6" and taped or glued ..
I sure hope not. :)
Before I started a recent repair of a heat duct in this
house, I spent two weeks excavating soil to form a path
from the crawlspace entrance to the area needing repair.
Removing the vapor barrier before excavation would have
been a show stopper. Replacing the barrier would have
been a non-starter.
(...)
Quote:
Crawl space ventilation does not work and is no longer recommended.
Do you mean ventilation by itself? I agree that without the peripheral
drain, ventilation (active or passive) would not keep the soil
in the crawlspace dry. It'd be like fanning a sponge whilst adding
water along one side. :)
--Winston
John Ferrell
Guest
Wed Feb 01, 2012 11:38 pm
I believe everything depends on local conditions. It comes down to the
fact that you need to do what you can to dry things up. If water is
coming in from outside then that is a good starting point. If gravity
drainage is available, by all means use it. There are situations where
a French drain can simply provide another way for water to come in.
Once you have eliminated the standing water run the powered vents full
time. If they ever catch up to the problem you can consider some kind
of controller to reduce the duty cycle of the fans. Here in North
Carolina there are houses with mildew problems that are unfit to live
in! Good luck!
On Mon, 30 Jan 2012 14:52:07 -0600, "Dave M"
<dgminala4444_at_mediacombb.net> wrote:
Quote:
NT wrote:
On Jan 30, 12:22 am, "Dave M" <dgminala4...@mediacombb.net> wrote:
I have a Honeywell H600A humidistat
(http://www.longviewweb.com/h600a.pdf) that I'd like to use in the
crawl space of my house. I know that this controller is intended for
indoor use, but I want to use it to control a couple of powered
foundation vents.
Is there any reason why it would be harmed or come to an early
demise if I mounted it in the crawl space (away from any possibility
of rain contact, of course)?
do you need a controlled fan instead of passive ventilation?
NT
Yes, I do need powered vents. I have seen mildew spots on large areas of
the underflooring. There's no standing water that I can see, but the ground
is wet. It has stayed wet almost constantly since early October (winter is
out wettest season).
John Ferrell W8CCW
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