Thanks for the comments. The Advanced Energy site is a good one, lots
of good info there.
Incidentally, the RH in my home seems much more stable since I put the
dehumidifiers in the crawl space. Seems more comfortable as well.
The goethermal heatpump was installed before I bought the house, so I
can't say for sure how much energy savings I'm getting. I believe the
house previously had a regular heatpump. The previous owners didn't
run the air conditioning as much as I do, though (I work at my home
office, so I have to keep it running through the day). But I can
compare to what I had at my old house, which was about 1/2 the size of
this house, and it had a gas furnace and a separate central air
conditioning unit. Other than the periods when the moisture problems
were occuring in the crawlspace, my heating/cooling bills have not been
too much higher, maybe in the range of 10-20%.
If you do get a geothermal heatpump, make sure the installer properly
fill the trenches they dig for the exchange loop. The poeple who
installed the system at my house just pushed dirt over the trench and
smoothed it out, without compacting dirt down into the trench. The
ground keeps sinking, and there are hollow cavities everywhere. I'm
having to dig up parts of my yard, and have fill dirt brought in to fix
it. It's not an issue for the heatpump itself, but it sure is a pain
to keep tearing up the yard.
Jay Stootzmann wrote:
Since you said you're a resident of Knoxville TN then the results from
Advanced Energy
http://www.advancedenergy.org/buildi.../crawl_spaces/
should be the bible you work from.
I would expect that as you correct the outside drainage problems you found
that should take a lot of load off your dehumidifiers. and as they work
less the temps should come down.
As Advance Energy showed in their field studies I think the only alternative
to a active dehumidifier is to have a supply vent from your HVAC system into
the crawl space [but NO return vent]
With the dehumidifier running in a closed space we should expect the temp to
be elevated above what it would have been with out the dehumidifier. I'm
not sure why I would be concerned about that.
In my own case, while I may be be burning more electricity running the
dehumidifier I'm saving energy because my home is quite a bit tighter and I
put R-35 in the floors [net AC and heating costs are lower]. My whole house
air quality is significantly better. The important thing is that the crawl
space is DRY with a RH 50% [50% is cutoff for dust mites and 70% is cutoff
for mold growth].
Check some links about Mold at:
http://healthandenergy.com/mold_prevention.htm
http://www.cpsc.gov/cpscpub/pubs/425.html
http://www.buildingscience.com/resources/homeowner.htm
As far as mold on your floor joists -- it really depends on how bad it is
and more importantly if it is a structural issue. Most of the research I've
done on the subject said that in most cases it's better to just leave it
alone if it's not causing a structural problem. Read the building science
references and see what you think.
If the insulation was "wrapped" around the outside of your ducts you may be
able to cut it off yourself and apply new insulation on your duct work
yourself. I insulated my duct work myself after first sealing all joints --
that really made a big difference in my home air quality and comfort.
I'm thinking of upgrading to a geothermal system -- what energy useage
improvements did you experience? What system did you have before?
"dblho39" wrote in message
oups.com...
The original symptoms last summer was that all of the a/c ductwork in
my crawlspace were sweating like nuts. The insulation on all the ducts
was soaked and dripping water. The floor insulation was also soaked
and hanging down everywhere. I also was having mold start to grow on
the joists.
I already had a vapor barrier, over the usual 80-90% of the ground.
I've owned the house for about 1.5 years. About a year before I bought
it, it had a geothermal heat pump installed.
Had a french drain and sump pump installed, as well as 2 large
ventilation fans in the crawlspace vents, at the end of last summer. I
also had new vapor barrier put down. That seemed to help at the time.
But this summer, I found that the ducts were starting to sweat again.
So I sealed up all the vents, disabled the vent fans, and put in the
dehumidifiers. Now, everything is dry. But the temperature is up
under there, and of course, I'm jacking up my electric bill. In the
short term, this is probably okay, though.
Since then, I had a patio installed, and the guys installing it
discovered that the underground drain pipe for all the downspouts on
one side of the house had been screwed up when the geothermal heatpump
was installed. The pipe was completely blocked. I think this is
probably where the moisture was coming from.
I probably also need to have the insulation on all the ductwork
replaced, though I have yet to find somebody to do this. The company
that installed the geothermal heatpump has just been jerking me around
on this for a year. I am really ****ed at them. It seems like no
other companies are willing to work on it because it is a geothermal
heatpump.
BTW, what are peoples opinions about having the existing mold cleaned
off the floor joists once the moisture problems are fixed for good?
The company that installed the french drain, sump pump, and vent fans
also sprayed some sort of anti-mold stuff under there. We've never
noticed any mold problems in the house itself (and my family would
notice this, we all have bad allergies).