On Wed, 2 Jun 2004 23:44:32 -0400, "CBhVAC:\)"
wrote:


"Chris J..." wrote in message
.. .

I'm thinking of adding evaporative cooling to my home, and none of my
local stores seem to know much about it regarding a non-standard
installation. So, I thought I'd ask here and see if anyone can spot
potential problems I've missed.


You asked..

And I am looking for criticisms, thanks. I'd rather find out here than
after I rip holes in walls whether this idea will work or not.

The reason I want to install an Evap cooler is to reduce my electric
bill because using my present AC can cost up to $200 a month. I'd
also like to be able to use the cooler on "fan only" as an alternative
to opening windows when the weather isn't too hot.


You got UpDucts for this too right??

No, I don't. I was planning on replacing some attic access hatches
with screens during the summer months (would that count as an actual
upduct?) . The attics are all ridge and soffit vented. I was thinking
that air flow through the attic would also help cool the house.

First, my install plan;
My home has a combined forced-air heater/AC (gas heater). I was
planning to use the existing ductwork for the evap cooler.

Nope..
Not a good idea. Do what you want, but the ductowrk for the AC isnt sized
correctly for an evap...period.

The ductwork in this house is almost all rectangular box, several of
them leading out from the junction on top of the heater/AC, and I've
seen that used for Evap. Of course, I have no idea if this is adequate
or not. If not, then my Evap cooler is a non-starter.

My heater/AC is in a utility room on the lowest floor of my home, and
ten feet from a wall that divides the living area from a dirt and rock
floored crawlspace (the air in there is cool and dry; no moisture in
the crawlspace at all.). The crawlspace has twelve-foot ceilings in
that area, and I plan on installing the evap cooler in the crawlspace.
(outside mounting is not an option; it would cause too long a run of
ductwork to get to an outside wall. Roof mounting is also much too
far, and in any case forbidden by my homeowner's association.

Then you need to give it up, and purchase a higher SEER AC unit..

That's an option... I'll have to phone Trane and see if they have a
SEER rating for my present system (XL 80, about ten years old) as I
can't find one anywhere on or in it, nor on the web (everything on the
web I've found is for newer XL 80's). (this unit was present when I
bought the house, so I wasn't involved with the installation). If I
can get significantly higher SEER, I'll do it if it isn't too
expensive.

Basically, I plan on running the cooler air into the main forced-air
junction box that's on top of my heater/ac. An alternate plan would be
to run the cooler output air into an AC return duct that passes right
over where I want to put the cooler. That would be far easier, but
it's only a 14" round duct and it does not look large enough. Aside
from easy installation, that configuration would also run the cooler
output air through my air filters, which I would like. In either case,
I plan on installing some sort of flapper valve that will close
automatically when the cooler is not in use (so when I'm using my AC
or heater I won't be losing air back through the evap cooler).

Read what I said about AC ductwork not being large enough.

If that's the case (not doubting you, but my ductwork capacity looks
larger than in similar houses I've seen) then that sinks my idea.
Thanks for tipping me off to this potential problem.

My main concern is that the utility room is vented, via a duct, into
the crawlspace, for ventilation of the water heater and heater/AC. My
concern is that the cooler will create low relative air pressure is
the crawlspace, and thus a reverse flow in the water heater "chimney",
which is a four inch vertical pipe over three stories tall.

If this is the case, could I just attach an airtight duct to the duct
between the crawlspace and the utility room, and extend it thro9ugh
the crawlspace to outside?

No. Thats called in the trade, just damn stupid.

It is also very illegal.

I didn't mean attach to the water heater "chimney", but rather to the
duct that vents the utility room into the crawlspace, basically just
extending it a little. Or is that what you thought I meant, and it's a
bad idea (and illegal)?

I'll be going to city hall to see about permit and code requirements
in a few days, provided this plan still looks feasible. There are no
city or state codes here, just national ones.

And your idea violates the International Mechanical Code...the standard
code.

Which part? Putting an Evap in a crawlspace, or the ductwork issues,
or both?

Also, how do I figure out what size evap cooler to get?

The evap cooler company can tell you...or, you can just go to Home Depot and
buy the biggest one you can find.....LOL

About the only place in town that sells them, other than installation
companies, is the home depot, and they were the ones who wanted to
base it solely on square footage. (I live in a fairly small town).

My present AC unit (Trane XL-80) is undersized for the square footage
of the house, but due to the house having good insulation and being
built into the side of a mountain it works just fine winter and
summer.

Then its not undersized is it?

I've been told it is, but I disagree as it works fine, or seems to. It
does not run anywhere near continuously (more like 10-15 minutes an
hour in severe heat or cold) unless I've just turned it on and it has
to make a major change in interior temperature.

There are NO Rules of Thumb for SF/Tonnage.
If your unit is working, (altho, I have doubts about how well, since I never
broke $200 in good old Palm Springs, nor did my father in law in Phoneix and
he had over 3500SF of home....) then its not undersized.

I managed to break $200 in Phoenix in a small apartment on more than
one occasion, but I suspect that was a cheap AC unit.

One problem with this house is the design; it's sort of staggered up a
mountainside, so it has a disproportionatly large surface area. It
also has a large cubic area due to having twenty foot ceilings in some
areas. It also has a heck of a lot of windows and walls with full
western exposure.

$200 was for a month with record heat. $70 to $110 is more common (but
that's just the increase caused by the AC, not the total electric
bill).

Thanks for your comments and help.