"Chris J..." wrote in message
...
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.
NP...installed, and ripped out and RE installed more units than I care to
remember...I have a pic on the office wall on my last evap install...on a
rooftop in CA, and everytime someone asks me about one here, I tend to look
at it and go....No.....way.....
Altho..most people dont understand why I dont like working on the duct
design n this are for them...since they are about as easy as anything...
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.
It would, but an UpDuct is a barometric duct. You dont have to worry about
heat from the attic, putting a cover back in place, etc....you just put one
in each room that you want cooled, or two, depending on the size and area,
and the amount of airflow you have from your ducts from the cooler, and when
the cooler comes on, badda bing, you have no windows to open, no doors to
worry with, and a cooler home.
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.
And the #1 design of western AC ducts...(Drumroll please.........) is what
you describe. Now, granted, Ihave said it before, and will say it again, *I*
cant see it from here, but I can promise you one thing....AC ducting, is NOT
adequate 99% of the time for a swamp cooler.....particularly a MasterCool2
unit.
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.
10 year old XL80 would be a max if 10SEER, the lowest rating there is
currently. ARI has jumped the min standard from 10, to 13 starting Jan 1st,
06. In your area, a 14 SEER would actually be a big jump now, and in a year
and a half, it will be the equal to todays 12 SEER.
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.
Ok..heres something to think about...6 inch duct....100CFM...roughly.
Depending on the tonnage of your current AC, you prob have either 8 or 6
inch take offs going to each run to the room.
Unless you have about 20 of them, 6 inch would be too small to properly get
enough airflow to each room, and be able to benefit from the
cooler.,...unless you are installing a tiny unit....and even then, its a
possibility that they are too small for that.
Most installs even with the smallest MasterCool unit or similar, used a min
of 8 inch duct, and most were 10, some even as large as 12...evaps need, and
demand airflow. in, and OUT of the home.
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)?
No..I know what you mean, and what you propose would create a negative
pressure zone, OR, the possibility of it. You cant do that. Your water
heater is going to fire up at some point when the coolers running, and all
that exhaust, will be pulled into the home.....granted, it SHOULD be heading
right out the open spaces to the outside...but its still not a good idea,
ever, to introduce exhaust gassses to the living enviroment...its also very
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?
The crawlspace idea, while novel, might run into a couple of issues....its
going to depend there on your inspections department. The
ductwork...Umm...doubt anyone there in the department has a clue about
that....its the gas water heater issues that I can see that kill the idea
from the word go.
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).
Let me explain one thing to you...HD employees are drones....total,
complete, idiots for the most part.
Go to the website for the brand of unit you are looking at, Adobe and other
brands all have a sizing chart that is fairly simple to understand.
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.
The ONLY way to know, is to have a manual J load calc done....to insure its
proper. Too large of a unit will short cycle, and cost you more to run......
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.
Or sized wrong..
See it all the time.
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.
No problem, but keep in mind, that you have other alternatives still yet to
consider.
Just curious...how much attic space do you have?