Shopping for a new gas, forced-air, downflow furnace.
Weighing whether a high efficiency furnace is worth the upfront investment
(taking into account gas company rebate, tax credit). The other options
are stay with a simple 80%, get a 2-stage, or get a variable.
But now a new wrinkle.
The guy selling Lennox said he would strongly discourage the high
efficiency furnace because this installation is in a closet and the new PVC
they would run through the roof would have to pass through 3 or 4 feet of
unheated attic space leading to condensation and potential freezing. The
guy pushing Carrier never mentioned this (he did say something about a
single coaxial pipe taking out exhaust and bringing in combustion air).
So what do the pros say? Is Lennox-guy right? Going through a short
stretch of unheated crawl-space / attic a bad thing?
A woman across the street with the same kind of house has an HE of some
sort since I can see the PVC on the roof. I suppose I could ask her if
she's had any issues with it.
Energy cost will rise down the road, I don't
think it is getting any cheaper. Here in
Canada, they can't sell/install none other than >90%
HE furnaces. Venting does not have to go up to roof.
You can vent it side ways to out side. But you'll need condensate
If I were you, by all means I'd choose HE furnace and would use rebate
money towards beefing up the insulation for the house; attic, walls.
windows. weather stripping, caulking, etc.
Here in Calgary, UofC graduate students are in the process of plotting
IR image from every single house in the city to see how well the house
is insulated. Google map made it possible for them to develop a program
for any one to use. Just type in your civic address then it'll show
how good your house is air tight. They finished two quadrants of city,
NW, SW. I am in SE, can't wait until I can check on my house.
Unfortunately the furnace/water heater closet is not on an outside wall but
about 7' from one. Add a couple feet to get from the back wall to where
the furnace outlet would likely be. The intervening room is a
laundry/utility room so ugly pipes crossing the space is not impossible but
it would be tricky to do this without excessive turns because of how
things are layed out. But what makes this a dead end concept is that this
is a one story ranch and there are eaves sticking out a couple feet. The
exhaust pipe coming out of the wall, even if done at about the same level
it comes out of the furnace plus the obligatory sloping, is going to have
all that moisture, condensation, and ice there under the eaves unless it
juts out beyond.
Best to go through the ceiling and roof and insulate the tubes as required.
I think one neighbor did that on his 2 story house from basement go
roof. It takes caare of fresh air intake, venting.Pipe straight iup open
ended/small one like umbrella handle ont eh side bending down
U shaped. Our Carrieer Performance series 96%, 100K BTU reeplaced 8o%
Carrier 3 years ago in the summer time(off season) Installer just
installed did all the piping work to the side wall. Ran B vent liner
up the stack to take care of water heater vent. I did wiring, installed
wireless 2 stage thermostat, CO detector. After passing inspection, I
paid him 4 Grand. Came with 10 year P&L, HE is life time warranty.
Here in Canada we can no longer sell or install lower than 92% ones.
Repairing old one is allowed. Local university is IR scanning every
house in the city to see how air tight the house is using Google map.
When the project finishes we can go onto the 'net using the app. just
input your address and see what you need on your house to make an
I have a 2-stage 92% Trane condensing furnace. In my case the pipes goes
horizontal about 15 ft and then through the wall to the outside. If you
have to go through the roof then I would think that a condensing furnace
would be the answer to your problem. It's been about 5 yrs now and the only
problem I've has so far has been a flame sensor failure. The colder it is
out the warmer the house feels--Obviously because the furnace runs more
frequently but it also stays on the 1st stage most of the time. The initial
furnace that came with the house was a simple off-on,100K BTU. The current
furnace is a 60K BTU and does a better job of keeping the house warm and
temperature swings to a minimum. The combustion air now is supplied from
the outside vs inside thus reducing the heating bill since you don't have to
use air that has already been heated to room temperature. Also, drafts are
significantly reduced since you don't have to replace the inside air that
goes up the furnace.
You need to take care of drainage for the condensate from combustion. I
have a tee in my supply air pipe right before the furnace. It has a trap
and drains into the condensate pump (which handles the heating and a/c
condensate). Any condensate in the exhaust line drains through the furnace
into the pump.
Any condensation in the attic pipes should likely occur on the inside of the
pipes. If you have condensation in your attic, you have a bigger problem.
Furnace condensate drains into the condensate pump. From there it is pumped
into my washing machine drain line. A/C has a separate line that drains
directly from the furnace evaporator pan to the outside through a sloped
pipe via gravity. All works quite well.
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