I have just installed new High Efficiency furnace (Keeprite). In the
manual 2 pipes are depicted (Exhaust and intake) running outside of the
house. However, the installer has left the intake pipe inside of the
basement (the pipe is about 20 inches long above the furnace). He says
it's OK to have an intake pipe to suck the air from within the
basement. Is it?
Thanks a lot!
City Hall may be able to advise. The Ontario
housing code was changed about 25 years ago
to require outside air for furnace supply. This is
usually done by piercing a four-inch hole through
the foundation or wall, and fitting an insulated
trunk which hangs down to near floor level.
You hired a hack, the efficiency rating specified won`t be met with
indoor air since you are pulling in cold makup air. Indoor air
pollutants actualy shorten the coils life, your warranty may in fact be
void with indoor air. Demand he fix it and stop payment. If he screwed
that up who knows what else, he just wanted to save time from drilling a
hole. Make sure he has the proper install on the intake -exuast, read
On Fri, 3 Mar 2006 12:14:33 -0600, email@example.com (m Ransley)
Yes, he hired a hack and got exactly what he paid
for...........nothing more, nothing less. Thought it was such a great
deal and now found out it wasnt.
If he wants a second pipe outside he can open his wallet and pay for
Not really. Because if it sucks in air, that air has to come from
outside, and then cold air will be sucked into your house. If you
have an extremely tight house, you may even starve the furnace for air,
and that is a very bad thing. So insist on putting the intake outside
of the house.
Yea sure, he is trying to tell you he knows more than the guys who
designed the furnace. If you think this guy know more than the engineers
who designed the furnace, then go with his easy way out. If however you,
like me, believe the guys who spent all those years in college and spent
time testing the design might know more than this guy, I suggest you demand
that he do the job right.
This thread get me interested. My gas furnace only has one 3" PVC to
outside - I think that is the exaust pipe. I wonder if my furnace is
taking air from the basement? One of the kids stays in the basement most
of time - even sleeps in one of the rooms there. Is it safe there?
Teah a single exhaust pipe is safe to the occupants BUT
It makes the furnace use pre heated air for combustion, wasting energy.
sometimes that indoor air air is contaminated with household chemicals
that can cause heat exchangers to rot out...
get the installer to finish the job, he is lazy cold air is more dense
and burns better.
You may want to review where the furnace is exhausting. There are a
number of ill-knowledged installers who place the exhaust pipe in the
wrong location (not recommended to be by any windows, etc...).
replying to never heard, Jerry wrote:
3" pipe is ok but you need one for intake and one for an exhaust. My guess would
be if you don't have a fresh air intake pipe you would be using up oxygen in
On Wednesday, December 6, 2017 at 6:14:08 PM UTC-5, Jerry wrote:
Sigh. This is an old thread, it's all been discussed before. It's generally permissible to install a furnace using indoor air for combustion, no outside air intake. Install manuals typically show both that way and with an outside air intake.
Furnaces and boilers used inside air since they were invented. Using
and outside source for combustion air is just in the past couple of
decades. The only difference is efficiency. Anything going out the
stack has to be replaced by sucking cold outside air in through every
crack in the house.
erally permissible to install a furnace using indoor air for combustion, no
outside air intake. Install manuals typically show both that way and with
an outside air intake.
Depends too on where the furnace is. If it's in heated living space, it's
worse. If it's in an unheated garage or basement, then it may not make much
difference. For one thing, if you bring in 20f outside air, the furnace w
inds up heating it too, ie you get less heat output than if it used 50f bas
I don't think they preheat the combustion air . It goes straight to
the burner at whatever temp it is when it enters . And as far as that
50° basement air , you'd only be heating that if your cold air returns
were in that space .
enerally permissible to install a furnace using indoor air for combustion,
no outside air intake. Install manuals typically show both that way and wit
h an outside air intake.
t's worse. If it's in an unheated garage or basement, then it may not make
much difference. For one thing, if you bring in 20f outside air, the furna
ce winds up heating it too, ie you get less heat output than if it used 50f
The furnace doesn't have to preheat the combustion air. If you put 20F
air into it versus 50F air you'll get less heat out, because the incoming
air is colder and some of the combustion heat goes into raising it's
And as far as that
That you're not heating the basement air much via the furnace
was part of my point.
The leaking air coming into the basement from outside gets heated
from 20F to 50F partly by the earth surrounding the basement. But
some heat is coming from upstairs, etc, it gets complicated.
Installing the intake pipe so that it takes air from the inside of the
house is not unusual and outside venting is often listed as optional in
the installation instructions.
Of course, as has been stated, this means that the air intake within
the house will create a vacuum and suck cold air into the house,
reducing the efficiency of the furnace (though not a great deal).
If the basement where the intake pipe is located is essentially closed
off from the heated part of the house, then it is effectively the same
as being outside the house anyway.
On 3 Mar 2006 14:46:29 -0800, firstname.lastname@example.org wrote:
Wrong junior. That would mean that a 90% eff furnace is located in an
outside environment and that cant happen. Condensate water freezes in
that instance and the furnace would crack parts and or shut off.
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