Originally Posted By: kwilliams
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On a high effic. furnace, isn’t best to have the cold air intake
piped to the outside ? I see a lot with just a 90 elbow on
them.
On a high effic. furnace, isn’t best to have the cold air intake
piped to the outside ? I see a lot with just a 90 elbow on
them.
Originally Posted By: gbeaumont
This post was automatically imported from our archived forum.
Hi Kevin,
to the best of my knowledge they are REQUIRED to draw combustion air from the exterior, I know the last couple I have been around were plumbed that way. I would suggest looking for the manufacturers installation instructions for any that took combustion air from inside the dwelling.
Regards
Gerry
Originally Posted By: gbeaumont
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Hi to all,
when I'm wrong I'm wrong, I just looked at a couple of installation guides for HE furnaces and it appears that combustion air may be drawn from inside the structure if sufficient combustion/dillution air is present.
Regards
Gerry
Originally Posted By: kwilliams
This post was automatically imported from our archived forum.
Thanks, I thought I read somewhere that it is
more efficient if piped to the outside, or something like that.
post some links if you can
Originally Posted By: pbolliger
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| gbeaumont wrote: |
| Hi to all,
when I'm wrong I'm wrong, I just looked at a couple of installation guides for HE furnaces and it appears that combustion air may be drawn from inside the structure if sufficient combustion/dillution air is present. Regards Gerry |
Here is the problem with that to me .. Since many new homes are installing H.E. FAU's in closets do you think that is the case. I would argue that is not always the case. Why does the exhaust piping to the exterior seem to be acceptable with respect to installation when the combustion air intake installation seem to be a problem? Cost? Does the contractor or client want it that way?.. It is PVC! What is so darn expensive about that?? Labor? The unit is designed for exterior combustion air intake so why not install that way? I see no sense in doing this this way. It's like putting low grade rethread tires on your Porche!!  
Originally Posted By: dedwards
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I see quite a few that get the combustion air (intake flue) from the attic, not the general living areas. Most furnace closet doors are solid (hollowcore) therefore the unit would be starved for combustion air if it was being drawn from the living area. One way to look at it is its one less hole in the roof or exterior wall.
Originally Posted By: phinsperger
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Kevin,
Some high eff. furnaces do allow the option of running a one pipe (exhaust to the outside and room air for intake combustion air). Providing there is sufficent air as commented in the above posts to do this and not stave the unit then there is technically nothing wrong with it.
However, the stated eff. rating will be a bit lower that is stated if it is not installed as a closed combustion furnace. It makes sense to install it as a two-pipe whenever possible.