Re: Fresh Air and Re-entry Air

[Guest guest]

Actually Ian, this is finished! It needs some cement patch and paint

outside to look okay but the installers are done. I looked at job

before paying but I did not see OTHER pvc pipe UNDER the 'overhang'.

I just saw the one.

The old furnace I had, had an all metal exhaust duct that went

slightly uphill to the bottom of a small chimney built for it, that

ran right along the side of house fireplace chimney, right through

all floors and out the roof, but they said with the high efficiency

furnace they were putting in, they didn't need to use metal as it

wouldn't get real hot and they would put it out the side of

basement. I don't remember explanation of why because it was quoted

to me over a year ago. Perhaps the reason is, it is convenient. I

put my level up to it yesterday and it is *very slightly uphill. I

doubt it is 4 inches. Old one you could see it went up, but this one

looks level so I had to get level out to see and bubble went over

just a bit from center.

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http://i145.photobucket.com/albums/r216/barb1283/FurnaceExhaust03.jpg

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http://i145.photobucket.com/albums/r216/barb1283/FurnaceExhaust02.jpg

[Guest guest]

I saw this done (but through the roof, not the foundation) for the

combustion air and exhaust for an extremely high efficiency furnace

in a house we were looking at to buy here in Sacramento back 12 years

ago. That particular type of gas furnace has a fan which drives

combustion air into the combustion chamber, and is designed so the

exhaust is low enough temperature to exit through PVC. The fan is

required because there isn't enough heat energy in the exhaust to

take it up a chimney under its own power.

The furnace design uses a rather low temperature rise between return

and supply air. I speculate it wasn't sufficient last week when the

temperature here actually got below freezing overnight. But it's

very energy efficient for its intended use.

Note: that is combustion supply air, *not* air to be introduced into

the house.

Agreed that the installation does not look finished.

Steve

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> > > > In Australia the code requires 6 metres segregation between

OA

> intake

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> > > > discharge.

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> > > > If you are supplying scavenged air from the exhaust - this is

no

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