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07-20-2015, 06:19 AM #1
New furnace install and intake air depressurization concern-
I wanted to know others thoughts on this furnace intake/exhaust pvc installation.
It is located next to a gas hot water tank in a basement area side room with two louvered doors. I have never seen anyone enter the chimney with a corrugated sleeve for hot water exhaust AND a pvc exhaust and go straight up to the roof (see photos 2 and 3). The other concern is photo 4 where the intake is just stopped on the other side of the furnace and not to outside air (see elbow in photo 4).
While I know this intake might be allowable as long as there is combustion requirements met for the other gas appliance, doesn't this just cause negative pressure and negate the efficiency of a high efficiency furnace by sucking hot/cold air into the home through depressurization?
Does this even remotely seem right to anyone besides the factors of inefficiency created by loss of conditioned air through exhaust? How does anyone really know if the depressurization caused will not draw flue gases out of the hot water tank? I am writing this up under inefficiency of interior intake and possible exhaust gas draw from hot water tank flue, but what else would anyone add?
I do not know how to figure out NFPA ANSI code combustible requirements etc, but those are my two concerns. Anyone have anything different?
Last edited by chris viscomi; 07-20-2015 at 10:32 AM.
09-19-2015, 12:00 PM #2
Re: New furnace install and intake air depressurization concern-
the furnace was not installed properly, and in order to satisfy combustion air and not draw exhaust from the hot water tank, the homeowner had to either:
1. Leave the basement door open always
2. Install a louver in the door in case it does get closed, or
3. install the supply air pvc pipe to the exterior
Obviously #3 not only is the proper and cheapest fix, it also improves the efficiency of the high efficiency furnace by lessening infiltration of combustion air.
THE BEST PART - they refused to allow it to be fixed because the current homeowner (Seller) would not allow them to pull the 20 year old ceiling tiles down on the finished side of basement to insert the pvc pipe. I told the Buyer to get a credit for the amount to fix it and then do it himself. I try to stay out of those contract "deals" as a rule, but this was just plain ridiculous.