05-26-2019, 01:40 PM
(05-25-2019, 08:06 AM)Dr Stan Wrote: .... but the sticker shock came when I purchased the double wall stainless steel exhaust vent. Youzer!
I hear that! After having to replace the stack vent on my 'new' furnace only two years after it was installed, and again a couple of years later I had had enough and started looking for stainless steel vent pipe. The only place I could find it was McMaster and even then they didn't have any elbows or Y-fittings in stainless.
After much
and 
I decided to go after the source of the problem. I invested in a combustion gas analyzer to check the furnace myself instead of paying the dimwits that installed it to come back out and check it. I found that the furnace was under fired and the stack temperature was too low, which explained the condensation buildup in the vent stack and causing it to rust out after two heating seasons. After clocking the gas meter and finding I was short on BTU's I ordered new gas nozzles one size up from the factory installed nozzles.After cleaning the burners and replacing the nozzles I clocked the meter again and was getting the full BTU's the furnace was supposed to be getting. Adjusted the manifold pressure for best combustion results and was getting a higher stack temperature in the normal range to keep the moisture in the flue gas hot enough to go up and out the chimney instead of condensing on the inner walls of the vent pipe.
I figure that it would have cost just as much to have the HVAC knuckleheads (the one's that put a 12 cent Lowes light switch on the furnace) come out again to do the work (that they SHOULD have done after installing the furnace) as I paid for the analyzer. So essentially I got my furnace fixed and got a free tool out of the deal for the same money.
Oh, and the furnace's efficiency (80%) is now up to where it should have been all along, so my gas bill has dropped quite a bit too.
Willie