My LP fired furnace vent has black soot on the inside of the pipe. Tech that came out immediately told me it was clogged and needed to be replaced and recommended a new furnace since mine was 11yrs old. First, can a heat exchanger be unclogged and second is$2000 to install a new one reasonable? Have two more appts. to get estimates. Exchanger is still covered under Ruuds warranty so $2000 is all labor. Second furnace working fine but tech recommended adding piping to the outside to bring in outside air for combustion. Apparently the installers didn’t run it and it draws basement air for combustion. Tempted to just replace the unit, but the cost is 3-7x the cost of just replacing the exchanger. Any thoughts would be helpful.
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Stupid question: Do you have (and have you always had) a decent air filter installed on the unit, and is it set so that no air can bypass it?
Sounds liek you are a landlord?
Furnace tech is rippin' ya off, find somebody else or learn to DIY.
Raise the rent to cover getting ripped off, force a couple of the tenants to sleep in their car .... big article in local paper on rents here going sky high and forcing homeless count to double in the last year.
Fire The "Tech"
Plugged? I doubt it.
Some soot might be unavoidable .... but soot is caused by poor combustion - and LP burns pretty clean. Maybe the orifice needs cleaning / replacement ... and an air compressor can blow out anything. If it's really blocked, all that soot will wind up in your face. Clear the blockage ... as in, get that birds' nest out of the vent pipe, and replace the guard on the top!
Ditto the burner assembly .... find out what's causing the poor combustion. Even turning that little 'dial' that controls airflow into the burner will have a huge effect on your soot.
11 years is not 'old!'
You do need to tell us what sort of furnace this is -- whether a more or less standard open burner unit or a high-efficiency unit of some sort.
Second, where is the soot, and how much is there? A heat exchanger has two sides, one side that the flame is on and the other side the air is on. There should not be soot on the air side, but a modest amount on the flame side is to be expected. However, a lot of soot (on the flame side) would indicate the burner is misadjusted and not getting enough air.