HVAC - Sooted Furnace

[Anastasis 23720]

Primary furnace would not fire up after community propane ran dry. Propane guy that came into to restore flow thought my orifices were clogged, scraped at them a bit and then gave up.  I went in with some compressed air and a brush and was able to get it firing back up.  Three burners looked like they ran clean, one burner was messy yellow flame.

Said fuck it and called the home warranty folks (Old Republic). Anyways, they sent out a tech this morning (quick service).  He showed me a lot of soot in the burners, as well as a good cake of soot in the exhaust.  Said the furnace was sooted, heat exchanger probably fucked, and will have to replace the entire furnace or at least the heat exchanger.  Said it probably happened when we went low pressure, also said some low pressure cut off that was suppose to be on the furnace was not installed. Asked him about cleaning, said it might or might not work but if the exchanger was clogged better to just replace it.  Based on what I saw around the exhaust, would not be surprised if it is pretty clogged up. Said that he was going to try to convince OR to cover it, but didn't know how they would process it. He ballparked me $2500 if they don't cover it.

Checked the secondary furnace, and no soot.  I am fairly certain that the soot build up pre-dated the recent gas run out as I noticed some prior but didn't think it is big deal. The tech was convinced that the amount of soot could be explained by the one instance of low pressure.  I am concerned that that gives OR an out on the claim, but we will see. 

So to those knowledgeable about such things, does this all sound correct in terms of replacing a sooted furnace?  Is breaking it down for cleaning an option, or just bite the bullet?  Other thoughts?

 

Edited February 22, 2021 by Anastasis

[Anastasis 23720]

Picture of soot in exhaust.

 

[Anastasis 23720]

OR telling me that after talking to the tech, the unit should be covered by Carrier's warranty.  Tech tells me that he told them it wouldn't be covered by the warranty. LOL.  Fuck heads. 

Edited February 22, 2021 by Anastasis

[washparkhorn 9973]

I thought the fix for a sooted, but structurally intact, heat exchanger was a good cleaning - not a new furnace. 

There are many causes of soot in the heat exchanger, including incorrect installation:

https://inspectapedia.com/heat/Furnace_Heat_Exchanger_Leak_Test.php

Carbon monoxide is a big danger with damaged heat exchangers - so make sure your carbon monoxide monitors are working with both furnaces. 

Good luck. Be safe.