Replacing heat exchanger on rooftop unit?

[onthefence777]

So I've done work on my house HVAC before. Replaced the a/c fan motor which actually turned out to be a sort of custom retro-fit job. Replaced the heater draft fan the next year. But last year the heat exchanger cracked a couple weeks into winter, couldn't afford to replace.

I thought the guy quoted me 750 for replacement, but that was a rooftop conversation, and I wonder if that could have possibly been just parts price now that I think back on it. I started saving several months back for this repair.

Just got off phone with another HVAC guy, quoted me roughly 1500, said the unit has to be torn down pretty deep.

Guy that "quoted" replacement last year will be coming out next week to revisit for clarity, but I find it hard to believe his estimate will be half of the other shops estimate.

I don't mind fixing things on my own, but I draw the line at things dealing with gas. I also have a couple of leads on guys that do work on the side.

Is this something best left to pros like I am figuring, beyond handyman DIY? I wonder about the liability issue that comes with having the side guys do this, where I would have more confidence leaning on official shops...

Any advice on this one? I do have room on a high interest credit card (30%) to bite the $750 bullet, but I've been fighting real hard to pay it down and would hate to go backwards again. It would probably be easier for me to just use floor heaters like I did last year and just pay the high power bill for another season and try to save up for the full $1,500 repair cost next year instead.

 

[zmaxmotorsports]

How old is the furnace,brand and model?

 

[Stuff]

The actual dealer parts cost is usually around a couple hundred bucks. Some have 10 or lifetime warranties on the heat exchanger that might be the difference if he tracked it down.

 

[naturalgas]

Don't let handyman do it. Your family's life depends on a pro doing the job. It's not a quick job . Like the hvac man told you has to be torn right down. I would look hard at replacement vs. repairs


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[onthefence777]

Its a Rudd Unit, either 1.5 or 2 ton unit. About 10 years old, maybe a few more. Printed model label, exposed to the outdoors, so label is no longer readable, so unknown on exact model. The heater worked awesome before, 10 minutes and the house is toasty.

EDIT: When I said side work, I meant licensed HVAC tech on the side, not a general handyman.

 

[Brian_WK]

In house furnace 80%, difficulty to replace: 4 out of 10 about 2.5 hours. In house furnace +90%, difficulty to replace: 6 out of 10 about 4 hours. Rooftop unit can range from from a 3 to a 6 out of 10 difficulty and can take anywhere from 2 to 8 hours depending on how the A/C is piped there will be about 100 screws taken out. RTV high temp silicone is needed in places and there are some high temp fiberglass gaskets that will need to be replaced.

Rooftop units also have a nameplate in the inside usually where the electrical panel is.

Brian

 

[bobbyjean]

10 years old...1500 to fix...natural or propane? if it runs 10 minutes and heats the place ....i ask ...sq footage,location...2 tons will be around 800 cfm..just got my hvac hat on here.....
if you repair ...check the manifold pressure at gas valve both static(standing) and while running..and outlet to burner while running...10 years is abit soon but i've seen it
ruud is a pretty solid unit-i'd get quote on new unit as well

 

[Stuff]

I think what bobbyjean was also trying to say is that an oversided unit is the main reason for heat exchanger failures. They overheat since not enough airflow gets delivered.

 

[onthefence777]

900 sq ft flat roof with 8' ceilings. It is a natural gas unit. Second HVAC guy came out today. Quoted me $2,200 - but I think he inflated his quote in order to push a used "6-year old 2.5 ton Bryant unit" for $3,500 installed with 6 mos no interest financing. He also said this unit is close to 30yrs old??? Again, maybe pushing the newer unit. He said the 6 year unit was replaced with a bigger one after a addition to a house.

I really dont know how old the unit is. 30yrs seems like a stretch though. I've had the house for 6 yrs. Previous owner replaced old swamp cooler with it. I thought it was around 10-12yrs when other things were remodeled, but honestly it could be 20, I don't know. I replaced what looked like the original draft fan 2 years ago and the A/C fan motor year before that.

Edit: Just spoke with neighbor. He said it was around the early 90's when this unit was installed, 2 owners ago, not the previous one. So the 30yrs is actually closer to the mark.

 

[acmikee]

look for a serial number on the top of the compressor.