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-   -   Repair or Replace 13 yr old Furnace with Cracked Heat Exchanger (http://www.diychatroom.com/f17/repair-replace-13-yr-old-furnace-cracked-heat-exchanger-120975/)

Thor73 10-23-2011 12:06 AM

Repair or Replace 13 yr old Furnace with Cracked Heat Exchanger
 
I have a 13 yr old Lennox G26Q3 high efficiency gas furnace that has a cracked heat exchanger. The heat exchanger is under material warranty still and I have a labor cost to repair of $1500. Would you recommend repair this furnace or buy a new one?

Thank you for your feedback!

Doc Holliday 10-23-2011 12:10 AM

I wouldn't even do it for $500.

new. for only a few hundred dollars more you can get a very decent new furnace installed and a new warranty which covers all parts for a few years and 20 or lifetime on the heat exchanger.

Thor73 10-23-2011 12:22 AM

Thanks for the feedback Doc. I forgot to mention I've had three quotes from different vendors for a new furnace:
Trane XV95 = $4000
Bryant Plus 90i 355 = $3900
Lennox - G61MPV = $5000

Thanks again for feedback.

Doc Holliday 10-23-2011 12:40 AM

Quote:

Originally Posted by Thor73 (Post 754486)
Thanks for the feedback Doc. I forgot to mention I've had three quotes from different vendors for a new furnace:
Trane XV95 = $4000
Bryant Plus 90i 355 = $3900
Lennox - G61MPV = $5000

Thanks again for feedback.


Those are some high dollar, high efficiency variable speed condensing furnaces. I was thinking something like a simple, 80% single stage furnace. I've personallly installed those for under $1900.

You will get much more return on your invesment with a high efficieny furnace though, a lower electrical bill, better comfort, etc. etc...

It's all up to you but you have to ask yourself how long do you want to continue to patch up yesterday's failing product?

My pick of those three would be the Trane.

Doc Holliday 10-23-2011 12:55 AM

One thing on condensing furances, you have a coil in the furnace. You need to absolutely make certain you replace air filters religously as well as make sure you have no air leaks anywhere, return air especially. You do not want to get that coil on the inside plugged as you pretty much have to un-install the furnace to get to it.

That and you will be needing a fresh air intake and an exhaust, both run in pvc and out of a side wall of your home.

REP 10-23-2011 01:26 AM

Your problem could of course be a natural defect in materials or of manufactuer,but ususlly it is a problem of bad duct size or design or an improper size furnace.
Unless you enjoy spending big dollars on an often basis you should pay someone to do a manuel "J" ,AND a manuel"D"
If you just decide to repair what you have,you will just be at this point again in half the time you would normally have to,plus you will be paying too high a monthly fuel bill until you get the proper size and correct ductwork installed.

beenthere 10-23-2011 05:39 AM

Quote:

Originally Posted by REP (Post 754507)
Your problem could of course be a natural defect in materials or of manufactuer,but ususlly it is a problem of bad duct size or design or an improper size furnace.
Unless you enjoy spending big dollars on an often basis you should pay someone to do a manuel "J" ,AND a manuel"D"
If you just decide to repair what you have,you will just be at this point again in half the time you would normally have to,plus you will be paying too high a monthly fuel bill until you get the proper size and correct ductwork installed.

Yep, most likely caused by a combination under sized duct and an over sized furnace.
Have a load calc done to find out what size furnace you really need. A static pressure test can be done to determine if your duct work is large enough.

What size is your house, and what is the full model number of your furnace. What size furnaces are they quoting.

Marty S. 10-23-2011 08:59 AM

It's a 92% or better AFUE furnace with a lifetime heat exchanger warranty so you won't get much better buying new. The reason many cracked was of a slight burner misalignment. Lennox includes new burners,burner box and all gaskets with the exchanger so it doesn't happen again. Takes me right at 2.5 hours to replace a heat exchanger in one plus shipping cost. I'd suggest calling around and finding a company with less overhead who doesn't need to charge $500 an hour to make a profit. Same guy with a freaking $5000 G61 I'm guessing?

COLDIRON 10-23-2011 05:54 PM

Replace after heat calcs are complete. Do not repair.

Tator1076 10-23-2011 07:48 PM

I just did a furnace heat exchanger on a 17 year old furnace Friday and found out the company who ever up it in. Put in 150 btu and it should be 80 btu furnace. Said part it is was 17old furnace is still under warranty but a new heat exchanger will be crack in a year. He going to have to go after other company or we put in the right size.

ben's plumbing 10-23-2011 08:26 PM

I would like to know who charges 1500.00 to install heat exchanger ..by the book this spects out at 3.0 hrs .....any decent company would like to have this job at 300.00 to 400.00 including travel..keep looking around...good luck

gregzoll 10-23-2011 08:45 PM

Thor73, here you go for some pricing comparisons http://www.alpinehomeair.com/viewcat...categoryID=470 As for the heat exchanger, that is a long job for just a homeowner, and not even worth the time.

gregzoll 10-23-2011 08:46 PM

Quote:

Originally Posted by Tator1076 (Post 755090)
I just did a furnace heat exchanger on a 17 year old furnace Friday and found out the company who ever up it in. Put in 150 btu and it should be 80 btu furnace. Said part it is was 17old furnace is still under warranty but a new heat exchanger will be crack in a year. He going to have to go after other company or we put in the right size.

Only way that it would crack in a year, is if there is another underlying problem causing it in the first place.

beenthere 10-23-2011 08:52 PM

Quote:

Originally Posted by ben's plumbing (Post 755114)
I would like to know who charges 1500.00 to install heat exchanger ..by the book this spects out at 3.0 hrs .....any decent company would like to have this job at 300.00 to 400.00 including travel..keep looking around...good luck

400? Including travel. Heck no, thats a cheap company. Not paying their employees much.

Thor73 10-24-2011 12:11 AM

Thank you all for the feedback! To follow up on a few of the threads, no company provided a written load calc but after talking to all three, it sounds like it is oversized. My current unit is 75k BTU. The Lennox dealer did not provide any load calc information when asked and specified a 70k BTU unit. The Trane dealer talked through his hand written calculations and specified a 60k BTU unit. The Bryant dealer said his experience tells him that the unit may be oversized but he specified a 75k BTU unit. The only dealer to do a static pressure test was the Trane dealer and he indicated that the test indicated that there is a pressure differential indicating the A-coil may be dirty.

Based on the differing feedback, I am discouraged by the quality of each company except the Trane dealer who seems better than the rest. However, I'm not sure that is a good thing.

Sounds like the most important thing to do is get the sizing right. Couple questions about sizing it correctly:

1) Should a manual J be more official than "experience" and/or hand calcs?
2) Is there an easy "Do it yourself" J calc or free on-line calculator?
3) Does a manual D make sense to do on an existing house where I have no exposed ductwork except the 6x8 furnace room?

Thanks for the continued feedback!


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