decision of whether to fix a bad heat exchanger or replace the furnace

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Old 03-11-09, 02:18 PM
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decision of whether to fix a bad heat exchanger or replace the furnace

I would appreciate anyone's input on whether to fix a bad heat exchanger in a 95% amana furnace or replace it. I am going to convert over to natural gas, and am being told that the current furnace isn't adequate to effeciently heat the house. It has a max btu of 69,000 and the house is a cape cod with over 2000 sq/ft of area.
 
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Old 03-11-09, 03:02 PM
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That does sound tight, but are they just guessing or have they run any calculations. Typically you would want a “Manual J” calculation done to determine the size furnace you need.

First, what fuel are you changing from, how old is your existing furnace, can they get a replacement heat exchanger and how much, and how well insulated is your home/age?

My personal preference is to lower the heat loss to match a smaller furnace as opposed to increasing the furnace size to waste more energy on heat. When possible.

Let us know,
Bud
 
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Old 03-11-09, 05:35 PM
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Heat Exchanger

I completley agree on the Manual J. Here is one I've found to be quite good: 99 HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations 99
It costs about $50 to download & run but does come with tech support if needed.

Is the heat exchanger under warranty? Most Ammana furnaces carried a lifetime warranty on the heat exchanger & labor is usually under 4 hours.
 
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Old 03-11-09, 07:05 PM
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Find the model number in the top compartment on the left wall. If it is a GUH, GUC or GCC, then Amana will give you a new furnace at no cost. If it is a GUCA, GCCA, AMV, ACV, GUCA, GCCA, AMS, or AMH then they will provide an exchanger. The exchangers for these furnaces are extremely easy to change and can be done in under two hours in most cases. If you happen to have an 80% model, I would upgrade to high efficiency.
 
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Old 03-14-09, 04:51 AM
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It is a GUY, but I am in the process of getting a mortgage to purchase the property, and thought that the warranty only applies to the original owner. I had an Amana contractor out to give me an estament and He is checking on the warranty. I don't know anything about the capabilities of furnaces, but this furnace is a 2 stage one, with the high btu being 69,000 and low at 48,000. The house has about 2200 sq/ft am I am being told that it really isn't big enough to do an efficient job. I am considering installing a heat pump system since presently, there isn't any air condition. So, I am feeling like I'm between a rock and a hard place. Any suggestion would be appreciated. Now, besides that, I'm hearing that Goodman furnaces have improved their quality immensely and may be a consideration.
 
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Old 03-14-09, 04:59 AM
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The energy source conversion is from propane to natural gas. I had an Amana contractor in to give an estament and he measured the whole house. He said that the whole house had R30 insulation. Being that the house is a cape cod, the roof also had the insulation. I've had 2 Bryan contractors in to give estaments and they both recommeded furnaces or heat pumps that gave over 100,000 btu on the max end. The house has about 2200 sq/ft
 
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Old 03-14-09, 01:19 PM
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Manual J

DO THE MANUAL J. Sorry to shout but anything short of an actual load calculation is simply a guess. Don't trust load calcs done by supply houses or most contractors. They use a "short form" & have a vested intrest in selling new, larger than you need, equipment. Larger equipment equals more profit.
 
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Old 03-15-09, 08:49 PM
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That furnace should have a lifetime warranty on the exchanger for the original owner or 20 year warranty otherwise. I agree with Grady, get the Manual J done. That is definitely number one. After that you can decide on your equipment. I have to say though, I am in the coldest region in the US outside Alaska and 100,000 would be too big in most 2200 sq. ft. homes here. It all starts with the Manual J though. And about Goodman improving their quality....they own Amana. The new Goodman furnace is exactly the same as an Amana except the material in the heat exchanger and occaisionaly some electrical components depending on the model. Their air conditioners and heat pumps on the other hand have not caught up to Amanas quality.
 
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Old 03-18-09, 02:13 AM
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If a furnace of that size isn't keeping up, you need more insulation, not a larger unit. (69k is plenty)

I would get the heat exchanger replaced and find out why it failed. (If not, the new one will be doomed to fail) Something killed it - could be insufficient airflow (caused by neglect or lousy ductwork) or overfiring.
 
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Old 03-18-09, 02:16 AM
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I am considering installing a heat pump system since presently, there isn't any air condition.
If you purchase a heatpump, keep the furnace for backup. (Dual fuel) Heatpumps don't work well below freezing and electric heat strips are prohibitively expensive to operate.
 
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Old 03-18-09, 11:07 PM
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personaly I would not bother replacing heat exchanger because even if you get free heat exchanger labor cost you might as well put new furnace. And as far as goodman I have put plenty of goodman furnaces, have not had any major problems with it maybe board once in while and ofcourse hot surface ignitors. And if you buy goodman high effeciency furnace and register it online you get 10yr parts warranty and 20yr heat exchanger
 
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