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Discussion Starter #1
I was noticing on Rheem furnaces while looking through data on their web pages that their heat exchangers are tubular steel, while most other manufacturers used stamped steel heat exchangers, where it looks like they take two stamped metal halves and either weld or clamp them together. The Rheem tubular steel heat exchangers look much more durable, but they don't look like they would transfer as much heat. What is the "real world" performance of these furnaces as far as durability goes? I am really liking what I see with Rheem/RUUD and am thinking of their equipment when I upgrade over the "big two" Carrier and Trane.

Also, I saw where one manufacturer (I think was either Lennox or Trane) said that their heat exchangers are not welded to reduce thermal shock and minimize cracking. Is this true with welded heat exchangers?
 

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Every manufacturer has there own way to build and describe a heat exchanger and the design of tubular vs stamped vs tubular/stamped hybrids is not the most important fact. The metallurgy and grade of steel that they use is far more important. I suspect some el cheapo builders grade units are using recycled metal and pop cans as the metal gets brittle and cracks prematurely. Goodman uses a tubular heat exchanger as well as Rheem. Suprisingly enough Rheem is a middle of the road priced unit and I have never had a heat exchanger failure from them so that design is good. They are a bit lighter built and noisier but a decent furnace for the money. Trane is the most expensive but good and you get what you pay for IMO. Welded vs non welded in not a big issue, the quality of metal is. A tubular heat exchanger is like a S and therefore can expand and contract easier like an acordian but the others expand sideways easily. LOTS of heat exchanger failures are from overfired units where the gas pressure was never set at startup or units running too hot from undersized ducts, dirty filters, dirty AC coils etc etc.
 

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Discussion Starter #3
Nice reply! Thanks for the info. One of the things I did notice about the Rheem funaces however was that the control board was not enclosed, but was in the "open" within the fan compartment. This is probably okay considering the furnace will be operated with a filter, but being in the electronics industry, I see the troubles dust and dirt-coated electronics can experience
 

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95% of them today are in the open. They have a plastic film coating to keep the dust off. Carrier had some black case closed ones yrs ago and had lots of problems, bad solder joints too and ever since then most are open. Moisture from damp basements is a bigger problem as it corrodes the solder joints and diodes etc and turns them green and will kill the board. The fan keeps the board cool. Suprisingly enough the Rheem boards in my experience have been very good BUT I absolutely hate the modulating furnace. WAY WAY too complicated and a nightmare to troubleshoot. The rest are OK.
 
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