What Are The Consequences If The Heat Rise On A Furnace Is Above The Rating On The Furnace

Oct 02, 2012 6 Replies

I Installed A New 95 % Furnace With A Heat Rise Rating Of 50-80 Degrees. When Checking I Found It To Be 90 To 95 Degrees. What Are The Consequences If I Am Unable To Get It Within The Specified Range ? The Blower Speed Is On High So I Cannot Increase That. Is There A Way To Reduce The Flame Or Adjust The Gas Valve In Any Way ?


Your problem is probably due to the size of your duct system. Normally when replacing a 60 % eff furnace with a 90 % eff unit, the return has to be increased and possibly the supply ducts are to small.

A higher than normal heat rise will cause a premature heat exchanger failure, and a voided warranty. If your orig. unit was old and the eff. was around 60% and you replaced it with a 95% eff. unit you have oversized the system by approx. 25% to 30%. The result is a improperly sized duct system, restricting the air flow and increasing the temperature rise across the heat exchanger.

I have actually run into problems like this. It happens to a lot of people I'm guessing now. Whenever I have problems I like to consult professionals. That is why I'm looking to hire furnace repair in oak lawn. I want to get it repaired the right way.

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