View Full Version : Minimum indoor heating design temp
05-02-2009, 12:09 AM
What is the minimum design temp allowed for residential heating? Would, for instance, a system that could heat a house only to 60 degrees F violate any mechanical or energy codes? Does Manual J have something to say about this?
05-02-2009, 12:22 AM
I think I read 68*F a heating systems shall be designed to maintain or a 24 hour period. It might be 70 because all might heat losses are rate at 70*F.
05-02-2009, 01:42 AM
I'd guess it's different depending on where you live. In Houston, a furnace by law needs to be able to maintain 68° indoor temp with a 20° outdoor temp. As such most furnaces are slightly oversized. Then again, the heating season here is so short, who cares? It used to be that 68° with 30° outdoor temp was the rule.
05-02-2009, 06:36 AM
I think the national is 65.
But most states have their min at 68.
05-02-2009, 08:54 AM
Thanks for the replies!
05-06-2009, 09:57 PM
I have 2 programs and manual j have 2 options 68/75/50 and 70/75/50.
F-280 Canadian versions is the exact same. Just wondering why they would put these numbers if they were not averages.
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