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Manual J and semi-conditioned spaces
I have a 3 bay garage, with 2 unit heaters. Above that there are two radiator heated bonus rooms that are rarely used. They are separated from the main house by a breezeway, and are on two separate zones, respectively.
I only heat the garage to as low as I can get it to keep the pipes from freezing, but the Manual-J that was done has the inside dry bulb temp set to 70F, resulting in a delta of 68F.
Is there provision in code to allow a lower inside target temp for semi occupied spaces like garages? Surely they're not expected to be constantly heated to the same temp as the house, are they?
If so, it means I need to oversize the boiler output by at least 40K to account for that space.
Thanks in advance