High Limit Thermostat

[03180318]

What is the normal set-point temperature of high limit thermostat for gas fired rooftop unit? 135F? 150F?
I am new here.Could someone help me? Thanks in advance.

 

[imok2]

States have Different codes for hi limit cutouts, however they range between 220 and 250*F. This switch can be combined with a fan switch

 

[cme]

Fire dampers usually have a 165 deg F fusible link. I don't see any need of supply air above 105 deg in which is the around the max for a packaged rooftop unit.

 

[lilliput1]

I agree with cme. You can also check your unit maximimum temperature rise above the heating indoor design temperature at the unit minimum CFM then add say 10 to 15°F above it.

°F temperature rise = MBH output x 1000/(1.08*Min CFM)

Say set limit °F = °F T rise + 72 + 10 to 15°F

 

[03180318]

Thanks a million to all of you.