What are the proper temperature settings for my boiler?

The average setting for the aquastat (the temperature control device on a boiler) for a forced hot water system is 180 degreesF.  It can be raised as high as 210 degreesF if needed in severe weather.  For systems that use coils to heat domestic hot water, the high limit setting is 210 degreesF and the low limit setting 140 degreesF.