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radiant hydronic heater temp setting

jimh12345 Member Posts: 1
edited December 2014 in Radiant Heating
I have a radiant system in my garage floor and it's started behaving oddly. The tankless heater (American Heating) temp setting has normally been 90 but recently the inline temp gauge started showing me that the heater wasn't activating, although the pump is running and the heater LED display turns on, indicating it's sensed the flow. If I bump up the temp setting to 105/110, it starts to heat, but only gets to about 85 per the inline gauge. if I return it to 90, the inline gauge drops back to room temp of about 60.

Might this be caused by air in the system? Or a failing temp sensor in the tankless heater?