furnace fires even when thermostats off

AlbertH

Hello,

I have a slant fin hydronics furnace. (sx210) Recently serviced. things seem to be running well.

I was wondering why my aquastat tells the furnace to fire and keeps the temp between 160-180 degrees even if my thermostats in every zone are turned off. is that normal?

It seems like the furnace should know that the thermosats are turned off and there is no call for heat. Like on a warm day, for example,).

any help?

thanks

radmix

Boiler

Is it coming on to make domestic hot water?