It normally will heat up with pump moving water, once the threshold is achieved - system will come out of its Freeze protection mode and will begin to work as programmed. If there is a heat call, heater will come on. You can also locate the sensors, both the Water & Air (they need to be very close in temperature for this to work) then place them in water warmer than the actual ambient temp, & above the temp that triggers "Freeze".
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It normally will heat up with pump moving water, once the threshold is achieved - system will come out of its Freeze protection mode and will begin to work as programmed. If there is a heat call, heater will come on.
You can also locate the sensors, both the Water & Air (they need to be very close in temperature for this to work) then place them in water warmer than the actual ambient temp, & above the temp that triggers "Freeze".