I have a takagi jr flash boiler set up for in floor heating. Circulator is a TACO 007.
The unit will fire up and heat the floor to the preset temp. However, it fails when restarting after the temp drops below the thermostat. 69F. At the same time the motor on the TACO 007 is warm and making a low garde buzzing noise
The only solution I have found is to unplug the unit, let the temp drop down to 65F- 66F then plug it back in. If it still fails on start up I open and close the inflow valve a few times (quickly) and it will generally start back up.
My heating guy thinks it is scaled up. I would think this could only happen if fresh water is getting in the loop?