We have hot water baseboard, 1 circulator, 2 zone valves, 2 thermostats (1st flr, 2nd flr), Honeywell. Last week 1st flr heat stopped working. Forecasted to be cold in a couple of days, need to fix this. I think its the powerhead on the 1st floor zone valve but need to make sure before I buy one.

With the furnace warm, if I manually open the 1st flr zone valve we get heat to the 1st flr.

If the furnace is cold and the 2nd flr stat is NOT calling for heat, if I turn the 1st flr stat all the way up the furnace DOES NOT come on. I thought this might point to a bad stat but if I cross the 1st flr stat wires the furnace still does not come on.

Thanks for any Help

hvac1000

If you turn on the first floor T-stat does the pump run?


((With the furnace warm, if I manually open the 1st flr zone valve we get heat to the 1st flr.))

If you open the first floor valvae manually does the heat come on when boiler cold?

KKfromNJ

Thanks for your help.

The only time the furnace fires and/or the pump comes on is when the 2nd floor stat is calling for heat

KKfromNJ

Funny thing (to me) is when I was checking the 1st flr stat, turning all the way on and off, I expected to see the little spark in the merc capsule but didn't. When I shorted the 1st flr stat wires I saw no spark.

hvac1000

It could be the power supply for the first floor area. Transformer I suspect. Get out the volt meter and start back tracking to find the problem.

KKfromNJ

There is only 1 transformer

hvac1000

You still need to trace back to find what happened to the signal from the first floor.

KKfromNJ

I changed the power head, all is GOOD! Thanks to everyone for their comments.