I have two zone HVAC system in my home. My lower level zone is working fine, the zone upstairs is the problem. I turn on the heat and the fan to auto and the thermostat calls for heat, as indicated by the blower coming on, but the blower or air handler is not communicating with the furnace, because the furnace is not kicking on. Any suggestions, before I call my service company?

Is this a boiler or furnace? If boiler it is the end switch on the valve.

It is actually a boiler. Is the end switch at the boiler? If so that is what I thought could be the problem. Am I correct that the end switch is at the boiler where all of the thermosates are wired in? Correct?

I answered your PM