3rd Zone won't doesn't start up furnace (boiler)

Whalerajm

I have  3 zone hot water gas heat, each zone with thermostat.  Thermostats in Zones 1 & 2 trigger furnace to start up just fine.  Zone 3 won't start furnace.



However, is Zone 2 is on and Zone 3 thermostat is "on", Zone 3 gets hot.  If Zone 2 thermostat is off, and Zone 3  thermostat is on, Zone 3 gets no heat.



I thought problem might be thermostat in Zone 3, but disconnected it and connected the two wires...still no heat. 



I have Erie Hotline Zone Valves on Zones 2 & 3.  Zone 3 valve must be working since iZone 3 gets heat when Zone 2 & 3 are on together....



Is there an electrical connection inside the Erie Zone Valve that could be malfunctioning and failing to trigger furnace lighting?



Thanks for your help!



Andy

Mark Eatherton

Yup....

There are switches inside of the valve that confirms the hydronic portion is open. When that is confirmed, the end switch closes the circuit that brings on the pumps and burners. Sometimes, the wires are bundled together, and if one of them slips out or gets loose, you get no call for heat. The fact you can feel heat in 3 when 1 or 2 is calling and three is calling tells me the motor is working, but the end switch is not.



Then ends switches are the RED wires, and they should be wired parallel.



ME

Whalerajm

Thanks ME...Next Step?

Thanks for input.  So do I need to replace the zone valve, or is do I need to double check wiring from the valve?  Initially when I checked all wires appeared to be connected.



Is changing the zone valve (Erie Hotline, Compression fitting) something a non-plumber can do?  I think I can handle removing old valve and putting new one on since it's compression...and then connect wires exactly as existing valve is connected.



Am I over-simplifying?  Any traps I'm not aware of?  And, do I just turn off fresh water feed and open bleeder valve to strat...and reverse when I'm done?



I know these sound like stupid questions, but I've never touched the boiler before.



Thanks!

Mark Eatherton

Traps??

Working on a hydronic heating system is fraught with traps.



If you are not familiar with all aspects of the heating system (electricity AND water) you might be safer and better off to hire the work out. Otherwise, expect to get wet, and spend a lot of time trying to clear the system of air once you've done your work.



It is probably just the micro end switch that has failed, but not sure if you can get just that component for replacement. With some valves (honeywell) it is possible to replace just the power head without getting into the water side of the system. Not sure as it pertains to your valve.



If in doubt, seek professional assistance. Click on the Find a Professional button on the top bar of this web page to see if there is help near you.



ME