Gas boiler keeps running

oderf

I have a Burnham # 205ncl gas boiler.It is a cold start boiler that only come on when a zone calls for heat.It has started to run without any of the three zone valves opening but the circulator is running. Forgot to mention it a hot water boiler
I eliminated the three zone valves by disconnecting the thermostat wires but still had the same problem. the control on the boiler is a honeywell r8582d 5001 with a r822u 1006 relay. replaced the relay and still the same problem any help or thoughts would be greatly appreciated

Jamie Hall

Disconnecting the thermostat wires probably doesn't do anything, since they don't directly control the boiler -- the end switches on the vavles do. Check and see if one of those valves is stuck open.

You might also check the aquastat on the boiler -- the boiler should turn off when it reaches the high limit.

EBEBRATT-Ed

I agree with @Jamie Hall sounds like it could be a valve end switch. Maybe a valve is stuck open

oderf

i checked the end switches none are stuck. The boiler shuts off on high limit[180 degrees]. bot will come back on when temp hits the differential which i think is around 160 degrees. Keeps cycling on and off.

oderf

I want to add that I also completely disconnected the zone valves from the system

Jamie Hall

OK. The zone valve end switches are all disconnected, right? Not the thermostat wires -- the wires from the end switches? And the boiler still runs? Check all your wiring for shorts. This isn't rocket science -- somewhere there is a closed circuit to the boiler control.

oderf

I disconnected both the t stat leads and the end switch leads on all zone valves.. the boiler still fires, the circulator runs . when the boiler reaches 180 it stops firing but the circulator is still running . After a short while the temp in the boiler lowers between 160-170 and the boiler fires again

Jamie Hall

Any relays in the system? As I said before, what should be happening is that one or more of the end swtiches should close, and if the aquastat is closed (cool) the circulator should run and boiler should fire. If the aquastat opens (hot) or the end switch(es) open, the circulator should keep running and the boiler stop.

What you are telling us is that the circulator runs and the boiler responds correctly to the aquastat. Which says that the problem has to do with the end switches and their wiring -- and any relays which are between the end switches and the aquastat/boiler circuit. If there is/are a relay in there, it could be failed closed. They do. Whether there is a relay or not, it could be a short in any of the end switch wires.

HVACNUT

Can you post a pic of the Honeywell relay control in the boiler? Not too close.
Did you replace the whole control or just the plug in relay portion. The relay itself is a very simple DPST so it's not likely a new one was faulty out of the box. The end switch wires from the zone valves connect to R and G on the relay control. If you turn off the power and remove the wire from G and tape or cap the end so it doesn't short. Turn the power back on. If the circulator and boiler stop, the problem is in the wiring between R-G and the end switches on the zone valves. If the circulator and boiler stays on the the problem is at the relay control. Something is energizing the relay coil.
If you replaced the complete control, is it possible you didn't rewire it correctly? Post the pic.