Intermittent Boiler Heating

reins8

Hello all,

I encountered a no heating situation last night with my Burnham boiler and Effikal vent damper. Upon approaching the boiler I noticed that my burners weren't firing but my circulator was running, the pilot was lit, and I had a command for heating. I noticed that the damper wasn't opening, so I flipped the manual operation switch and opened it. After doing this, the burners still did not kick on. I inspected the flame roll out and blocked vent switch and found these components to be functioning correctly.

I figured my next step was to jumper pins 2&3 on the damper vent with the damper in the open position to see if the burners would kick on this way, but it was 2am and this was my garage boiler so I decided to wait for the morning to do more troubleshooting. This morning I woke up to find my boiler functioning perfectly. Great, I fixed it!

Given that I might run into this issue again, what would have been your next steps? Have you run into a situation when burners still don't kick on with the vent manually rotated into the open position? Thanks in advance.

JUGHNE

What kind of gas valve is on it?

reins8

It's a Honeywell VR8200C gas valve.

Honeywell R8285D control center (R8222U Relay)
Burnham Series 2 24 Volt Standing Pilot and Intermittent Circulation Boiler

HVACNUT

As of now it's working so previously the circ was running and the boiler was cold?
Is it possible the boiler was at limit but not pumping water and that's why the damper wasn't open?
If the boiler was cold, start at the thermostat. Where does the thermostat wire connect at the boiler? Left side Fan Center control? Thermostat wires connected to R and G?
If so, the brown G.P. relay there could have a bad N.O. contact. Make sure the relay is seated completely. Its removable.
If all is good there, trace the circuit from the gas valve back.

reins8

Yes, the circ was running and the boiler was cold.

When I first noticed the issue, there was frost on the windows/garage door and I could see my breath. I typically keep the garage at 60 degF and it's insulated. The temp gage showed no heat in the boiler and all lines were cold to the touch. Given how cold it was in the garage, it seemed to me that there had been no heating for some time (24 hours or so?). Obviously, the first thing I did was check the breaker and I found that it had not tripped, but I flipped it off/on anyway.

The thermostat wire connects to the boiler at R and G. I did measure 24V across R and G with the burners not firing and the thermostat set to 80 degF.

I pushed firmly on the relay and reset the wire retainer on the center of the relay (it had slipped of center, slightly). However, doing this didn't seem to change anything and I continued troubleshooting for another hour before going to bed.

JUGHNE

Thermostat is a simple switch, if closed calling for heat, should have no voltage across it's terminals.
Is there a battery in the T-stat?

reins8

No batteries in the thermostat. I have a round mechanical heat only style thermostat.

JUGHNE

Take the wires off the T-stat and tie them together, boiler should fire up to high limit. If a mercury stat it needs to be level for accuracy, and you can see the mercury in the glass bulb travel to make contact.

reins8

Looking back, I may be not recalling the 24V across R and G correctly.

The boiler is connected to 2 thermostats, both were set to 80degF and I find it unlikely that both failed.

Still, if this happens again. The voltage across R and G will be the first thing I fact check myself on. Thanks, JUGHNE.

HVACNUT

2 thermostats?
2 zones, 2 circulators, zone valves, zone board?
If you read 24v on your meter across R and G then whatever is doing the switching is not closing i.e. end switch, thermostat, N.O. contact.
If you read 0 across R and G then whatever is doing the switching closed (24v across G and C). If that's the case, the fault is between the G terminal and the gas valve.

Edit: How did you check the rollout? It shoul be a "one and done" thermal safety.

SuperTech

I always love how everyones first instinct is to jack the thermostat up all the way as if they are flooring the gas pedal in a car.
It's just a switch, it can't get any more on with the setpoint maxxed out. 😉

With multiple thermostats (sounds like a nice garage) you have to trace back to whatever controls the zones. Is it zone valves or circulators? Do you have a control panel?

reins8

Thanks HVACNUT and SuperTech.

Haha, well, I wanted to be certain I had the set point above the garage temp so yea I put the pedal to the metal! But I agree with what you're saying. Anything above freezing should have prompted the system to turn on,

Yes, I have 2 thermostats. One zone for where the cars park and another zone for a workshop. The two zones are insulated from one another by walls/doors.

Thanks for the additional detail on the behavior of R and G, HVACNUT. I'll take a closer look at the zone valve, thermostat, and relays and take better notes on my voltage readings at the control center if this happens again.

With regards to the flame rollout switch, I just checked the continuity of the device after checking for loose wires at the gas valve, blocked vent switch, and flame rollout switch. '

I don't have a control panel for zone control, but I do have a cabinet where various mixing valves, shut off valves, and zone control valves are contained.

What I could do this evening is turn the thermostat down in one zone and turn it up in the other to see if I get a response out of the boiler. Then do the same in the other zone to see if I can pin point the issue to a specific zone.

Really appreciate the comments everyone. I'm a novice to all this, but I'm learning a lot. Very helpful community you have here.

reins8

Hey guys, just wanted to give you an update that I found the culprit!

Today I came home from work and the garage was obviously cold again. Drat. So, as one does, I cranked everything up to full throttle (80 degF!) and started to investigate the problem.

The pilot was lit, all pipes were cold, boiler reading 70 degF, circulator at boiler was off.

So I started probing G-R
Zone 1: 80 degF, Zone 2: off degF - 24V
Zone 1: off, Zone 2: 80 degF - 24V
Zone 1: 80 degF, Zone 2: 80 degF - 24V.

Thanks to your advice, I went to check the zone valves next. When I popped off the cover, zone 1 instantly came to life. It opened and I heard the zone circulator click on. At this point, the boiler burners kicked on and everything came back to life. I turned the thermostat from heat to close several times and watched the zone 1 valve open and close each time and the zone circulator and boiler to turned on, also.

However, after removing the cover for the zone 2 valve, it appears that this valve is stuck somewhere between open and closed where the springs on the valve are not able to close the valve completely shut, but the motor on the valve also isn't opening it when I change the zone 2 thermostat from off to heat. I attempted to free the motor/springs up by removing the device, however I haven't been able to free it up.

Still, it seems like I was having issues with both my zone valves. They were pretty dusty/dirty under their covers, so a good cleaning is in order and possibly a replacement of the zone 2 valve motor/spring assembly.

Just wanted to give you all a quick update. Thanks again!

SuperTech

Glad you got it figured out and thanks for the update! If you have the typical Honeywell zone valves (V8403E?) Your will find that they don't last very long. Be careful, sometimes changing the motor isn't enough. Make sure the shaft that the motor mounts on spins nice and easily. If there's any resistance you need to change the innards of the valve, which is more work involved.

reins8

Yea, it's a V8403E.

Good point, SuperTech. I just pulled off the old assembly and was able to manually rotate the shaft slightly less than a quarter turn. Does this sound like about the right range of motion?

SuperTech

It sounds close. Thats about all they turn. The fact that you can turn it with your fingers is good.
Your best bet is to just buy an entire zone valve for whatever pipe size your zone is. That way you can compare the range of motion between the two. Sometimes the smallest fraction of a rotation is enough to keep the zone valve from closing the end switch. I find myself changing everything on zone valve repairs more often than not.