Burnham V84/Beckett AFG will not fire

ktm1217

I woke up one morning to a cold house (temp was at 58*, thermostat set at 65* and calling for heat). I had just serviced it back in the beginning of October with new filters, nozzle, etc. to which it has been running fine since. My low water cutoff is working as it should, and the switch opens and closes as it should. I have blew threw the pigtails making sure they are clear. I have replaced the oil primary control, the fan center switch and transformer. The oil primary reads that the Limit Circuit is OPEN. If i jump the R and G terminals on the fan center switch, the limit closes and allows the unit to fire. At this point, i am leaning towards a bad Pressuretrol or something is wrong with my Cyclegard CG450. Is there anyway to bypass these, or further test them without replacing them?

ktm1217

EBEBRATT-Ed

If you jump R & G and it fires the limits are ok......that's what it should do.

It's not a limit. Sounds like your thermostat is not pulling in the fan center. Take the thermostat apart and jumo W & R and see if it fires.

Thermostat batteries dead?

Robert O'Brien

Oil limit controls must be wired 120V, not 24V. You don't need that fan center

Steamhead

Robert O'Brien said:

Oil limit controls must be wired 120V, not 24V. You don't need that fan center

Burnham and other makers supply that fan center to get around the fact that Riello burners don't have thermostat terminals. This one has a Beckett but I'd bet the TT terminals on the primary are jumped from the factory.

The limit controls are supposed to be wired into the 120V circuit before it gets to the relay contacts. For whatever reason, someone has added redundant limits to this boiler and wired them into the 24V circuit. Maybe the inspector wanted them?

I'd make sure the #67 low-water cutoff and the Pressuretrol mounted above it are working properly.

ktm1217

EBEBRATT-Ed said:

If you jump R & G and it fires the limits are ok......that's what it should do. It's not a limit. Sounds like your thermostat is not pulling in the fan center. Take the thermostat apart and jumo W & R and see if it fires. Thermostat batteries dead?

The thermostat also works the central air system and seems to work fine for that. The batteries are good in the thermostat as well. I jumped the RC and W/E terminals on the thermostat, but still no fire. 

Robert O'Brien said:

Oil limit controls must be wired 120V, not 24V. You don't need that fan center

I had two friends tell me that fan center is not needed as well.

Steamhead said:

Oil limit controls must be wired 120V, not 24V. You don't need that fan center

Burnham and other makers supply that fan center to get around the fact that Riello burners don't have thermostat terminals. This one has a Beckett but I'd bet the TT terminals on the primary are jumped from the factory. The limit controls are supposed to be wired into the 120V circuit before it gets to the relay contacts. For whatever reason, someone has added redundant limits to this boiler and wired them into the 24V circuit. Maybe the inspector wanted them? I'd make sure the #67 low-water cutoff and the Pressuretrol mounted above it are working properly.

The TT terminals are jumped, but were not jumped from the factory on this Beckett R7284. The #67 seems to be working just fine. I opened the drain and the float drops, and the switch opens. I can hear the switch click back in as the water level comes back up again. I did clean the pigtail underneath the pressuretrols, but is there a way to actually test the pressuretrol, or does it have to just be replaced?

Steamhead

Turn off the power, disconnect the wires in the Pressuretrol and use your ohmmeter to make sure there is continuity between the screw terminals.

EBEBRATT-Ed

You have to get a test meter and trace the circuit out and figure what is open. If you jumped R &G and the burner fires look at whats wired in to R & G

Probably the pressure control and/or low water cutoff. Check the pressure control as @Steamhead mentioned. The ones mounted on the low water cutoffs tend to plug the pig tail and your pigtail looks like it's a steel, brass is much better

ktm1217

Steamhead said:

Turn off the power, disconnect the wires in the Pressuretrol and use your ohmmeter to make sure there is continuity between the screw terminals.

I get 1.3ohms at the pressuretrol. And i get 3.5ohms at the pressuretrol mounted to the #67 LWCO.

Steamhead

Should work..............

EBEBRATT-Ed

@ktm1217

Take the wires off the pressure control mounted on the low water cutoff and ohm out the control itself. Could be 0 ohms or have continuity. Also do that to the low water cutoff (top two terminals) put wires back when done

ktm1217

EBEBRATT-Ed said:

@ktm1217 Take the wires off the pressure control mounted on the low water cutoff and ohm out the control itself. Could be 0 ohms or have continuity. Also do that to the low water cutoff (top two terminals) put wires back when done

I got 1.5ohms on the pressure control mounted on the LWCO, and 1.8ohms at the LWCO switch itself.

ktm1217

Update: after some hunting, it was discovered that the thermostat wiring had disconnected at a splice (I believe i may have hit it when stacking firewood in my basement). All is working now! 

However, we did find that my Cyclegard CG450 was hooked up wrong by someone previously and wasnt allowing the burner circuit to cut out for low water. Since fixing that connection, i found that the boiler cuts off every 10-15mins when running for the system to do a ILT. I think I may switch that cyclegard out for a safgard over the summer.

Thank you everyone for the help! Kinda cant believe i didnt find that disconnected connection, but glad its up and running!

Steamhead

You just dodged a bullet. If the boiler had gotten low on water and the low-water cutoff had failed to stop the burner, you would have had a cracked boiler. The last thing you need in the middle of winter is to have to replace your boiler.

Did the other low-water cutoff work as designed?

ktm1217

Steamhead said:

You just dodged a bullet. If the boiler had gotten low on water and the low-water cutoff had failed to stop the burner, you would have had a cracked boiler. The last thing you need in the middle of winter is to have to replace your boiler. Did the other low-water cutoff work as designed?

Yes, the McDonald 67 LWCO does work. But the cyclegard was not hooked up correctly. I think they may have done that so that it didnt do the ILT every 15 minutes. 

ethicalpaul

So you got the cyclegard wired up correctly by a licensed steam pro (or by someone who really knows their stuff)? That would be good.

The cyclegard's interruption is not bad at all, I think it is the safest LWCO out there. Run it this season and see if you can get used to it doing its job. I really like mine now after having lived with it.

Also I don't think you are measuring the resistance of the controls correctly. In its normal state the pressuretrol should be absolutely zero ohms with no other reading possible. It's basically a piece of wire when it's not in the "cut out" state. Same for the LWCO. But that's OK it looks like you found the problem.