That was interesting...

Jamie Hall

Cedric has five safeties -- 2 pressuretrols (one manual), one vapourstat (really a control, but in the safety circuit), on MM67 low water cut off, and one Safeguared low water cut off.

Been running perfectly for years.

Came down this morning, and he had run away. All three pressure controls tripped and the MM67 low water cut off tripped. I don't want to tell you the pressure. House was nice and warm.

Normal operation, when any of the safeties (or the thermostat) opens, butner stops, post purge runs, everything shuts off and waits for the next call.

Which leads me to believe that something hung up in the control? It's a Carlin 60200 control. Is there a relay in there which could have hung up? Cedric was running pretty hard last night (12 below and windy).

Suggestions while I wait for @Charlie from wmass to get here? I can run the thing manually, but that's not my idea of a way to spend the day...

ChrisJ

So...
What was the pressure?

ChrisJ

It's pretty concerning that even the LWCO didn't stop it........

Jamie Hall

ChrisJ said:

It's pretty concerning that even the LWCO didn't stop it........

Uh... yeah. Kind of. To put it mildly.

Would you believe 10 psi? The system traps will be OK -- the Differential Loop protects them -- but the main vents... well, we'll just have to wait and see.

JUGHNE

First suspect would be welded motor burner contacts....but there must be an oil solenoid valve that would also have to stay energized. (you said post purge happens so there must be at least 2 separate circuits).

(This is equivalent to a gas valve stuck open IMO)

Jamie Hall

I'm thinking the same sort of thing -- is there one relay that controls both? I'm also thinking new control... I don't want to have to stay up all night running this thing by hand!

ChrisJ

Jamie Hall said:

ChrisJ said:

It's pretty concerning that even the LWCO didn't stop it........

Uh... yeah. Kind of. To put it mildly.

Would you believe 10 psi? The system traps will be OK -- the Differential Loop protects them -- but the main vents... well, we'll just have to wait and see.

Well.

If the boiler was sized by my method, that wouldn't be possible. That 33% oversize is what allows this behavior.


I'm sure your main vents are fine. 10 PSI isn't anything huge. Once Mr Garrity gives the system a once over you'll be fine.

JUGHNE

Because of pre and post purging, the blower would have one signal, proving air flow to a pressure switch.
Then another relay step to provide spark ignition and oil/gas valve opening.

But it seems that 2 things had to be "stuck on" for the fire to run away.

I assume he is bringing a new flame control.

JUGHNE

On one hand the fire stayed on.....that would have been a pretty flooded oil pot by morning.
But getting low on water is a concern, do you leave the auto fill supply on?

Jamie, you know by now someone usually asks for pictures of your boiler,

KC_Jones

JUGHNE said:

On one hand the fire stayed on.....that would have been a pretty flooded oil pot by morning.
But getting low on water is a concern, do you leave the auto fill supply on?

Jamie, you know by now someone usually asks for pictures of your boiler,

I don't think I have ever seen pictures of Jamie's boiler.

Yes we need pictures. Also where do you live we might know someone good in your area that could help. lol

ChrisJ

Yes.

@Jamie Hall has been very closed mouthed about his boiler........

JUGHNE

Maybe he had it removed to install FAF...with heat pumps!

EBEBRATT-Ed

power comes to the boiler and powers RED on the control as a constant hot. it also branches off & goes through the limits (controls and low water cutoff) and returns to the control and powers the black wire.

Seems to me there is an internal short in the control. If the limits were shorted the thermostat would still shut it down.

I was thinking of suggesting you rewire the controls temporally to wire them in series with the red (constant hot) wire. Then they would have to shut the burner down....but

I am more concerned with the fact that maybe the burner wont shut down on flame failure. You could start the burner and pull one of the cad cell wires off to test it....see if it locks out. If it does putting the controls in the constant hot should work for now...you won't have pre or post purge

Other than that I would replace the control

JUGHNE

Ed, so line voltage control goes thru the safety/control components?
The only 24 VAC is the T-stat?

EBEBRATT-Ed

Control has pre purge and post purge so they have a constant hot (red on the control) which internally powers the burner motor for pre & post.

the power to the red on the control "tees" off and goes through the limits (LWCO pressure control etc) and then returns to the control to power the black wire (end of limit circ) which starts the burner if the thermostat is calling.

T stat wired directly to the cad cell control, 24v trans internal just R & W to stat & a common if used

Jamie Hall

@Charlie from wmass is on his way with a new control. And a new Gorton main vent, which is stuck closed -- amazing what a difference that makes.

Sigh...

Solid_Fuel_Man

Generally all of the operating controls, high limit (manual reset), LWCO, and any kind of BMS (thermostat in your case) are all wired in a series loop. So a welded contact could make this happen, I've never wired a Carlin burner control on anything but resi stuff (TT only). The Websters and Power Flames all have an aux contact on the burner contactor which will still lock out the oil solenoid even if the burner blower still runs due to a welded contact.

Some investigations are in order for sure! Please let us know what you find out.

Jamie Hall

I'lll keep y'all posted!

ChrisJ

Jamie Hall said:

I'lll keep y'all posted!

In the mean time, how about some pictures of that boiler?

JUGHNE

So to have both the aux contact and motor contact welded would seem unlikely. It seems the "brains" in the control are scrambled.
I just speculate as I have not seen an oil burner for 30 years.
Just relating to HW Flame Safeguard primary controls which have more reading materials than one wants to see, but have to read thru.

Jamie Hall

OK, OK. Let me see if I can do this...



First one is Cedric's home. Other three are Cedric...

ChrisJ

If the #67 was tripped why wasn't the feeder feeding?

Jamie Hall

The huge drum covered in insulation in the first one is the old steam drum from an HB Smith, which was the original boiler. It really guarantees dry steam! The second on is head on of the drop header arrangement and the controls -- the vapourstat is on the header, not on the boiler. Works much better. Single riser, but no problems with wet steam. The third one shows the connections from the drop header to the steam drum -- and the differential loop.

JUGHNE

Thank you, pretty awesome Jamie!
How about a shot of the control....I have never seen one before.

Jamie Hall

ChrisJ said:

If the #67 was tripped why wasn't the feeder feeding?

It was malfunctioning so it's valved off. Something for spring...

STEVEusaPA

Is that a ghost, on the right side, just coveralls, going thru the wall like Harry Potter at the train station?

Yeah I'm with Ed, probably welded contacts in the primary.
Seems like Carlin controls more than the others just don't like heat, and don't like not having a good ground.

GBart

Are you sure all those safeties tripped? Aren't they auto reset?

Solid_Fuel_Man

After the runaway boiler stories, especially this one which we know has been regularly seen and studied. I'm really beginning to think we should consider making LWCO and manual reset high limit, as a separate contactor to cut all power to the boiler. That way even if the controller or primary flakes out the burner will stop. At least on oil it has to stop, gas valves could still stick open.

JUGHNE

On some larger gas boilers redundant gas valves are standard.
"Block-vent-block" is the term IIRC. Vent to outside between valves with electric solenoid valve normally open...power to close when firing.

Jamie Hall

I'm thinking about having the manual reset LWCO and the manual pressuretrol in the main power, rather than the burner control, as @Solid_Fuel_Man suggests.

However, update; the problem was a welded contact in one of the relays on 60200. It wasn't totally welded, but enough to hang now and then. Replaced it with a 70200. Fixed the water feeder while we were at it. Now to get the house back up to temperature...

ChrisJ

> @Jamie Hall said:
> I'm thinking about having the manual reset LWCO and the manual pressuretrol in the main power, rather than the burner control, as @Solid_Fuel_Man suggests.
>
> However, update; the problem was a welded contact in one of the relays on 60200. It wasn't totally welded, but enough to hang now and then. Replaced it with a 70200. Fixed the water feeder while we were at it. Now to get the house back up to temperature...

Be careful Jamie, you don't want that oversized boiler cycling on pressure.

JUGHNE

Would the LWCO and the manual hi pressure switch be rated for enough current to handle the burner motor?

Solid_Fuel_Man

No, they would be used as pilot devices to pull in a contactor generally. Down side is a contactor energized 24/7. No chance of welding that though. A more elegant design would be a normally closed contactor with the LWCO and manual reset high limit as normally open devices. Then no energized contactor, but reliability wouldn't pass inspection on commercial boilers I suspect.

Fred

Glad you are up and running again, @Jamie Hall

JUGHNE

Sounds like a good place for a RIB? I like those with the indicator light on.....you can tell when something is calling.

Charlie from wmass

All contacts are rated for the load and then some. The relay was internal to the burner control and the wiring is by Weil Mclain suggested diagram. The new control acknowledges limit circuit is closed and if thermostat is calling. Bit of an upgrade. Also displays ohms from cad cell

STEVEusaPA

I do like that control...also better onboard diagnostics.

EBEBRATT-Ed

@Jamie Hall

If it was me during the summer I would put the manual reset high limit and the secondary low water cut off in the 'HOT WIRE" to the control and leave the other safety's in the limit circuit.

If the contacts welded and the amps is below the control rating I would be on the lookout for any short cycling of the burner as a possible cause. Something caused it to weld the first time.

Or install a relay to switch the burner motor power. That way if the contacts in the new motor relay welded and the motor stayed on the burner could not run away. The cad cell control would drop out the oil valve, ignition etc if a safety opened

Jamie Hall

I think that rewiring those two safeties is the direction I'm thinking, @EBEBRATT-Ed . That would eliminate one more single point failure.

I'm not sure why the contacts were so damaged -- the boiler does cycle on long runs (like tonight -- 5 below and 40 mph winds are pretty near capacity for the system!) but not unusually so. I'm going to look more closely at them -- but not tonight. Enough disasters for one day.