Another Mystery!

New England SteamWorks

We installed a Weil McLain 380 in the summer of 2018, which ran fine for the first season. This September we performed routine maintenance and encountered no issues.

Friday the customer emailed that the VXT read out said LOC (which means it fed twice without satisfying the LWC), the TT was not satisfied, the Safegard primary LWC light was on, and the water level was halfway up the gauge glass

We didn’t get back to him and so he did nothing (there is auxiliary heat in the home).

Saturday the boiler resumed operation on its own. Saturday night it ran out of water, but continued to fire until the alarm went off and the boiler was manually shut down.

The boiler has two LWCs. The secondary is a Hydrolevel 500 with manual reset. When we arrived there was no water in the boiler, and both LWCs had their lights on. After adding water the burner would not fire until the 500 reset button was pushed, clearly indicating normal function.

So the mystery is: How in the world did the dry fire occur? The boiler needs new gaskets, but otherwise seems fine. The obvious worry being a reoccurrence if no cause is established.

SeanBeans

Manual reset LWCO wired wrong? Or jumped out?

Ironman

Since both LWCOs failed, I'd look to see if there are mineral deposits on the probes causing a false reading.

Whatever the cause, it's common to both. Check the wiring as Sean suggested.

acwagner

The feed water line between the two is also common. Obstruction in the feeder water line?

Any chance the city main water lines were redone over the summer? That usually dumps a ton of debris into the lines that will clog things.

Jamie Hall

@New England SteamWorks -- the above ideas are good, but... there is another possibility which should be at least looked at. There is a relay in the burner control which is the last line to bring the burner on (it connects mains power to the burner motor). The one for Cedric welded on last winter, with rather spectacular results much like what you are describing (ask @Charlie from wmass !). If that really welds on, nothing other than the manual "emergency" switch will shut things off, unless one or more of the safeties are wired into the 120 volt feed to the whole show, rather than into the burner control.

New England SteamWorks

> @SeanBeans said:
> Manual reset LWCO wired wrong? Or jumped out?

No, as stated everything wired correctly, and the burner would not come on until the manual reset was pushed.

New England SteamWorks

> @Ironman said:
> Since both LWCOs failed, I'd look to see if there are mineral deposits on the probes causing a false reading.
>
> Whatever the cause, it's common to both. Check the wiring as Sean suggested.

As
> @Ironman said:
> Since both LWCOs failed, I'd look to see if there are mineral deposits on the probes causing a false reading.
>
> Whatever the cause, it's common to both. Check the wiring as Sean suggested.

> @Ironman said:
> Since both LWCOs failed, I'd look to see if there are mineral deposits on the probes causing a false reading.
>
> Whatever the cause, it's common to both. Check the wiring as Sean suggested.

As stated, both LWCs tested and passed.

New England SteamWorks

> @acwagner said:
> The feed water line between the two is also common. Obstruction in the feeder water line?
>
> Any chance the city main water lines were redone over the summer? That usually dumps a ton of debris into the lines that will clog things.

The VXT refilled the boiler without incident. Water supply seems fine.

BobC

Are the LWCO in the 24 or the 120v line? @Jamie Hall might be right about a stuck relay if the controls are in the 24v line.

Bob

New England SteamWorks

LWCs are both 120v

JUGHNE

Would the piping retain enough water to fool the probes.
The long one on the left could have perhaps enough tilt down to keep the probe wet??

Is this gravity return, if so it seems like it not run out of water.
Just overheat the building by constant running.

New England SteamWorks

Gravity. We think there are steam leaks somewhere in the finished basement.

New England SteamWorks

> @JUGHNE said:
> Would the piping retain enough water to fool the probes.
> The long one on the left could have perhaps enough tilt down to keep the probe wet??

Will check this.

JUGHNE

Do you test the function of LWCO by draining boiler or simply pushing test buttons.
To me the test buttons are testing the electronics of the LWCO and not the probe. Just old school thinking of an old guy.
Perhaps they are more sophisticated than I realize.

clammy

I think your on the right track w a possible steam leak . I have seen them do crazy things to water lines and dump copious amounts of water out of whatever pipe has developed a leak you would be surprised I certainly was, especially on dry returns and on drips but don’t count out run out s to rads .the boiler emptying may be the result of a few things all happening at once and when she finally shuts down she hot and the rest of the water just steams off . Was the block leaking from the gaskets being toast ? When you refilled was the boiler muddy when first fired in my experience that’s a indication of make up water always seems to be a lot of mud especially when it was pretty clean before any issues . It seems that even when systems do take of water normally there’s never as much mud in the boiler as to when there was a good size leak and you repair and wash and skim the boiler about a week or two later there’s chocolate milk back at the boiler usually way more then you would think . I think the leaks really increase the carry over and wash everything back but it just a thought , Peace and good luck clammy

New England SteamWorks

> @JUGHNE said:
> Do you test the function of LWCO by draining boiler or simply pushing test buttons.
> To me the test buttons are testing the electronics of the LWCO and not the probe. Just old school thinking of an old guy.
> Perhaps they are more sophisticated than I realize.

Well, in this case the primary concern was if the LWCs opened to shut down the burner, and the answer was yes.

New England SteamWorks

The water was not muddy when we refilled. Small leak at top gasket. we will replace all gaskets tomorrow.

I think the fact that the VXT went to LOC when it never did before is an important clue, but can’t identify what it is....

Then: Off on low water on primary LWC Friday and a day later it starts running again without intervention...

ChrisJ

New England SteamWorks said:

The water was not muddy when we refilled. Small leak at top gasket. we will replace all gaskets tomorrow.



I think the fact that the VXT went to LOC when it never did before is an important clue, but can’t identify what it is....



Then: Off on low water on primary LWC Friday and a day later it starts running again without intervention...

Are you absolutely sure this information is correct?
No one else touched the boiler? For sure?

New England SteamWorks

As sure as one can be. The owner is a physician and I questioned him carefully. He is very sharp. Wife and two small kids never go in boiler room. No one else lives there.

ChrisJ

New England SteamWorks said:

As sure as one can be. The owner is a physician and I questioned him carefully. He is very sharp. Wife and two small kids never go in boiler room. No one else lives there.

Trust no one.

The first thing I'd do is fill it, fire it and drain it while firing and watch what happens. Do the LWCOs actually shut it off, do they trip in a reasonable amount of time etc.

You technically don't have to actually run the burner, just be sure it would be running if it was on etc.

ethicalpaul

Did you determine where the water went? Something is fishy, I share ChrisJ's skepticism.

Also you said the boiler fired until "the alarm went off". What alarm?

New England SteamWorks

Smoke alarm

New England SteamWorks

There is a steam leak(s). Always has been. Just can’t find it. Not a new condition.

Of course we will repeatedly test everything once we change the gaskets out tomorrow. But I am pretty certain that everything is going to check out.

As far as trusting him, I do. He is the only person in the world with more of a vested interest in discovering the cause as I.

ethicalpaul

New England SteamWorks said:

Smoke alarm

Wow

Yeah I wasn't thinking he was lying to you, I was thinking kids' mischief

acwagner

Did you find out what happened?

New England SteamWorks

No, we did not. We took it all apart, replaced all the gaskets and controls, and tested a zillion times. Never found anything out of the ordinary.

However: the customer did say their city water mains were recently replaced. Hat tip to @acwagner above.

Steamhead

Long shot here- check to make sure the hot and neutral wires are not reversed.

New England SteamWorks

> @Steamhead said:
> Long shot here- check to make sure the hot and neutral wires are not reversed.

We did. We checked the wiring until our eyes crossed...

Ron Jr._3

Looks like one of the probes is way too far out on a nipple to work to manufacturers specs ?

EBEBRATT-Ed

sludge around the LWCO probes in the long nipple is the only thing I can think of

lchmb

Is the LWCO wired to interrupt primary power or just on the limit power leg on the burner control?