Probe style MM LWCO not activating pump during cycle but will when manually draining.

Danny_Jr

We have a Williamson model GSA-175 we replaced with like kind in a 8 unit apartment house. We re-used the control setup. They have two MM probe style LWCO, the lower one of course is a manual reset. When we manually test the primary LWCO it responds properly and brings the pump on. When we let the water evaporate to that level during operation it does not trigger the pump and then eventually the manual reset shuts down the boiler. We do have the controls isolated by a peanut relay and bring the pump on through a fan-center. We replaced the probe and got the same results. We installed a Hydrolevel and got the same results.
The boiler is piped with a 3" main riser on the side of the gauge glass. The waterline seems relatively stable. Scratching our head. Waiting to hear back from Williamson.

Any input is welcome.

Thanks,

Dan Wood
Kalamazoo MI

Jamie Hall

When you say you manually test the probe, is that by activating a test switch on the probe or by manually drawing the boiler water level down to where it should operate? If it's the latter it's some sort of problem with the probe itself or the fiddly electronics within the controller which sense that the probe is out of the water -- which the test switch bypasses.

Danny_Jr

Jamie, when we did the manually draw down test it worked as designed. When we did a Slow LWCO test that is when we had the problem. So we were thinking some how it was the probe. So we replaced the probe in MM and got the same results. Then we installed a brand new Hydro Level and got the same results doing a Slow LWCO test. Some how the probe is not breaking the continuity during an evaporative drop of the water level during operation. The light stays green until it gets down the Manual reset LWCO which operates as designed and shuts everything down until we reset it.

Thanks,

DAN

Jamie Hall

OK. That's a little weird... it trips OK on a relatively fast drawdown, but not on a slow one? Let me think about that a little...

EBEBRATT-Ed

Did you skim the boiler? If the water level is bouncing the probe may not catch it quick enough.

Did you use teflon tape on the probe?...shouldn't maybe check from the control ground to the boiler for any resistance.

Does the LWCO have a delay before bringing on the pump?

What's the m/n of the controls?

ChrisJ

How is the water quality?
Is it good and clean? Any oil?

How is the boiler piped? Can you share some pictures with us?

There's a reason I'm asking.

Danny_Jr

Guys thanks for all the good questions. I was out on the job this afternoon. And I think it was a water quality issue. The water is not oily but it does have it's share of debris. We had flushed the piping fairly well and we added a softener because it was hard water that killed it. I tried to talk her into a softener 3 years ago when we replaced it. She had one of those gimmick magnets on her water service. Fortunately she owns her decision and remembers my strong recommendation.

The water is bouncing a little. Less than a half inch. Today was the first day on was on the job since it was installed. We did do some skimming and draining. But the funny thing is, the Hydro Level LWCO finally started to respond in due time. The control does go to amber and off as the water bounces a little. Then when it finally evaporates enough water the amber light stays on for 10 seconds and then it kicks the pump on. When it wasn't working my tech (and he is a good one) said the light never turned to amber. It just stayed green until it got low enough to trip the manual reset LWCO.

I do have some pictures I will have to get back to the wall when I have time to get them uploaded. The main thing I don't like is the main dead heads into a tee for the equalizer. The system is very quiet. The immediate piping is a little convoluted. All we did was change the cast iron block assembly, Some of the piping was plugged solid. We have 22 grain hard water and it will kill a steam boiler in a hurry.

Regarding the probe. We did not use Teflon tape. We learned that lesson the hard way.

Thanks for your input.

Jamie Hall

Cheer up. Softened water -- if it's a conventional ion exchange -- will kill the boiler even faster than the hard water will...