Can't stop the cycling!

josephny

I did the push-the-rocker-arm-down test after the boiler stopped firing multiple times and it sure does seem to be the pressuretrol shutting it off. There is a second high pressure safety cutoff that I have not tested. Am I correct that if that one tripped then a red button press would be needed to make the boiler fire again?

josephny

I’ve been looking for a drain valve on the return line to see if the return lines have accumulated sludge. But, I don’t see any drain valves.

See below. Some of the drain pipe is encapsulated in concrete.

josephny

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1877901#Comment_1877901

Not a bit surprised.. It's doing exactly what it is supposed to do — control the system pressure to a reasonable level. Technically what is happening is that the boiler is producing a little more steam than the system can condense, so the pressuretrol just shuts it off now and then to let the system catch up.

Now the one with the red button — yes, you need to press that button to get it to turn back on again. Like anything else with a red button, though, you need to find out why the pressure got high enough to trip it before you reset it. Obviously the operating — control — pressuretrol didn't shut the system off when it should have — so the next question is why?

mattmia2

when you flood the boiler to look for leaks above the water line in the boiler, you look under the boiler for water leaking out.

buried wet returns commonly leak without being noticed so your returns under the floor could be leaking.

josephny

https://forum.heatinghelp.com/discussion/comment/1877909#Comment_1877909

I need to go a little slower please.

1) The larger, red-button pressure control does not trip (that is, the button has never needed to be pressed.

2) My push-the-lever-down test was supposed to prove that the pressuretrol was NOT shutting off the boiler.

3) If the above is true, then we are back to the LWCO shutting it down, which seems to make sense to me and is the current direction of exploration. that is, to determine whether there is a leak or a failure in the return lines.

Is my understanding incorrect or misguided?

Thank you!

mattmia2

if the water is leaving and later coming back, tripping the lwco, it is not a leak and probably not clogged returns though that is a possibility. it is more likely that the boiler is throwing liquid water in to the mains with the steam.

Jamie Hall

'll give you full marks for persistence. However. You need to find out if that control pressuretrol is tripping on pressure. You haven't yet.

I really think you need to go back to basics here. There's been a lot of fog in this thread!

There are, on your boiler, apparently three active controls: the thermostat, the control pressuretrol, and the low water cutout.

The cycle behaviour which you describe of perhaps 20 minutes on, then a 1 minute shutdown, then running again. is almost certainly either the control pressuretrol or the low water cutout doing what it is supposed to do. If it is the control pressuretrol, stop worrying about the cycling. It's quite normal. If it's the low water cutout, you should be able to veryify that by observing the water level in the sight glass. Where is it when the boiler cuts out, and where is it when the boiler cuts back in?

Check the control pressuretrol with a multimeter. The jiggle the lever doesn't tell you anything useful. When the pressure is below the cutout, the multimeter will read zero voltage across the terminals. If the pressure is above, the multimeter will read voltage across the terminals (it may be 24 volts AC — but be caution: on some systems it may be 120 volts AC).

Now if it turns out to be the low water cutout — which you can verify by observing the sight glass — there are things involving slow returns which can be done to eliminate or at least reduce the problem.

But at least find out what's turning off the boiler before fussing about anything else…

josephny

https://forum.heatinghelp.com/discussion/comment/1877930#Comment_1877930

https://forum.heatinghelp.com/discussion/comment/1877761#Comment_1877761

How "cold" is cold in "starts from cold?" If I shut it for an hour will that be cold enough for this test?

Is it a sufficiently valid test to check which gets hot first: The returns or the mains at the edges of the basement (where the main vents are)?

mattmia2

off long enough for the returns to feel cold or cool at least. if they get as hot as the boiler early in the cycle it is probably throwing water in the mains

Jamie Hall

Please tell me which control is actually cycling the boiler… please…

josephny

https://forum.heatinghelp.com/discussion/comment/1878003#Comment_1878003

I would truly love to — I very very much appreciate your patience and help.

I'm not onsite until next week and the guy I have there probably can't follow the instructions of using the multimeter.

I thought that putting downward pressure on the pressuretrol rocker arm was a good test, but I now understand (well, i don't understand, but I believe) that it is not.

In the past 48 hours the boiler has been behaving much better, with longer off times, and water level in the sight glass that returns to a nice level during those off times. I don't know how diagnostically value that info is.

So, I am still unsure if the boiler is stopping because of the pressuretrol or the LWCO.

Right now (just as an example), the boiler has not been firing for 30 minutes (outdoor temp is about 43* F).

The image below shows the water level now (after not firing for 30 minutes). Green marks the current water level with the boiler not firing but moderately hot. Water has not been manually added in at least 48 hours (maybe 72).

Jamie Hall

Thank you! The reason pressing on the lever in the pressuretrol is not really a good test is that while it does say that the switch works — which is nice to know! — is that it doesn't say, reliably, whether that is the control which is doing the cycling.

Looking at the water levels, I do wonder now if it may not be the low water cutoff — or cutoffs. From the photo it looks as though there is also a float type LWCO. That green line is very close to where the control gets unhappy. Since you are not adding outrageous amounts of water, it doesn't seem that you have a serious leak (you may still have one, but let's worry about that down the road here). So… try adding water manually, with the system cool (it doesn't have to be cold) to that black mark on the sight glass. Some systems may have slow returns, but not so slow as to be a problem, and are just happier running with a higher cold water level. It won't hurt anything to try!

I remain baffled by the pressure. If that valve is the boiler feed, it should raise the level in the sight glass — but that has almost no effect on the pressure. But… I notice that there is what almost looks like a compression tank hanging above the boiler. Is there, by any chance, a hot water heating loop connected to this thing as well as the steam?