Faulty pressuretrol AND thermostat??

mookie3333

Crazy thing happened tonight. I received a notice a few weeks back that there was a recall on my Wi-Fi thermostat due to a fire hazard. Received a replacement yesterday, looked like it was refurbished. Swapped the old tstat, setup, and turned on the heat. Turned back off, and realized although I heard the thermostat click, the boiler was still running. Pulled the stat and ran through setup again. Tested again, this time it worked fine.

Woke up at 2 am to realize the same thing had happened again - thermostat was set for 70, but had achieved 86 degrees (!) And was still running. Pulled the stat and the boiler promptly shut off.

Ok, faulty or wrong installed thermostat.. I can deal with that. But after 5 mins I went down into the basement to take a look, noticed water still boiling and my 0-5 gauge pushing past 5psi. I have it set to cut out at 2. Then, I stood there for two mins, and watched the pressure come down gradually to 0.

What the hell happened??? Why didn't my pressuretrol kick in to regulate pressure?? Literally yesterday I noticed that it was functioning properly ( heard the boiler cut off and on a couple times while trying to achieve set temp, boiler is slightly oversized). Gauge and trol are on same pigtail, which makes me think the pigtail is not clogged (same psi exerted on the gauge is same as on the trol).

Even if the pressuretrol was malfunctioning, what's the chances it happens at the exact time add this thermostat malfunction? Going to do some more testing tomorrow. Will get some rest now. Hopefully I won't wake up to a 40 degree house!! (Thermostat left unconnected for the night). Thanks all for your help.

nicholas bonham-carter

Take the cover off the pressuretrol, to expose the mechanism.
Cross the wire on the thermostat to simulate a call for heat.
While the boiler is running, use a pencil or non conductive probe to trip the rocking switch in the pressuretrol, and verify the burner cuts off.
Let the boiler fire up again, and test the LWCO, and see if the burner once again turns off.
If the burner does not turn off during these tests, then check all the wiring against the factory diagram. The safeties could be wired in parallel instead of series.
Don’t forget to uncross the wires at the thermostat.—NBC

mookie3333

Ok, figured a couple things out.

1. I was wrong, pigtail was fill of muck. Cleaned and reassembled all.

2. Think my 0-5 gauge is gone. When I took everything apart, it "tares" at 1.5 psi. I put it to my mouth and blow, needle goes up. I put to my mouth and suck, needle goes down. But zero is still now 1.5

3. Pressuretrol is acting funny. Last night, it didn't trip at all. Now, it will trip, but not resume after pressure drops. Almost as if it needs some wd40. If you manually push up with your finger, it will also click up. If you push down with finger, it will also click down. Needs adjusting? Cleaning? Need a new one?

Thanks again guys.

ethicalpaul

2. Your gauge might have a zero adjust screw. If not, just create a new zero with a sharpie, it’s just for your own troubleshooting anyway

3. Why does everyone think WD-40 is good for things?? 😅

Fred

Did you fiddle with the Pressuretrol Cut-In screw and dropped it so low that the screw fell off of the linkage behind the scale?

Chris_L

3. Pressuretrol is acting funny. Last night, it didn't trip at all. Now, it will trip, but not resume after pressure drops.

The adjustments on the Pressuretrol are not that precise. If you turn down the cut-in too low, you sometimes get the behavior you describe.

Set the differential wheel to as low as it will go (1), and put the cut-in at a little higher (between 0.5 and 1), and see what happens--assuming your Pressuretrol is additive (post a picture).

You may need to calibrate the Pressuretrol. You'll find instructions by searching the archives.

EBEBRATT-Ed

pressure control needs:
cleaning if muck got into it, or may just need adjustment.

Either way it needs to be 100% especially with a troublesome thermostat. If not thing will get exiting when the safety valve blows.

If your not 100% sure of it's reliability ...replace it. If you think the old one is ok and your boiler actually "runs on the pressure control" ad a new one and have 2. Your supposed to have 2 if you run on pressure often.

mookie3333

Ok, I am stumped.

I cleaned the crap out of the pressuretrol, and readjusted so it operates fine. Took off the "new" thermostat, and set it up again (I have RC, RH, W, and C wires). It advised me this time to clip the RC/RH jumper on the back of the stat. I thought for sure this is what the problem was.

Ran heat for about 1.5 hr to bring back up to temp (67 to 72), noticed it still didn't shut off, even though the room temp already surpassed the SET temp. Boiler was firing away all the while. When I went down, the gauge was waypast 5, pressuretrol was past cut off pressure, and boiler was still firing.

Pressuretrol is wired in series with the boiler circuit, at this point, I tested both contacts on the trol and there was continuity whether I manually clicked up, down, etc. I disconnected one end of the trol that goes to the burner, and noticed the trol was working perfectly - continuity was cut when I pushed up, and there was continuity when I pushed down.

The pressuretrol is being bypassed somehow. THe craziest part is that in the same 1.5 hr cycle where boiler failed to shut off, I observed the burner cut off/on a few times on pressure earlier in the cycle (trol was working FINE then, and not now???)


Wiring problem?? Something shorting?? Faulty control/LWCO?? (MM PSE 802) I have no idea what's going on. And, I really have no idea how this is related to the swapping of thermostats!!!

Reverted back to the old tstat for tonight, to see if it goes back to previous (working) condition.

Any help is appreciated. Thanks.

EBEBRATT-Ed

You have to forget everything and start from scratch. Don't know if this is oil or gas but I am assuming gas the wiring is somewhat similar.

First you find your power source. I am assuming it's 24 volt transformer fed by 120 volts

One side of the 24 volt circuit (the common) will go to your gas valve. The other 24 volt wire should go into and out of the pressure control then into and out of your low water cutoff into the thermostat (RH) and out of the thermostat (w) to the other side of the gas valve.

the thermostat, pressure control and low water cut off are wired in series....anyone of them will shut the burner down. They may not be wired in the above sequence could be low water cut off first, thermostat second pressure control third etc sequence isn't important as long as they will shut the burner down.

This is pretty basic. You could have other controls or you could have an oil burner which will change things.

Look for shorts or miswiring. I would disconnect the controls (pressure and low water) test them individually low water should be close with normal water level and open on low water. Pressure control closed with no steam open on a pressure rise.

Could be a staple driven to deep in a wire.

Fred

Could be the contacts in the micro switch on that Pressuretrol. It must be sticking closed but when you manually trip it, you break the contacts.

mookie3333

> @EBEBRATT-Ed said:
> You have to forget everything and start from scratch. Don't know if this is oil or gas but I am assuming gas the wiring is somewhat similar.
>
> First you find your power source. I am assuming it's 24 volt transformer fed by 120 volts
>
> One side of the 24 volt circuit (the common) will go to your gas valve. The other 24 volt wire should go into and out of the pressure control then into and out of your low water cutoff into the thermostat (RH) and out of the thermostat (w) to the other side of the gas valve.
>
> the thermostat, pressure control and low water cut off are wired in series....anyone of them will shut the burner down. They may not be wired in the above sequence could be low water cut off first, thermostat second pressure control third etc sequence isn't important as long as they will shut the burner down.
>
> This is pretty basic. You could have other controls or you could have an oil burner which will change things.
>
> Look for shorts or miswiring. I would disconnect the controls (pressure and low water) test them individually low water should be close with normal water level and open on low water. Pressure control closed with no steam open on a pressure rise.
>
> Could be a staple driven to deep in a wire.

Thanks.my system is actually a three pass oil boiler converted to a gas gun. So the controls are set up a little differently, and not actually in series. Everything goes into the lwco.

The gas burner has 3 wires - black, red and white. White goes to neutral, red to constant 120v (H/C terminals jumped on my lwco, PSE801-120). And black to limit, in this case, the trol. Other side of the trol goes to B on the lwco.

I'm pretty sure the pressuretrol isn't the culprit here. When I was experiencing the high pressure, and trol was showing continuity between both terminals no matter what I did (click up, click down, etc) ..... As soon as I disconnected the wire nut between the burner black wire and lead going into the trol, continuity broke right away. Pushed down on the trol to override, and continuity came right back.

Strange thing .. And I really don't know what role the thermostat plays in this. But seems it does play a role.

Jamie Hall

If the safety controls aren't in series -- and that includes the pressuretrol(s) and LWCO(s), it's wrong. The safeties all have to be in series. The thermostat can also be in series with the safeties.

If the pressuretrol ties into the LWCO in parallel, it will always show continuity so long as there is continuity at the LWCO. And vice versa. And neither of them will shut the boiler down. A very dangerous situation, and should be fixed before the boiler is run again.

EBEBRATT-Ed

sounds like you wiring is correct.

It's pretty simple. Either the p troll shuts the burner down when tripped manually or not. If it doesn't shut the burner down when tripped and the wiring is correct then it is one of two things. If the ptrol is clicking when you trip it but isn't shutting the burner down then the p troll is defective. You can check this by disconnecting the wire coming into or out of the ptrol to see if that shuts the burner down. If it does but when u trip the ptrol manually and the burner doesn't shut down the ptrol is defective

If the limits Ptrol and low water control don't shut the burner down then the burner control is defective.....if your wiring is correct.

a defective control would be rare but would explain the burner not shutting down on t stat or pressure.

Try disconnecting the black wire to the burner control and with the wire disconnected see if you have power on the black from the control. the control could have an internal short

ethicalpaul

I agree with what everyone wrote above, but something you said caught my eye:

> Pressuretrol is wired in series with the boiler circuit, at this point, I tested both contacts on the trol and there was continuity whether I manually clicked up, down, etc. I disconnected one end of the trol that goes to the burner, and noticed the trol was working perfectly - continuity was cut when I pushed up, and there was continuity when I pushed down.

This doesn't make any sense. I'm not sure you are measuring continuity through the p-trol correctly. The p-trol's state of working is not affected by whether it's connected--if things start working when you disconnect a terminal, then your wiring is not correct.

mookie3333

ethicalpaul said:

I agree with what everyone wrote above, but something you said caught my eye:

> Pressuretrol is wired in series with the boiler circuit, at this point, I tested both contacts on the trol and there was continuity whether I manually clicked up, down, etc. I disconnected one end of the trol that goes to the burner, and noticed the trol was working perfectly - continuity was cut when I pushed up, and there was continuity when I pushed down.

This doesn't make any sense. I'm not sure you are measuring continuity through the p-trol correctly. The p-trol's state of working is not affected by whether it's connected--if things start working when you disconnect a terminal, then your wiring is not correct.

Ethicalpaul: I agree. P trol continuity testing should be the same whether it is connected or not. The point I was trying to make is that somehow, the pressuretrol was being bypassed, and continuity was being made through the boiler circuit by some other means. Up until now I can't figure out what happened. I put the OLD thermostat back on, and boiler is working flawlessly. As much as I wanted to think these were two isolated problems (bad thermostat, and some short/bypass of the pressuretrol) I positively know now that the two are related. Just can't figure out why.

Jamie Hall

The next thing to do is to lift one wire at the pressuretrol -- either one. If the burner will still run on a call for heat, it is indeed being bypassed -- which can have interesting results. If you find that this is the case, you are going to have to carefully trace your wiring to make absolutely certain that the pressuretrol is in fact in series with the other controls, and not paralleled with one or more.

ethicalpaul

Gotcha @mookie3333

Jamie's test will tell you a lot, good luck!