Boiler won't come on

Shemp

Looking for some help here please...

My steam boiler would go through one cycle then not come on again. When I let some water out of the low water cutoff it would come on again for just one cycle. Then I would have to tap the LWC or let some water out and it would come on. Finally it wouldn't come on at all.
Had a guy come in and he replaced the float in the LWC, only cost just over $1200.

The boiler worked ok for a month, now it's doing the exact same thing again.

It won't come on, I managed to get it going earlier when I let some water out of the LWC but I don't know if that was the problem.

Does anyone know if something else could cause this? Something wrong with the pressuretrol?

The pilot light is on, The water is at the correct level. I tried touching the two thermostat wires together, nothing works.

Any help is appreciated, I'm hoping someone can give me a few trouble shooting tips that might help me find the problem.

Thanks.

Shemp

Could it be the vent damper? I noticed that when it did come on there was a noise from the vent and then it would fire up a few moments later.

Fred

My guess is the pigtail (looped pipe) that the Pressuretrol is mounted on is clogged and holding a little pressure so that the Differential doesn't drop down to the cut-in pressure. Tap the Pressuretrol and see if the boiler fires. If it does, clean that pigtail. If that doesn't work, the inside walls of the LWCO could be caked with crud and the float is hanging on the side walls, especially if you blew it down or the float dropped enough for the boiler to call for water, and then hung up against the side wall. Did the tech clean it out when he put the new float in? If it's the LWCO, tapping it a bit should cause the boiler to fire. If that is the problem, the LWCO needs to be scraped out.

Shemp

Tapping on the LWCO used to get it started, I've also tapped on the pressuretrol and it would start. Now nothing seems to work.

I will clean out the pig tail and see if that works.

To do that I would have to remove the pressuretrol and clean it from the top?

Fred

Yes, you have to take the Pressuretrol off and clean the pigtail. If it's really clogged, you may have to take the pigtail off too to wash it out. Once you take the Pressuretrol off try to blow into the pigtail and see if you can clear it that way. When you put the Pressuretrol back on, make sure it is level as that is a mercury bulb Pressuretrol and it needs to be level. Did you agjust the Differential? If so, did you turn it all the way down? If you did, it is possible that the linkage behind that scale dropped off of the end of the screw and that will keep the boiler from firing. Take the plastic cover off and look behind that scale and see if the linkage dropped off. If so, thread the screw back onto the linkage.

EBEBRATT-Ed

Please tell me he didn't charge you that amount to replace a low water cutoff float?

If (and only if) your comfortable with electricity, shut the power off at the circuit breaker panel. Take the cover off of the pressure control and the low water cutoff.

get a piece of insulated wire 6" long and strip both ends. Set the thermostat to call for heat. Turn the power back on.

use the wire to jump the pressure control terminals. hold the jumper on there a few seconds and see what happens.

If that doesn't work jump the low water cutoff terminals and see what happens

Do not under any circumstances permanently jumper any controls.

If it does start then the low water cutoff or pressure control need to be serviced

Shemp

Thanks for all of your help.
I'll do all of that tomorrow.

Yes, just over $1200, that included 13% tax and it's in Canadian dollars. lol.
I thought it was high but he did leave the old parts.

He also replaced something else (I forget what it was but he said he may as well do it at the same time) and also a pressure release valve.

Shemp

Shemp

Could the grey box below the pressuretrol be causing problems?

Neild5

Is there a pigtail on the grey pressuretrol? I see only one, but it may be the camera angle .

Neild5

Also it could be the camera angle but it looks like the water level is high. If there is no pigtail on the grey pressuretrol and the water level is at or above the pressuretrol that could be the problem.

nicholas bonham-carter

Sharp eyes-Neil!
To test the pressuretrol system, both of them must be electrically jumped at the same time.--NBC

Abracadabra

Did he clean out the LWCO chamber before he replaced the float?

Shemp

There is only one pigtail. The grey box is connected just underneath the pressuretrol and just above the LWC. So the water level should be below a certain point in relation to the grey box?

Shemp

I don't know if the LWC was cleaned out. I'll have to ask the guy that did it. I hope so.

Shemp

The grey box is set at 5.

Johnson_Rod

> @Neild5 said:
> Also it could be the camera angle but it looks like the water level is high. If there is no pigtail on the grey pressuretrol and the water level is at or above the pressuretrol that could be the problem.

This makes a lot of sense since the boiler fires up again when water level is lowered. Install a pigtail under the second pressuretrol (gray box) to protect the control and elevate it further from the water level.

Gsmith

The grey box is a high pressure pressuretrol which acts as a backup to the pressuretrol with the clear cover and is supposed to stop the boiler if pressure gets above its setpoint (you said 5 psi) if the lower pressure pressuretrol (the one with the clear cover) for some reason fails and does not stop the boiler at it's setpoint (usually about 1.5 psi).

I suggest you put the grey box on a separate pigtail mounted like the one with the clear cover so that the bottom of the grey box is above the top of the glass tube (about the same height as the pressuretrol with the clear cover). The pigtail is there to provide a water seal between pressuretrol and steam in the boiler so that the pressuretrol is not damaged by high temperature steam. I would try mounting the grey box higher on its own pigtail and see how that works. It is possible the grey box pressuretrol was damaged by no pigtail and low mounting (within the boiler water level), but maybe not. Mount it higher to see if it works that way, if not, perhaps have it (grey box pressuretrol) tested or replaced.

Good eye @Neild5 for spotting that!

Shemp

Shemp

Here are some better photos. So this morning I tapped on the grey pressuretrol and the boiler fired up. Everything was just as you see it in these photos.

Shemp

It looks like it should be pretty easy to install a pigtail...

Tim McElwain

What is the voltage that powers your system? If it is Powerpile Self Generating control system the problem could be a millivolt problem.

Shemp

I don't know Tim, lol. I'll see if I can find that out.

Fred

That grey, smaller Pressuretrol is actually below the pigtail and has not been protected from steam. It needs to be on a seperate pigtail and on a seperate boiler tapping. Also, if you can move both off of that McDonnell Miller #67 LWCO, that would be best. I had the same set up on my boiler and the pigtail and tapping on top of the LWCO get plugged with gunk very, very easily and, if you leave it there, the pigtail and tapping need to be cleaned at least twice every heating season.

Tim McElwain

It is either 24 volts or powerpile. The millivolt systems tend to act like yours and many times it is just a poor connection or a bad splice. It can also be the low water cutoff switch using up too many Millivolts and the same for the pressuretrol. The double pressuretrol was a requirement that was added a few years back. One pressuretrol is wired into the control circuit and is set 2 pounds off 1/2 pound on. The other pressuretrol is wired in series with the pilot generator and is designed to shut the system off in an emergency were the pressure is heading toward 15 pounds and would blow the pop safety, In that case that pressuretrol is a safety and not an typical pressuretrol limit.

Tim McElwain

On some 24 volt gas valve systems the limits are wired on 120 volts which is what yours looks like so it may be some cleaning is needed on pigtails and the low water cut-off.

JUGHNE

Seeing the metal BX cabling; it is not impossible that the safety controls run on 120 VAC, cutting out the 24 VAC transformer?

He has a vent damper, so guessing not millivolt system.

Shemp, is your pilot burning all year long?

Does anyone else notice the "skimmer trough" plug? Never seen that term before, but then I haven't seen much.

Note: if controls are 120 VAC then some caution when jumping out controls!

Shemp

Hi Jughne, yes the pilot burns all season long. I shut it down completely in the summer.

JUGHNE

A picture of the gas valve so the numbers could be read and some pictures of the boiler from far back would be helpful.

Fred

Follow those cables from the Pressuretrol and/or the LWCO and see if they go to a box mounted on a joist or on the boiler that has a 24 volt transformer on it. I suspect it is 24 volt but it could be 120 VAC.

EBEBRATT-Ed

The pigtail has one function...to protect the pressure control(s) from steam

Mounted on the #67 LWCO they are below the water line and do not need a pigtail.

That being said I am not a big fan of mounting them below the water line although a few boiler manufacturers show them mounted there and provide the fittings to do so

WayneMech

Just a side note: The pigtail should be turned 90*, so that heating it does not affect the mercury bulb action.