System cutting off at 0.25 PSI - Pressuretrol Bad?

alexh

Hello all,

I have a 1 pipe steam boiler system and recently replaced my 30PSI pressure gauge with a low pressure gauge (wasn't ever getting a reading on the 30PSI gauge). I have a pigtail coming out of the boiler with a T attached to it. The pressuretrol and gauge are both attached to this T. I made sure all the pipes were clean and fired up my system. The pressuretrol is set to 0.5PSI with a 1 PSI differential. After a few moments the pressure started hovering around 0.25 PSI. The system ran for a few minutes and cut off before hitting temp (cut off at 64 despite thermostat being set to 68). The pressure never rose above 0.25 PSI. Any ideas what might be going on here? Is it my pressuretrol or potentially something else?

Thank you,
Alex

Long Beach Ed

I suspect that neither the pressuretrol or the gauge have the precision to discern .25 lbs from .50 lbs. If the boiler is shutting on pressure before all the radiators are filled with steam, improve the venting of your mains and radiators or set the pressuretrol higher.

If accuracy is important to you, a vaporstat is generally offers more low-range precision at a higher cost.

alexh

Long Beach Ed said:

I suspect that neither the pressuretrol or the gauge have the precision to discern .25 lbs from .50 lbs. I would set the pressuretrol higher or improve the venting of your mains and radiators.

If accuracy is important to you, a vaporstat is generally more precise.

Hey Ed, thanks for your response. The pressuretrol is set to turn off at 1.5PSI, not 0.5. If the venting was insufficient woudn't my pressure at the boiler be higher than 0.25PSI? Also I redid all my venting recently.

Jamie Hall

The pressuretrol may be out of calibration. Wouldn't be the first time. Try increasing the setting to cutout at 2 and see what the gauge reads.

alexh

Jamie Hall said:

The pressuretrol may be out of calibration. Wouldn't be the first time. Try increasing the setting to cutout at 2 and see what the gauge reads.

I first I upped the cut in pressure to 1-1.5 (hard to tell). When the boiler kicked on it maintained pressure at about 0.5PSI for a while. The system still shut itself off after 4 minutes. I also tried upping the differential to 1.5 which didn't seem to have much effect. It seems that something is telling my boiler to shut off after 4-5 minutes every time.

neilc

what do you have for a low water cutoff?
care to post a picture of the boiler and the controls?
does water leave your sightglass while firing?

Jamie Hall

Ah, We've gotten ahead of ourselves. First thing to find out is just exactly which of several possible controls is shutting off the boiler. From the description, it may well not be the pressuretrol.

alexh

neilc said:

what do you have for a low water cutoff?
care to post a picture of the boiler and the controls?
does water leave your sightglass while firing?

I do have a low water cutoff and have verified that it works properly. My water level bounces around a bit while the boiler is running, but stays within the acceptable range.

Here's a picture of my setup:
https://imgur.com/a/bEtekTz

EBEBRATT-Ed

One of three controls is shutting the boiler down. Thermostat, low water cutoff or pressure control.

You have to troubleshoot them 1 at a time.

Shut power off. Find the wires going to the thermostat. If it is a two wire cable jump the two thermostat wires at the boiler together and then turn on the power the boiler should run. If it cuts off leave the thermostat jumpered shut off the power and jump the two pressure control wires.

Turn the boiler on. DO NOT LEAVE THE BOILER AREA STAY AND WATCH THE GAUGE WITH THE JUMPER IN PLACE. If the boiler now runs the problem is the pressure control. Take the jumper off and re adjust until the burner cuts out at 1-1.5 psi and back on at.25-.5 psi.

If the boiler cuts off with the pressure control and thermostat jumped the low water cutoff is the problem.

BE SURE ALL WIRING IS BACK IN IT'S PROPER PLACE AND CHECK OPERATION OF ALL THREE CONTROLS (STAT, PRESSURE, LWCO) BEFORE LETTING IT RUN UN ATTENDED.

Your bouncing water level could be the issue. Skim the boiler if it is

EBEBRATT-Ed

You should leave the 0-30 gauge on the boiler along with the new gauge code required. Best practice is to put a valve between the 0-5psi gauge and leave it closed.......open it when checking pressure. No valve allowed between pressure control or 30psi gauge and the boiler.

It would be good if you can post some pictures of the steam piping above and around the boiler

alexh

EBEBRATT-Ed said:

You should leave the 0-30 gauge on the boiler along with the new gauge code required. Best practice is to put a valve between the 0-5psi gauge and leave it closed.......open it when checking pressure. No valve allowed between pressure control or 30psi gauge and the boiler.

It would be good if you can post some pictures of the steam piping above and around the boiler

I tested the 30psi gauge to make sure it works and will be adding it back to the system and soon as I get another T and elbow.

Here's some pictures of the pipe routing:
https://imgur.com/a/1QWYYwt

EBEBRATT-Ed

@alexh

Unfortunately, Alex whoever installed the boiler didn't pipe the steam header right which can be contributing to your problems. It can make the water level bounce. I think you may find the LWCO is causing the boiler to shut on and off.

But maybe not we have seen some poorly piped boilers run ok, but you may or may not be able to control the surging without re piping.

If interested check find a contractor on this site. In any event you can download the install manual for your boiler and have a look at the piping diagram. You will see what I mean

reggi

You just changed the gage , cleaned some pipes , adjust the pressuretrol ? and was up to 64° set for 68° and this all began ?
Now you didn't disconnect anything in the 'trol when you were adjusting it or mess around with it's mechanism because the gage is only for your visual, the boiler doesn't need it to function, it needs the pressuretrol functional and that and wires are what you touched.,. so think now and take some closeup pictures and post them..
You're in the right place for troubleshooting it ..

alexh

I jumped the thermostat and the boiler kept running with no issue. So for some reason, the thermostat is telling the system to turn off before it hits temp. Before reinstalling the thermostat, I took a look at the settings on the back of the unit and noticed it wasn't in the "steam, gravity" mode. When I changed the mode, the thermostat no longer worked at all (I cranked thermostat up to 80 and it didn't tell the boiler to turn on. Any idea why this mode doesn't work?

https://imgur.com/a/gLHo5Il

EBEBRATT-Ed

No. Guess it's time for a new stat

ethicalpaul

Or new batteries