How do pressure gauges break?

zsobhani

I've been looking around and not been able to find an answer to this question. I'm concerned about my condo neighbor's boiler. I've noticed the pressure gauge reading very high (13psi or so) after a long burn when I assume that all the vents are closed. Most of the time I think it cycles off before any pressure is built up, but occasionally I will see these high pressures, ramping up from zero. I have pointed this out twice and her plumber has come out to look at it. Last year he declared that the gauge was broken and planned to replace it (although I'm not sure if it was replaced). I just noticed it again sitting at 13psi with the boiler firing for an extended period. I suspect that the pressuretrol is not functioning and this is a safety problem. However, before annoying her *again*, I am trying to understand how do pressure gauges fail? Is there a failure mode that would read multiples of the actual pressure? Is it possible for a system to be running 0-2psi and have the gauge read 0-13psi? It just seems like a weird failure mode to me. (I suspect the plumber is a knucklehead). If I can figure out how I will attach a picture. The only problem I have seen with her boiler piping is that the pig-tail on the pressuretrol is in the same plane as the control, where I think it should be oriented perpendicular.

JUGHNE

Does the gauge return to zero with the boiler cool?

Is the gauge on the pigtail with the control?

Was the pigtail cleaned? If pressure control cannot sense the pressure correctly then the boiler could run up to high pressure.

Pictures would help.

EBEBRATT-Ed

Gauges usually only actually fail from vibration (which isn't an issue on a steam boiler), being over pressured, or plugged. The gauge should be removed and cleaned and the pressure control should be removed and cleaned with the connecting piping.

As @JUGHNE pointed out see if the gauge goes back to 0 when the boiler is off.

The pressure control is a safety control the boiler should not be operated if this control is not working

zsobhani

The gauge does return to zero when the boiler is off, so it currently reads the range 0-13 during operation, sorry that wasn't clear from my previous post. The gauge is not installed on the pigtail with the pressuretrol. Last year a plumber did remove the pigtail and clean it. After this the gauge continued to read 0-13 and he declared it broken... I am waiting to confirm if it was actually replaced.

@JUGHNE and @EBEBRATT-Ed thanks for your feedback. I'm new to the forum and didn't get any email notifications this post was posted, sorry I didn't check back sooner to see your responses.

Here is a picture of the boiler:

zsobhani

I've also noticed the sight glass seems pretty plugged with gunk at the bottom. The water level never waivers (ours bounces around a bit), but I am not sure any of that is relevant.

ratio

If the gauge moves & returns to zero, I'd call that working. It perhaps isn't in calibration, but to expect a 50# gauge to be 25% off to the high side, that sounds a little unbelievable.

Even the possibility of 13# in a 2# system needs to be checked out though, why not stick another gauge on the system somewhere & find out?

Leonard

Just for future I think I might add a tee and a dial pressure gauge off a ball valve. That way can test new gauge while operating. Unscrew gauge and see if it returns to zero , and also test gauge at pressure to see if it's any good. Or just add a new gauge

zsobhani

We had another plumber come out and take a look. They were happy with the system (near boiler piping not what they would do, but meh). They were pretty adamant the gauge was busted and they are worthless and it wasn't worth replacing with a working gauge. This part seems so weird to me. That is the second plumber who has recommended just leaving the busted gauge there and ignoring it. They did pull off the pressuretrol and check the pigtail, which was clear. They left before bringing the whole system up to temp and so I still haven't seen the pressuretrol turn off the boiler, but they were pretty confident.

I did do a little test and when the gauge was reading 25psi I opened the drain. The boiler wasn't full hot yet and the water didn't spray out as if it was under pressure, so I'm totally okay with saying the gauge is busted. I'm just still surprised no one wants a working gauge or to test the pressuretrol is actually working. It was like they couldn't fathom it could be bad, so I guess they are really robust!

Thanks everyone for your input.

Zia