Resuscitating a sick gauge?

Orple

I'm pretty sure that the stock gauge that came with my boiler (0 - 30 psi) is on the fritz. It reads 15 psi long after the boiler is off, and reads 27 psi at peak. If this were accurate, neither the pressuretrol nor the emergency pressure relief valve should have let this happen. So I'm guessing that something got into the gauge and fouled it up.



My question is this: can these gauges be cleaned and recalibrated, or are they pretty much toast when this kind of thing happens? If the answer is "it depends...," then what should I look for?



(Background: this is a standard 1 - pipe steam system. The gauge in question has an "internal syphon" but was not mounted on a pigtail, so if the line feeding it is gummed up it is inside of the boiler itself. I do not currently have a 0 - 3 psi gauge to confirm brokenness of 0 - 30 gauge, but have it ordered and it is en route. I doubt this is necessary to confirm the diagnosis; what I need is a prognosis.)

nicholas bonham-carter

Cleaning a stuck gauge

Try soaking it in vinegar for an hour or so, and then rinsing in soapy water.

The passages in those internal symphony's are very small, and prone to clogging.--NBC

Hap_Hazzard

The gauge isn't the only problem!

I didn't have any trouble zeroing my gauge, which is a 30 year old US Gauge 30-0-30 internal siphon model, but I think the gauge can wait. You need to look at what it's telling you now.



Basically your gauge is reading 15 psi high. In other words, 15 is your zero. That means your pressure is running up to 12 psi. That's way too high, and probably higher than what your Pressuretrol is set to.



If your Pressuretrol is set to break at 12 psi, turn it down! You should be able to run a one-pipe steam system at less than 8 oz/in². If it short-cycles after you reduce the pressure setting, you either have too little main venting or your boiler is oversized.



If your Pressuretrol is set to break at less than 12 psi but you're still developing 12 psi of pressure, the Pressuretrol isn't working, probably because the pigtail is clogged. This is something you need to fix now, because nothing is limiting the maximum pressure other than the safety relief valve, and the colder it gets outside, the more you'll be flirting with hitting that 15 psi limit and getting a basement full of steam, and you really don't want to see that.

Hap_Hazzard

Gotta love autocorrect.

I bet you posted that from your "smart" phone. ;-)

Orple

So, what should my next step be, then?

The pressuretrol is set to 5 psi with a 2 psi differential (a bit high, I know, but I'm just getting started and those are the settings I inherited.  I figured I'd replace all the crappy vents before trying to drop to lower pressure). 



So if the gauge is still accurate with an offset of 15 psi, that should indicate that the pressuretrol is broken as well. 



I'm  not sure what my next step should be, then.  My 0-3 psi gauge should be here tomorrow; if I install that and the boiler is set to hit 12 psi, will that ruin the new low pressure gauge?  If not, it would be a nice way to figure out what's going on.  If it would, then I guess I should try to clean the old one and/or buy a new 0-30 and see how it reads?



FWIW, I also inherited an older pressuretrol with a mercury switch; was planning to test it against my existing one, but maybe I can use it to actually test the existing pressuretrol.

ChrisJ

Settings

This is where my mercury style Pressuretrol is set to achieve 1.5 PSI off and 0.5PSI on.  This will give you an idea that you don't have to stay in the numbers on the scales.

I'd like to switch to a vaporstat one day just because I'd much rather know it would trip at lower pressures perhaps something around 8oz off at 1oz on.  My system does just fine at 1oz.

BobC

The problem

is that if that pigtail or pressuretrol is clogged and allowing the boiler to run at high pressure you could destroy any new vents you add. many vents don't tolerate pressure thats higher than 5 PSI.



Remove the pressuretrol and verify the pigtail is clear, then look at the base of the pressuretrol to make sure the small hole at the base of the brass fitting is clear. Then put it back together and see how it all works.



Bob

nicholas bonham-carter

Auto speller

How right you are! I am constantly having to correct the spelling, when I am using my iPad. It does capitalize for me which is nice with my non-existent typing skills.--NBC