bad Pressuretrol or pressure gauge?

David Nadle

Three years seems like a short time for a new pigtail to get clogged, but I only have experience with one steam system, my own, so take this for what its worth.

I'm trying to conceive of a way a pressure gauge could go so far out of calibration that 2.5 psi registered as 5 psi, and I can't. Seems to me a bad gauge would be more likely to fail "low", reading zero, or less than the true pressure. However, it's possible the gauge you have is not made for direct contact with steam and is reacting to the the high temperature.

Assuming the gauge is correct, the fact that the gauge is not on the pigtail points to the pigtail or the pressuretrol being the culprit. You can rule out the pigtail by direct inspection.

I gotta say, as a fairly handy homeowner, I'm comfortable with removing the pressuretrol and replacing it with a new one or a vaporstat, but removing the pigtail from the boiler's tapping is something I would only try in the summer. If you bend or break off the pigtail you'll have no heat until the old one can be removed. Call a pro.

If you do go with a vaporstat you should be aware that they are quite a bit larger than pressuretrols. You may need add some fittings to get it to clear the boiler, like I did. Also, I would add a tee and put a second gauge that reads low pressures next to the vaporstat. Otherwise you'll always wonder what the pressure is ;-)

bklynick

bad Pressuretrol or pressure gauge?

wow, I'm absolutely amazed by the quality of information available in this forum! I have so many questions, but I'll keep it very simple for starters.

I just bought a small 3 story brick townhouse in June, so this is my first winter with the steam boiler.

First obvious issue was the main vents - both were shot. The first one, closest to the boiler was completely corroded on the inside. Steam just shot out of the air vent fogging up the cellar. The second main vent wasn't so bad, but there was leaking from the body. So I replaced them (originally Dole Model 90 size 1) with Gorton size 1 air vents.

So far so good.

Next I noticed the Pressuretrol (appears to be a Honeywell PA404A) was set at 2.5psi with a 1 differential.

After doing some online research, it seems that 0.5psi with a 1.5 differential should be sufficient for a residential steam boiler, so I adjusted the settings as such.

Everything appears to be working - heat is getting to the radiators on all floors ...

My question is, why does the pressure gauge go all the way up to 5psi, then the boiler shuts down? Shouldn't it stop before when it hits 2.0psi?

It cycles a lot before it gets to the thermostat temperature. The pressure gauge moves up fairly quickly, less than 10 minutes before it his 5psi and shutdown.

Is this normal? Not sure if this helps, but the pigtail on the Pressuretrol would be hot from the boiler up until the curl. After that it was basically room temperature.

The boiler is about 3 years old.

Any advice appreciated!

thanks.

Steamhead (in transit)

Sounds like a plugged pigtail

replace it with a brass one if it's steel. While you're at it, spend some money and get a Vaporstat to replace the Pressuretrol- it will give you much more accurate control at lower pressures, 1 PSI and less, saving some fuel.

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David Nadle

Pigtail temp

What you described in terms of the pigtail being hot below and cool above the curl is normal. The curl holds some water like a trap, keeping the steam away from the pressuretrol. That doesn't mean it's not clogged. If anything I say contradicts Steamhead please listen to Steamhead.

Is the gauge installed on the same pigtail?

bklynick

Pressuretrol only cause of pressure build up?

The pigtail appears to be brass (it's brownish color).

Should I remove and clean the Pressuretrol and see if that solves the quick pressure build up issue before I replace it with a Vaporstat? (you've recommened the Honeywell model L408J1009, so I'll try and pick up one of those).

Is it the Pressuretrol causing the boiler to quickly build up pressure, or could there be something else in the system (closed air vents, small piping, etc) that would cause this problem?

thanks!

bklynick

gauge location

The gauge is about 10" or so diagonal from the Pressuretrol - connected to the body of the boiler (from what I can see).

ttekushan_3

pigtail

just remove the pressuretrol, and take a long narrow nylon wire tie (zip tie) and run it through the pigtail. Now take a tiny funnel and pour some fresh water through it. Voila!


BTW, the standard pressuretrol can fail by the internal switch/differential dial assembly cracking at the hinge points. Inside the switch assembly lies the differential wheel with its spring load. If the plastic where those tiny hinge pins are, the boiler will ALWAYS go to 5 lb no matter that you've got the cut-in set at .5 lb and the diff a 1 lb.

5 lb sounds too close to that "magic" number associated with a cracked pressuretrol switch assembly.

So go with the vaporstat as Steamhead said. You have a good excuse.

-Terry

J.C.A._3

While you've got ....

The pigtail off for cleaning, check the pressure gauge port and fittings too.

If the pressuretrol is plugged, the pipe leading to the gauge will probably be too. Steam gets in but can't get out. The gauge doesn't know that and just shows what it reads. It could be a LOT different from what the pressuretrol is seeing.

Give it a shot. Chris

bklynick

remove pressuretrol

I agree David - I'm very hesitant to start removing the controls especially since it's starting to become extremely cold here in NYC and I have 7 tenants in the building! One screw up and out come the electric heaters, which I'd rather not have to deal with now.

Regarding the gauge - the cut-out is actually 2psi (0.5+1.5 on the diff).

I spoke to a neighborhood plumber and he assured me today that it's not unusual for a pressure gauge to hit 5 even if I have the cut-out set to 2!

He also told me a clogged Pressuretrol would simply not work and cause the boiler pressure to overload and blow the release valve. He told me not to worry, everything is OK.

sigh.

So right now the heat is working, but the quick raise in pressure just has me concerned (which causes it to cycle very quickly).

I'll post some pix in this topic w/ some more questions.

bklynick

test the 5lb limit?

Would I be able to rule out the cracked pressuretrol switch assembly by setting the cut-in and cut-out higher than 5? If it makes it past 5, then it may not be a cracked switch?

bklynick

now with pix!

Does it look like the pigtail is steel (I may have answered incorrectly before)?

I like the idea of removing the Pressuretrol, keeping the pigtail attached to the boiler and pushing out the clog - is that a reliable way to clean? I don't want to have the gunk just come right back up.

When I'm ready to re-attach, do I just use pipe dope on the threads?

Everyone seems to be recommending a Vaporstat, but I'd like to keep things simple at this point ...

thanks again.

David Nadle

More speculation

Something is shutting off the boiler, could be 2 psi, could be 5, we can't be sure. That's the only problem I have with your plumber's answer. I'd want to know which device is right. But I do agree with him that you shouldn't worry.

This is just guessing, but maybe you found the pressuretrol cranked up to 2.5/3.5 because the cycle was too short for someone's liking at the lower setting? Maybe the boiler is way oversized for the load? Before you do anything you should get Dan's book "The Lost Art of Steam Heating." With the info in there you'll be able to measure all your radiators and add up the EDR then compare that to the boiler's net rating. By the way I'm not so sure ten minutes is bad if the building is heating well. Hope someone more expert will tune in on that one.

Another thing to check is, are you sure none of the tennants shut off their radiators if the room gets too hot?

Your pigtail looks like steel to me, and yes, use pipe dope when you put the pressuretrol back on.

David Efflandt_2

I am just a homeowner, so I do not know how gauges are typically connected to the boiler. But my gauge is on top of the boiler on a snubber, and the snubber was plugged up when the new boiler started its second heating season (my 1st winter in the home). So the gauge was just reading trapped air pressure (way high) being heated by the steam. A sign of plugged gauge connection might be if the pressure does not drop to zero almost immediately (within 30-60 seconds of boiler pressure cycling or shut off).

Since soaking the snubber in vinegar did not help, I drilled a tiny hole through the snubber with the smallest drill I could find. And since most pressure gauges had a stop at 2 psi, I used a pressure/vacuum gauge (all metal except plastic lens) to actually watch it cycle between 1.5 and 0.5 psi (0.5 cut-out, 1 psi rising diff). 5 years later this fall it seemed to read high again, so I rodded out the tiny hole in the snubber with a paper clip and the gauge is accurate again.

I probably should put a pigtail on the gauge connection to isolated it from steam, but the temperature of low pressure steam has not adversely affected it yet.

Some steel wool may help you determine if your Pressuretrol pigtail is copper/brass or other (gray metal).

BRIANJ

Pressretrol

I'm also a Home owner. I get the same readings on my Internal Syphon usuially 4 to 5 lbs. however, this number doesn't seem relevant because my Vaporstat shuts down the system at 10oz. all the time. I called Peerless for an explanation but they couldn't/wouldn't help. Said only engineering could answer the question. Is there anyone who can explain this for us.

As always thanks for the help. Brian