possible pressure problem

Josh_14

Hi,

I just had a boiler tune-up performed by a keyspan tech. I have one-pipe steam heat. I hate to second guess professionals, especially since I know so little, and I'd like your opinion on the matter.

Barring what I think are minor issues, everything is fine with my system (before and after tuneup) - every room heats up, and the heat is quite even.

My concern is what is shown on the pressure gauge. If I get the house really hot - 75+ - I've seen the pressure (on the gauge) reach as high as 10 psi. I don't think I have ever had the pressuretrol trip to turn off the boiler. It is set at 0.5psi with 1.5 diff. The boiler fires continuously until the thermostat turns it off as the desired temp.

I asked the tech about this - he said 9/10 times the pressure gauge is broken. I can buy that. But he didn't test or replace it! He did replace the pigtail going to the pressuretrol. It was clogged. (I would imagine that a clogged pipe leading to the pressuretrol may cause it not to function properly!!)

I told him I was concerned about the pressure because I've seen the gauge read at 10psi before. Didn't think this should happen. He told me that if there was high pressure the safety relief valve would blow. I asked him at what pressure, he said typically between 12 and 15 psi. I'm no math whiz, but I know my concern of 10psi is less than that, so why would it blow?? Arg!!

So, my question: how can I test the pressure in the system and how can I check if the pressuretrol actually functions? I know that when the gauge reads more than 5psi, some of the air vents in the radiators (which have already clicked shut) start to hiss very quietly and consistently. In my imagination, I figure they are venting due to excess pressure beyond what they can handle (the instructions say they will open and close up to, I think, 3psi. Don't know what they do after that).

thanks for all the help, apologies for the large post.
Josh

Brad White_9

You call THAT a big post, Josh??

Stick around when some of us get going!

I too suspect the gauge and am frankly amazed to see any gauge provided on a boiler actually working. Like the Easter Bunny or Elvis, I am sure that it exists. They are often installed without pigtails, directly into the steam chest which occasionally becomes a water chest. I have seen gauges constently go to 20 PSI while the actual pressure relief valve, when tested, was indeed at 15 PSI as it should be.

The way to be sure is to use a trusted gauge in a clean pigtail. If you can locate a low pressure gauge (say 0-15 or even better 0-5 psig) with a larger dial (say 4") it makes life a lot easier.

Keep in mind though that the 0-30 PSI gauge on the boiler is code-required so the newer gauge we are talking about is, if permanent, in addition to the boiler code gauge.

Josh_14

thanks for the quick response, Brad.
Actually, my gauge is installed without a pigtail! I don't know if the gauge is accurate, but it is consistent, at any rate. Maybe if I find out the actual pressure, I can just draw it on the outside of the gauge glass

So - about the pressure: In a typical one pipe residential steam system with just a single main, is there any telltale signs at the radiators or elsewhere that would indicate what pressure the system is under? Do they make pressure gauges that can fit in the place for a radiator air vent?

Apologies if the above sounds absurd - but I'm not equipped to make permanent changes to the piping or otherwise by myself. Simple (reversible) things I can handle.

Brad White_9

Pressure at Radiators

Yes, you can get a gauge with either a 1/8" or 1/4" nipple plus some fittings and elbows to fit your vent tapping (usually a 1/8" FPT tapping).

But be warned to do this when the system is off or the radiator valved off.

Also, this is the tough part, properly designed, your system would run at less than 2 PSIG and ideally, just ounces at the radiator.

Most gauges are 0-30 so this is like using a Mach Meter to clock a snail. Get a low pressure gauge, 0-5 if you can. H.O. Trerice is one of several good companies. May not be stocked but you can ask.

I would test it at the boiler though; that is where it counts.

Josh_14

pressure

wow, you are fast!
re: gauge at boiler. Is this as simple as unscrewing the gauge that's there and temporarily putting on a better one? If I don't use a pigtail, is the reading going to be inaccurate?