Pressure Questions

JohnW2

I recently had a Gorton #2 main vent and some Tunstall adjustable radiator vents added to my one pipe steam system. Our house is pretty small, about 1200 square feet. I'm getting hissing and whining from the new radiator vents, not when the system comes on, but after it has been running for a while. If I try to set the numbers on the vents low, one of the small radiators in the house starts going crazy. I have to turn them up to at least 5 to stop the noises, but I'm still getting a little bit of hissing and squealing. So my questions are:



1. Does this sound like too much pressure in the system? I have an additive Pressuretrol, and the cut in is set at 2, and the differential dial is at 1.



2. I'm virtually certain that the gauge on my pressuretrol is broken. It's a 1-15 gauge, and I've never seen it move. I've tried tapping it, but that does nothing. We just had a new brass pigtail installed, so there should be no problem with the pigtail. Is there any safety danger to having it not working? Does the gauge effect the operation of the pressuretrol in any way?



3. I've never been aware of the pressuretrol shutting off my system. It's always shut off by the thermostat. Is there any way to verify that the pressuretrol is working correctly?



Thank you.

nicholas bonham-carter

A cry for help

I have always thought of noisy vents as a sign of over pressure and under main venting. Is the connection under the new pigtail free and clear?

Turn the boiler off, and unscrew the gauge, and fire it briefly, to see if the boiler tapping may be plugged. Even a 0-15 psi gauge, is rather inaccurate for diagnosis.--NBC

Jamie Hall

Almost certainly

the cutout pressure is too high.  I'm not quite sure what the numbers for cutout and cutin you cite are saying; the cutout must be higher than the cutin, so it makes me wonder if one of those two numbers is a differential rather than an actual pressure.



It is possible to set a pressuretrol lower, although iit needs to be done with care to avoid having the thing come apart on you.  Try to set it so the cutout is 1.5, and the cutin around 0.5.  Depending on the particular pressuretrol,, this may be a main dial setting of 0.5 and a differential of 1.0 (that would be called an additive pressuretrol) or it might be a main dial of 1.5 and a differential of 1.0 (that would be a subtractive pressuretrol).



The 0 to 15 gauge is there for the insurance and code folks, and I'm not surprised it doesn't show much.  They usually don't.  You could add a 0 to 3 psi gauge on the same pigtail as the pressuretrol, though, which would show something.



If the pressuretrol never shuts your system off, even on a very long run, either you boiler is very closely matched to your system or the pressuretrol isn't working...

JohnW2

Additive Pressuretrol

Sorry, I should probably go back and edit my main post. I'm still trying to grit the lingo down. I have an additive Pressuretrol. The cut in is set at two, and the white differential dial is set at 1. But now you're freaking me out a little bit. You mean if I just turn the screw that controls the cut in pressure, the whole thing can fall apart on me?

Jamie Hall

Don't freak -- it's not that bad

If you have an additive pressuretrol, you should be able to safely dial the cutin down to 0.7 without having it fall apart.  Then your differential -- set at 1 as it is -- will give  you a cutout of 1.7 -- still higher than ideal, but much better than what you have now.

JohnW2

Thanks

Thanks, Jamie. The only problem is that it looks like there are no numbers between .5 and 2. I'm not in front of it right now, but it's kind of weird. The numbers aren't evenly spaced, and I think it goes something like .5, 2, 5, 8, 9. It looks pretty much like the one pictured in Dan's book We Got Steam Heat. He says to bottom it out, but the concern is that it might fall apart if I try to do this? I'm not sure if I could tell what .7 is, since I don't see anything between .5 and 2. Should I just try to lower it a little, but not all the way, and see what happens?

Jamie Hall

Yup...

that should do -- try it just a smidge above 0.5