One pipe residential, pressure gauge doesn't register

Fatbackbeat

One pipe residential steam, P-troll set at .5 & 1.5, gauge never moves. Heat is working well. Is the boiler not building any pressure or ??? Thanks

JUGHNE

What does the gauge look like?

Jamie Hall

If it ain't broke, don't fix it. Chances are, unless that is a 3 psi gauge and not the code-required 30 psi gauge, it wouldn't register the pressure your system is running at.

JUGHNE

I believe it is worth having a 0-3 or 0-5 PSI gauge as the controls are not very reliable. I have seen a 0-60 PSI and even 0-100Psi installed. The 0-100 is about the cheapest made and most available.
Does your boiler short cycle while operating?

Fatbackbeat

Thank you for the quick replies - boiler is not short cycling, though sometimes having trouble getting large radiators hot all the way across (except on really cold days when the heat very well) - I'll confirm the range of the gauge to you later, I am certain it is a lower range, definitely not 0-60.

Fred

Fatbackbeat said:

Thank you for the quick replies - boiler is not short cycling, though sometimes having trouble getting large radiators hot all the way across (except on really cold days when the heat very well) - I'll confirm the range of the gauge to you later, I am certain it is a lower range, definitely not 0-60.

That's exactly how the radiators should heat. Not all the way across when outside temps are moderate, more hot when outside temps are cold/closer to design day. Don't mess that up. Do add a 0-3 PSI gauge to your boiler. It will let you see what is actually happening, pressure wise.

ChrisJ

Radiators aren't expected to heat all the way across most of the time.

The more you heat a radiator, the more you heat the room. Heating them all the way across on a 40F day isn't going to be very comfortable or efficient.

Are your rooms all comfortable?

marcusjh

I was going to ask the same question - I just got a 0-3 psi gauge, and it registers two tiny marks above 0 after it's been running awhile.... Also, after several cycles, it shows a negative pressure (which re-sets when I unscrew the gauge temporarily). Normal?
Thx!

JUGHNE

Marcusjh, you must be operating in the ounce range. When the burner shuts off the steam begins to condense/ collapse creating a low vacuum in the system. After the air vents open and air enters the piping the gauge should return to zero.

marcusjh

Yeeup.... the main vents are old Hoffmans and need to be updated.... so thar's the problem I guess. The operating pressure is ok though I'm assuming? I would have thought the needle would have gone higher, but she's barely moving. Once new main vents are put in, would that change?

Jamie Hall

marcusjh said:

Yeeup.... the main vents are old Hoffmans and need to be updated.... so thar's the problem I guess. The operating pressure is ok though I'm assuming? I would have thought the needle would have gone higher, but she's barely moving. Once new main vents are put in, would that change?

May I humbly suggest that if the gauge is reading in ounces when the system is running, and it drops into a slight vacuum when it stops... the Hoffmans are doing a completely adequate job. There is no need to change them.

If it ain't broke, don't fix it.

Abracadabra

Jamie Hall said:

marcusjh said:

Yeeup.... the main vents are old Hoffmans and need to be updated.... so thar's the problem I guess. The operating pressure is ok though I'm assuming? I would have thought the needle would have gone higher, but she's barely moving. Once new main vents are put in, would that change?

May I humbly suggest that if the gauge is reading in ounces when the system is running, and it drops into a slight vacuum when it stops... the Hoffmans are doing a completely adequate job. There is no need to change them.

If it ain't broke, don't fix it.

I'd add "..and the system is well balanced." to that.

A system can have a gorton D on 10-12 rads and never raise an ounce of pressure

Fred

@marcusjh , also know that while the needle does drop slightly into the negative range, it will zero out before the next heat cycle and hurts nothing. It sounds like your system is running fine!

marcusjh

Ok, great to know that the vacuum isn't a big deal, and the pressure is good. Thanks! BUT, takes 45 to 50 minutes for the radiators to start to get hot - so I'm still thinking the vents are too old & small (was told in another thread).

Jamie Hall

Well, maybe. There are two stages to the process before the radiators start to get heat: getting the kettle up to a boil and getting the resulting steam to the radiators. Bigger vents or more of them will affect the second stage, but not the first.

What you need to do is to take the time from when the boiler starts to produce steam -- the header gets steam hot -- to when the radiators start to get steam. If that time is long -- anything much over two minutes for each ten feet of main is long -- then yes, more venting may help.