Pressuretrol settings and no heat (in ONE main)

John Shea

I'm trying to work the bugs out of an old two-pipe gravity return system used in a 3 story (38 unit) Detroit apartment building.

There are three(3) apartments that are getting NO steam to the radiators. These three apartments (ONLY) are served by one main. My first course of action, of course, was to replace the end of main trap. While doing so, I decided it would probably make sense to change ALL the end of main traps (total of 10).

The other strange thing I noticed was the Pressuretrol setting. The Peerless boiler is equiped with a subtractive Pressuretrol. The settings were: MAIN: 3/4 psig DIFF: 1 1/2 psig. I immediately decided that this was incorrect and reset the Pressuretrol to MAIN: 1 1/2 psig DIFF: 1 psig. I understand these settings are based on the pressure drop in the system (piping, fittings, etc.) but does it sound like I'd be in the ballpark??

Were the previous settings irrational?

Anyway, I still have no heat in the three trouble apts. And now there's 2 psig of VACUUM after the boiler shuts down, and water spewing from my main vents. Is the Vacuum drawing leftover steam and condensate back to the boiler so fast that it's pulling wet return water into the air vents?

Is there ANY time in which a vacuum is GOOD in the system (natural gas fired)?

Any help would be much appreciated.

John Shea

I forgot to mention...

I spoke to the installer of the Peerless boiler (install some 7 years ago) and he said that according to Peerless, the pressuretrol should be piped WITHOUT a pigtail??

Is he out of his mind? How can I tell if the pressuretrol is working properly?

Thanks in advance.

Steamhead

Main Vents

First, is there a vent on the dry return from this section of the building? If not, the whole section won't heat.

Second, are there any vacuum-type vents on that system? These can keep water from returning as it should, causing spillage from the vents.

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John Shea

Yes, there's a vent on the dry return. It's tapped into the top of an F&T trap. However, that vent also serves an adjacent section of the building that is heating fine. Also, it seems to vent well and does not spit.

Now that you mentioned it, I have been thinking about the vents. They maybe be vacuum type. I will have to check. They're either a Hoffman #75 or #76 and I know that one of those is the only vacuum vent that Hoffman still makes.

However, that is part of what I do not know as well. You see my father had tweaked the system and had it running beautifully. He added (some) thermostatic ratiator valves, we wrapped all the pipes, etc. Sam, a heating contractor that we occassionally worked with, installed a new boiler a year or two before my father died. He claims that my dad was running a vacuum (vapor?) with good success. I have been reading that this only worked well with old coal fired boilers.

Should I check and/or replace vacuum type vents if they exist?

Any idea what my pressuretrol should read?