Vacuum/Presure system

Low-grade

I am working to resolve several issues in what appears to me to be a vapor/pressure residential heating system. There are no steam traps on the radiators and it most definitely is a two-pipe steam system. The vent (above and near the boiler on the return line) appears to be clogged or stuck. Apparently the pressure cut-off is sticking or not otherwise working, as I found the system operating at 21PSI this morning. Heat was making it's way to the radiators. There was an inordinate amount of steam from the chimney while the burner was firing.

My main question is this - is there anything to control the steam pressure in the system beside the pressure cutoff safety switch? Further - is the vent malfunction a root cause of the problem or is it a sympton of the overpressure caused by something else malfunctioning. I do realize that I have a real problem in that steam is escaping up the flue, but if I can get the other issues resolved for now, then I can possibly buy some time till I can repair the boiler.

Any and all help is appreciated.

J. Brad

Mad Dog

You may have a section leak that is allowing the steam

to go up the flue and out the chimney - bad scene. You could have a clogged pigtail if the pressure is going that high. But why didn't the relief valve blow off @ 15 psi? You really need a steam pro in there before someone gets hurt. Use Find A Professional at this site. Mad Dog

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Low-grade

Vapor/pressure - more questions

MD,
Here are some pics to clarify. The Boiler is a Peerless JOTTW150SP and it was installed about 11 years ago. The system had been an old coal systen, converted to oil till the subsequent boiler replacement in 1993. It has functioned fine and been serviced semi-regularly ever since.
The problems recently surfaced when the occupant occasionally heard make-up water re-filling the system. The low water cut-off is functioning properly. The relief valve is set at 15psi and seems to function freely when opened manually although I've not accurately tested it.
Interestingly, when I manually opened the relief valve while the gauge was showing 20-25psi and the escaping steam appeared to have nowhere near that amount of pressure. I would guess it to be more like the recommended 1-2psi.
I believe my first action will be to replace the gauge with a new one with a 0-5psi range then monitor the amount of make-up water going into the system and the level of vapor emitted from the chimney. I'm convinced that there really is no overpressure problem.
Again thanks for any and all help!

J. Brad

Mad Dog

Its taking forever to download your pics

try to resize them to 640/480 megapixels. Anyway from what i saw, you definitley have a vapor system - whether it is a vacuum system or not remains. If it was last a coal burner it very well could have been. Do you have any main vents? Hoffman #76? A vacuum pump? Mad dog

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Steamhead

It looks like an Orifice Vapor system

where orifices in the radiator shutoffs limit the amount of steam getting into the radiators. A Vaporstat is essential with this type of system as over-pressure can allow steam in the dry returns, causing banging.

In the boiler pic, the gauge was reading in inches of vacuum. The scale for pressure is on the right side of the zero. So you probably have a vacuum-type vent on it.

Have you found any maker's info on the radiator shutoffs or any odd-looking devices in the piping around the boiler? This would help us identify the system.

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Low-grade

More info

Steamhead & M.D.
The steam shutoff valve on the radiator in image #322 is simply marked with the letter "L" in a pointy-ended ellipse, situated between the words "Open" and "Closed". The handle turns about 7/8 of a turn from the open to closed positions.

Low-grade

More info

Steamhead and M.D.,
The shutoff on the end of the radiator in image 322 is marked only with an "L" situated in an oval and between the words "Open" and "Closed". There are no other name markings. The valve handle turns approximately 7/8 of one turn from open to closed.
The vent shown in image 331 (this post), Has the following cast into the top "Jas. P. Marsh & Co. --- No.5 Thermodisk". There are no other unusual devices on the system unless you consider the auto-fill device or the low water cutoff unusual. Both are shown in image 330 (this post)
Steamhead - the gauge showed 10 or 20 in/hg in the photo when the system was at rest (hadn't fired for 1 1/2 hours or so). When the burner is firing and steam is traveling to the radiators, the pressure typically reads 20 to 25 psi. Even when the gauge reads 20in/hg of vacuum, when any drain is open water flows freely from it. Also, when the gauge is showing 20psi, opening the relief valve manually only yields a light puff of steam; certainly not 20psi worth. All things considered, I do believe the gauge is bad and it will be replaced ASAP. Bear in mind that this system has operated normally for the past 11 years and the only attention the system received was it's normal service from the fuel oil supplier. BTW - there is NO water hammer or banging and the system still heats well.
My concern materialized when the occupant noticed the sound of make-up water being added and water vapor coming from the chimney. It was only after observing the system in operation, that I realized that the pressure appeared to be so high.
Thank you!

Unknown

With the system at rest

for an hour and a half , and the gauge reading 20 in. hg , the gauge is bad . When you replace it , I would recommend using a pigtail with it , facing up like the pressuretrol , to protect the gauge . I've installed many a JOT with the gauge in the spot just like yours , and they were lucky to be accurate after a year .

I see you have 2 LWCOs in conjunction with each other . Never saw that setup before . Are both functional ? It looks like the 47-2 valve handle is open ?

I would also look into a small water meter to install on the feed line . You can always reuse it if you need a new boiler in the future . I couldn't see in the pictures , but is the auto feeder in the 47-2 connected , or are you using an external feeder ? Good luck with the boiler J.B.

Low-grade

Ron, Jr,
Thanks for the info. I'll do as you suggest with the gauge.
The two LWCOs were installed that way by the installer 11 years ago. I'm not really sure of the reasoning. Possibly it was to place redundancy in the system so that if one failed, the other might still protect the boiler. Yes, both are functional.
The valve handle on the 47-2 has been rotated 180 degrees to allow it to snap shut in an effort to get it to seal more effectively. It is actually closed in the photo although the handle appears that it is not.
The water meter suggestion is interesting. Are they subject to attacks from hard water? This is a real concern in this area. City water feeds this system and is notoriously hard here.
The auto feeder is connected and appears to be doing it's job well. Water level always appears consistent in the sight glass.
'ppreciate all the help!

J.Brad

Unknown

With the water meter

you can also install a strainer with a flush out port to keep it nice and clean . It is very handy to have to keep track of exactly how much water is going in . From what I remember , Peerless does not have an average water consumption chart in the installation manual .

Burnham goes into much greater detail about excessive makeup water with their steam boilers . I am not sure if this is the best comparison , but your boiler is almost the same in water content as a Burnham V86 . The instructions say that anything more than 11 gallons a month in makeup water is excessive , for the V86 .

Bob_19

FYI

JB, the steam pressure gauge has to read up to 1.5 to 2 times the MAWP of the boiler(ASME code), seeing that this is a lo pressure boiler you'll have to replace with a gauge similier to what's on there now as far as dial reading.
You can go with smaller incremants so you'll be able to read pressures more accuratly.
Most lo pressure boilers will have a compound gauge with or without a vacuum return, being that they run so lo thier more apt to go into vacuum quicker during of cycles.

Steamhead

That radiator valve

may have been made by Lunkenheimer. That's the only old-time valve maker I can think of that starts with L.

The Marsh #5 is a vacuum-type vent, which looks like it has been leaking. It has a capacity similar to a Gorton #1 or Hoffman #75. Is it on the steam main or dry return?

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