I assume more than 1 failed trap is causing this.

Double D

This is a Webster system with convectors in a 3 story Pre-K school.
https://youtu.be/qbppfaLFZlc

Jamie Hall

Be surprised what one failed trap will do -- but yeah, probably more than one.

Double D

@Jamie Hall I'll be back to put a low pressure gauge on this one Monday. I dropped the pressure on the pressurtrol from 5 - 2psi on the scale. When the burner trips off, the 0-30 gauge is reading 6psi. I know you cant trust that gauge but could excessive pressure cause this? Is there a chance this system operated with a vacuum pump? The mains look rather small for the size of the building. Do you see a problem with me doing a load calculation and asking to have the boiler fire at that rate? I'm not well versed on this type of burner.

Double D

More than 1 failed trap, still have more to hunt down but @Jamie Hall I am now surprised what one trap can do.

JUGHNE

I have an old 1930's school with the same potential problem.
There are 6 dry returns coming into a large boiler room.
As I do any re-vamping of piping, I add a tee to the return as soon as the pipe enters the room, with the 1/2-3/4 branch pointing up. An open pipe riser is added some up to 6' high.
This lets me know which section of the system is blowing steam.
These steam indicators narrow down the search and saves a lot of steps in a 3 story building

I got this idea as there were a couple of taps like this installed with the original 1930's piping, some were 1/4" tap on the top of the pipe, some had a stop valve installed. Both were piped to the sump pump pit as there was apparently some steam passing early in the game.

This place has about 35 rad traps and about 30 drip traps as the main is in the attic.
It has Webster traps and originally Webster valves, otherwise just another 2 pipe system.

Double D

Thanks @JUGHNE I may try that if I have difficulty finding the failed traps. So far the failed ones have been obvious. You described this building to a tee.

JUGHNE

Actually, I removed all the guts from the radiator traps and installed orifices in the rad valves. If a replacement trap element cost 50....the orifice to eliminate it cost 12...and never wears out.

Average pressure was based on 2 PSI.
The sizing varied from 50% to 80% max EDR.
Depending upon each room.....some rads removed.....maybe 2 outside walls.....north & west exposure....new windows....some closed up....input from teachers etc. All scientific by the seat of my pants...WAG.
We have had minus temps and the phone has not rang...so everyone is happy so far. The orifices could be drilled slightly larger if more heat needed.

All the 1/2" drip leg elements were changed to B&J 1972 (reuse old caps)….found some 1932 WW elements even.

With the main in the attic all 34 drip mud legs were full of mud, overflowing sludge into the drip trap bodies. Most had to be chiseled out with insert pipe and 2 LB hammer.

I was fortunate to find the original 1933 print showing attic piping. This led me to place 5 B&J BM vents in what seemed to be strategic locations for air venting. There a 4-5' riser has the vents.....even in a class room.....apparently no water spray so far.
I did add a ball valve under them in case of that issue.
This is 50 miles from me.

Boiler is 1974 1B-J1 1.8 million Btu....a real beast.
Nearly twice what is needed today for building.
The air venting seemed to help a lot on the short cycling.

This was an interesting hobby/project for me...also kept my Grandson busy for the season.

Happy to offer any info.

SeanBeans

Comparing this video to the system across the alleyway from me, I can’t imagine how many traps are bad.