Proper pressure setting on large steam boiler

NJSteamhouse

The steam boiler at my child's school has been having issues the last couple weeks. It has been staying off while the thermostat is calling for heat. I looked it over with the maintenance person and it is clear that the pressuretrol is being tripped on high pressure but isn't turning back on after the pressure drops. This is the case even after hours of the boiler not firing and the pressure gauge dropping to zero. It will only turn back on after the pigtail is tapped a little. My assumption is that the pigtail just needs to be cleaned to fix this issue but I wanted to check if anyone else has come across this as well. The boiler was installed 2 years ago.

Secondly, I wanted to check to see if the pressure settings should be adjusted down on this system. I am familiar with keeping the pressure settings as low as possible on my steam boiler at home but this one is larger than mine. Should it also be turned down lower? Attached are some photos of the current settings.

EBEBRATT-Ed

You should first take the pigtail off and make sure it's clean and theconnection into the boiler is clean. With the boiler being that new it probably ok but should be checked.

2psi is the maximum pressure the boiler should cut out on.

The cut in should be as low as you can get it....just above 0

So on your control you set the cut in (boiler start) just above 0

Set the differential inside at 1 -1 3/4
So if the cut in was say 1/2 psi and the diff was 1 1/2 the cut out would be 2

To adjust it acuratly you need a low pressure gauge 0-5 psi. You could put a tee under the pressure control and put the new gauge on it.

The adjusting scales are fairly inaccurate.

In you case with the burner not starting just raising the cut in (maybe 1/2 a turn of the screw) will should get the boiler started

neilc

that black pigtail is likely steel,
and if so, more prone to gunking up than its neighbor, the brass one,
consider changing to brass under the operating Ptrol,

NJSteamhouse

Would someone be able to identify this vent? I am looking to replace it with a Gorton #2 or some Gorton #1s. I am not sure if it is still working. It services a 1 pipe system with a 74' long 2.5" thick main.

JUGHNE

It is known as "being too small" of an air vent. (AKA a collector item)

You may need at least 2 Gorton #2 main air vents or even B&J's Big Mouth's (if you have no water spitting problem).

Can you back up for more pictures of the end of the main?
Is there only one main?

NJSteamhouse

There is a 2nd supply main in the other 1/2 of the building. It has a similar setup and we will also add vents to that. It is in a crawlspace so I don't have pictures as readily.

Below is another picture of this vent location. This is an older picture and we have since added insulation to the supply and return. You can also see the return from the 2nd supply main coming through the wall to join the return from this one.

NJSteamhouse

If the 1st main is about 74' long (2.5" pipe) and the 2nd main is about 98' long (also 2.5"), would two Gorton #2 be suitable for each? Or will they not be filling with steam at the same time?

By my calculations, the 2nd main should be filled about 15 seconds after the first is filled at 2 oz. (Or 22 seconds at 1 oz.)

Will it make a huge difference to have the venting more finely tuned?

Jamie Hall

No. And don't be disappointed if it takes longer than you calculated to fill the main, especially if it is cool. The steam has to heat the main first before it can get anywhere.

Steamhead

That vent was made by American Radiator Co, probably in the 1920s. These days it's mostly decoration. Start with two Gorton #2 vents on each main and see where that gets you.

Steamhead

neilc said:

that black pigtail is likely steel,
and if so, more prone to gunking up than its neighbor, the brass one,
consider changing to brass under the operating Ptrol,

This. On our jobs we always replace steel pigtails with brass.

NJSteamhouse

Will do. Thanks for the guidance. I'll follow up afterward since the radiators will need balancing next.

JohnNY

Side note: On that last picture you sent, on the horizontal main pipe just before it drops down vertically, there is a pipe hanger that has been dislodged from its anchors. Find out what the heck happened there and check the pitch on that main.
And what those guys up there ∆ said. Change that steel pig tail to brass asap.

nicholas bonham-carter

Good call John!

JUGHNE

In your last picture you have 2 returns dropping into the "wet" return.
The horizontal piece connecting the 2 drops needs to have a water seal within it.

Without this water seal between the drops the shorter main will get steam to the end of itself, close it's vents and then go up the longer main drop to close it's vents before steam gets to the end of the longer main.

That horizontal pipe looks fairly high and perhaps close to the boiler water line.