Weil-McLain EG-75 tune up

brick23

I’m trying to take over the maintenance on the 2-pipe steam system at my parent’s house. The system has never really run well in the 30+ years they’ve lived there. It's a rural area and difficult to find any to work on it.

There was a lot of water blowing out of the main vent (Hoffman 75) and the heat was very inconsistent. The Pressuretrol was set to 2 psi cut in/2 differential, which I guess is way too high. I lowered the Pressuretrol to 0.5/1 , added a low pressure gauge and cleaned the pigtail which was completely blocked. (When I had the Pressuretrol off, I bench tested it with a low pressure gauge and even at the lowest setting it would only go as low as 1.5 cut in/ 2.5 cut out) The lower pressure helped quite a bit but the main vent is still blowing some water. This seems to happen after firing for about 10 minutes and just as the pressure crosses 1.5 psi. This continues until the pressure hits 2.5 psi and the pressuretrol cuts the burner off.

I noticed that the dry return leading to the main vent was very hot. Initially I though that is was due to some bad radiator traps letting steam through but I traced the heat back to what I guess is a “loop seal” at the end of the main just before a riser leading to the 2nd floor (see pic). The heat is coming from the main, down the loop seal and back into the dry return. I’m guessing this is where some of the water is coming from and that the high pressure is causing the loop seal to blow out. Also, It seems like the loop seal is not long enough. The bottom is right around, or maybe even above, the boiler waterline.

Questions:

1. Is that a loop seal and if so should I extent it to the floor? I can go down at least 2 more feet.
2. I got a Vaporstat and I was going to wire it in series with the Pressuretrol to lower the pressure more. Can I tap in before the relief valve on top of the boiler? I just wanted to avoid having too much stuff hanging on the pigtail that’s holding the pressuretrol. I would add a tee and another pigtail before the relief valve.
3. Not really a problem right now but the automatic damper has caused a lot of problems over the years. I’m not totally sure why it’s there in the first place since this a power vent system and not hooked up to a chimney. Also, At some point someone put it in “hold open” mode so it isn’t doing anything anyway. So can I get rid of it? I think I would have to jumper the wires to get it to run correct?
4. Should I replace the main vent with a Gorton #2 or is the Hoffman 75 good?
5. How does the boiler piping look?

AlexE

Hello!

1. Yes, that’s a loop seal, and it’s too short for the pressure you’re running. Every 1 psi of pressure can push water about 28" down the steam side of the seal, so at 1.5 to 2.5 psi a seal that only reaches the waterline gets blown through, and steam runs straight into the dry return. That matches the hot return and the water at the vent. Extending it 2 feet will help a lot, but the real fix is the pressure. At Vaporstat levels (8 to 12 oz) even your current seal might hold.
2. Don’t tap the relief valve line, nothing should share or restrict the relief valve inlet. Use another tapping on the boiler, or put a tee or cross on the existing gauge/pressuretrol pigtail and mount the Vaporstat there. Wiring it in series with the Pressuretrol is the standard way to do it.
3. On a power-vented boiler the damper usually isn’t needed, but it’s part of the boiler’s safety circuit. Don’t just jumper the wires, use the manufacturer’s jumper plug or harness for removing the damper, per the Weil-McLain manual. Since it’s held open anyway, it’s not hurting anything in the meantime.
4. Fix the loop seal and pressure first, since a bigger vent won’t stop water coming through. After that a Gorton #2 is a good upgrade. Mount it on a 6" or longer nipple so any water drops back before it reaches the vent.
5. Hard to judge fully from the photos. Check two things against the manual: the header should be at least 24" above the waterline, and there should be a proper Hartford loop on the return. If the risers are short or the header is undersized, the boiler throws wet steam, and that’s another source of water at the vent.

EBEBRATT-Ed

I agree with @AlexE on most points.

Yes to the vapor stat

yes to extending the loop seal

Putting a tee between the relief valve for the vapor stat is fine no issue it will not restrict the relief valve