Way overfired boiler

HowardLong · February 19

I have a boiler in a 3 story apartment building that used to also heat the 2 sections next to it. We can see the pipe in basement where the returns used to connect. It has a shared wall with one section and the other section of the building was completely removed and torn down years ago.

The section of the building that it heats now is only 800sqft EDR, but the boiler there is a LGB-9S, which is rated to 2633sqft! The vents are getting soaked with water and then getting stuck, I've started replacing the old single vents with Gordon no2s and have double the venting capacity to try to help with the issue, but it's not enough and I don't want to add 20 vents. We've already downfired the boiler to the ratings on the boiler plate as low as it can go. Is there anything else we can do short of replacing the whole thing with a smaller unit?

mattmia2 · February 19

if the piping is right and the water quality is good it shouldn't be throwing water everywhere, it will just short cycle. is it 1 pipe or 2 pipe?

HowardLong · February 19

It's a 2 pipe system. I don't think the water is very good. I had an old tech come out and he skimmed it but I don't think it helped. I can still see the sight glass level bouncing and inch up and down. I have PH strips to test the water and it comes back at ~7.

mattmia2 · February 19

that skim port with the ell pointing up isn't going to work, it will fill the boiler above the skim level and the oil will just stay in the boiler. if the oil is still there after 30 years is somewhat doubtful. the piping itself at the boiler looks good although on 2 pipe pressure that is too high can push the water out of the boiler and in to the returns. do the traps work? i assume they have not been looked at in a long time.

HowardLong · February 19

When the tech came out and skimmed he turned the port down, this is just an older picture. I've already replaced a trap on one of the radiators which was broken. It didn't have any actual guts, just an open pipe, so I put a working one in. There are these 2 traps in the basement as well though that I haven't touched. They come off of 2 of the return lines.

Jamie Hall · February 19

Those two traps you show in the basement are … just weird. If the outlets go below the water line, they won't vent anything (if they went into a dry return they might be crossovers) and I have to ask what the pipe is to which they are attached?

I will also ask what pressure this system is running at, maximum? Anything over 2 psig is going to be a problem…

I think you need to trace every single pipe you can find and figure out what it is supposed to be doing and how, if it needs to be vented, how it is vented.

As to fixing the ridiculous mismatch between boiler size and installed radiation… more copious venting isn't going to help. Almost anything you do isn't going to solve the problem of having to bring that monster up to a boil, so this is one case where you're stuck with really poor efficiency. However, it is likely that it might help to have a time delay on restarting after an on cycle.

techforlife · February 19

Sounds like too much steam pressure. Pigtails/manifold clogged?

HowardLong · February 19

I'll get some more pictures and I'll make a drawing of all the pipes.

Those pipes come up from 2 return lines, into the traps and into a 2in return around the boiler.

This boiler used to have an Illinois Vapor Heating System which let the boiler go into vacuum intentionally. It's long since been defunct, but the float bowl is still in place, just valved off so it isn't connected to anything. The original venting/vacuum sealing mechanism is long gone though. I assume that's why these two little traps are installed way up at the ceiling, something to do with this vapor system.

HowardLong · February 21

Ok, here's the drawing of the system. It is set to run between 0.5 and 2psi and the gauge says that's what it does. My next step is to open the traps and see if they are still working. I installed a sight glass on the tank that has both valves closed off so I could check if it ever filled with water and it didn't, but it would fill with steam based on how hot it got. So I turned off the line supplying steam from the main to stop steam from going back into the return. I've checked the check valves and they are both working.

techforlife · February 22

Do I see a check valve at the wet condensate return at the boiler? May be clogged not allowing condensate to return fast enough into the boiler, stacking up in the return. Also, how much higher above the water line are those vents? This is called the "A" dimension. You need about 28" above the water line for each pound of steam pressure. Remember, this used to be a low pressure/ vacuum system. You may need a Vaporstat to replace the pressuretrol. All critical.

mattmia2 · February 22

the condensate will have to stack to a certain height to develop enough pressure to open those check valves too. since it is no longer running in the way that the boiler return trap returns condensate in batches there is probably just a trickle through those check valves so that can cause numerous problems. if you aren't running it it very low pressure and the boiler return trap isn't operational the pressure in the boiler vs the returns might be such that the condensate can't return to the boiler. i don't know this system specifically, but usually the job of the boiler return trap is to let some steam in to the returns to equalize the pressure between the supply and the return so that the condensate can return to the boiler.

HowardLong · February 24

Now that you mention it, when I opened the check valve to see if it was free to move the water was under a surprising amount of pressure. I'll look into that.

I do have an extra vaporstat lying around. I'll give it a try.

I don't know how high the A dimenions is, I'd estimate 4 1/2 ft. So that would put it at max pressure of 1.9psi, which is about where it runs. But I'll put in that vaporstat and try going lower to solve these issues.

There is a single return line vent in another part of the basement that looks like someone recently extended that vent up another 5ft up, maybe to deal with this same water level issue. But that one also spits.

Steamhead · February 24

That is still a Vapor system, because the pipes were sized to operate at a few ounces pressure.

The Return Trap (where you added the sight glass) is actually a pressure-powered pump that operated when the boiler pressure got too high for the water to return by gravity. See chapter 15 of @DanHolohan 's excellent book "The Lost Art of Steam Heating" for a detailed explanation of this.

First thing to do is put the Vaporstat on. Then increase your venting. How long are your steam mains, and what pipe size?

clammy · February 25

Change out the two cross over traps they most likely are failed and if not they look to be a few years old and remove those no 1 Gorton's and install either a pair of no 2 Gorton's or if you feel daring install a hoffmann 67 vapor vacuum vent . As others may have stated check the pigtails on your pressure trolls and do yourself a favor and get a decent 0-3 psia gauge .

i would hope that being a two pipe system that you have ensured that all traps are working properly and that none of them are passing steam into the dry returns . If so replace or repair .As for down firing have some one install a 2 stage gas valve and a vaporstat in conjunction w either the existing pressuretrol or yet another vaporstat

peace and good luck clammy

HowardLong · February 25

That's on my list, those traps are in a bad spot and my wrenches can't fit between all the pipes and get any good leverage. I'll need to be creative. I've put on the vaporstat, set it to 16oz with 14oz differential, it's running at a 30% duty cycle right now.

I have checked a couple of the other traps in the apartments, one didn't have anything at all. I'll be going through the rest of them soon. The main is 2inches and goes into a cement wall and up 3-4 stories. So I'm not sure how long it is, but I would guestimate 40ft tall and 20ft in the basement.

mattmia2 · February 25

What kind of valves are on the radiators? Usually they have metering valves that prevent the steam from reaching the returns if you control the pressure if it is a vapor system.

HowardLong · February 28

The radiators have standard single handle valves, I don't believe there's any metering device, at least nothing visible. I opened up another trap though and the diaphragm fell right apart so I'll be tearing more of the traps open.

mattmia2 · February 28

Most styles of vapor metering valves have lever handles but a few that were pretty popular just had a regular round knob. The valve usually is a plug or disc valve that has some sort of stop that is set to limit how far the valve opens to match the radiator size. Most of them do a good job of hiding the stop. A few used a needle valve that was part of the valve body to set the orifice size.

Jamie Hall · February 28

https://forum.heatinghelp.com/discussion/comment/1845756#Comment_1845756

Most … do a good job of hiding…

You can say that again. You really have to go looking for the mechanism on a Hoffman valve!

HowardLong · March 3

I'm waiting on the new traps to arrive in the mail. But this weekend the boiler flooded with water, I'm not sure how high it was because it clouded the sight glass. But this system doesn't have an autofeed on it(it's on the list to install one this summer) and we feed water in about once a week when it's get's about to the LWCO and inspect it every other day so I know the water isn't being added unless I'm doing it. I'm hypothesizing that because of bad traps the water is trapped somehow in the radiators and comes down once the boiler has been off long enough to cool down.

mattmia2 · March 3

https://forum.heatinghelp.com/discussion/comment/1845763#Comment_1845763

Then there were a couple that had valves with different fixed orifice sizes and you'd use different valves for different size emitters.

Way overfired boiler

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