have i runined my air vents?

dillbilly

Posted this question over at This Old House and go no replies, so hopefully you all can help me out.



About a month ago I spent a non-trivial sum replacing all of the air

vents on my single pipe steam radiators. I went on vacation for two

weeks, and while I was gone I turned my thermostat down to 55 to save on

the gas bills. I got home yesterday [two weeks ago now] and turned the heat back up to 65.

The boiler cranked for a really long time and radiators around the

house started hissing, not closing off, and just venting steam. I

figured the boiler pressure was too high, so I cut the heat and things

settled down. Unfortunately now some of them seem to be stuck open and

continue to vent steam. Are they completely trashed? Was it because of

too much pressure? I really don't want to spend $20 per vent to

replace them again, but if that's what it comes to I'll chalk it up as a

learning experience and figure out how to not let it happen again.



The air vents are Gorton 4s, 5s, 6s, & Cs, and after two weeks they are still hissing very loudly.

BobC

Pressure?

Do you know what your steam pressure is? What does the gauge read when the system is cold or cool and what does it read when it's been making steam for a while (just before it turns off).



What is the pressuretrol set to, the front tab should be set at 0.5PSI while the white dial behind the front cover should be set at 1.



Bob

Steve_175

Main Vents

In addition to Bob's Q's the other thing to look into is what type and condition of the main vents you have. These are larger vents located near the boiler usually on top of the pipe that loops back to the boiler. It is important to do most of the venting in the basement so the radiators only have to vent the air in the pipe that leads to them and not all the pipes in the basement.

Gary explains it well here.

http://www.gwgillplumbingandheating.com/webapp/GetPage?pid=415

dillbilly

pressure

Thanks Bob.  I just headed down to the basement and checked everything out.  The pressuretrol was set to 0.5, but the diff was at 2, so I turned it down to 1 and turned up the heat.  PSI is zero when the boiler is cold and doesn't move off of it even after firing for quite a while.  Radiators are still hissing something fierce and not closing off.  I don't think I mentioned it in my first post, but everything was working fine before I left for vacation.



I've also attached a snap of the only vent that I didn't replace.  It's a Hoffman 76 on the supply main.  I have no idea how old it is, but it still seems to work properly.

Mike Kusiak_2

Clogged pigtail?

If the vents are hissing loudly, but the gauge always reads zero and the pressuretrol is not cutting out, perhaps the pigtail is clogged? Is the pressuretrol actually shutting down the burner when the indicated cutout pressure is reached? 

BobC

Could well be a clogged pigtail

Mikes question about a clogged pigtail is valid. 30 PSI gauges don't last forever and if that gauge is on the same pigtail as the pressuretrol a clogged pigtail would cause both of them not to see the boiler pressure. With the cover off of the pressuretrol you will see a bent beam that goes from the diaphragm piston to the micro switch; use a small screwdriver to move that beam up a bit at the switch end - that should shut the boiler down. That doesn't confirm the pressuretrol is good but it does tell you that switch is good and the contacts are not welded shut. Post some pictures of the boiler that show the gauge, the pressuretrol and the piping around the boiler.



If your up to it you can shut off the circuit breaker that powers the boiler, unwire the pressuretrol and then twist it off. Once it's off see if you can blow into that open pipe. There should be some resistance but you should be able to blow into the boiler to confirm the pigtail is clear. If that pigtail is blocked you will have to remove it and try to clear it. Running the boiler with a clogged pigtail is dangerous.



The main valve may still be ok but find out if your pressuretrol is working and that pigtail is clear.



Bob

dillbilly

pigtail was clogged, but something is still amiss

OK.  Snaps of my boiler and pressuretrol are attached.  Boiler is a Weil-McLain Series 4, Model EG-65-SPDN.  I checked the pigtail, and it was in fact clogged, so i cleared that out and hooked everything back up.  Pressuretrol seems to be working, as does the pressure gauge.  Boiler shut off just shy of 2 PSI, but seemed to take forever to get there.  The vent hissing has been much reduced, but is still present, and it's definitely steam and not air as it continues until the boiler shuts off.



Thank you all for your help so far.  Even if I can't solve this problem the situation is much improved, and I was truly lost before I stumbled in here.

Carl1979

Is the Hoffman 75 main vent working

Its a weak vent under the best of conditions . all your new radiator vents could be overpowering it. forcing the steam to blow right past it be vented thru the radiators only

possibly creating a vacuum where it essentially is not there. you can test it when your boiler kicks in does it get hot fast . can you hear it click shut when it fills with steam if not you need to get a gordon #2 main vent on there. and even if its does you still need a gordon #2 you can't over vent the main and its at least as important as all the other vents combined

neilc

Piped correctly ?

Not that it relates to the venting question directly but,

Do I not see a complete header, or equalizer?

Could we see more pictures of near boiler piping ?

and where that main is?

neilc

Piped correctly ?

Do I not see a complete header, or equalizer?

Could we see more pictures of near boiler piping ?

and where that main is?

BobC

Good to hear that!

Glad to hear you found and cleared that clogged pigtail, this is not the weather to have the heating down.



You said the pressure is now about 2PSI when the boiler shuts down, are all the radiators fully hot then? Is the boil,er shutting down on pressure, by the pressuretrol? The high pressure may well have killed the vents on the radiators, you don't have any of the old ones lying about I suppose. Also make sure the Hoffman 75 is working correctly, they don't like high pressure. If you have to replace that I'd suggest a Gorton #2 because your steam main looks pretty big.



The near boiler piping is not correct but you can wait for the good weather to address that.



The EG-65 is rated for 650 sq ft of EDR. How many radiators are you driving and what is the square footage of all of them? If you do have about 600 sq feet of radiators attached to the boiler it could take a while to get it all up to temperature but then again if the vents are not closing your pissing away the steam. Pexsupply - http://www.pexsupply.com/Air-Valves-300000 - has some good deals on Hoffman and Gorton radiator vents. I bought a 6 pack of the Hoffman 1A's from them a while back.



Bob

Carl1979

Help Wallies, he really has a Hoffman 76 VACUUM main vent

This is over my pay grade. Can he just add new radiators vents to his system like he did.

what about the main, Can you just change a vacuum system to a regular system by just changing the vents?

BobC

76?

You have better eyes than I do Carl.



The question is how long has that Hoffman 76 been there?



Also what are the vents on the radiators?



Bob

Carl1979

He typed hoffman 76 earlier I thought it was a mistake

I never heard of a 76 . but out of curiosity I checked it out and sure enough its real a Vacuum vent and he has it . I think here in lies the problem . now who's got the answer ?

BobC

Was this a vacuum system at one time?

It doesn't seem likely but a normal single pipe steam system should not have a Hoffman 76 vacuum vent on it.



Please post more pictures of the boiler from different angles so we can see what your dealing with. Also take some pictures along the steam main so we can see how it's piped.



Bob

Rod

Hoffman 76

Hi- I believe a Hoffman 76 vacuum vent can be turned into a 75 by removing a small disk in the outlet orifice attachment. When new,the 76 has about the same venting capacity as a Gorton #1 . Removing the disk almost doubles the venting capacity though I think I'd still add more . Unlike radiator vents, you can't have too much main venting capacity!

- Rod

dillbilly

hope I answer everyone's questions

I'll try to address everyone's inquiries here, but I may miss something.  Everyone has been far more helpful than I expected and there's a lot of info flying around in here.



First, I've attached two shots of the insane piping around my boiler.  I would come as no surprise if it were incorrect.  I've been in this house (built 1927) for just over a year and don't think I've come across anything that wasn't done incorrectly, jury rigged, or just screwed up.



Pressuretrol seems to be doing its job.  Like I said the boiler is shutting off at just below 2 PSI, triggered by the pressuretrol.  I turned the thermostat up to 80 just to make sure that wasn't the reason for it.  Took an eternity to get up to 2 PSI, which I imagine is simply because the vents are letting the steam out of the system.  Rads all heat up nicely though, and the hissing is much less than before.



Boiler is driving 13 radiators, but I'm not sure of the square footage.  The house stays comfortable though.  I replaced all of the radiator vents about a month and a half ago with a mix of Gorton vents: 1 #4, 4 #5, 5 #6, and 3 C.  The vents that were replaced were a mix of Hoffmans (40s I think), maid-o-mists, and a few random others.  Rooms are more or less evenly warm, so I think I sized them correctly.  As for the Hoffman 76, I haven't the first clue how old it is; it looks like a relic though.  What makes a vacuum vent different?  Hope I don't have to replace it; good lord that thing is expensive.

dillbilly

more pics of piping

As far as I can tell there are two parallel runs from the boiler that go the length of the house and join together to make a loop.  I don't know for sure because it's all behind drywall in the garage.  Lines for the radiators branch from the main line running through the basement, but I can't figure out quite what's going on with the one that runs through the garage.

dillbilly

more pics of boiler

yay boiler

Steamhead

Whoever installed that boiler

didn't even attempt to read the instructions. Have it repiped properly. 

nicholas bonham-carter

hoffman 76 vacuum vent

unscrew the top, and remove the disk and it will be a regular 75, though probably still not enough, so i would put on an antler, with an additional gorton #2.

one thing you can look forward to is lower fuel cost, when you put on the gorton, and even lower, when you re-pipe the supply pipes for the boiler. many here have done that themselves [in summertime].--nbc

dillbilly

thanks all

Just wanted to say thanks again.  If it weren't for this forum I never would have even thought to check to see if the pigtail was clogged.  I got a lot of insight into the mess down there.  The system seems much happier today though.  Now if I could just get it to stop knocking...

neilc

Now the knocking,,,

Repipe the near boiler piping to spec and dry out that steam, insulate, and I bet the hammering quiets right down