Baseboard Vent one pipe steam system

FredsOldHouse

The vent in my second floor cast iron baseboard never seems to shut off like the vents in on the regular radiators. if the heat is on it constantly vents steam and moisture. Should it close when it reaches temperature? Anybody know what type this vent is so I can find a replacement. Photo attached. Markings may say 711 or maybe 7H on the side. Thanks

Jamie Hall

Is that picture right side up? Does the vent lay on its side like that? If so, it's hard to see how it works at all!

If you can get it off -- and I see from the picture that someone has used a vise-grips or some such on it at least once -- it should be possible to clean up the threads, add a nipple and a 90 elbow and install pretty much any good vent. May have to use some bushings to get the thread size right.

FredsOldHouse

Hi Jamie,
The vent does lie on its side as shown in the photo. Maybe that is the problem? It is tapped into the top end of a 4' run of cast iron baseboard in the bathroom. There would be no room for a standard vent on a 90 elbow as this vent is already almost to the top of the area. At the end of the baseboard there is a little door that lifts up allowing access to this vent. Directly above this vent is a tile wall. If someone makes a vent as small as this one that is on a 90 then maybe that would do it. Anyone know of anything?
Thanks

Double D

Maybe this will work. http://www.supplyhouse.com/Hoffman-401475-508-1-8-Straight-Steam-Convector-Air-Valve-3521000-p

Larry_52

Always had better performance venting cast baseboard with one pipe steam like this.

FredsOldHouse

Larry, I agree that would be the way to go but I don't have the clearance to fit a vent that way.
Double D, I am going to give that vent a try. Reviews look good and it will work in a horizontal application. Won't be able to do it till next Saturday. Will post results when complete. Thanks all.

Larry_52

I can clear that piping configuration within the end typical valve cover.

Steamhead

That type of vent has never worked well on steam. I'd get a 1/8" brass elbow and close nipple and mount a Hoffman #41 vent vertically. There appears to be enough room for this.

FredsOldHouse

Steamhead I didn't understand your configuration at first as I did not know what a "close nipple" was but now I think I know what you mean. The close nipple would give me distance from the end of the baseboard. The elbow would get me vertical then the Hoffman could screw straight down. I know I can't rotate a vent to screw it down like on standard radiator due to the clearance issue. The maximum clearance from the center of the hole in the radiator to the top of the enclosure is 2". Do you think the stack up of the elbow and the Hoffman 41 would be less than that?
Thanks

nicholas bonham-carter

Maybe a street elbow, instead of a close nipple, and elbow would take up less of the space.--NBC

Fred

Do you have anywhere near that would allow you to pipe straight out from or elbow to the front of that baseboead rad to get to a space that will give you the headroom you need?

FredsOldHouse

Fred, great name by the way. That could be an option if a street elbow wont work. I would have to drill thru the baseboard cover and mount the vent outside of the enclosure but it would work. Wouldn't look great but it's something to think about.

Fred

I'm thinking that will be one of your last options because the smallest vent, including the Hoffman is better than 2", not counting the elbow rise and you do need to leave a little space for the vent to vent out of the top unless you find one that vents out the sides of the top.

FredsOldHouse

how about the Varivalve 925005-00 Adjustable Angle Vent Valve. Any opinions on those?

Fred

FredsOldHouse said:

how about the Varivalve 925005-00 Adjustable Angle Vent Valve. Any opinions on those?

Some say they spit water. I have never used them so can't say for sure.

FredsOldHouse

Quick update. I went to Webb supply and they didn't have the Hoffman 508. They gave me a ER-40 which they felt was comparable. I tried it and it doesn't work well. I looked it up and think it is just for hot water. Ordered the 508 on line today. will have to wait and see how that goes.

Abracadabra

er-40 is not for steam. it's for bleeding hot water radiators.

Larry_52

If you bush down the two taps from 3/4 to 1/4 or 1/8. Then use two elbows npt to compression, one compression tee with npt on the bull, connect with copper tube, then as I drew on my attachment earlier you can fit a right angle gorton vent on the bull tee for the valve box cover. If both ends are vented and the vent is half way height the radiator will heat better. I proved this on one house that had all one pipe baseboard.

FredsOldHouse

Larry,
My old cast iron baseboard only has two holes in its end. One at the very top for the vent, one at the bottom for the steam pipe. Maybe if I put a T in the steam pipe I could configure the vent somewhat like you describe but as I am just your average homeowner without a lot of plumbing talent or knowledge. I will try the Hoffman 508 first and hope for the best.
Will post results when it is done.
Abracadabra, thanks for confirming that the ER-40 vent is for hot water. I told the guy at Webb it was for a steam radiator at least three times but it doesn't surprise me it was the wrong one. Maybe I'll return it. Hardly worth the trip for less than ten bucks but I should just on principle.

Fred

Don't put a Tee on the steam pipe. That will close the valve sooner than you want. The current configuration allows the air (and subequently steam) to be pushed through the entire length of the loop in that radiator and out the vent.

Larry_52

on the end that does not have the steam going to it, no tee into steam line. If you would like to fit a traditional right angle vent on the radiator within the end cover and vent it better than just at the top connection follow the Picasso drawing I made. You just need two reducer bushings to drop down to 1/8 or 1/4 as I had mentioned. Then it will fit within an end cover.

FredsOldHouse

Thanks to all for all of the good ideas and input on this topic.
I installed the Hoffman 508 on Wednesday night and so far it is working fine. I had to rotate the adjustment on the end somewhere between automatic and manual to find the balance I wanted. The automatic setting didn't seem to work well. Without this radiator constantly blowing steam from the old defective vent my water consumption in the boiler is also much, much less.

Larry_52

Remembered to take a picture of how I vent one pipe baseboard. Just put this one together with my spare parts box, all NPT no compression and fits right in the valve box end.

Larry_52

here are two better pics, my phone sucks. Don't mind the vent it was all I had at the time. Going to replace with Hoffman 40, slow rate venting typically works out better for these things.

Charlie from wmass

The vent sticks out the cover. Cut the cover for the straight vent and be done with it.

Larry_52

Charlie from wmass said:

The vent sticks out the cover. Cut the cover for the straight vent and be done with it.

??? I was showing how I vent a baseboard one pipe. The vent shown fits neatly in the valve cover. Is the pic that bad? By joining the top to the bottom full air removal is realized in lieu of premature vent closure in the last section with just the top vent.

Steamhead

Now why didn't I think of that?

Charlie from wmass

@Larry I am using my phone and cannot open the PDF. I was referring to simply venting out the top tapping. If I read your description right I will be checking it out and using it on baseboard from now on. Love the Wall.

Larry_52

Steamhead said:

Now why didn't I think of that?

Would love to take credit for that, but it was my father who showed me that one.

LionA29

Excellent work Larry

Paul3

Love this site - it’s helped me a lot in keeping my house warm and system quiet.

I have a similar problem with a one pipe cast iron baseboard - Hoffman 508s seem to work for a bit, then fail. Would a Straight Varivalve 925006-00 Adjustable Vent Valve installed horizontally work properly. Or does it need to be installed vertically?

My other idea is to just run a nipple out from where the Hoffman 508 is installed now, through a drilled hole in the sheet metal cover and use a Maid-o-Mist vent installed outside the cover. Would fit, and look reasonable. Thought?

Again thanks to you all for the advice and info.

EBEBRATT-Ed

A straight vent needs to be vertical. Yes, you can drill the cover and put the vent outside

Charlie from wmass

I will try to find the diagram for venting cast iron baseboard. If somebody else has it readily accessible that would be great. It used 1/8-in pipe coming out the opposite end from the valve supplying the radiator.

Paul3

For Charlie wmass, I think that drawing and a few pics are earlier in this thread (pipe out of top and bottom ports, teed together to a vent). Not sure I want to open up the bottom port though. I’ll do some more digging and let folks know what I did and if it worked. Thanks.

SteamingatMohawk

Varivalves, either straight or angled, do not shut off completely. The minimum setting is about a #5 and maximum is greater than a #1.

Gsmith

To the original poster: I think that valve you pictured is a hygroscopic vent ( may be misspelled), it has some disc like things in it that swell on contact with heat/steam/hot water. As Steamhead said they often don’t work very well on steam systems, but sometimes they do. I had one on a 3ft cast iron steam baseboard in a bathroom for many years. Had to replace it once. They’re not terribly expensive, so you could try replacing it and see if it works. Also, the one I had had a screw in the end that could be turned in or out to “adjust” it. If yours has that screw you might try screwing it in a bit to see if it will stop the leaking.

Here’s one by Caleffi: https://www.caleffi.com/sites/default/files/file/38455_na_02.pdf

Paul3

Thanks all for the info. My baseboard is in the same room with the thermostat (single zone steam for 2 floors, 3000 sf) so how well the baseboard and vent works impacts the whole house.

I ended up removing the Hoffman 508 and installed a 4” 1/8 MIP nipple with union to a Maid-o-Mist vent (using #4 orifice) that sits outside the baseboard end-cap. The Maid-o-Mist vent worked well because it’s not too large and could be easily screwed into place. So far, this seems to be working well - the radiator registers 200-205 degrees end to end soon after start up. With the Hoffman, the vent end took a long time (if ever) the get hot.

I attached some pics as they might help others.

Thanks again for your help!

Gsmith

Looks nice

Larry_52

For all who asked about this venting setup, here is a picture.  Been in service for years and it is by far the best venting setup for 1 pipe steam on baseboard.

Waher

@Larry_52 do you happen to have a parts list for that assembly? Is that all 1/4" brass threaded into a 3/4" to 1/4" reducer at the two Baseray end tappings?