Steam Baseboard

mmc239

My steam baseboard is banging like crazy when it first comes on. It lasts about a minute then stops and heats up. I’m assuming it’s not draining correctly. I checked the pitch and everything seems good. If I make a small manifold with a ball valve and screw it in where the air vent goes, will I be able to release any excess water/air that is trapped in there while the system is running? 

Jamie Hall

The existing air vent -- I presume this is one pipe? -- will release any air in there. It won't release water -- but if there is water actually in the baseboard it is because it doesn't have enough pitch back to the inlet valve -- or the inlet valve is a water valve, not a steam valve. Or both. A one pipe steam baseboard takes a lot of pitch to work more or less well. Others will come in with their experience, but I would venture that anything less than a quarter inch per foot isn't going to be enough -- and maybe more.

You should also check and make sure that the runout coming to the baseboard has enough pitch everywhere, as water hammer there may appear to be coming from the baseboard.

mattmia2

If you have good access from below there are numerous ways to pipe it as 2 pipe on a one pipe system, that usually works a whole lot better unless the baseboard section is very short because you can direct steam and condensate in opposite directions. If this is mixed with cast iron radiators it may never really heat the space well even if you sort out the banging because they hold heat so much longer than the baseboard.

Waher

If you pipe the vent side of the baseboard this way it helps trapped water circulate through the baseboard and siphon out. (not my image or work)

mmc239

Is that pipe coming off the the existing hole where the air vent screws in? How would that help with the issue?

EBEBRATT-Ed

I agree with @Jamie Hall long baseboards need to be hooked up two pipe for best results. You can drop the return into a wet return ot tee the new baseboard return back into the bottom ofsteam supply after you drop and make a loop.

mattmia2

mmc239 said:

Is that pipe coming off the the existing hole where the air vent screws in? How would that help with the issue?

It gives the water and air someplace to separate instead of getting pushed in to the vent. If it is CI baseboard like that putting the vent on the top tapping instead of the bottom would help too.

mmc239

Is that just a pipe cap on top of that brass nipple? I’m interested in this idea. Right now I don’t have the money to convert to a two pipe system. In the short term, would my idea work with draining the radiator? 

mmc239

What is the bottom fitting called if I wanted to order it?

Long Beach Ed

That photo appears to be cast iron baseboard which has two pipes running through it. They are connected to the vent with elbows, a nipple, tee and union. You are probably dealing with a single pipe copper baseboard.

If it's a single pipe 3/4-inch and longer than a couple of feet, you really should pipe it back to a return.

Waher

That photo is cast iron baseboard with 3/4" taps top and bottom.

My guess on the parts used:
There's a reducer bushing in each tap taking the 3/4" tap down to I think 1/4".
They have 1/4" street elbows (square profile instead of the usual round) to a 1/4" nipple of unknown length (wish I knew the length) at the top, a 1/4" tee with a 1/4" street elbow (or 1/4" elbow with a close nipple to the Hoffman No.43 convector vent, beneath the tee is a 1/4" close nipple 1/4" union, and then finally a last 1/4" close nipple connecting into the bottom 1/4" street elbow.

JUGHNE

IIRC, Gordo of All Steamed Up has a Utube on this method.
Explains it well.

mmc239

Do you have the YouTube link?

Waher

Someone else on the forum at one point did this with compression fittings. I'd be worried about thermal expansion eventually causing them to fail compared to threaded fittings or something like ProPress. The tubing in this case should ideally be radiused to pitch drain from the top to bottom, which isn't what that person did.

mmc239

I’m am going to try the option with the threaded fittings. Should I do everything 1/4 inch? Also, should I try my idea about drawing any excess water out of the baseboard using a ball valve while running the heat? Thanks for the ideas!

mattmia2

mmc239 said:

Also, should I try my idea about drawing any excess water out of the baseboard using a ball valve while running the heat?

No

mattmia2

Waher said:

Someone else on the forum at one point did this with compression fittings. I'd be worried about thermal expansion eventually causing them to fail compared to threaded fittings or something like ProPress. The tubing in this case should ideally be radiused to pitch drain from the top to bottom, which isn't what that person did.

Compression fittings are fine for something like that. The thing you have to think about no matter what fittings you use is to try to avoid or minimize horizontal reductions in diameter in the direction of condensate flow that can cause condensate to be retained.

New England SteamWorks

If the baseboard is longer than 4', you'll need to pipe a return with a water seal. You can put the vent in the basement before the seal.

TonKa

FWIW, I'm currently sitting next to an eight foot long, 3/4 inch hydronic cast iron baseboard radiator on a one pipe steam system with the vent plumbed only to the upper tapping at the far end. It works pretty well, keeping my feet toasty.

I will admit, though, the radiator will occasionally (but not always) make a faint water hammer ping for a short while when it's cold and steam initially hits it. I attribute this to the fact that it is venting a bit too quickly, but I'm currently too lazy to replace the bajillion year old Gorton #D vent with something slower.

I know a lot of pros here would suggest it needs to be set up as a two pipe with a loop seal return, but I write this to give an example that even long cast iron baseboards meant for a hydronic system will work adequately on a one pipe steam system when the pitch and valve plumbing are correct.

Long Beach Ed

The cast iron ones seem to take steam better, as do 1" copper ones. The real problems seem to come with the 3/4 copper baseboard.

Waher

I'm sitting next to a 8' section of Burnham baseray improperly piped with soldered copper, not pitched other than the settling of the house, and vented only from the top tapping with a Hoffman 508 vent (major improvement over the stock Burnham TACO/Swiss branded coin vents).

It does eventually 'work' after thermal expansion pinging and some spitting from the vent. The bottom section doesn't get completely hot and it gurgles/sloshes biggly after a heating cycle.

Does it get full heat output? No
Does it get hot in a timely fashion to use fuel efficiently? No

1.Setting up a vent loop with nipples/fittings as shown above would increase the efficiency and output.
2.Setting up a proper return with water seal as New England Steamworks stated above would maximize the efficiency and output.

If you aren't a pro option 1. is the best you are going to get it.

Ideally you'd never use more than a 4' section of baseray with one pipe steam because 3/4" pipe is not ideal for one pipe steam in the first place. If you are using more than 4' of baseray you'd be better off having a conventional radiator in the space.

mattmia2

Of course the other option is to just get a salvaged cast iron radiator and replace it.

mmc239

If I pipe the vent with copper fittings shown in the picture above, what size fittings should I use, since it is 1/8 coming out of the pipe?

Waher

The threaded connection (tapping) out of the top and bottom of the cast iron baseboard is 3/4" NPT. From the factory they come with a 3/4" plug on the bottom and a 3/4" to 1/8" reducing bushing to accept a typical "coin style" vent.

If you reused the existing reducing bushing with 1/8" copper pipe to brass compression fittings you'd need a 3/4" to 1/8" reducing bushing to replace the bottom 3/4" plug.

1/4" copper tubing or brass nipples/fittings would be better to allow more volume for air/water/steam to sort themselves out. Any pipe larger larger 1/4" than that won't fit in the end cover due to the limited space to screw it in place. Well.. maybe you could get 3/4" copper with compression fittings in there, bending the radius to fit that tight of a space to mate into a 3/4" tee with a reducer bushing for an air vent to screw into would be difficult.

You could do a close nipple top and bottom tapping with unions to make it a little easier to put together. That's getting expensive though and I'm not sure a union horizontally at the top tapping would clear the cover.