Converting 2 pipe Bundy radiator to 1 pipe system

Ldallas_87

I found some Bundy loop style radiators in excellent condition that I’d like to pick up for my 1 pipe system. Does anyone know if they would work with 1 pipe steam heat? It has a tap for a vent so I’m assuming they are dual purpose but just want to make sure.

Steamhead

What size are the pipe connection tappings?

Ldallas_87

I think 1 inch for supply and 3/4 for the return. Have to go check them out tmrw. If it is indeed 1” is that too small to accommodate steam and condensate return flow?

Jamie Hall

I'm not at all sure they will. Why? Because it does not appear that they are connected across the tops of the columns — and that means that normal one pipe steam radiator venting, with a vent on the last section and air and steam moving across the top to reach that vent, won't happen.

But maybe… @Steamhead ?

Steamhead

There is a bushing on the inlet end but it's hard to tell its actual size.

Steamhead

There is a bushing on the inlet end but I can't tell what size it is.

Ldallas_87

Thank you Steamhead, I noticed that too. Hopefully it’s 1 1/4” but I think more than likely 1” since that was standard. I just read that 1 “ supports 25-30 EDR if this style does actually work. Jamie that is a great observation. I was hoping

that the steam would push the air out through the columns in a up/down and repeat manner but I’m not so sure about that.

Mad Dog_2

I made the Large Bundy in my Parlor two-pipe (The only one in my house). Its been 25 years, but I believe its 1" Supply. Ill look behind the couch tonight. Mad Dog

Long Beach Ed

I have a round one and piped it just like Mad Dog did his on single pipe steam.

If it's going on the first floor you can use both pipes and put an inverted loop on the return into the bottom of the supply runout.

13 Loops, 36" high, 1-1/4 inlet, 1" outlet. The steam distributes up and down the loops just fine. Put a vent in the last loop if you need it.

Ldallas_87

Mad Dog/ Long Beach Ed could you please share a picture of the piping when you get a chance so I can better visualize/understand what I can do? I’m not exactly following your description. Thank you.

Mad Dog_2

Yup...mad Dog

Mad Dog_2

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Mad Dog_2

1" inlet on right. 3/4" outlet on left. No trap. Loop seal is in basement closet below. Mad Dog

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Mad Dog_2

20260412_014547.jpg

Ldallas_87

Thanks for sharing. I wouldn’t be able to add a loop downstairs. Could something like this work for a larger radiator?

Steamhead

Lose the trap. You don't need it.

The check valve would have to have a very lightweight flapper so the weight of the water would open it. And the rad would need a vent.

Mad Dog_2

Just try to use one pipe. See how that goes. Mad Dog