Two pipe steam radiator fitting question

justind

Good evening all, I am servicing large two pipe steam system for a new customer, and while changing traps, I came across three radiators with these 90's with a bulge in it on the returns. The piping goes to steam traps directly underneath these radiators in the basement. What are these 90's for and what are their purpose? What are they called? I tried googling it, also tried some of the old timers at the supply house and they never seen them before. See attached pics and thank you for your time and help

Steamhead

Those are Broomell return fittings, which tell us this was originally a Broomell Vapor system. The bulge is a water seal that helped keep steam from reaching the returns. There is a small hole drilled into the fitting to vent air around the water seal.

This system was designed to run on no more than 7 ounces pressure. See chapter 15 of "The Lost Art of Steam Heating" (available on Amazon) for details.

justind

Thank you for the info, I'm going out to the truck to get my book and read chapter 15, so being that this is not a vapor system anymore, these can be taken out and replaced with a trap right? Reason I ask is part of the house is under renovation and the GC removed one of the three radiators that had this fitting and damaged it to paint behind the radiator.

Jamie Hall

Par for the course. But why not keep it as a vapour system? That's not all that hard to do -- the main trick there is to keep the pressure low, which means a vapourstat. There are a number of advantages...

justind

Yea, the 20 other radiators in the house have regular Barnes and jones #120 steam traps except for three with broomel fitting, now two since the general contractor damaged one

Jamie Hall

justind said:

Yea, the 20 other radiators in the house have regular Barnes and jones #120 steam traps except for three with broomel fitting, now two since the general contractor damaged one

That won't keep you from setting it up to run as a vapour system. And if nothing else, if you run it as vapour those traps will last forever -- particularly if you adjust the radiators properly!

Koan

@Jamie Hall Jamie, when you write adjust the radiators properly, are you referring to pitch toward the return?

Jamie Hall

No -- although that is necessary. Most vapour systems -- if they haven't been kludged -- have inlet valves (or orifices if they really are original!) which can be adjusted so that just enough steam can get in to fill the radiator and be condensed -- and no more. It's a little tricky and you need a cold day, because you want the boiler to run long enough to fill the radiator if it's going to. If you do that, the trap never sees steam at all, and never has to close. If you like to live dangerously, you don't even really need a trap! And, of course, it assumes that your system runs on very low pressure -- a couple of ounces.

Koan

@Jamie Hall
Most of our radiators have the old Hoffman no 7 valves. Some work (or will at least move) some will not. Ours are all set Wide Open Throttle. I think those valves can be rotated in their housings to do as you explain. So I understand better can you explain the process? I assume you measure the inlet and outlet temps and "map" the heating time and try to match the time duration to heat up for all radiators?

thanks!

Jamie Hall

Those Hoffman valves are interesting. If your system was originally set up properly, there is an internal movable sleeve which should have been set to match the size of the radiator. Then, when the valve handle which you can see is moved, you can go from wide open to closed -- but wide open would be limited by the internal sleeve to be just enough to allow enough steam in to "fill" the radiator, but not escape into the return.

They probably weren't set up that way...

In which case, the procedure is radiator by radiator, and has nothing to do with time, but the boiler does have to have been running long enough so that it would heat across if it could. Then... it is a bit repetitious, but the idea is to set the valve so that the radiator heats across and down, but not quite to the outlet, and the return is slightly cool (say around 200 or so). You will probably have to rinse and repeat -- several times!

Koan

@Jamie Hall
All our valves are set wide open, not adjusted to radiators. Still looking for a way to rebuild those Hoffman No 7 valves. No luck yet, any info you might have would be great! Most of mine move but several are stuck wide open. So you explained 200 degF at the return - Is that measured on the return pipe just before the trap or on the exit or at the outlet bushing? I attached a 1925 data sheet on the Hoffman 7 valve.

Jamie Hall

The return temperature should be measured on the pipe at the exit from the trap -- but it is useful to also measure the inlet to the trap, if they are painted the same, as the finish can affect the temperature. You are looking for at least a 10 degree difference.

Those Hoffman valves are lovely -- they are what is used on the system I care for. And if they haven't been used for a while -- like, perhaps, forever -- they can be difficult to turn. But not, usually, impossible with a some persuasion. One does want to be careful not to break the handle! But placing a short piece of pipe over the handle will give you a little more leverage (don't get carried away -- if you can't move it with a piece about 8 inches long, give up) and you may be able to get it to go by moving it a bit one and then the other, and gradually increasing the range.

Don't loosen the lock nut to adjust the range until the regular control is free!

Koan

Thanks @Jamie Hall . For now I am going to leave them wide open then I will take some measurements. I'm about 5 days from firing the boiler up - it will be nice to have heat again!