Vapor System Fitting

David Barto

I am looking at an old vapor system that has been modified over the years. It looks like the original system was coal fired boiler, cast iron radiators, two-pipe gravity return. What is new to me is the fitting on the outlet of most of the radiators. It is a 90 degree elbow in the shape of an 'L' and there is a "bulb" on the bottom of the horizontal, longer portion of the 'L'. "Vapor System" is cast right into the fitting. I have a picture, but I am sure this crowd knows what I'm describing. Is this an orfice trap and how does it work? Thanks in advance.

Steamhead

Congratulations- you have a Broomell Vapor system!

Vapor was the Cadillac of heating in the old days, and is still one of the best out there.

The fitting on the radiator outlet is a water-seal device, with a small port to vent air. No moving parts, nothing to wear out. Its job is to keep steam from getting into the dry return.

We have some Broomell information here in the Library- go here to view it (requires Adobe Reader):

http://www.heatinghelp.com/pdfs/54.pdf

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

gerry gill

just make sure you dont

replace the radiator valves with a standard inlet valve..if you do you will blow right thru that water seal..the water seal was there only to stop any ''wisps'' of steam from getting to the returns..the real work was done by the inlet valve that was selected to only allow ''just so much'' steam into the radiator as it could condense...

David Barto

The Story Continues

Now that I read the Broomwell booklet, the rest of the story...at some point the boiler was replaced with a gas fired, cast iron sectional and it appears that air vents were added at each of the radiators. Pressure must have been put on the system at this point changing it into a "steam" system rather than "vapor" system according to Broomwell. I believe the gravity return remained with a Hartford loop connection at the boiler. Thermostatic traps were added to two out of about twenty radiators. All the radiator valves look original. I have no idea how well, or how poor, the system worked at this point. The water seals must have been blown out.

The boiler was recently replaced again. Unit heaters were added, with F&T traps, and a vented condensate receiver pump set was added. Traps were not added to the original system at this point. On start-up, steam just blew through the system and vented to the outside through the receiver vent. Can I add traps to the radiators or return lines and increase the boiler pressure to accomodate the unit heaters?

Steamhead

Lower the pressure!

This is why the water seals blew out. The Broomell was designed to work on about seven ounces of pressure. You need to put a Vaporstat on that boiler that cannot be set higher than 1 pound.

The unit heaters should work OK with the lowered pressure, if the pipe sizes feeding them aren't too small. You may have to add more air vents to the lines feeding them to get steam to them more quickly. If the unit heater piping is too small, it would be more economical to increase the pipe sizes rather than to run higher pressure. High pressure wastes fuel.

Oh, and you really shouldn't need that condensate pump. As long as all the horizontal steam and return lines are more than 30-inches above the boiler's waterline, the water will return by gravity just fine with the Vaporstat. If you deep-six the pump, make sure the dry returns are well vented.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"