one pipe vacuum system

Bernard Smith

what is a one pipe vacuum system? I have a one pipe system and I need to buy the correct main vent.I have been told to get either a Gorton 2 or a Hoffman 76. Are they the same? I read that the hoffman 76 is for a one pipe vacuum system

ttekushan

main vents

The Gorton 2 and the Hoffman 76 are different. The Gorton 1 and two are standard main vents in that they do not have a return check valve. Most other vents are this way, including the Hoffman 75 and 4C (i think).

The Hoffman 76 has a return check valve, which is appropriate for vacuum systems. A vacuum system allows very low to subatmospheric pressures to exist, lowering the boiling point, and expanding the steam vapor. These systems allow more efficient operation for coal or modulating boilers especially during mild temperatures.

You probably don't have this kind of set-up, so standard vents are fine. They used to make a non-return radiator vent, but if the system is not tight anymore and if any of the radiator vents are standard stuff, or the boiler is now gas or oil fired, good venting with no vacuum check features is your best bet.

Now. If your radiator vents actually have the 1/4" line coming off of them disappearing somewhere to a central location, this is a Paul or Norwall system. Check out the Library to read about the Norwall system. I see Hoffman still makes the #3 radiator vent for Paul/Norwall systems. In this case you need the vacuum check properties of the Hoffman #76 vent. But make sure the vacuum breaker that is now necessary with these systems is included and operating somewhere.