Losing Vacuum

Hiram

I have a Vari-vac steam heating system. I have low vacuum on one of my two zones. At the end of that zone furthest from the vac pump, I get no heat on the riser above the the tenth of 20 floors. This riser serves a bed room and living room radiator a total of 40 radiators. We have done everything mechanically possible and yet no steam above the tenth floor. Please help me. I am going to start closing off risers one at a time to see if I can isolate the one line which easily represent up to 120 radiators. I have changed all disk steam traps in all of the complex radiators 3 years ago.

nicholas bonham-carter

Vari-vac

Have you read any of the articles about the vari vac in the library here?

http://www.heatinghelp.com/files/articles/1991/varivac2180.pdf

Could this be a control problem, as I see the intensity of vacuum is varied by an outside air temperature controller. If this controller is not functioning properly, then the vacuum pump may not run long enough to get all the air out of the system. When the steam rises, it will find some air in the way.

Could one of the rebuilt traps be leaking air into the system through the cover? Good luck!--NBC

Pumpguy

can you tell us

more about your system; operating vacuum, condensate temperature, type, brand, and CFM of vacuum pumps?



Also, are there any steam supply zone valves associated with this problem area?

jumper

accuracy

You need a calibrated thermometer and vacuum gage. Then you have to tap in supply and return to accurately measure temperature and pressure(vacuum) at tenth floor. From a steam table book you can estimate how much air is there.