Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Please help with a crazy system

My husband and i have a gas fired, one pipe steam system with an older boiler. The main problem is uneven heating of the radiators. We have two radiators on the first floor and three on the second floor. We have changed all the radiator vents, pitched them all and none of the are clogged.

Last night we drain the system, waited for it to cool, refilled it and fired it up. It worked perfectly, all radiators heated up and the house got to the temp set on the thermostat.

It seems like when it cools down and heats up again the radiators never work like they did the first time we ran the system. Each time the boiler fires up there are more cold spots in the radiators and the boiler shuts off before steam makes it all the way to the end.

I hope this makes sense.

Please help us!



  • BobC
    BobC Member Posts: 5,182


    What make and model boiler do you have?

    What pressure is it running at when making steam?

    What kind of radiator vents are you using and what kind of main vents?

    Is the water moving around a lot in the sight glass?

    Is there any water hammer?

    Post pictures of your boiler and the piping around it, stand far enough back so we can get a good idea of how it's installed.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Steamhead
    Steamhead Member Posts: 14,318
    If draining and refilling cured it

    then you have dirty or oily water in the system, which makes lousy steam. When the water becomes contaminated again, the problem re-appears.

    Keep doing what you're doing, and eventually it will remain clean. Just remember each time to let the boiler cool down before re-filling, and fire it up to make steam after refilling to drive off the entrained air.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • Fred Harwood_2
    Fred Harwood_2 Member Posts: 195
    Thermostat settings

    How often does your thermostat call, and for how long?

    What thermostat?

    What main vents do you have?
  • mahoney
    mahoney Member Posts: 13
    check for sag

    check for sagging pipes in the basement. If you have a sag, condensate will collect and get spit out the air valve on the next cycle.
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!