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danfoss one pipe steam control valves

Steve L.
Steve L. Member Posts: 35
Yes the system needs to "breathe". But another thing to check is the packing nuts on the radiator valves. Any little leak at the radiator can cause over heating.


  • danfoss one pipe steam valves

    we install Danfoss IPS control valves with RA2000 controller on one pipe steam radiators in order to allow the tenant some sense of control without them having to touch the supply valves which leads to leaks, banging and damaged floors, however, they don't seem to completely stop the steam from entering the radiator even though they are completely off and room temp doesn't fall below opening point. Any one have similar problem
  • DWood
    DWood Member Posts: 60
    1 ps

    A couple of quick thoughts. Check connections around the valve body and vent to make sure that they are air tight. The 1 ps controls the flow of air out of the radiator, if air leaks out steam comes in. What pressure steam is being supplied? The valves work best at low pressure, under 2 psi. If your main is close to the radiator, the "pressure" of the steam can compress the air in the radiator allowing steam to enter the first couple of sections causing overheating. Is the valve installed with the vent (straight shank) at 12 o'clock? The vacuum breaker in the valve must be located in the 6 o'clock position to function properly and stop air flow. Are you cycling the boiler to zero pressure or vacuum at least once an hour? Air must be allowed to get back into the system for the valves to function properly.
    Hope these help. Good luck.
  • Danfoss one-pipe steam radiator vents

    One problem I noticed with the Danfoss one-pipe steam radiator vents is with the vacuum vent itself. If you take the valve off of the radiator and close the actuator control all the way, you should not be able to blow any air thru the 1/8" NPT inlet and you should be able to suck air back thru. But sometimes the vacuum breaker does not seal and allows air to vent out, allowing steam to enter. If you take the brass hex cap off the vacuum breaker, you can make sure the tiny ball seats properly to seal. I also second the advice given above to check to make sure the boiler cycles off and goes to zero pressure every once in awhile to allow air to enter the radiator, and to operate at 2psi or less.

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  • Barbarossa
    Barbarossa Member Posts: 89

    We had this problem on a school job; as previously posted on this thread the unit must cycle and let air back in. Our fix was to place an interval timer in the circuit ($25). On set up to occupied, the timer is cut out of the circuit and the firing under the normal control scheme. On occupied, set back, and unoccupied the interval timer interrupts the firing 2 minutes out of every 20. This we found to be enough time for the system to draw air back into the radiators and permit the valves to work as intended. This was easy and worked well to get the air back in with out noticeable swings in the room temperature.
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