radiator thermostats

Brad White_39

The thermostatic heads I have seen typically have no "dimension" and the scales are a tad arbitrary. There should be a ring or faceted nut within the outer thread where the head seats. This nut should be able to be turned to adjust how far the valve actually strokes when the head is in place. It may be that the piston is too far removed from the seat to be effective. There should be a tool to do this available from the manufacturer.

Keep in mind also that these you describe are vent valves. They only hold back the air relief from the radiator based on temperature within the room. When open they merely allow the normal air vent to do it's good work as needed.

These types of valves are not positive shut-off devices. If the steam pressure is high enough you will get some steam into the radiator as the air compresses.

M Owen

radiator thermostat valves

I have a three story home that I rent out. When someone is
living upstairs on the third floor I have to use the thermostat up there to get heat to the top floor which
overheats the middle floor. I recently had Danfoss RA 2000
thermostats that fit in the air holes and are supposed to
shut the radiator down at a preset temp. The tech man myself and the factory rep can not figure why the are not shuting the radiators down at the setting.(about 70 degrees) I have been dealing with this problem for years and hoped these valves would do the trick. Please help.

DWood

A couple of thoughts

If the valve fits into the air vent on a cast iron radiator, then you have a one pipe steam system. With this type of system, your system must go to zero psi at least once an hour to allow air back into the system. If the air isn't allowed to get back into the system, you will have a continuing overheating situation. Are the vent connections on the Danfoss 1 ps located at 12 o'clock? The vent location MUST be in the 12 o'clock position for the proper operation of the valve. If not at the 12 o'clock position, air can bypass the seat and disk assembly and allow an overheating situation. Lastly, you may have some dirt on the small vacuum breaker that is allowing air to bypass the seat an disk assembly. Once again, this will cause overheating. Lastly, what pressure are you running your boiler. One pipe steam systems typically were designed to operate on ounces of pressure not pounds. The lower you can run your boiler, the better off you will be, but definitely not more than 1 1/2 psi.
I'll send you some more info when I get off the road.
Hope this helps, good luck.
DWood

Steamhead (in transit)

Danfoss RA2000 one-pipe steam TRVs

If this is a one-pipe steam system, one thing We've noticed about the Danfoss units is that the vacuum breaker can sometimes allow the passage of air into the vent, even if the actuator is all the way closed. And this is right out of the Box! The vacuum breaker is contained in that brass hex nut on the opposite side of the vent outlet. Take it out and blow thrugh it and suck thrugh it until the little tiny black check ball seats, then put the vacuum breaker back into the body and the vents should work (provided the system shuts down on temperature every once in awhile).

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