autmoatic steam radiator supply valves

David Laidlaw

My understanding is that thermostatic vents will not do the trick. Once the radiator has purged the air through the vent, it will keep pulling steam in until the heating cycle is finished. The vent can't pull air back into the radiator regardless of how hot the room gets. It seems to me that supply valves (not vents) are the mechanism of choice here.

David Laidlaw

multi-zone single pipe steam using automatic supply valves?

I am looking for sources for automatic steam radiator supply valves and (possibly wireless) controls to link them to thermostats.

I would like to "zone" my single-pipe steam system. Our house is large and different parts respond differently to the outside weather. Different rooms vary by 10 degrees, sometimes. Other times they are perfectly balanced. To keep everything comfortable and to save on oil, zones seems like they could really help.

After a lot of thinking, reading about steam systems (thanks Dan!), and extending our existing single-pipe system to include about 50% more radiators, I think that automatic supply valves on each radiator together with thermostats that control them and the boiler. My control stategy is to have the valves open any time its thermostat is below the high end of the swing range. The boiler would come on any time that any of the zones went below their low-end swing value and go off when all thermostats reach their top end. That would minimize heating cycles and keep all the zones at the right temperatures.

My current problem is that I can't find the pieces. Any suggestions for sources of appropriate valves (the less expensive the better...), thermostats, and wireless connections would be much appreciate. I can do some logic to make connections.

I'd also welcome feedback on the plan and pointers to existing solutions or partial solutions.

Thanks!

Mike T., Swampeast MO

Look into TRV (thermostatic radiator valves) from Danfoss or others. Contrary to the name, when used with 1-pipe steam the TRV replaces the vent, not the valve. To ensure no problems with condensate becoming trapped in the radiators, the use of one-pipe steam TRVs with integral vacuum breaker is highly recommended. Please do not use conventional TRV bodies designed for hot water or 2-pipesteam! The internal passageways of such are far too small and improperly aligned for allowing both steam to flow into the radiator and all of the condensate to drain back to the boiler.

While TRVs offer thermostatic control, they do not use electricity and do not use a wall thermostat. Remote operators are available but they are connected via a tiny tube--not a wire.

TRVs are incapable of telling the boiler to fire or stop firing, so particularly in steam applications, you usually need a wall thermostat to fire the boiler; the best location for such being a relatively underheated room or hallway. Commercial or large residential applications can use a Heattimer or similar instead of the thermostat, but such can get quite expensive and or finicky...

For many good reasons, pricing is not discussed here in any but the most relative terms. TRV bodies and operators don't come for free, but neither are they particularly expensive. Since they replace the vent on one-pipe steam rads, they are exceptionally easy to install and take FAR less time than replacing the valve itself. Since time is money,

[Deleted User]

TRVs don't pull anything.

On 1-pipe they simply shut off steam entry by blocking air access to the vent. 1-pipe radiators stay hot because the vent releases cooled air during the entire operating cycle. When the vent can't expell air, the radiator cools off.

If you install a valve type TRV on a 1-pipe steam radiator, the valve will hold condensate in the radiator. The result - anvil chorus & erupting vents. Valve type TRVs are for 2-pipe steam or water.