One-Pipe Steam System Advice

Bob_16

I'm working on an early 1900's gentleman's club (no, not that kind) that has a one-pipe steam system. The building is 4 stories plus a basement, about 50,000 sq. ft. total.

The problem is that the building has dining rooms and public gathering spaces on the first three floors and sleeping rooms on the fourth. There are three separate zones (east, center and west) feeding perimeter radiators.

When there's a large gathering on one of the lower floors, the spaces overheat, so they turn down the boiler and the upper floors freeze and vice versa. Is there a way to provide individual heat control at each radiator? I wasn't sure how well throttling the steam valve at the unit would work.

Also, we're proposing adding a few air handlers for ventilation and we'll need re-heat coils. Can you hook two-pipe coils into a one-pipe heating system without causing issues with the rest of the system? (Perhaps taking a supply main off near the boiler and connecting a return below the waterline?).

Thanks in advance for the advice!

Steamhead

Thermostatic Radiator Valves

that replace the air vents on your radiators, should do the job. Try Honeywell or Danfoss. Do not try throttling the shutoff valves, this will cause the radiators to fill with water and bang. Also, if the boiler is controlled from a thermostat the radiation in the space containing the thermostat should not have a TRV. You may have to move the thermostat to accomplish this.

It is possible to hook up your steam coils to a one-pipe system, but you must do the following: 1- make sure the steam mains can handle the load, 2- size your steam piping for a very low pressure drop, 3- install a properly-sized vent on the return connection, and 4- run the return line to a point below the boiler's water line before tying it in to the main wet return.

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