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Best thermostat type for single pipe steam heating

I have a one-pipe steam system and wonder what the best thermostat system for it would be. I have a Honeywell Chronotherm III installed (as below) and running now.

The thing that makes it a bit unusual is that the home is a three family (two one bedroom apartments first floor, and a two bedroom apartment on the second floor) and there is only one thermostat located centrally in the second floor two bedroom apartment.

My concern is that cooking with the oven in the upstairs apartment (next room to where the thermostat is) adds heat and causes the two downstairs apartments to get quite chilly. Is there a system which could take into account the temperature of the two apartments in addition to the main thermostat location so that this does not happen?

I have contemplated adding fixed thermostats to both apartments (in series) so that if both apartments go below a certain temperature then heat would be called for regardless of the setting of the upstairs thermostat, but I worry that it would throw off the adaptive cycle of the honeywell unit, causing temperature fluctuations.

I'm looking for thoughts or suggestions on how to deal with this situation. Thanks!

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  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
    Consider the Honeywell PC8900/W8900...

    This control supports up to 9 remote temp sensors, and averages their input with what the main stat is sensing. This a fully digital, 4 period set-back system. You would mount the PC8900 where the existing stat is now, and the sensors in the other apartments, and connect them all to the W8900, which is wired into the boiler and cooling system in the mechanical room just like any stat. You may over/undershoot the temperatures in the various apartments, remember, the system is averaging between several sensors, and is not a true zoning system. These are available from any Honeywell distributor, and should be professionally installed. Check out www.honeywell.com/yourhome, and type in PC8900/W8900. The two are required, and can't work seperately. The part number for the remote sensor is C7189A1001. Using setback on one pipe steam is controversial, this system is capable of doing that, but you may choose to just run it at fixed temperature, based on your own experience.
  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    You may want to look at TRV's

    Thermostatic radiator valves could be installed on some of the radiators to control overheating in apartments without the thermostat. Or you could install an outdoor control and cycle the boiler off that and install the TRV's on some or all the rads for the absolute best in comfort and economy.

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