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Thermostat Placement in zone with panel rads w/ thermo valves

hydronicsmike Member Posts: 855
...since it is a 5 Zone System, I now see why you have a Zone Valve on this loop.

Yes, you could leave this zone open all the time when running with an Outdoor Reset Control (or even without it for that matter), as the the TRVs will control the indivudial Zones on that loop.

Outdoor Reset is the most cost effective way to run your system and also results in inceased system effieciency and comfort level by minimizing temperature swings in your other zones operated with standard thermostats and zone valves. Without Outdoor Reset, you would be supplying the water temperatrue needed at the coldest day of the year even when it is milder outside and when the heatloss of the building is reduced because of the milder outdoor temperatures. With the same supply water temperature as needed at the coldest day of the year (Outdoor Design at 100% Heatloss of the Building), then the tehrmosatts would naturally call for a shorter period of time and then be off for a longer period of time, which does create the temperature swings and possible expansion noises (especially with Fun Tube Convector Baseboard) every time the building is not at aits maximum heat loss.

Based on your application, it sounds like the 260 tekmar Boiler Control would be best suited. -see attached D260 Manual or visit for more info, or call 250-545-7749.

Best Regards,



  • Phil Reeves
    Phil Reeves Member Posts: 6

    I'm gutting an area that is heated with a single zone of baseboard fin/tube rads. I'm replaceing everything with Myson Panel Radiators, they suggest using monoflow t's and thermostatic valves.

    Question: Where do I put the main thermostat for the zone, the one that calls for heat (opens the zone valve and starts the cirulator)?

    My thought is to put the thermostat in the room that we want to be the warmest because the valves will limit heat, not create heat. (We can lower the valves in the bedroom) The only problem with that theory is that the room we want to be the warmest is the bathroom. Is it OK to put a thermostat in the bathroom, considering DHW from showers, etc, can affect the temp?

    I want to make sure we have a solid, balanced system. Please help with any ideas or experience. Thanks!!!

    Phil R.
  • hydronicsmike
    hydronicsmike Member Posts: 855

    ....I would say that if you only have a single zone system, you won't need a Zone Pump AND a Zone Valve. All you need is ONE pump. Would suggest you let it continuously circulate with a water temperatrue based on Outdoor Reset. A thermostat is not required, as the air temperature will be controlled through the thermostatic radiator valves. If anything, you may add an Indoor Sensor to an Outdoor Reset Control to fine tune the outdoor reset water temperature, but even that is not required.

    At least thats my suggestion. Hope this helps.



    PS.: Happy Canada Day (July 1st) and Happy Independence Day for my friends in the South.
  • Phil Reeves
    Phil Reeves Member Posts: 6

    Thanks, Mike.

    I was hoping not to mess with the rest of the system so much. The zone I'm gutting is one of five. They are a mix of fin tube and cast iron radiators of various vintages. A single circulator feeds all five zones. Each zone has its own thermostat.

    Could I just let the one zone stay open all season with out an outdoor reset controller? I'm wondering how much it would cost to keep the water in that loop hot all winter.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    As long as you have a thermostatic valve (TRV) on EVERY radiator in the zone, really no need for a wall thermostat, and certainly no need for a zone valve.

    One way to control the circulator for the zone is to use a simple outdoor temp control set so that the circulator runs at all times the zone is expected to need heat--typically below 55° or so.

    You can use a wall thermostat to control the circulator however. If so, you can put in any suitable and convenient location--actually an unheated interior hallway is good. For "normal" operation set the thermostat higher than desired in the area with the thermostat. This keeps a continual heat call to provide constant circulation. The TRVs will all modulate at their setpoint.

    For setback you can set the wall thermostat down without changing the TRV settings. This will "starve" the TRVs and the room temp will "bouce" around the wall thermostat setting as normal.

    Provided they have constant circulation and supply of heat, TRVs automatically and individually respond to changing loads--be they from the outdoors or indoors (like a long, hot shower).

    For best results using TRVs, give HIGH consideration to a two-pipe system. They will work with monoflow tees, but because they change flow through each radiator they also change delta-t through each radiator--this makes it EXTREMELY difficult to engineer the system to maintain balance in some conditions (particularly "cranking" a TRV or two).

    Also, outdoor reset is VERY desirable when you use TRVs. Depending on the type of boiler and the rest of the system you may reset the entire system; you may use primary/secondary and reset everything on the secondary (radiation) side; you may use a mixing valve to reset only the new TRVd zone.
  • Big Ed
    Big Ed Member Posts: 1,117

    Always put the thermostat in the coldest heated room .You can always cut down on the others..
  • hydronicsmike
    hydronicsmike Member Posts: 855
    where is the coldest room??

    In my house, in the morning it's on the West Side, in the Evening on the East Side. Depending on thermal gains and Wind Losses.
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