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Radiant loop with cast iron radiators

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Unknown
Unknown Member
in THE MAIN WALL
Want another fuel saving trick?

Put in a two stage heating thermostat, and have the licensed installer connect the first stage to the circulator relay for the radiator zone, like it is with the single stage thermostat that you have now.

Have him connect the second stage in series with the relay contacts that start the (24 volt ONLY) burner circuit. Yes, you probably will need him to pull another thermostat wire through the wall.

This means that the radiators will be constantly the same temperature, but changing up or down with the weather changes, rather than cycling up and down all day long, and the burner will fire occasionally to "touch up" the room temperature. The run cycle lengths will vary exactly proportional to how much heat you lose. The radiant zone will run independantly, and contribute to the overall load.

It's better'n outdoor reset.

Noel

Comments

  • Kevin Shaw
    Kevin Shaw Member Posts: 8
    radiant loop kitchen with cast iron radiators rest of house


    Guys,

    I have just installed a radiant loop (staple up under the joists) in my kitchen. This loop has its own thermostat and is plumbed with a taco 007 circ pump. It is controlled through a taco priority controller. The issue I have is that the radiator loop (2 story house) runs between 120 and 140 supply water temp. The aquastat is set at 190, but the system has never goten that hot. I suspect this is due to the large volume of water contained in the cast pipes and radiators. On design days the temp gets up to 170. Since installing the radiant loop the boiler is bouncing up against the aquastat (only when radiant zone calls for heat). This seems like a waste of energy because this super hot water gets tempered down to 140 by the mixing valve. Do you guys think if I wire both circ pumps to the main thermostat and eliminate the thermostat in the kitchen that the system will still work? I am thinking that if I have both circulators come on when the main thermostat calls for heat this will give me the benefit of higher volume of water that will be closer to the useable temperature of the radiant loop. What do you guys think?

    Kevin
  • Unknown
    Unknown Member
    You might try this first

    Disconnect the wire from the radiant zone to the burner, leave the pump and thermostat wired the way that they are. This zone would need to be on a relay by itself, not a multiple zone relay panel.

    That way, they'll run the way that you describe, but neither zone will overheat. The burner only runs when the radiator zone calls for heat.

    It's called Master Zoning.

    Noel
  • Kevin Shaw
    Kevin Shaw Member Posts: 8



    Noel,

    I will give this a try. By disconnecting the wire when the radiant zone calls for heat it will now only start the circulator and not fire the burner correct? Do I have to change the setting on the mixing valve? Currently the mixing valve is set to supply 140 degree water to the radiant floor. Does the mixing valve only ensure the temp doesn't go above 140?

    Kevin
  • Unknown
    Unknown Member
    sort of

    The mixer will bring it right up to the supply temperature, then mix with return water to hold it at the mixer setpoint without going above it.

    Noel
  • Kevin Shaw
    Kevin Shaw Member Posts: 8


    Noel,

    What happens if the radiator loop only gets to 120 degrees? Will the 120 degree water still flow through the radiant loop?

    Kevin
  • kevin_49
    kevin_49 Member Posts: 3


    > Want another fuel saving trick?

    >

    > Put in a two

    > stage heating thermostat, and have the licensed

    > installer connect the first stage to the

    > circulator relay for the radiator zone, like it

    > is with the single stage thermostat that you have

    > now.

    >

    > Have him connect the second stage in

    > series with the relay contacts that start the (24

    > volt ONLY) burner circuit. Yes, you probably will

    > need him to pull another thermostat wire through

    > the wall.

    >

    > This means that the radiators will

    > be constantly the same temperature, but changing

    > up or down with the weather changes, rather than

    > cycling up and down all day long, and the burner

    > will fire occasionally to "touch up" the room

    > temperature. The run cycle lengths will vary

    > exactly proportional to how much heat you lose.

    > The radiant zone will run independantly, and

    > contribute to the overall load.

    >

    > It's better'n

    > outdoor reset.

    >

    > Noel




    A monkey wrench in the spokes. My taco zone controller only has one set of wires to the boiler burner. It energizes the circulators and the burner through relays. I cannot disconnect the radiant loop burner wire. Will your idea with the 2 stage thermostat still work?

    Kevin
  • Unknown
    Unknown Member
    If there isn't a water heater as part of this system, it will.

    Noel
This discussion has been closed.

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