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Temp control for buderus and radiant

My system has radiant cement slab in part of house and radiators in a single pump system wirh two manifolds. House is well insulated but is remodeled 1810 upstate ny post and beam house wirh partial bluestone crawlspace 5’ high and the rest is on bedrock with bluestones under floor joists. So not much I can do for insulating floor of spaces wuth radiators and built on bedrock.

one zone that has radiant in slab and under old wide plank floors, on standoffs so not very efficient nor should they be too close because wide boards will shrink a lot. I want to get rid of that radiant under those wood floors and run radiatora in that living room, can I then loop in the supply off the return of the radiator so that the water is cooler, or is it pretty simple to just change one of the manifolds that runs all the radiant into a mix valve to lower the radiant temp?

The manifold on left is radiators and the manifold on right is radiant.


Comments

  • ZmanZman Posts: 4,753Member
    You will have much better temp control if you give the lower temp manifold it's own mixing valve and circulator. It would not be that difficult to do. What model boiler is it?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • IronmanIronman Posts: 4,936Member
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • IronmanIronman Posts: 4,936Member
    You would also get more btus if that supply and return were increased to 1" from the boiler before teeing to the manifolds. A 1" line has twice the capacity of a 3/4".
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • betweentheframebetweentheframe Posts: 97Member
    Zman said:

    You will have much better temp control if you give the lower temp manifold it's own mixing valve and circulator. It would not be that difficult to do. What model boiler is it?

    The line to manifold is insulated cast in concrete, cannot get changed, is a small 1666 sq ft house.

    Do I have to run a diff pump for that manifold, or can I just T off the supply, with a thermal valve from uponor and run a cold line over to it, and then run the mix into that manifold? Do I need a check valve between the line going from supply to thermal valve? Or can I just add it in line?

    Weirdly I have an outdoor reset wired in for this baxi and temp sensor but temp sensot reads high and when is set to work in the setting and apply curve it seems to not work vecause temp change does not select curve like manual says , 00 10, 20, etc

    I am also confused on why the right angle supply and return fittings coming out of boiler seem to be 1/2 in that increase to 3/4..
  • hot_rodhot_rod Posts: 11,228Member
    Also, wood shrinkage is more related to humidity change the space not the heat, per say. Wide boards are the toughest to hold still.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GordyGordy Posts: 9,263Member
    edited February 13
    ^ Also if that wide plank flooring is original to the home it’s old growth. It’s been acclimated for quite some time. Controlling humidity is the key, but hard to do.

    Wood flooring manufacturers like to limit “surface temps” to no more than 82*. But you are not dealing with fresh lumber, and whether it gets properly acclimated before installing is hit, and miss. I’m in the fence about the temps. Many scenarios where wood flooring sees much higher temps from solar gain that’s not even a radiant floor......
  • IronmanIronman Posts: 4,936Member
    @betweentheframe
    These are the lines I'm referring to:



    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • betweentheframebetweentheframe Posts: 97Member
    > @Ironman said:
    > @betweentheframe
    > These are the lines I'm referring to:

    Yes, those are insulated and cast in heated concrete slab part of house as they make their way to the old bedrock basement/5ft ceiling crawlspace under part of house, house is from 1810 post and beam barn originally built, wide plank floors are original heart pine 11imch wide full of gaps and cracks and refinished with character and have no subfloor but are about 1.25 thicj(were prob 1.5 but have been refinished a few times.
  • betweentheframebetweentheframe Posts: 97Member
    > @Gordy said:
    > ^ Also if that wide plank flooring is original to the home it’s old growth. It’s been acclimated for quite some time. Controlling humidity is the key, but hard to do.
    >
    > Wood flooring manufacturers like to limit “surface temps” to no more than 82*. But you are dealing with fresh lumber, and whether it gets properly acclimated before installing is hit, and miss. I’m in the fence about the temps. Many scenarios where wood flooring sees much higher temps from solar gain that’s not even a radiant floor......

    Agree on the old growth etc. that is old heart pine from 1810, but still moves a lot and no subfloor lol. Right now is black plastic staple up so not against floors, wider the wood floor planks the bigger each crack because shrinkage not spread out over several boards.

    Right now it has foil bubble insulation and fiberglass below that, i am thinking ove spray foaming over the foil stuff to cut drafts from the crawspace that is literally bedrock, or just spray foam the underside of floors and change that one 16x19 room to two 12x48 buderus panel radiators, because it is adjacent to the heated slab and on the same zone/thermostat. I was wondering if I could run that zone through the radiators first and then tie it’s return into the slab, then adjust the flow rates and radiator valves to balance it. Because as it stands the radiant under wood does not hold the heat like the cement does and the cement floor in kitchen makes toom feel way warmer than living room with the radiant under the hardwood.
  • betweentheframebetweentheframe Posts: 97Member
    Can I T off the supply and the return for the small living room staple up system to the supply and return of the zone that controls a single 24x48 buderus radiator? Effectively putting the staple up system on that adjacent room’s thermostat?

    That way all 140 degree stuff would be on left manifold and I could run the 3 used zones on right manifold wirh a mix valve to lower temp as they are all concrete radiant?

    Do I need to use a monoflow T on the supply so I can send 65 percent of hot water to staple up and 35 percent to the radiator? Then a regular T to connect the returns before they enter the manifold?
  • betweentheframebetweentheframe Posts: 97Member
    Or shoukd I feed the radiant supply with the return from the radiator, connecting them with a coupling, then connect return of radiant loop into current return for the zone that just has radiator on it? This way they all flow in one loop
  • betweentheframebetweentheframe Posts: 97Member
    Run zone on right into zone on left. So all are 140 degree and more common cycling/heat loss.
  • betweentheframebetweentheframe Posts: 97Member
    In meantime can wire zone control to make both run off same tstat and see if better balanced
  • betweentheframebetweentheframe Posts: 97Member
    Never mind they sell add on zomes for thos ep manifolds
  • Paul PolletsPaul Pollets Posts: 3,160Member
    Where is the home located?
  • betweentheframebetweentheframe Posts: 97Member

    Where is the home located?

    Upstate ny, currently still struggling with the damn return taking in supply water, i think this baci does not need a primary loop below boiler and should be straight piped, going to call baci monday, manual says only needs a prinary loop if all rads are on TRV’s
  • betweentheframebetweentheframe Posts: 97Member
    > @Zman said:
    > You will have much better temp control if you give the lower temp manifold it's own mixing valve and circulator. It would not be that difficult to do. What model boiler is it?

    Zman, can I just bypass the grundfos in basement for the non cement slab low temp radiant zones with a T, using internal baxi pump to pump the non radiant manifold, and then let this pump feed the radiant zone with a mix valve with a T in main return line for the “cold” connection.

    Red is the supply from baxi to 140 degree manifold, and then the grundfos there in basement is feeding the 120 degree manifold, the green being a 3 way mix valve tapped into main return.

    Question, will the water get suck into the manifold on the left through the T? Or will it bypass that and go into the grundfos because of the pressure diff?
  • SuperTechSuperTech Posts: 938Member
    You can see the obvious problem with how radiant works better heating a concrete slab floor rather than wood. Instead of trying to add monoflo tees and spraying the underside of that old growth flooring with foam why don't you cut your losses and start over using a more appropriate heat emitter? Cast iron radiatiors would be the most appropriate for a house that age, and they offer similar comfort as the radiant flooring. Panel radiators are a more modern option, and take up less real estate.
  • betweentheframebetweentheframe Posts: 97Member
    Agree on staple up, I did not install it, but the concrete slabs in kitchen, bath and laundry room additiona are not going anywhere.

    So I can switch over to radiators, but whatever I do the spray foam would def seal up floor gaps and rim joist from drafts in a bluestone stacked foundation and that crawlspace is literally broken up bedrock that house is built on LOL, the rock tends to radiate the cold pretty serious.

    So I need to hopefully temper the mix for better control. For now the nest seems to be learning the time to temp in true radiant, adjusting its algorithms and not overshooting by more than a degree or two
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