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Taco Circulator settings

DNelson
DNelson Member Posts: 1
in Radiant Heating

Hi,

I'm a homeowner and new to radiant heat. We have a Tekagi on-demand water heater (set to 135 deg) on a loop with a taco circulator set to constant speed of 4 that connects to the secondary loop with a taco set to a TD 20. Then there are two zones with Taco circ set to constant speed 4 and a Grundfos on the third zone

20241107_200504.jpg

. The upstairs zone struggles to heat up and will run all night. I'm not sure how the system was laid out upstairs. The downstairs is in a slab. The water leaving the circuit has never been over 105 degrees and usually returns at about 96 degrees.

I cleaned out the filter to the water heater and am able to get 2-3 GPM of flow. Are there any blatant problems I can adjust?

I apologize if none of this makes sense.

Comments

  • Dave H_2
    Dave H_2 Member Posts: 579

    The zone that is not heating, what setting is that particular circ set for? and what are the reading on the circ.

    Yes, there is alot of other info needed in order to diagnose why that zone is not working fully. It may well depend upon the installation method, floor coverings, water temp, heat loss of the space.

    Is this system new you or did you move into this house with the radiant already there? Did it ever work properly?

    Dave Holdorf

    Technical Training Manager - East

    Taco Comfort Solutions

    Rich_49
  • hot_rod
    hot_rod Member Posts: 23,108

    that looks like a tankless water heater? Those typically need a high head circ to get full output. The manual may have a pressure drop curve to help size the pump

    Its not the best device for hydronic loads they are designed for low flow high delta, just the opposite of what a hydronic system needs

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Rich_49
  • Kaos
    Kaos Member Posts: 144

    What are the rest of the emitters?

    Is the main circ a VT2218? If yes you will only be able to get about 30k out of that unit. This is fixable if you put both pumps in series instead of the double loop.

    You want both circs to run in delta T mode (looks like the senor is there, if not add it), same temp target.

    If you need 130F supply to get enough heat and you want decent efficiency, the delta T should be about 30F to 35F. If you can't get heat out like this, you can bump up the outlet temp a bit.

    Once you have this set up, turn on all the zones and post temps/flows at different locations to troubleshoot further.

    The venting on the unit needs to be fixed, you can't share a vent with a condensing unit. These can be vented with plastic pipe, so that should be easy to fix. Do it soon before it corrodes your flue.

    What is the PSI and BTU rating of the relief valve?

    GroundUp

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