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  1. Thanks, everyone, for your thoughts. I think the insulation isn't an issue but I'm going to inspect and confirm. I like the idea of determining flow rate from pressure diff, but I agree, it might be hard to pull off. I think I'm going to investigate the notion of air in the lines. That seems like a really promising avenue. Does anyone have any tricks for ensuring all the air is out of a circuit?

  2. #15
    300' on a 1/2" tube is, to me, on the high end of acceptable. Knowing the rest of the info is pretty important.

  3. I assume it's the circ pump your wanting the specs for? I can email my HVAC guy and ask for the model #.

  4. #17
    Yes, and the total number of loops

  5. Total loops is 13. I've sent an email off asking for the model of the pump.

  6. I'm told the pump is a Grundfos UPS26-99FC.

  7. #20
    According to this info:

    That's a three speed pump with a top pumping capacity at zero head of 33 gallons per minute.

    So I'm wondering if your pump may not be set at a higher speed?
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.

    A building is NOT beautiful unless it is also comfortable.

  8. #21
    Join Date
    Oct 2010
    Anderson, South Carolina, United States
    A hydronics tech should be able to purge air from a loop, no DIY.

  9. Yeah, I'm pretty sure it's at the highest speed. The original installation used a smaller pump but we went to this one to try and increase temps by increasing flow.

  10. #23
    Join Date
    Oct 2010
    Anderson, South Carolina, United States
    Are the zones that are not working well at the highest point?

  11. #24
    Is the pump feeling HOT, not warm but too hot to keep your hand on for more than 1-2 sec?

  12. #25
    Join Date
    May 2012
    Upper Michigan
    Are any of the tubes getting warm, maybe a few runs are air locked, or pump is bad. There should be temp gauges on supply and return, do u know any temps? 300 feet is too much, 250 is max.

  13. #26
    When you say "get up to temperature," can you explain what that means? Up from where?

    One pump? 13x300' loops?

    These insufficient zones, in rooms the furthest away from the boiler for those floors?

    Boiler make & model? Modern high zoot boiler (to match the house... And if so, why no ECM pump)? Temp setting? Water temp programmable by zone? Reset setting?
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to, or RESNET, and find an auditor near you.

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