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Compromised Pump?

We installed this heating system 21 years ago and it's been working flawlessly until recently when the heat started struggling to keep thermostat setpoint even with moderately cold outdoor temperatures.

I played with the heating curve and shift and it improved slightly, but not close to where it used to be. Also checked the outdoor sensor and supply sensor which were fine.

And then I saw a 40° ΔT and checked the pump. It's a Taco 0012 which should draw 1.33 amps. My clamp meter read 1.7 amps. What does that tell you?
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    Bad pump. That has a replaceable cartridge, though, with all the moving bits, so unless the problem is in the motor windings (shorted -- but almost impossible to test for) you might try that first.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterManAlan (California Radiant) Forbes
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,563

    Bad pump. That has a replaceable cartridge, though, with all the moving bits, so unless the problem is in the motor windings (shorted -- but almost impossible to test for) you might try that first.

    The replacement cartridge sometimes is just as expensive as the complete pump. I have often replaced the cartridge and motor body on 00 series pumps by purchasing the complete pump and removing the housing that connects to the piping, Do the same with the replacement pump and put the new pump parts on the existing housing. Sometimes that is faster than unbolting the flanges. Sometimes not.


    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,936
    edited December 2023
    I thought this might be a good chance to replace it with a ECM pump.

    But in the meantime, I'd like to be able to further test the pump before I replace it. Maybe @SteveSan could tell me what the 0012 ohm reading should be. Thanks in advance.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • SteveSan
    SteveSan Member Posts: 231

    I thought this might be a good chance to replace it with a ECM pump.

    But in the meantime, I'd like to be able to further test the pump before I replace it. Maybe @SteveSan could tell me what the 0012 ohm reading should be. Thanks in advance.

    Morning Alan, the ohm readings for your 0012 should be between the y-r, between 12-14, y-b between 14-18, and r-b between 26-32.

    The 1.7 amp reading is close to lock cartridge or possible air. Rule of thumb is any amp reading that is close to or more than 1.5 times the nameplate amps would suggest that.

    Removing the cartridge, I would do a visual inspection on the winding to make sure no damage to them before replacing the cartridge.

    Hope this helps, and enjoy your weekend.
    Alan (California Radiant) Forbes
  • SteveSan
    SteveSan Member Posts: 231
    https://www.tacocomfort.com/documents/FileLibrary/Taco_Circulator_Replacement_Guide.pdf

    Alan, the link is a nice cross reference that we have on the website from standard a/c models to ECM.
    Alan (California Radiant) Forbes
  • leonz
    leonz Member Posts: 1,051
    Hello Alan,

    Keep in mind that the ecm circulators will affect pacemakers and pacemaker defibrulators due to thier permanent magnets.

    Alan (California Radiant) Forbes