Louisiana Scared of my pumps

Discussion in 'Maintenance and Troubleshooting' started by bjl, Aug 14, 2019 at 9:51 AM.

  1. bjl

    bjl Member

    I have two miami heat pumps, 2.5 ton and a 3 ton 2 stage. Been running since 2015, with few problems. I did the whole installation learning as i went. After the install for the first year everything was perfect till ewt started rising. Started at 68* and at 85* or so the 3.5 ton (now a 3 ton from a blown compressor, which is what the manual j called for) went to high pressure lockout. Figured out not enough water flow. Each unit had a single ups15-42f 1/25hp pump set to high and the same pump for the desuperheaters combined. I installed my swing pump in a push/pull configuration and it solved the problem.
    Fast fwd to now, I haven't installed enough insulation for what the system was desined for and the ground loop temps have been slowly rising. More Insulation is at the top of my list right now, but doesnt explain the pump overheating, i think. One pump on the the 3 ton actually melted the paint in one spot, see pic. 20190814_073135.jpg This pump was locked up, but i guess the other kept it from burning up, maybe. Never triped the breaker. Amp test on each pump is .38, below the .41 max. Housing temps on the 3 ton (both pumps) are at 140* in one spot by the manufacturer connections. The same spot on the other unit pump is 108*. Well last night the desuperheater pump almost caught on fire. This is the same spot I am testing on the other pumps 20190814_072636.jpg
    It almost seems like bad connection leading to overheating, but i dont know for sure. Is this a common problem? Or Do i have something wrong? Maybe need larger pumps?
    Ewt is at 111*
    Lwt is at 120*
    The delta T on both units has stayed at 10* +- 1* since install.
    I am in southern Louisiana (gulf coast)
    Predominantly hot and humid for most of the year.
    Loop field is horizontal unpressurized closed with 8 loops @ 90' spaced out 7' centers buried 10' down. Each contain 680' of 3/4 hdpe.
    It took me 3 years to build this house basically by myself and would hate to see it burn from a stupid pump (i do have small circuit breakers on the pumps)
    please advise!
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi and welcome,
    grundfos pumps have a wet rotor design. That looks to me like the motor/pump was locked and the unit was calling for the pump. Capacitor could not take it and burned. Just replace the faulty pump and maybe try to filter your loop fluid doing a purge to check for debris.

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