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Ground Source Heat Pump Compressor Life

contrawise
contrawise Member Posts: 7
in Geothermal
I'm hoping to get some real-life information about compressor life in ground source heat pumps used in a cold climate. I'm working on a project for a church that's interested in the technology. Unfortunately, they've been spooked by some folklore that the typical compressor life is six years. My expectation is that they would be likely to last twice that or more in most cases. I'm aware of an apartment complex where compressor life is that bad on average, but its because the heat pumps they selected were not designed for ground source service! So ... what's the life expectancy like when units are appropriately rated for that service - and the ground source exchanger is adequately sized?

Thanks in advance!

Comments

  • SuperTech
    SuperTech Member Posts: 2,156
    I've seen plenty last over ten years in NY. Are you planning on using package units or split systems where the compressor and air handler are in separate locations? Split systems require proper evacuation and refrigerant charging during the installation process. More room for lifespan decreasing errors with split systems.
    Honestly the most important factor in having a reliable system that lasts is making sure it is installed and commissioned properly to the manufacturer specifications.
  • contrawise
    contrawise Member Posts: 7
    Thanks for the data!
    If we do as I hope, we will be installing a couple of packaged water to water units. I'm right with you on the uncertainty introduced by split systems. Though, I've done gobs of AC & Refrigeration - so I'd be supervising a split system if we do that.
    Thanks again for the report!
    SuperTech
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,517
    @contrawise
    I wouldn't be suprised to see them go 20 years with proper installation and maintenance. But proper installation and maintenance is hard to find these days.

    Especially with a water cooled condenser/evaporator.

    compressors don't go bad. Improper sizing and bad maintenance kill them
    SuperTechcontrawiseGEO80
  • GW
    GW Member Posts: 4,692
    I get the heebee geebies when people get “spooked“. I don’t twist arms. If you twist their arm and there’s a glitch, you’re cooked, they will never let you forget. I say my schpeal and say “you get to decide” . Never forget that last simple statement when you’re dealing with people on the fence.

    With that said, never heard of bad compressors on geo, that’s a new one for me. I don’t do much geo though.
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • motoguy128
    motoguy128 Member Posts: 393
    The Bristol Compressors didn’t last long. Haha.

    Otherwise We have several out there at 10+ years old. One two compressor Enertec we have out there lost one compressor after about 15 years.

    The compressor sees a lot less lift than a traditional heat pump and isnt jumping from heating to cooling for defrost all
    Winter.

    I think more often it’s the condenser water coil failing due to poor quality or water quality.

    We also have a lot of air source heat pumps over 15 years old out there too.

    But ac only system so seem to last longer. I can’t remember the last time I saw a 30+ year old heat pump still running. Plenty of 30+ AC units out there. I run into a few pushing 40 now and then.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,517
    Worst compressor ever was the Bristol two speed.

    3 contactors low speed, high speed and ty contactor=nightmare.You could loose a perfectly good compressor due to a faulty ty contactor. There is a sequence where the overloads cannot protect the motor
  • ratio
    ratio Member Posts: 3,624
    It sounds even better if you call it a two-direction compressor! I had one I replaced in a friends' heat pump. I was going to cut it open to see how it worked, then I ended up finding a crankshaft sitting on the counter at a supply house. Neat.

    Still can't believe someone though it was a good idea though. Too clever by half!

    pecmsgGEO80
  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    Seems to me that for any given compressor basic design, most of the variation between heat pumps and AC units is going to be in the number of actual operating hours -- not the calendar. I wouldn't expect a compressor in a heat pump application to last as long, in terms of years, as AC, for that reason.

    Assuming the same basic compressor -- and equally good care and skill in installation, of course.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • jumper
    jumper Member Posts: 2,245
    My guess is that starting is what wears stuff out. An unmentioned plus for thermal storage?
  • ratio
    ratio Member Posts: 3,624
    I'd think that elevated head pressures in heating mode would also add (deduct?) to life expectancy.
    dehv
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,517
    I agree with both @ratio and @jumper. I agree that oversizing dirty filters lead to short cycling and kills many compressors. It easy to spot, the units with crappy looking contactors are short cycling. High head pressure is also a killer and high superheat leads to a long slow compressor death
  • contrawise
    contrawise Member Posts: 7
    Thanks for a lot of helpful replies! Mostly confirming what I already expected. I appreciate being able to tap the experiences of others in the field!
  • contrawise
    contrawise Member Posts: 7
    motoguy128 said:

    The Bristol Compressors didn’t last long. Haha.

    Otherwise We have several out there at 10+ years old. One two compressor Enertec we have out there lost one compressor after about 15 years.

    But ac only system so seem to last longer. I can’t remember the last time I saw a 30+ year old heat pump still running. Plenty of 30+ AC units out there. I run into a few pushing 40 now and then.

    I worked for 25 years for a development company that built, and managed lots of high-rise buildings. Most of our buildings used horizontal, above-ceiling, water-source heat pumps, with a boiler/cooling-tower central plant. The oldest of those buildings had a sizable fraction of their original heat pumps still running. Many at 25+ years, with a couple of the oldest office suites still using a majority of their original units, many with original compressors, and even some original fan motors, at 32 years! Manufacturer for all the early units was AAF. Almost all used Copeland recips. The long lived fan motors were GE, apparently made to order for the heat pump manufacturer. Another reason is that we actually oiled those fan motors periodically.

    At some point, McQuay went on a buying spree - and bought Schneider-General and AAF. Quality and support went downhill like a bobsled. I could tell dozens of McQuay heat pump war stories. It's nice to be retired.

    GEO80
  • GEO80
    GEO80 Member Posts: 11
    Have had tremendous success with Bristol through 32 year life , and other inertia, but then the variable (!) Control, I believe left them to their bankruptcy...

    Old command-aire 35 yrs old, 1 compressor 15 yr ago.

    Find an installer-refg-tech knowing and proven follows mfr spec...

    Longest lasting have had sufficient cycle times and never over-charged with rfg.

    25yr life is normal to the normal. (since 1980, Geo-T)

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