Michigan Help evaluating quotes for open loop systems

Discussion in 'Quotes and Proposals' started by michiganman, Jul 2, 2018.

  1. michiganman

    michiganman New Member

    Hello all, we are looking at replacing our existing electric central air and LP furnace with a geo thermal heat pump. We currently utilize a well(20gpm) for our water needs. We've gotten quotes from a couple of different installers and although we were initially thinking about closed loop systems we've been pushed in the open loop direction due to the fact it is much cheaper, more efficient and(so we've been told) water is one of the great resources and luxuries available to us in this state so we may as well use it since there is no worry about the aquifer drying up.

    We have a 2400 sqft home that is 20yrs old and the 2 quotes feature different size systems. Both Bard, one a 3ton GV38S3AAN and the other a 5ton GV61 with 14kw aux heater. Personally I feel that a 3ton may be a bit small(the guy did absolutely no measurements) and a 5ton perhaps a bit large(this guy did measure the place and said we could go 4ton if I wanted and save a few hundred bucks but said energy savings on AC never leaving the first stage and having plenty of heating made the 5ton the better option).

    Both systems would discharge the water out back behind the house and include everything needed to perform that as well as all the electrical required and a new thermostat.

    The 3ton system was quoted at $17k and the 5ton system comes in at $18.2k

    My questions for all of you fine folks:
    • Do these quoted prices seem reasonable/on the mark for these types of systems? Online research is all over the dang place on pricing these out and most seems to be for closed loop systems so it's hard to tell.
    • Size-wise these systems seem pretty different so at least one must be missing the mark.. does splitting the difference and going with a 4ton make sense here or should I really just go with the 5ton and save some money on cooling in the summer?
    • Any gotchas or things to be aware or leary of from people who have went the open loop route? Maintenance, water quality, water draining etc?.

    We usually keep our house 65 in the winter and 74 in the summer. With this system we would probably go closer to the middle and aim for 68-70 if that matters/helps at all.

    Thanks in advance for your help, let me know if there is any additional information that I can provide that would help! :)
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi and welcome!

    Red flag number 1. open loop is more efficient
    Do the quotes include upgrades to your current pumping system?
    a gross rule of thumb is 1 ton of load for every 600 square feet, 3 tons to small 5 tons with 14kw aux is over kill.
    Has either one done a blower door test?
    A blower door test is critical for determining the load for an older existing home.
    The best money you can spend on your home is on envelope improvements. So take the data from your blower door test, apply monies for better insulation or new windows to reduce your load/cost to heat and cool.
    Hope this helps
  3. michiganman

    michiganman New Member

    Can you elaborate on why this is a red flag please? Also no it does not include upgrades to my well pump(is 20gpm not sufficient? I was lead to believe it was more than) although we did discuss getting that upgraded as well due to the fact that it is 20 years old and if I perform that upgrade the same year as geo I can re-coup 1/3 cost via tax incentive. Is that true?

    So I was on the mark with the 4ton system? What exactly is the harm in a 5ton system? I just want to be sure I understand everything going in.

    Not to my knowledge, never heard of a "blower door" test. What is that and how do I have one performed? Is this something that HVAC folks can perform? Is it a similar to a "Manual J" calculation?

    I plan on having an energy audit done, is that an "envelope" improvement? I think it is along those lines.

    Do those prices seem correct? Thanks for the info/help, everything about these subjects seems so wishy/washy and unscientific that it's a lot to absorb when everybody is saying all sorts of different things!
  4. moey

    moey Member

    The harm of a system too large is in cooling your air delivery temperatures will be too cool even with a 2 stage compressor. This will result in a damp feeling in the house. The house will be cool but high humidity. In heating if your ductwork is not sufficient it will be noisy as you have to run a 5 ton system at more CFM. Sure you can turn down the CFM but then you loose efficiency and the benefit of a 5 ton system.

    The best approach is to do a heat loss calculation on your house then decide.
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Open systems are not necessarily more efficient. Warmer water temps, yes, but also significantly more pumping power. I prefer the reliability of a closed system any day over an open system. Sometimes you have to play with the cards you got.

    My sizing scheme has changed over the years, since the availability of variable speed equipment. You can have a heatpump match the load, and we now size for the whole load, meaning if possible without supplement heat, with the electric strip heat only for emergency purposes.

    So there is no such thing with oversizing, since a 5 ton variable speed heat pump can behave like a 1 ton heat pump.

    While you loose some compressor efficiency when slowing down the blower, it usually compensated by spending less for fan energy, so you have some leeway. Nothing wrong with right sized ductwork, but sometimes you have to play with the cards you have. Not sure why you would loose the benefit of a 5 ton system?

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