Enough ground loop?

Discussion in 'Quotes and Proposals' started by woodbutcher, Oct 13, 2011.

  1. woodbutcher

    woodbutcher Member

    I live in northeast Texas and have 4 - 210' vertical loops to operate my Addison 3.5 ton unit. It has worked well for 16 years, but I have added a 13 X 19' room which I would like to run a duct into. The Addison needs to be replaced soon, so I'm looking at the Water Furnace Envision 4 ton. Some of the dealers who are bidding say I have enough ground loops to operate the new unit. Others say it's iffy. Any opinions?
  2. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    What are the high and low water temps coming out of your loop in the summer and winter?

    This will tell you what you want to know.
  3. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    I would be very careful about hooking up a much more efficient Envision unit to an old ground loop. A less-efficient (but still more efficient than your old one) unit such as a Versatec or such may be an option.

    In doing this, I just design "from scratch" and if your loop ends up matching what we need, then you're good to go.

    But more efficient units hooked to older ground loops can be a real problem - ie more btu's from/to ground vs. unit.

    Sounds like your local guys get this as well.
  4. woodbutcher

    woodbutcher Member

    I can't say what the temps are for the tubing. I don't have the equipment to test it. One of the more knowledgeable bidders who visited said that the unit seemed to work well after feeling the lines where they go underground. They were engineered to work with the 3.5 ton unit. In this area, we don't have a great variety of brands to choose from. I suppose that's because of low demand for geothermal. I bought my Addison from a dealer who went out of business a year after he installed mine. So, the only brand of geothermal that is recognized and offered within 50 miles is Water Furnace. Versatec...I'll check into it.
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Why not start with a load calc on the house versus assuming you need more. You might find modest envelope improvements permit you to use another 3.5 ton.

    I don't know how many feet/ton of bore is common in your area, buy you would have 4+ tons in mine with 4, 210' utubes.
  6. woodbutcher

    woodbutcher Member

    Thanks, it would probably be wise to do a load calc. Some contractors say the 4 wells I have will be enough for 4 tons. The others say, if it's not we can call in the driller. To me, that's an extra expense. The Envision does noit seem to be available in 3.5 tons.
  7. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    The caution Chris Koch (urthbuoy) mentioned concerns heating - a more efficient unit will need to extract somewhat more heat from loop since it contributes less from its own heat of compression.

    However, since your location is NE TX, I'll guess your primary concern is cooling, and the higher efficiency system works in your favor - somewhat less heat needs to be rejected into the loop for same cooling to house. In other words, a loopfield that supported an old reciprocating 3.5T system should do fine with a newer 4T scroll compressor.

    Add the hot water assist option with its own preheat tank and you'll be in even better shape.

    I do agree with Joe at al...a room by room Man J load calc and airflow analysis is in order before spending big bucks on new stuff.
  8. woodbutcher

    woodbutcher Member

    Thanks, Curt. Yes, cooling is the main concern here. I may have a hard time finding anyone who can perform the tests you mention. I'll ask some of the guys who submitted bids, but my guess is that they will say,"Well, it can be cooled with 3.5 tons just fine, or 4 tons better. So, it's your choice," and leave the decision to me.
  9. woodbutcher

    woodbutcher Member

    The location of our unit has always been an issue. When it comes on, the noise interferes with conversations and makes it necessary to turn up the volume on the TV. I like the soft-start and the 2-speed compressor offered in the Envision units I've read about. Would these be offered in a Versatec?

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