is hot water hook up worth it?
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  1. #1

    Question is hot water hook up worth it?

    I have a new house, with a 8 ton split (5/3) geothermal system, horizontal loops (8-125' loops), in the Pittsburgh area. The Carrier units are both in the basement furnace room, side by side, with the second air handler in the attic for the second floor.

    We have gas hot water heater (80 gal). Both geothermal units have HWG in and out connections.

    After reading as many posts here as I could find about the use of the geothermal for heating water, I still have a few questions:

    1) is it cost efficient compared to gas? I understand it really would only be beneficial in the cooling season (I understand that pricing is against the rules, just wondering if it makes sense)
    2) How big should the second tank be? 80 gal? 40?
    3) Since I have two separate units, each with their own pumps and loops, is it possible to use both for the HW?

    Thanks!

  2. #2
    Join Date
    Aug 2009
    Location
    Dell Rapids, SD
    Posts
    44
    My setup is a 3 ton Waterfurnace split system. I have a 40 gallon NG water heater, and a 50 gallon electric as a buffer tank. After about a day of run time of the geo, the 50 gallon tank has 50 gallons of 130 deg water in it, and the geo actually shuts off the HWG pump.

    My NG water heater is set for 120 deg, so the water going into the NG is higher than the thermostat. My NG water heater doesn't hardly kick in anymore. When the kids were all home from college, it would come on for a while, but since then, it just sits there waiting.

    I never expected to be this happy with my geo system. Pleasant surprise I guess.

    Dave.

  3. #3
    Join Date
    May 2005
    Posts
    159
    Quote Originally Posted by djastram View Post
    My setup is a 3 ton Waterfurnace split system. I have a 40 gallon NG water heater, and a 50 gallon electric as a buffer tank. After about a day of run time of the geo, the 50 gallon tank has 50 gallons of 130 deg water in it, and the geo actually shuts off the HWG pump.

    My NG water heater is set for 120 deg, so the water going into the NG is higher than the thermostat. My NG water heater doesn't hardly kick in anymore. When the kids were all home from college, it would come on for a while, but since then, it just sits there waiting.

    I never expected to be this happy with my geo system. Pleasant surprise I guess.

    Dave.
    Is this with the electric water heater turned on?

  4. #4
    Join Date
    Aug 2009
    Location
    Dell Rapids, SD
    Posts
    44
    No. It's not even wired. Just an insulated tank.

  5. #5
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    is it cost efficient compared to gas? I understand it really would only be beneficial in the cooling season

    Cost depends on electric and gas rates.
    DSH works in heating also and probably cheaper that non condensing gas would.
    Tank size depends on hot water usage, but I would go no less than 50 gallon buffer tank.
    You could connect both GEO units to one buffer tank

  6. #6
    Join Date
    May 2005
    Posts
    159
    Quote Originally Posted by djastram View Post
    No. It's not even wired. Just an insulated tank.
    So if your geothermal unit can keep the entire 50 gallon tank hot enough, why do you have 2 tanks?

  7. #7
    Join Date
    Aug 2009
    Location
    Dell Rapids, SD
    Posts
    44
    http://www.waterfurnace.com/literatu...ion/IM1592.pdf

    Page 13.

    It takes a day to make 50 g of hot water with my geo. The buffer tank is there to preheat the water, to whatever it can, before it enters the NG waterheater. The performance is based on the outdoor temp.

    This summer, it will probably be keep up just fine.

    Dave.

  8. #8
    Join Date
    Feb 2006
    Posts
    468
    On days with little or no heating or cooling (spring / fall) primary water tank steps in and provides all domestic hot water. Geo with DSH only produces hot water in the course of heating or cooling the house

  9. #9

    Not worth it on climatemaster Tranquility 27

    All summer long, when you would expect the hot water production to be the best, the water exiting my climatemaster was hardly warm. In testing with a digital thermometer, water entering the system was going in at 80-85 degrees and exiting at about 95 degrees. Small increase, so I am sure it is doing something, but no where near the 130 that some of the waterfurnace folks talk about. This was tested on 95 degree days in the summer when I would expect tons of heat being built up in the house.

    We have two water tanks. Tank 1 sent to 130 degrees, tank 2 set to 95 degrees. The geo pulls from the bottom of tank 2 and feeds into the top.

    I have called my installer and asked and they have told me "you can't heat all of your water with the geo"..

    If someone else is having better luck I would love to know.

    My neighbors on both sides have waterfurnace and both indicate that their hot water is noticably warmer in the summer, they assume because of the geo, than winter.

    just my $0.02

  10. #10
    Join Date
    Sep 2009
    Location
    Iowa
    Posts
    139
    with all the geos i have put in.. i always put a 50 gallon or 80 gallon depending on size, electric marathon in there. the geo helps a little bit in the winter to heat it but in the summer has no problems. and the good thing with the marathons around here.. is the rec gives a lifetime warranty on them and they say you only loose 2 degrees of hot water through a 7 day cycle when your not there. i've noticed when people say they don't get enough hot water, sometimes i found the lines going to the water heater from the desuperheater are undersized.. mostly i see people run vanguard pex which is only 3/8" id and you really need 1/2" id so wirsbo is a good choice or just copper.

  11. #11
    I have a 6-ton Waterfurnace unit with DSH. I have two water heaters: one is an 80 gal electric that is not energized -- it is simply used as a buffer tank (electric because it was inexpensive) and the other is a natural gas 50 gal.

    The two tanks are connected in series. I have nothing to compare it to because my house is new and this is the setup I installed from the start. However I can tell you my holding tank is always hot in both the summer and winter.

    My unit will supposedly halt DHW heating if the unit can't keep up with the house, however my DHW -- High Level indicator is on quite a bit... indicating the tempurate in the holding tank has reached the maximum temp. This tells me my unit is cranking out the hot water.

    My natural gas water heater is set to a fairly low temp. Hot water coming into the gas heater means it does not work very hard. We have yet to run out of hot water.

    My DSH draws from the top of the holding tank and sends the water back up through the drain at the bottom of the tank.

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