Geospring Hybrid water heater and Series 7

Discussion in 'General Discussions' started by Neokane, Aug 23, 2016.

  1. Neokane

    Neokane Member

    I read in another thread about the use of hybrid water heaters, Instead of thread hijacking I thought I would open a new one.
    I am intrigued by this idea of using a hybrid water heater.
    I am going to be remodeling my downstairs bathroom/utility room. I want to use my existing Series 7, and use my existing electric water heater as my new buffer tank and then use a new water heater as a primary tank.
    I see that the geospring 50 gal is $899 and my co-op offers a $650 rebate for stand alone Heat Pump Water Heaters. (I am trying to get clarification from there on their wordage of heat pump water heater)
    Wouldn't using a geospring reduce the efficiency of the Series 7?
    How does using the DSH in the winter affect the efficiency?
    Do most people turn of the DSH in the winter?
    What would be the best situation for this situation?
    I have a 5 ton series 7 and a 10kw electric heat strip. I live in Iowa and winters can get cold. I have yet to have the electric heat strip turn on (only had geo one winter).

    Thanks for the advice!
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Wouldn't using a geospring reduce the efficiency of the Series 7?
    No, the 7 series heat pump dumps all the DSH heat into the buffer tank and is unaffected by the HPWH.

    How does using the DSH in the winter affect the efficiency?
    You simply steal about 10% of the heat from the heat pump and make the hot water in the buffer tank with the efficiency of the heat pump.

    Do most people turn of the DSH in the winter?
    No, see above.

    What would be the best situation for this situation?
    Let the DSH heat your buffer, and supplement the rest with the HPWH.

    I have a 5 ton series 7 and a 10kw electric heat strip. I live in Iowa and winters can get cold. I have yet to have the electric heat strip turn on (only had geo one winter).
    All good.
     
  3. Neokane

    Neokane Member

    I guess I should have clarified this portion.
    I mean more so during heating months, how much extra heat load would the HPWH need?
     
  4. arkie6

    arkie6 Active Member Forum Leader

    According to the GE website, the Geospring HPWH compressor is rated 550 Watts with a rated energy factor of 3.25. This means that if the water heater is consuming 550 watts electricity, then it, on an average day, is putting 3.25 x 550 Watts of heat into the water, or 1787 Watts. 550 Watts of that is heat generated by the compressor. The remainder or 1787 -550 = 1237 Watts is heat extracted from the air. 1237 Watts converts to 4220 BTU/hr, or ~1/3 ton of hvac.
     
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    But only when running. So if the HPWH is running one hour per day, it uses up 1237 Watts/per day of heat which the 7 series might be putting in the room.
     
  6. Neokane

    Neokane Member

    Are the GE Geosprings the recomended HPWH? It is hard to beat the deal, with $650 rebate and $300 tax credit on a $999 hpwh, so it would only cost $50!
     
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I personally love the Stiebel Eltron, but it comes at a price, around $2500.
     
  8. Neokane

    Neokane Member

    It also looks like they don't offer a hybrid model, just a heat pump version.
     
  9. ChrisJ

    ChrisJ Active Member Forum Leader

    "We use a single resistance element for back-up water heating during times of high demand." From Stiebel Eltron's site.

    That's still a hybrid to me :)
     
  10. Neokane

    Neokane Member

    I did read that... after I posted.
    Still $2500-950 = 1500 or $999-950= $50 for a GE Geospring
    I'm totally cool paying $50 for a new hot water heater!
     
  11. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It has a heat element in there for high demand or backup.

    It is 80 gal versus 50 gal.
    There were a lot of recalls with heat pump water heaters. The Stiebel is a high quality machine which gave us zero issues ever. As always, there is no free lunch in this world.
     
  12. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I have a couple objections to the Stiebel (other than the healthy dollop of seemingly German arrogance in its marketing):

    Last I checked it had:

    1) No air filter - Germans apparently believe heat pump water heaters will be installed only in clean-room class mechanical rooms.

    2) No provision to adjust water temperature setpoint to anything other than 60*C (140*F)
     
  13. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Good points.
    The german engineering can come though as arrogant, although I use it sometimes too :)

    But outdoor condenser's don't have filters either.
    The germans argue the lack of thermostat with the KISS principle. But I agree, an adjustment would be useful, but not absolutely necessary. I would think about the risk of scalding without mixing valves, and the loss of efficiency of bring the water up to 140F.

    Having said that, the one we put in so far have been bulletproof for years.
     
    Last edited: Aug 31, 2016
  14. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Outdoor condensers can easily be soaped with coil cleaner and hosed off (required action during our semi-annual preventive maintenance routine)

    Try that with a heat pump water heater...

    KISS??? How can a heat pump water heater imported from the Fatherland costing upwards of $3k justifiably lack a $5 thermostat included at no extra charge with every American (Chinese...whatever) $200 storage electric water heater?
     
  15. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Curt,

    I am not saying you don't have good points, however it has never been created any issues in the field and they have been bulletproof for years. How is your field experience with them? How many other brands had recalls? I never had a customer complaint about it, the opposite is the case. They love it.
    So we have a unit here which you plug in and it makes your hot water the way you want it. There is a lot of unique features on it, from its ultra quiet operation, to the condenser embedded in aluminum transfer plates wrapped around the outside of the tank, between the tank and the insulation. So there is no heat element in contact with the potable water. Nor is any refrigerant circuit component close to potable water. And they might have figured that the amount and velocity of air funneled through the evaporator in a basement environment 5 ft above the ground does not warrant an air filter.

    It is maybe part of the german (corporate) culture where an engineer makes the decisions for you. It is like their refusal for years to install cup holders in the cars, or them deciding that 85 miles fulfills 98% of your driving needs for electric vehicles.
    That is changing since the U.S. consumers were not buying their products because it did not suit their lifestyle. So the Germans slowly start to listen more, which is good.

    Pricey yes, but again, they have been bulletproof in my experience.
     
  16. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    "Having said that, the one we put in so far have been bulletproof for years."

    I interpreted the above quote to mean you had installed only one.

    I've installed none - their cost and "features" don't make sense for me.

    Every heat pump water heater I know of isolates the refrigerant from the water in a manner that assures the refrigerant and accompanying oil won't contaminate the water...that's code...any refrigerant leak in a listed heat pump water heater must have a path to atmosphere rather than water.

    Stiebels do in fact have a backup electric resistance element in contact with water in the tank.

    I simply can't buy that the air pulled / pushed through the heat pump water heater does not require filtration regardless of quantity...a $99 5,000 Btuh window AC comes with an air filter, however primitive.

    While I have a heat pump water heater fed by a desuper with a dedicated storage tank I can't in good conscience recommend that setup on the basis of payback alone...Now that good heat pump water heaters are widely available the economics simply don't justify the geo desuper with dedicated tank
     
  17. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Autocorrection feature played a typo on me, I put in 10 or 11 of them in the last couple years. With heat element I meant refrigerant fed. Yes, they do have a small electric backup element.
    The question here was what is the recommended HPWH, and I responded that I like and prefer the Stiebel, your milage and scenario in Florida might differ.
    But given your lack of experience (Stiebel), you seem to have a very strong opinion against them. You don't like the features or its design, don't put them in.

    In the north, a desuperheater with HPWH might make more sense then in the south, since you might have more heat in your basement or garage in Florida to have the HPWH supplied with.
     
  18. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Agreed
     

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