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Geyser DHW owners

Post in 'The Green Room' started by hemlock, Jul 29, 2012.

  1. hemlock

    hemlock Feeling the Heat

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    Hello,
    Are there any Geyers HPWH owners here? I am seriously considering getting one, but would like to here from a few owners, and perhaps ask a few questions. From what I've read here and elsewhere, they seem to get good reviews. Specifically, I would like to here from owners how much heat they were "losing" from the room where it is located by running the unit. Any input would be great. Thanks.

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  2. woodgeek

    woodgeek Minister of Fire

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    IMO, old tech. The 'all-in-one' HPWH units are supposed to have better performance, i.e. COP.

    The answer to your question depends on the size of the space where it is located. Figure that half the BTUs that end up in the water come from the space, the other half come from the grid (i.e. COP ~2).
  3. Slow1

    Slow1 Minister of Fire

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    Even old tech has its place... I'm considering one as well. I have a nice oil boiler heated tank - it basically can not be run cold in our home (run 2 showers at same time as laundry and nobody notices). Given the recovery time of a pure HP solution I would need a much larger tank. Never mind the cost - simply replacing the tank and going all electric (even if HP) isn't my preferred option here so using something like the Geyeser may well do the trick for me (is there another option for add-on btw?).

    What I desire to do is have the ASHP keep the tank hot and cover minor use, then have the oil set point a few degrees lower to insure that it won't fall too low during peak demand times. I currently have a surplus of electric production so that would likely reduce my overall fuel costs...
  4. GaryGary

    GaryGary Feeling the Heat

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    Have you seen Tom's entertaining video on installing one?

    Gary
  5. hemlock

    hemlock Feeling the Heat

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    Thanks for the info so far. Does anyone know of a good place to order one from, and roughly what they should cost? I have heard and seen anywhere from $1000 to $2000 - quite a variance. Thanks again,
  6. Redbarn

    Redbarn Burning Hunk

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    I have one. Bought it about a year ago from Tom in Maine (americansolartechnics.com).
    Have run it for over a year now and it works great.
    We were using 1 gallon of oil a day to heat our DHW.
    The Geyser increased our electric bill by circa $15 per month but saves us 30 galls of oil a month.
    Coupled with the $300 with the tax credit, it has paid for itself already.

    I installed it in parallel with our current 80 gall oil water heater.
    Just switched off the oil burner and used the Geyser.
    If we get a house full of people, just turn the oil burner on and use both.

    Installed it in our basement.
    I ran a temperature probe attached to a data logger in the basement.
    Recorded the basement air temp at 2 hour intervals all year.
    Basement high temp was 74 deg in July and a surprising 59 deg in February.
    Kinda Geothermal heating I suppose.
    The Geyser has run 24/7 for 15 months now.
    The COP dropped a bit in Feb with 60 deg air temp but the electric bill barely changed.

    I connected the air in + out to some air vents in a room on the first floor in summer.
    Used these as a dehumidifier/air conditioning.
    The wife soon learned to run laundry in the afternoons to cool a chunk of the first floor.
    For winter, these vents were shut off and the Geyser used basement air.

    Water recovery is Ok if you plan a little.
    Mornings showers just about empty our 80 gall tank (3 adults). Geyser recovers it by mid afternoon and the system can handle home from work showers. It runs till late evening and has 80 galls ready for next day.

    All in all, so far so good.
  7. Slow1

    Slow1 Minister of Fire

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    Thank you for sharing your experience!

    Can you tell me what your cost/Kwh is? What I'm getting at here is an estimate of how many KWh you are burning with it each month (I can then more accurately project onto my own situation).

    Thanks.
  8. Redbarn

    Redbarn Burning Hunk

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  9. Redbarn

    Redbarn Burning Hunk

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    We live in PA which has a "market" electricty supply. Our current cost is $0.134 per kWr but this has dropped throughout our Geyser ownership.

    As for kWh used by the Geyser every month, I've never bothered to break it out accurately. Too many other changes to specifically itemize it.
    I think its a case of "your mileage may vary" in that household use, household size, intake water temperature etc. will have a significant effect on kWh used.
    Besides, we are saving $100 a month over oil use so I wasn't worried about a kWh or two.

    I was concerned about feeding it warm air and thus keeping the COP up.
    Hence my temperature monitoring. I thought it would run April through October but was pleasantly surprised to find that the basement was warm enough to feed it year round.
  10. Slow1

    Slow1 Minister of Fire

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    How are you calculating and/or otherwise monitoring COP?

    In any case, if you are in fact burning about $15/mo average in electricity (as you reported initially) with a cost of 13.4c/Kwh then it would seem you are running about 112Kwh/mo. Now, I'm a bit confused about this as it seems that at about a 41:1 ratio (139Kbtu/gallon oil:3.4Kbtu/Kwh) this would imply that you are using enough electricity for about 3 gallons of oil a month. Either the estimates on how much electricity the Geyser is using is far too low, your oil offset is too high, or you have one seriously inefficient oil heater there. Perhaps I miscalculated somewhere...

    Working the numbers the other way, if your oil burner is running at say 60% efficiency to heat that water, then I would expect that it would take about 736Kwh/mo for a resistive electric to equal out to your 30 gallons of oil (hopefully your oil system was better than that, but..). Now if the Geyser runs at the COP 2 that it claims then it should burn about 1/2 that - so about 368Kwh which would likely boot your electric bill up about $48/mo. Still not bad considering you estimate that the oil was running about $100/mo. Of course if that oil system runs at 80% then the equivalent electric would be about $67/mo, still a savings but it is narrowing that gap rather quickly.

    Understand that I'm not trying to nit pick your statements; rather as someone seriously considering the purchase of a Geyser I really do want to understand how well it runs not just from the "can it heat the water" but also how efficiently does it run - meaning how much electricity will it likely burn over time in a real-world situation such as what you have described.
  11. Redbarn

    Redbarn Burning Hunk

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    I cannot provide the information that you are requesting.
    I am certainly not going to comb through the minutae of my electric bills to do so.

    I suggest that you contact the manufacturer and get their data. This coupled with some measurements of your usage should get close to answering most of your questions.

    The OP asked for experiences of existing users. I provided that.
  12. woodgeek

    woodgeek Minister of Fire

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    Slow, its all about standby. I too was burning about 0.8 gal/day of #2 to keep my boiler hot for DHW, but prob delivering a tiny fraction of that as DHW BTU out a tap. The rest was making my AC run more during the summer. SInce I went to the HPWH, my elec bills are net **lower**, presumably because I have shut off my garage dehumidifier (now handled by the unit), and my AC is running a lot less (b/c my boiler has been scrapped).
  13. woodgeek

    woodgeek Minister of Fire

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    The test reports I have read suggest that the AO Smith and Steibel Eltron consistently get a COP a bit over 2 in a conditioned space, while the geospring and retrofit units are a bit worse. The problem comes down to difficulties with optimal control and lack of stratification. IOW, the all in one units use stratification to get higher COP....a lot of the BTUs are pushed into a low temp reservoir at COP>3, and the last few BTUs to finish the tank have lousy COP. A system that that is recircing a well-mixed, always hot reservoir is at a big disadvantage.
  14. Redbarn

    Redbarn Burning Hunk

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    I can verify that when using the Geyser air in/out to cool part of our first floor in the summer that our electric bills went down. Significantly. The A/C kicked on a whole lot less.

    For us the retrofit was cost effective in that we did not have to replace a perfectly good oil DHW unit.
    Just added a Geyser and used some pex.

    For sure an "all in one" unit should be more efficient but if you have an existing system, I doubt the difference in efficiency and potential operating cost would ever recover the larger installtion costs.
  15. woodgeek

    woodgeek Minister of Fire

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    Sure. My unit costs $2200 retail and I had it installed by a plumber. I assume you got the geyser for half that and put it in yourself. Even with a couple pips difference in the COP I will never get caught up to you $$-wise. In my situation, I didn't already have a tank, could get a rebate, and needed a plumber to run the new lines, so a new geyser+nice tank would have cost me the same amount.

    As for Slow's question....your boiler went from hot 24/7 to cold, and you are only heating an (indirect) tank with the geyser?? Do you think the reduced AC could be partially from the lower standby heat of the boiler? A gallon a day of oil is ~5000 BTU/h, the same as a space heater on high or a small window unit AC running 24/7.
  16. Slow1

    Slow1 Minister of Fire

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    So in the case of the recirculating (such as I believe the Geyser falls) you are essentially getting more hot water ready and waiting and 'paying' with a lower efficiency rating. The other aspect that I imagine must come into play though is the question of heat loss in the connection between the storage tank and the heating unit. Integrated units don't have much to worry about; external units however will have greater losses here. I'm surprised that the installation videos I've seen for the Geyser have not shown insulation on these pipe runs - at least on the hot water side as I imagine it would make a difference.
  17. Slow1

    Slow1 Minister of Fire

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    No doubt that when you can get the secondary benefits (retire a dehumidifier) the energy benefits are magnified significantly. I don't currently run one but I don't think it will hurt to pull some moisture out of the air during the summer either.

    As to standby - I do wonder exactly how my oil boiler works. IF the zones don't call for heat I don't ever hear it firing up (I would as it has quite a fan on it to provide draft). Thus although it does kick on periodically, it is generally when we have used some hot water and lowered the temp in the HW tank (not every time though - depends of course on how much HW we use). Occasionally it may kick on to re-heat the tank due to the tank cooling on it's own - but that is not too common. So, my my conclusion is that the boiler only runs when it needs to in order to heat the hot water (or if heating the house) so the only standby losses would be those from the actual tank itself - would you agree or is there something I'm missing here?
  18. Slow1

    Slow1 Minister of Fire

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    Again, I thank you for sharing your experience.

    I apologize for the offense that I have caused, that was not my intention. I don't expect you to comb through any minutiae on my behalf, however as you had provided some numbers in your posts I was merely trying to extrapolate them to my own situation and having a difficult time understanding the end result. My apparently incorrect assumption was that since you had been able to report these numbers in the first place that you had a way of retrieving them that you were willing to use. By pointing out the questions I rather hoped to get you to re-asses them and perhaps help me find the flaw in my assumptions or an error in your reporting. I am a bit of a 'numbers guy' by nature and thus this is the lens through which I perceive the world and when things appear blurry I find it frustrating.

    I have in fact asked the manufacturer for their data and received the generic "it will vary with your installation" answer which although accurate I did not find very useful.
  19. Redbarn

    Redbarn Burning Hunk

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    Woodgeek. I do not know for sure but I agree with you that the reduced AC is probably from the lower standby heat of the boiler.
    Our oil boiler seemed to run for 10 mins or so every 2 hours to maintain 80 galls at 100 deg F, no matter what.
    So our average DHW temp was likely close to 100 deg F for 24 hours, whatever the usage.
    With the Geyser, the temperature varies more so I sure that the average DHW temperature is lower over 24 hours.
    That heat difference must show up in the AC usage.

    Slow1. No offense taken. I have just never bothered to deeply analyse the numbers.
    I just filled the oil tank in April when the oil heater went off and refilled it before turning on the oil boiler for the winter.
    Just calculated oil galls used over the summer. With the Geyser, this was zero.

    For the electric bills, I just looked at the averagel kWh over the similar periods and provided they had not changed significantly, was happy.
    I had embarked on an extensive insulation program and the number of occupants had changed (daughter went out into the world)
    so I had no real basis for accurate comparisons anyway.
  20. woodgeek

    woodgeek Minister of Fire

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    Interesting. I had a 90s vintage standard oil boiler running a 1.1 gph forced air burner, with a tankless coil. When I bought the house, I was running 1.5 gallons/day, which turned out to be a thermosiphon (which I fixed by closing a manual valve on that zone during the summer). The case on this guy had something like 1/2" fiberglass as a jacket in places, but maybe 40% of the surface had no insulation. I had to run that guy hot (>140°F) b/c of a crppy tempering valve, and I estimated the standby heat loss (DeltaT*Area/R) and got something like a few thousand BTU/h. I also installed a 120V hour timer across the blower motor to measure run hours during standby (when we were out of the house). Anyhoo, even after I stuffed FG insulation all around that case, I was still wasting 0.8 gal/day in standby alone. Measured. Passive losses only out the (insulation upgraded) case. Looking at the boiler specs, it seems that the manufacturers spec the standby loss to be less than a certain percentage (2-3%) of the running BTU output, rather than a low absolute figure, perhaps to just prevent severe overheating of the mechanical room? It can be very hard to estimate standby usage....get an elapsed hour run timer or work backwards from your oil usage - your DHW BTU usage.

    To the OP: there is a lot of misinformation re 'heat stealing' by these devices on the internet. Some would have you believe that you could end up spending more net on your heating+DHW bills than if you stayed with a conventional (elec) tank. That is not mathematically possible. Basically half of your DHW BTUs come from elec (all year round), and the other half are either free or negative cost during the summer or cost whatever your space heating BTUs cost during the winter. You will save with one of these in your conditioned space, even in the winter, unless your space heating BTUs cost more than elec BTUs (which seems rather unlikely for a reader of Hearth.com). IF you are using a high-standby oil or propane fired DHW system now, you will make out like a bandit with a HPWH.

    And in case I am unclear....I think the geysers are a worthy investment for installs where you already have a tank you like. But you could cost out an all in one also, and maybe assume it would cost $50/year less to operate if you ran it year round.
  21. maple1

    maple1 Minister of Fire

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    These Geysers have my interest. I'm in the middle of a boiler changeover (turning out to be a 3 season project) - I've got my new electric hot water tank in place and up & running, and my oil boiler is shut off & has gone cold. I have one of these in mind as a possible add-on upgrade once this project is finished and I have recovered from it. I am thinking that with a couple of installation mods it would be a very efficient unit. My electric tank is bottom entry - I would T the geyser input into that, and T the geyser output into the top to help with stratification & lessen mixing. Then I would duct the geyser air input stream into a vent at the rear of my fridge - that area is always very warm, and it should help with fridge efficiency also. Then the possibility of not having to drag the dehumidifier out & running it anymore, plus added AC effect which could be ducted to the living room really makes things tempting.
  22. Redbarn

    Redbarn Burning Hunk

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    My oil DWH tank is also bottom entry and I T'd the geyser input into that. I T'd the geyser output into the top and it does seem to help with stratification & lessen mixing. Works well for me.

    The benefit of using the cool dry air elsewhere in the house in summer to replace AC is the a real plus.
    In the winter however this exhaust air cools the same space that the Geyser draws heat from.
    We are fortunate to have a large, fully in-ground basement where the heat flow back from the bedrock was enough to feed the Geyser all winter long.
  23. maple1

    maple1 Minister of Fire

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    I guess I'd add that if I did get one, it would be shut down in the winter as we would get all our DHW from the wood fired boiler in heating season - i.e. the Geyser would only be a 3-season unit for us. We only have one small window AC unit that really doesn't help a lot in the real hot days. I have been holding off on adding another one (pretty well ruled it out at this point) on hearing about the Geyser, and also while learning more about mini-splits - I'm kind of wondering what's around the corner for us tech-wise in the next couple years or so.
  24. hemlock

    hemlock Feeling the Heat

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    Thanks for all the great info, everyone. I've got a few quotes for a unit delivered, and I think I may pull the trigger. I'm not to concerned about "heat loss", as I heat 99% with wood that is free/cheap. Electricity in these parts is costly, so I'm quite confident it would be a fairly short pay-back.
    One question I do have is this - would it be possible to vent the unit outside to minimize the cooling effect during the winter? Thanks once again.
  25. Slow1

    Slow1 Minister of Fire

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    While I'm sure anything is possible with a bit of creativity, I am not sure it would be worth it. Consider the fact that the air you pump out of the house (venting it out) while cooler than the room temperature is still likely to be warmer than the outside air in the winter. Then consider that whatever air you pump out of the house will have to come back into the house somewhere (you aren't going to maintain negative pressure after all) so you will be pulling in the same volume of outside air - which will be even colder so the net effect of venting the unit outside may well be to cool the house even more than if you just vent the unit into the home (assuming the temp outside is lower than inside).

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