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Heat your water with a heat pump - 50% electric savings!

Post in 'The Green Room' started by mikeathens, Jan 22, 2009.

  1. Shipper50

    Shipper50 Minister of Fire

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    Could you ask your coworker what kind of savings he saw with his? I didn't even know they made such a thing till I read this post. :)

    Shipper

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  2. Redox

    Redox Minister of Fire

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    Yeah, I'm curious too. I venture to guess they are no longer in business. I have been watching Nyle and other companies come and go for years. It would seem to be a simple matter to add a heat exchanger to a cheap window AC unit, but the reality is much different. A window shaker runs in a pretty consistent environment like 95 outside and 75 inside. Put one in your 55 degree basement and it will turn into a snowball. Increase the size of the evaporator and put a bigger fan on it and now it's too loud and drafty. Then, there's water conditions. Put a thin coating of scale on that heat exchanger and it kills the unit's efficiency. These problems are just the tip of the iceberg (no pun intended). The practical limit for a refrigeration compressor is about 110 to 120 degrees and this isn't hot enough for most people. The compressor's discharge line can top out over 200 degrees (this is the "superheat" they are talking about), but the remainder of the condenser is going to be about 100 degrees. GSHPs are ideal because they have a large compressor running a lot and it is possible to "steal" a little heat off the discharge without anyone noticing.

    I really would like to see someone market a simple HPWH that worked for less than $1k. They make a lot of sense, especially for those of us that live south of the Mason-Dixon line. I have seen commercial varieties that put a large heat exchanger inside the tank, but they are rare due to their expense. Restaurants would be ideal for this application, but I'm just not seeing it happening.

    FWIW, I would be especially wary of ANY company that compares its product's consumption to a coffeemaker. They pull 1 KW for about 5 minutes and then 100 watts or less for the warmer. I think my Kill a Watt was claiming $15 a month for ours last time I checked. Amish mantelpiece, anyone? :roll:

    Hansson; You keep teasing us with this European technology! Know anyone in the import/export business? We will just have to keep dreaming...

    Chris
  3. mikeathens

    mikeathens New Member

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    I asked my coworker about his again. He said it's a "marvair" or "crispaire" (He can't remember). His has been in service for at least 10 years. He says his biggest complaint is the noise, which he compared to a furnace blower. He hasn't done any exact measurements, but he said it definitely is a big savings.

    I would guess that these things won't heat water up like your electric elements do. I would also guess that you won't see as short of a recovery time, either. I, however, have my water temp set at about 110 F right now, and I'll bet one of these will do the job just fine. I'm willing to risk the $400 that it will cost. I plan on putting mine on one of those kill-a-watt meters out of curiosity.

    (BTW, Redox. I called at the right time, and I was lucky enough to get my Amish mantle. It is beautiful, and only uses as much electricity as my 8-cup coffee maker.)
  4. Redox

    Redox Minister of Fire

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    Marvair used to make a line of residential equipment, but now I see that they have concentrated on the modular office market and telecom biz (wall packs). I don't see any HPWHs in their lineup, but I did find they have branched out into the marine business and have a 12VDC unit now; interesting. Solar guys: http://www.marvair.com/12vdc.html

    Like any heat pump, you have to lower your expectations a little bit. If you want screaming hot water, these aren't going to do it for you, but would make an excellent preheat for a conventional DHW heater. If you can get your 30-50 degree incoming water up to 90 degrees, that's a lot less conventional water heating you have to do. I think a second water heater for storage would be a good idea.

    Mike; the Airtap is up to $700 now that they are in production. It's possible that early versions lacked certain features that would make them last. I dunno. That's still the best price I have seen for anything like it. IIRC, other units I've seen in the past generally started over $1000. Let us know how it works if you go this way.

    Bet that Amish mantle is giving the 'ol Mansfield a run for its money! You DID buy your limit of two of them, didn't you? I was kidding; hope you were too... (insert large smiley here).

    Chris
  5. mikeathens

    mikeathens New Member

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    HUH??? I could a' got two of 'em?? Of course I was kidding...
  6. mikeathens

    mikeathens New Member

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    ok...my coworker revised his story. Apparently, he actually looked at the label this time.

    He has an "E-tech WH-6BX-1". He said this one isn't in production any more, he suspects because it uses R-22. But, the company is still in operation, and still in the heat pump water heating business:

    http://www.aers.com/etech.html
  7. Redox

    Redox Minister of Fire

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    The E-tech has been around for years and from what I can tell is a good unit. AERS probably has the largest installed base out there, but their primary business is commercial/industrial equipment. I can't find any pricing online, but I recall seeing $1200 for one of these units and that was a while ago. Most of their business was probably subsidized for government research installations, most of which show that (surprise), a heat pump saves energy over electric resistance! The reason for the high cost and the lack of manufacturers is the limited demand, not unlike the GSHP business. Now that energy costs are rising, there's a renewed interest, but we're really still in the '80s as far as the development goes.

    Sometimes I appear to be overly negative here at times, but the HPWH can work if applied properly and be labeled a POS if not properly applied. It is a completely different animal than an electric water heater and you may not realize you are going to have a problem until you get one installed in your basement. I think if I lived in a colder climate, I'd let the manufacturers chew on these a while longer before springing for one. Get a company like Trane or Carrier behind it and you will see some development.

    BTW: http://www.inhotwater.org/index.htm is a good source of info, but hasn't been updated since 2006 or so. From my vantage point, not a lot has happened since then......

    Chris
  8. Wet1

    Wet1 Minister of Fire

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    Any update Mike?
  9. mikeathens

    mikeathens New Member

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    No update yet, Wet. I just paid off the credit card (I didn't want the compounded balance), and I'm planning to order one of these in the next week or so. There's a prospect of a 6% pay cut + possible layoffs at my job, so I'm trying to be careful. I can still justify this, though, because of the fast payback period - if it works.

    One thing I'm concerned about is the lack of "real world" reviews on these...I'm leaning toward the AirTap A7, but I don't want to be a guinea pig. I had, in fact, just called the company this morning, but tose lazy dogs in Texas weren't at work yet. You know, everything should revolve around EST/EDT!!! (joke...just kidding). If I'm going to shell out $700, I don't expect to receive crap. I was going to see if they would provide me with some guarantee that I could return it after a month if it was garbage. If the infomercials that I read are accurate, there was some subdivision in (I think) Tennessee where these were standard equipment in new homes. There's one review on Amazon, but it sounds too much like a company rep planted it there.

    Heating 100% with wood, this thing sounds really dreamy...I only wish they would explain the fact that you're robbing your house of heat that you already paid for once (if you heat with gas, electric, or pay for wood).

    I will definitely report back when this happens...as well as any buying tips I can come up with .
  10. Wet1

    Wet1 Minister of Fire

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    Thanks Mike. I have a damp basement that requires me to run a dehumidifier for about 5 to 6 months out of the year. I know there's some things I can and will do on the exterior of the house that will reduce this, but I know I'll still need some dehumidification even after these changes. I've historically needed more hot water (on demand) than I think one of these HPWHs will provide, but between the indirect gas (for backup), me switching over to almost all (free) wood heat next year, and some DHW usage changes, I'm now thinking this HPWH might be the answer to my prayers. Actual performance, reliability, and over-inflated product price still have me concerned. I'm very much looking forward to hearing some real world results.
  11. mikeathens

    mikeathens New Member

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    Well, even though I am still a bit unsure about this whole thing and hate being the experiment, I went ahead and placed an order for the Airtap. I ordered from a dealer independent from the manufacturer, and heard nothing but praise from them. $699 and free shipping. Maybe I should look at it as "stimulating the economy" :roll: and this coming from a guy about to take it in the a$$ with a 5.4% pay cut. Oh, well. I guess better to have a job than be out begging for bread crumbs. When I get it installed and run it for a week or so, I'll let y'all know if it's worthwhile.
  12. Wet1

    Wet1 Minister of Fire

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    I'm very much looking forward to hearing about your results Mike. Specifically, what your kill-a-watt meter reads comparing your electric DHW heater to this HPWH. Also, please let us know what your ambient temps are where the HPWH will be located. I'm not heating my basement right now and the temp down there is only about 47° (less than ideal for one of these), but that wont be an issue this summer or even next winter since I'm planning on heating with wood down there going forward. My other concern is the actual recovery time for this system w/o using the other electric heating element in the tank.

    If this doesn't turn out to be a 'FSM', I think I'll be ordering one as well. Please keep us up to date as I'm be needing humidification in the not too distant future.


    BTW, I hear you about the pay cut (I took one too), but it's better to take a cut than to be out on the streets. I hate to spend money on something like this right now, but if it saves even more in the long run, it's money well spent IMO.
  13. mikeathens

    mikeathens New Member

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    I'll definitely post updates...the usage meter really won't show a comparison between current usage and the airtap...for one, i've only had the tank in for a month or so, and second, it's hard-wired into the breaker box.

    I am planning to place an intake vent in the wall right beside the wood stove (the HPWH will be just on the other side of the wall) and exhaust into the bathroom where the HPWH is located. If the exhaust air is too cool for the bathroom, I'll probably place another vent to exhaust bleow the intake near the wood stove.

    BTW, I happened to find another web site selling these for $599 w/free shipping (I paid $699 w/free shipping). I'm going to see if the place will refund the difference (or at least 50% of the difference). Hard times, man. At least I can still afford to brew my own beer (the wife let me get a kegerator and 4 corni kegs before we heard the bad news about the pay cut!!).

    Edit: BTW, what's with the FSM comment? If it wasn't for His noodly appendage, I wouldn't have found out about the HPWH!!! HAHAHA...
  14. Wet1

    Wet1 Minister of Fire

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    If you wouldn't mind sharing the $599 source via PM, I would certainly appreciate it.

    Regarding the FSM, it's pretty rare to find a FSM worshiper in your part of the country (I'm a big fan of him myself)... I use to live out that way, the 'influence', pressure, and never ending 'reference' (not to mention the time wasted doing so) drove me insane at times! Long live the FSM and IPU!
  15. CarbonNeutral

    CarbonNeutral Minister of Fire

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    Definitely looking forward to updates - especially with your climate being similar to NE - easily 50 or lower in the basement in the winter - will this cause issues with efficiency/icing? I love their vent kit that I could use to pipe the cold air to the living area in the summer....
  16. mikeathens

    mikeathens New Member

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    From what I know about heat pumps, even at 50, you're operating with a pretty high degree of efficiency. FYI, their vent kit is $70. There's no way I'm paying $70 for $7 worth of materials. I plan on making my own. Once it all up and running, I'll post some pictures, including whatever intake/exhaust contraptions I end up making.
  17. Wet1

    Wet1 Minister of Fire

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    I believe these units work down to 32° F, but they are less efficient at these cooler temps. Also keep in mind they will be blowing out even cooler air while operating.

    Below is the efficiency chart provided for the Airtap A7:
    [​IMG]
  18. CarbonNeutral

    CarbonNeutral Minister of Fire

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    I'd also love to know where you saw it for $599.

    Did you look at your state and federal rebates? If so, how much was on offer?

    Nice clue about the vent kit... I don't have vents, but I would consider pushing a vent through the living room floor and putting a register fan in....
  19. mikeathens

    mikeathens New Member

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    In the summer, the cooler the better, but I really don't want a freezing bathroom. There's a chance that if I'm pulling 90 degree air from near the wood stove that the exhaust will actually be warmer in than ambient in the bathroom. If that's that case, it will just exhaust there.
  20. mikeathens

    mikeathens New Member

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    Well, the thing showed up today ($100 more than I could have gotten it for; my fault I guess). Probably won't have any time to mess with it until saturday - of course, gotta split another cord of wood that day, too!!
  21. Wet1

    Wet1 Minister of Fire

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    Completely unacceptable, it needs to be in operation TODAY!!! :)
  22. oldmilwaukee

    oldmilwaukee New Member

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    I got real interested in one of these units last fall, but didn't pull the trigger once my geothermal installer told me about the desuperheater option for the GSHP I was ordering from him. I'm anxious to hear how yours works for you. Thanks for being the guinea pig!

    One question I never got answered... is it possible for refrigerant to leak into the DHW if these units fail? You would think that would make the FAQ list?
  23. Redox

    Redox Minister of Fire

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    IIRC, it is a national code that the HX has to be a double wall vented design between potable water and refrigerant. That way, if either the water side or the refrigerant side were to leak, it would leak to atmosphere and not cause contamination. I haven't seen this "feature" mentioned much, but it is a good idea.

    Let us know how it goes, Mike. I wouldn't mind seeing a sample of temperatures on the air and water while it's running. And don't beat yourself up over the $100; I couldn't find them any cheaper last month, and I know where to look.

    Chris
  24. xpertpc

    xpertpc New Member

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    They do not have a double walled heat exchanger, don't know of a national code but it is common sense and needed in most communities for antifreeze, and as far as a "freon" leak it would probably boil off -as far as I am concerned water from the hot tap is non-potable anyways. The output is distilled water at worst and am doing something similar myself.
  25. CarbonNeutral

    CarbonNeutral Minister of Fire

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    So I was browsing their site (airgenerate.com) and came across the forum they have. It wasn't well used, but It concerned me that there were people on there with issues that had not been addressed by representatives from the company. Why go to the effort of creating a forum, where most posts will be of technical/complaints, and not answer them? Then their contact form script wasn't working.

    I have emailed them with some concerns - we'll see if they get back. If they don't, it would really make me think twice about buying.

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