15 Comments

1. 
   gusfhb | Feb 08, 2015 03:20pm | #1

   service
   I have not had a heat pump die in service yet, but most modern units I thin would not get serviced aside from a relay or board

   CO2 is a common welding gas so I do not think that long term CO2 units would have a service issue

2. Expert Member
   Dana Dorsett | Feb 10, 2015 04:44pm | #2

   I'ts a chicken & egg thing...
   CO2 is cheap & available, but refrigeration techs in the US have no training or experience with CO2 refrigerant systems, nor do they have the necessary equipment. CO2 refrigerant systems operate at a much higher pressure than HVC or CFHC systems, and the CO2 is never in liquid form during any part of the refrigeration cycle- it's an always gaseous system. It's just different from the paradigm that precedes it.

   I'm sure 95% of the reefer-techs out there could learn how to deal with these heat pumps in under a week, but until there's a reason to buy the tools & get the training, so for the time being it will be a specialty skill.

   I'm personally pretty happy that small CO2 heat pumps have finally made it to the US. They have more than a decade of experience with the EcoCute systems in Japan, and coming onto a decade for similar systems in Europe. CO2 is a much more environmentally benign refrigerant than any HFC or HFO solution.

3. 
   user-626934 | Feb 11, 2015 07:59am | #3

   Sanden's CO2 refrigerant connections
   Sanden's refrigerant systems are a "packaged" system sealed at the factory...the tech does not make any refrigerant connections. The connections that bridge the "split" between the water tank and the outdoor unit are all plumbing (water).

   In theory, with quality control at the factory the sealed refrigerant system should be a non-issue over the life of the outdoor unit...similar to refrigerators, window AC units and our current crop of heat pump water heaters....of course, we've seen some major issues over the past couple of years with refrigerant leaks in a couple of different heat pump water heater models (namely the first gen. GE and the AirTap units, both of which were supposedly made in the same factory. GE seems to have the issue under control now that they've developed their own unit and moved production to the U.S. The AirTap units are still a question mark in my opinion).

4. GBA Editor
   Martin Holladay | Feb 11, 2015 08:53am | #4

   Response to Keith, Dana, and John
   Thanks to all three of you for your comments.

   The fact that the connections between the outdoor unit and the insulated water tank are all water connections is reassuring. There is a good possibility that these Eco Cute water heaters will prove to be as dependable as refrigerators.

5. 
   user-626934 | Feb 11, 2015 03:32pm | #5

   Response to Martin
   Yes, there's a good chance they'll be as dependable as refrigerators....as long as they don't add on an ice-maker to the outdoor unit.

6. Expert Member
   Dana Dorsett | Feb 12, 2015 01:01pm | #6

   Ice maker indeed!
   As I understand it, it's the ice-up potential of the water connections between the outdoor unit and tank that limits the operating temp of the Sanden version of EcoCute to +14F, a limitation of their anti-freezing design. If used for space heating only it's likely that it would still do OK at sub-zero with a bit o' glycol in the water (albeit at somewhat reduced heat transfer efficiency on the water side of the heat exchanger in the outdoor unit.)

   Sanyo's (discontinued) heating/hot-water combi EcoCute w/CO2 refrigerant had a specifed output & efficiency at -20C/-4F (see the second page):

   http://www.esru.strath.ac.uk/EandE/Web_sites/10-11/ASHP_CO2/data/sanyo2009.pdf

7. 
   bradrh | Apr 30, 2016 06:11pm | #7

   sanden
   It looks like the sanden unit is available in the US now. http://www.sandenwaterheater.com/resources/
   I haven't found a price.

8. 
   severaltypesofnerd | May 27, 2020 03:39pm | #8

   I'm pretty sure most of the these unit the CO system is precharged, pre-ready. On site you're only hooking up the water heat exchanger. See also https://www.ecohome.net/guides/2197/heat-pump-water-heater-with-exterior-compressor/

   Thus the HVAC tech training is much less of an issue.

9. 
   kevin_in_denver | Dec 16, 2020 09:53pm | #9

   Well Sanden gave up apparently.

1. 
   SPDX | Dec 29, 2020 07:53pm | #10

   Kevin, can you elaborate? I am doing a rehab/conversion to radiant heat in Portland, OR and am just now looking into the Sandens instead of what we'd originally planned: a tankless gas combi-boiler.

10. 
    kevin_in_denver | Dec 30, 2020 04:16am | #11

    The old link was dead so I thought they pulled out of the US market. All the distributors are out of stock, however, and at $4500 they might be too expensive.

1. 
   charlie_sullivan | Dec 30, 2020 09:23am | #12

   The new US distributor is Eco2 systems--same people under a different organizational structure. They don't have stock because they are in the transition from Gen 3 to Gen 4 units. The web site says they expect stock in the US warehouse the last week of January, 2021: one month from now.

   https://www.eco2waterheater.com/g4availability

11. 
    SPDX | Dec 30, 2020 07:15pm | #13

    Thanks, Kevin and Charlie.

    I'm going to have main-floor staple-up radiant and basement in-slab radiant. Discussing with Tad Everhart (featured in the article) whether the Sanden might make sense for my situation.

    I had planned separate zones for those floors but Tad's initial thought is that if I run high-temp through the staple-up and return it through the basement slab, that might achieve a sweet spot of appropriate heat for each area and sufficiently cooled water returning to the tank.

1. 
   charlie_sullivan | Dec 30, 2020 08:38pm | #14

   That sounds like a clever design that would use the Sanden efficiently. My question would be whether it leaves you with any way to tune the relative heating of the two spaces. Maybe if there is a valved bypass for each, you can partially bypass whichever is too hot? You could even do that with zone valves to allow automatic control.

12. 
    ArchitectJudge | Feb 07, 2023 04:01pm | #15

    For 2018 Washington State Energy code, one can get 2.5 out of 6 required credits for using this type of water heater. Unfortunately, Sanden is the only option I can find, as a sales rep just told me the Daikin Altherma is not sold in the US, as it focuses on European market.

    I am waiting on pricing from a local distributor, but my main concern is serviceability as mentioned earlier. Has anyone used this for domestic water heating only?

    Seems like a lot of money, and the hybrid heat pump water heaters are so efficient, odd that the state is pushing for this type of system. I suppose their concern is the hybrid heat pump water heaters give off coolth, increasing the heating loads in the winter. I was just going to have it in my unconditioned garage...