# Air to water Mini split



## peakbagger (Nov 10, 2018)

This month's Home Power has an article by John Siegnthaler regarding the use of air to water minisplits for heating in place of a standard air to air minisplit. Home Power currently limits access to their articles to subscribers so I cant post a viable link. This may change at some point as they just published their last issue.

He makes some very convincing arguments that for heating, an air to water unit combined with low temperature emitters is a better fit for heating and I tend to agree with him. My air to air minisplit is installed to manufacturers specs but I find that the placement is optimized for cooling. In heating mode it does tend to stratify the air in the room more then radiant baseboard would. It throws the heat into the center of the room while the heat loss is in the walls and windows. The heat is also moved by air and that does cause drafts which for most folks mean they want to turn the thermostat higher. Of course using this approach for cooling would be a disaster for most as moisture would collect on the emitters. This means the big advantage of all in one solution for heating and cooling that is somewhat solved by a minisplit doesnt apply to an air to water so a separate cooling only air handler is needed. It wouldn't take much to put in some two way valves on the glycol lines but it would be extra equipment and piping. 

The big advantage to air to water is no need to hire a tech to purge and charge the lines. All the refrigerant stays outside in the outdoor unit and the only plumbing needed is glycol. This means the potential for DIY install is much easier and I expect the potential for refrigerant leaks is less. Tom in Maine on this site sells one brand but I  believe he stated he went through a few brands before he found one that he could depend on. 

The scary part to me is the list of manufacturers of air to water minisplits are all unknowns. Aermec,Chiltrix, Maritime Geothermal, Space Pak and ThermAtlantic Energy Products were all mentioned in the article but are not household names to me. I am curious if there is just one chinese company that makes them and just badge them for different firms.?  

I dont plan to replace my air to air unit as I mostly use if in shoulder seasons until its worth running the boiler but if someone were starting from scratch it may be worth considering.


----------



## maple1 (Nov 10, 2018)

The Maritime Geothermal line has been making Geo units (Nordic) for quite a while. The local fellow who does Daikin here (just did mine yesterday) has been putting in Nordic geo setups for longer than he's been doing Daikin splits. I think. As far as I know they have a decent rack record. But I don't know how localized they are or how far they are used & distributed. Have friends with installations but haven't seen them for a while to ask how time has treated them. I remember running across Thermatlantic stuff before in websearches, a few years ago, but don't know anything more about them or of any local installs.

I am hoping the tech evolves to a point where it might be feasible to hook one up to my storage tanks, even though I only have baseboard (so far). There were interesting stories a year or two ago about I think C02 refrigerated ones in development that could put out much hotter water, but haven't seen anything on them since.


----------



## semipro (Nov 10, 2018)

I've subscribed to Home Power on and off over the years and am sad to see it go.


----------



## Brian26 (Nov 11, 2018)

Similiar concept with this first of its kind heat pump water heater available in the US. The compressor unit is installed outside and just water lines need to be run. Interesting that it says it uses CO2 for refrigerant. Expensive at around $4k. If I had money to throw around I would try one out but my Ge Geopsring has been chugging along for 5 years just fine. 

These products include the new Sanden CO2 Heat Pump Water Heater. The innovative "SANCO2" is the first CO2-refrigerant heat pump water heater available for residential use in the North American market. The SANCO2 is a flexible 2-piece system that is easy to install.


Unlike a conventional heat pump water heater, the SANCO2 can operate in colder climates (to -15°F) and features a 2‑piece split system. The hot water storage tank is installed indoors, the heat pump unit outdoors (up to 50 feet away).

This flexible design offers several advantages including maintaining comfortable indoor air temperatures. The outdoor heat pump unit operation is rated 'whisper quiet,' it won't disturb you or your neighbors!

The hot water storage tank is constructed of long-lasting glass-lined stainless steel to provide years of reliable use.

https://www.sandenwaterheater.com/for-homeowners/


----------



## peakbagger (Nov 11, 2018)

semipro said:


> I've subscribed to Home Power on and off over the years and am sad to see it go.



Me too, but I have seen the size shrinking and the content getting less interesting. I will miss the code update section in particular. I will admit that without Home Power I would not have felt comfortable DIYing my 3 arrays.


----------



## peakbagger (Nov 11, 2018)

Brian26 said:


> Interesting that it says it uses CO2 for refrigerant.



CO2 is the pretty well regarded as the "last refrigerant" as it has zero ozone depletion. Many of the refrigerants in use today are transitional and would be phased out at some point or too hazardous to use in homes. The downside with CO2 is that the pressure required is much higher so the equipment tends to be more costly.


----------



## georgepds (Nov 12, 2018)

semipro said:


> I've subscribed to Home Power on and off over the years and am sad to see it go.




Me too.. I'll always remember the guerilla solar issue with a guy and his dog next to the clandestine back feed solar panel


----------



## maple1 (Nov 12, 2018)

Brian26 said:


> Similiar concept with this first of its kind heat pump water heater available in the US. The compressor unit is installed outside and just water lines need to be run. Interesting that it says it uses CO2 for refrigerant. Expensive at around $4k. If I had money to throw around I would try one out but my Ge Geopsring has been chugging along for 5 years just fine.
> 
> These products include the new Sanden CO2 Heat Pump Water Heater. The innovative "SANCO2" is the first CO2-refrigerant heat pump water heater available for residential use in the North American market. The SANCO2 is a flexible 2-piece system that is easy to install.
> 
> ...



Interesting. Not sure how old their website info is but their latest version on there gives hope. Supply temps of 170. Now if they could up the btu/hr to the 30k range, it might keep my house warm all winter. Wonder how much that outdoor unit costs?


----------



## georgepds (Nov 12, 2018)

Re "  In heating mode it does tend to stratify the air in the room more then radiant baseboard would"

I had the same problem. What I did was put in dc ceiling fans on each floor and run them at the low setting (3 Watts) to stir up the air

You can use an AC fan, but the power draw is larger(~30 Watts)

Also works really well with the wood stove


----------

