16 SEER Heat Pump with Two-stage Compressor

Jimbo,

From what I know they work great with demand hot water. The heat pump delivers water to a preheat tank. The demand then only heats as needed, if at all,, like my solar pre-heat tank.

Fuzzy,

You are right, the "free" hot water is available only on a cooling cycle, and your mini splits are pretty efficient out the door. Personally, before I would consider a water heat pump heater, I would look at solar pre-heat and demand. Solar hot water is really quite cheap (compared to PV) and will yield meaningful BTUs even in cold or grey climates. Look at evacuated tube systems.

Just my opinon,

Icarus

 

But not having room for a tank is why I chose tankless to begin with. Needing the laundry room space, I could move the washer and dryer to my computer room's (ex bedroom for prior owners) closet, but could not find space for the water heater until I realized some builder had used a smaller tub enclosure than needed and I had 10 inches inside the walls behind the upstairs tub. This allowed a flush mount tankless install that takes no new room. finding room for a preheat tank, puts me back where I started.

I did save info in case my wife buys a pool, as threatened.
Heat Recovery Pool Heater | Compare To Solar Pool Heater | HotSpot Energy LLC
This appears to be entirely outdoors.

 

I've yet to find anyone here that even recommends them or installs them. I'm not sure why, but I would definitely be interested in it here. I think any improvement projects that I've looked at are going to get pushed to next year at this point. My remodeling/upgrading project downstairs ended up costing about double what I hoped because I paid people to do some parts of it.

 

I have one. Unfortunately it was good for three years. The downside is the heating of the water precipitates out minerals and eventually plugs the water tubes. More unfortunately, the manufacturers and installers leave no way to clear this out without either major disassembly for a major chemical cleaning or replacement. Replacement requires purging and work on the freon lines, something that I don't want to risk till a better answer comes along.

When it did work it was great. The problem is the design I got was not "sustainable". More engineering needed.

 

I have a "desuperheater" on mine, pre-heating water in the summer. Has a separate pre-heat tank that feeds the gas water heater. (My system is ground-source, and came with the house when I bought it.) I guesstimate it saves about 30 therms of natural gas a year, here in Virginia, on a total annual use of about 160 therms (so would be 190 without the desuperheater), all for hot water. That's based on winter/summer difference in gas use.

 

I confess not to be an expert on the subject, but merely passing on what I read on reliable alt. energy sites. Precipitation of minerals is an issue with any water heating system, especially in areas of high mineral content. Suggestions include, extra large sacrificial anodes, and proper flush tanks and procedures.

There is a very well respected solar engineer in Florida who introduced the concept to me. (solar guppy, who has extensive blogs and publications, search the web). He swears by heat recapture heat pumps, and even though he designs and tests solar systems has calculated that they are more efficient (in Florida) than solar hot water,, and since solar hot water is "falling off a log" easy in Florida, that is saying something.


( a simple google search reveals he has closed his forum however)

Icarus

 

I used Solar Guppy to get the program that is used to monitor my solar inverter production. I didn't realize that's who it was, but your mention of solar reminded me that I needed to get that website for someone. It's too bad about his forum, because that was a good place and a good simple program that was written.

 

solar Guppy is still active in this solar forum,, the best out there IMHO

Solar Electric Power Discussion Forum by Northern Arizona Wind & Sun

Icarus

 

The concept works great. It's just that the "off-the-shelf" system I have from a decade ago was not engineered for long life. I'm quite ready to do it again if I can find a properly designed and engineered version.

 

Some time ago I did look at the evacuated tube systems with a pre-heat tank in front of the regular heater. Not yet having the needed plumbing skills, someone else was going to have to do the install, and the price was too high. Layout of this house is also not favorable. The space for the preheat tank was in the garage on the north side, not very close to the south roof pitch, and even farther from the south wall where I'd rather have a near-vertical tube installation.

Since evacuated tubes work much better than flat plates in this climate, I'd almost certainly include them in any new construction.

A heat pump water heater will fit the available layout better, cost much less than the solar rough quote, and kill three birds with one stone, better justifying the expense. In addition to energy efficiency, moving the tank from a kitchen closet to the garage will free more space for an enlarged pantry, and move any future water tank failures to a much less risky location.

But it is also time to re-price the solar option.