I’m struggling. You see. For about a year now. I’ve been smitten. With what is quite possibly the world’s most expensive domestic hot water heater. Yes, I’m simply entranced by the the SanCO2 heat pump water heater. I want one. Badly. Precious.
We’d like to renovate our kitchen. It’s not a large house. So, not a large kitchen. Part of the available floor/closet space is taken up by a rather dull, traditional, 30 gallon, natural gas-fired water heater. I’d like to use that space to enlarge the pantry.
So the question becomes how to move or eliminate the standing tank water heater. I’ve surveyed alternatives. As is my way, I’ve done research.
Traditional, tankless gas water heater
On-Demand Water Heater
I had a local company quote us on a natural-gas-fired on-demand water heater that would mount on the outside wall of the house. This is quite common here in Houston. The gas meter is at the northeast corner of the house, essentially at the corner of the kitchen. That makes this arrangement eminently practical.
The quote was for $4,900 all-in. It was enough to give me pause.
Gotcha?
Twice in the past few years we’ve had unusually hard freezes. That sort of thing imperils an exterior mounted, on-demand water heater. They must be drained or a hard freeze will literally destroy them. That means there is the potential of not having hot water should we experience the equivalent of another Winter Storm Uri.
Call me crazy, but the possibility of a hot shower on an otherwise freezing day seems like a good thing. Not something that should readily be given up.
A New Heat Pump
In the fall of 2021, faced with an old and apparently irreparable Fujitsu mini-split air conditioner, I had a Mitsubishi heat pump installed in the garage apartment that serves as my home office. That marked the first time I’ve had anything more than electric space heaters in my workspace.
It’s been great. It’s blissfully quiet. It keeps the dogs and I comfortable all-year-round. It has easily handled both the hard-freeze of late-December 2022 and the insufferable (and currently ongoing) summer heatwave of 2023. I believe heat pumps are preferable to other methods of heating & cooling.
Heat Pump Water Heaters
When I learned of heat pump water heaters I thought that might just be ideal. It would transition our water heating from using natural gas to electricity, which is both more energy efficient and healthier/greener.
Alas, most heater pump water heaters are physically very like their predecessors. They’re tall cylindrical tanks. In fact, most designs put the heat pump mechanism on top, making them even taller than the gas or electric tank they’d replace.
Being tall as tall as a Victoria’s Secret model, these won’t fit in the attic above the kitchen. It just doesn’t seem right to locate it outside. While the heat pump is appealing, in picking one of these tall boys I just can’t see any way we’d be able to reclaim the floor space in the kitchen closet.
As Leonardo DaVinci once said, “I need more time. More thought.”
SanCO2 Heat Pump Water Heaters
As I continued to learn about heat pump water heaters, I came upon an episode of Matt Risinger’s Build Show that surveyed various electric water heaters. His round-up included the Sanden SanCO2 system, a split heat pump system. Just like my office heat pump, it comes in two parts; (1) a compressor & heat exchanger unit that is entirely separate from (2) the hot water tank.
The more I learned, the more I came to admire the SanCO2 system. The exterior unit is basically a 15K BTU heat pump with an entirely self-contained refrigerant loop. The CO2 refrigerant stays within the unit. Only water flows between it and the stainless steel storage tank inside the house.
Further, it heats water to up to 170F. That’s much hotter than a traditional water heater. This truly hot water is held in the stainless steel tank that’s in the house. At the output of the tank, the very hot water is mixed with some cold, so as to deliver the more typical 120F hot water to locations in the home.
Since the tank holds very hot water, it can be smaller. Their smallest tank is just 43 gallons, but is the equivalent of a 60 gallon traditional water heater. This small tank (pictured above) is just 38” tall! That’s short enough to allow me to install it in the attic above the kitchen. Thus freeing up the floor space in the kitchen! Eureka!!
As if that wasn’t enough, the compressor is an invertor type that draws very little power. It only runs when more hot water is required. When more hot water is required, it hums along at low-speed, drawing around 800 watts. That’s compared to 4,500 watts (!) for a typical electric water heater. That means that it would mesh perfectly into our existing plan for standby power. In a post-hurricane situation, without utility power, even with a SanCO2 system installed, our entire home would be able to run indefinitely on power from our portable invertor.
In more sophisticated installations, it can be programmed to only run at certain times of the day. That’s great for places with time-of-day pricing for electricity, or homes leaning hard on solar power. This doesn’t really apply to our home, but it’s certainly very cool.
Issues
It’s not without issues. The SanCO2 system with the 43 gallon tank costs a whopping $5,200 (ouch!) I suspect that makes it the most costly domestic hot water heater available. Installation would be extra.
That cost, while high, would be partly offset by the tax rebate that’s part of the Inflation Reduction Act (IRA.) It provides for 30% (up to $2k) of the cost of installing heat pump water heaters. That makes it basically competitive with the quote for the gas-fired tankless water heater. Electrification is a greener solution.
The importer tells me that they have previously shipped them to two of the largest plumbing & HVAC distributors in the area; Ferguson and Reece. They also recommended a distributor who handles the DIY market.
I’ve not been able to find a local plumber who has ever actually dealt with one. That gives me pause. While the warranty terms are very good, I’d be more comfortable if there was a local plumber who was familiar with the system. In truth, they’d likely be more familiar to an enterprising HVAC technician.
Years ago, I bought a mini-split air conditioner for my office before they were common in the US. I had seen them in the UK and was convinced it was perfect for my office. So, I bought one online and hired an AC tech to do the installation. I might need to take that approach with the water heater. Semi-DIY.
Close
As you can probably tell, I remain well and truly smitten with the SanCO2 heat pump water heater. I’m a sucker for elegant engineering. Or as the great Leonard Cohen once put into song, “…I’m guided by the beauty of our weapons.”
We’re shortly going to have the house re-piped. That will be PEX from end-to-end, getting rid of the legacy mix of galvanized and copper pipe. Once that’s done it’ll be time to decide about the water heater. Perhaps by then we’ll know a plumber who is curious enough to do the installation for us.