Electrification Journey: Water Heater

Christopher Johnson
5 min readDec 22, 2021

Electrification of everything is our fastest way to decarbonizing our homes and the grid. Electrifying everything means that whenever you need a new <insert device or appliance name>, get an electric one. This is because these appliances last many years or even over a decade, so the choice made when buying has a lasting impact on carbon production.

Electrification is a very localized process, so when I moved into a new place right before the pandemic lockdown, I had plenty of house projects to think about. The obvious first step (after efficiency) was the water heater. The existing one was a gas tank water heater and was already 15 years old, which meant that any day now it could die. Most water heater replacements only happen when the appliance gives out, and that turns into a scramble for whoever is available quickly and whatever equipment they choose or can find. I wanted to be proactive about electrification, so I started in advance. Moving to electric would allow me to use more of my solar energy, which I have excess of for half the year when the days are longer, as well as get rid of a fossil fuel burning appliance in the house.

Finding a contractor was made easier by the awesome, free resource for Bay Area residents called BayRen. I used their free consultants and their directory of installers who are qualified and can access all the local rebates. I phoned up three different contractors to get quotes for replacing my gas water heater with an electric heat pump water heater.

Heat Pumps Rock

If you aren’t familiar with heat pumps already, they are amazing. Chances are you actually have used one, but may not have known it. Most often they are used as heating, cooling, water heaters and now even clothes driers. They are incredibly common in the places I’ve lived in Europe and South America, though less so in the US. The technology involves exchanging hot for cold or cold for hot, depending on what you need, and is incredibly energy efficient. Note that there is a difference between an electric tank water heater (which uses an electrical element to heat the water only) and the heat pump water heaters (which uses a heat pump). The element-only electric ones do not have the energy efficiency of heat pumps. That said, most heat pump water heaters are actually a hybrid (offering the heat pump for regular, slow heating, as well as the element for faster heating).

Contractors Are Still Unfamiliar

Unfortunately, there are a very limited number of contractors who do a variety of electrification steps. And given limited supply (and the cost of doing business in San Francisco), I found them surprisingly expensive for a device that costs ~$1,000. After shopping around I found the lowest price from a company that seemed to know what they are doing. Unfortunately that turned out way worse than expected (more on that later…).

Tuning and Running the Heat Pump

I’ve now been running on the heat pump water heater for almost three months. It took a little tweaking to program the device to optimize for low-carbon energy usage and cheap electricity usage (only resulting in one day of cold showers for the family during the learning process!). Now it is pretty dialed. With that I can also tell the impact on the overall electricity usage, which has been substantial.

Our house is pretty energy efficient (and also has not had most appliances converted to electricity yet), so we were only using about 400–450kWh per month at a cost of about $125. October was my first full month with the heat pump water heater and it used 178 kWh in a month where the total was 550 kWh. So it was 32% of total usage for the month! That’s not the whole story…since the installation wasn’t actually completed and is not running efficiently. I’ll have to report back again when it actually gets done.

Before I installed the heat pump, I put solar and a battery on the house, which caused the entire electricity rate plan to change, so it is harder to say what the actual cost of the water is now. According to one of my devices, it should be around $20/month for the water (before taking into account any electricity from the solar).

Some Lessons Learned

Choosing a device
I have been working on getting all the devices in my home connected to a home automation system. For that reason, one of the criteria that ended up being a big factor in which unit I chose was whether or not there was an internet-connected control setup. Turns out I could only find one in my local market that met that criteria, which is from Rheem (or Ruud).

Planning ahead
When electrifying, you may need more 240V circuits in your house, typical for running large loads like driers, air conditioners, etc. I had one installed when I was doing the solar installation. That made it easier for the water heater installer as they only had to do plumbing work, the electrical was already complete.

The Installation Experience

Out with the old (gas tank heater) and in with the new (hybrid heat pump heater)!

Well, like most home projects, this one had a lot of surprises. This one was much more messy than I expected.

  • Heat pumps are not stocked well at typical locations (eg Home Depot, Lowes, etc). We ordered a unit, which took two weeks to deliver. And then…it was damaged. It took multiple attempts to actually find a unit, even when inventory systems listed it as in stock. This got to be an urgent situation in subsequent steps. This is a weakness for adoption, since people will not be able to acquire the equipment when needed.
  • The installers removed my old heat pump before discovering that the new one was damaged. They tried to reinstall the old one, which worked for a couple of days…and then failed. The bottom rusted out and started leaking water. I was unable to stop it through any controls other than shutting off all water and in the process cutting off the water to the bathrooms!
  • After three days of frantically searching for an actual unit in stock, I was able to purchase one and get the plumbers back. The new unit was (mostly) installed, getting hot water working again.
  • Due to the small space of the mechanical room where the water heater lives, it required venting to the exterior. However, the venting kit had to be ordered separately and not available during the install. Supposedly that would be a couple weeks till it could be completed.
  • The installer went MIA and has not responded in more than three months now…so the installation is running, in completed, unpermitted, and running incredibly inefficiently. Ahh contractors…

This only reasonably worked since my wife was traveling during the whole debacle.

I haven’t run the conversions to see how much gas vs electrical energy is used, even in this inefficient state yet.

But…progress…of sorts. #facepalm #stillnotdone



Christopher Johnson

Christopher is a force multiplier called to accelerate the deployment and adoption of climate tech solutions at massive scale, and this blog shares the journey.