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How quickly will we electrify our homes?

Uploaded: May 28, 2023

How quickly will we electrify our homes? This is an important question as we set emissions goals and formulate plans to achieve them. A few years ago, Palo Alto determined that the most cost-effective approach to hitting our 80x30 goal would entail (among other things) replacing nearly every gas appliance in our single-family homes with electric heat pumps. (The “80x30” goal aims to reduce emissions 80% below 1990 levels by 2030.)

Some of you may be thinking that’s a non-starter. Some of you may be curious about the possibility. Others of you may already have done it and see little downside. What the city wants to know is, in general, how long can we expect this to take if the city provides a good assist?

A gas-free home, as depicted in Peninsula Clean Energy’s excellent Design Guidelines for Home Electrification

There are many factors that affect the answer to that question. Where are gas heaters installed, how hard are they to swap out for efficient electric versions, how much will that cost, what concerns do homeowners have, and so on. How do you go about determining how long it will take?

Well, it helps to look at a lot of homes and to start by focusing on one type of appliance. The city’s compelling heat pump water heater program is designed to provide some answers. Palo Alto is offering homeowners not only a significant financial subsidy to replace a gas water heater with an efficient electric one, but also a turnkey service that enables residents to make the switch with little more than an email or phone call to the city.

Says Jonathan Abendschein, Assistant Director for Utilities Resource Management: “Our program is meant to make it really easy for people to replace their gas water heater with a heat pump water heater. It is designed to be a white glove service. We have our own contractor. You call us, we’ll get your site assessed, we’ll take care of the permits, our contractor will do the installation. You don’t really have to think about it.”

In practice, the homeowner fills out a brief online form and then sets a time for an assessor to come by. The assessor will determine what’s needed for the installation and will also go over options for electrifying space heating if there is interest. Within a week or two, the homeowner receives an estimate and can schedule the installation.

Abendschein adds: “We’ve been able to offer a really attractive price for the first pilot phase of this program. The total cost is $2700 but we also have on-bill financing where you pay just $1500 up front and then $20 per month on your utility bill for five years.”

Since in many cases it costs about $1500 to install a gas water heater, and households can save $5-$20/month on their energy bill with an efficient heat pump water heater, the cost can be similar to that of installing a gas water heater. (1)

Palo Alto has made a substantial investment of time and money in this program, and has forged a close relationship with a committed partner in Synergy. Together they are pursuing a goal of replacing 1000 gas water heaters with heat pump water heaters in one year. That is a rate of 20 per week for 50 weeks. How is it going?

So far 500 households have expressed interest and over 200 assessments have been completed or scheduled. The contractor and the city have addressed some staffing issues that led to response and scheduling delays in the first few months, and are now ramping up the process. It should take only about one week from when a homeowner reaches out to the city to when an assessment can be scheduled.

The assessment in and of itself is a valuable free service. I’d love to see everyone sign up for it, or at least everyone with an older gas water heater. It helps a homeowner to understand the electrification potential of their residence and to qualify for the excellent pricing and service this pilot provides before it ends.

In turn, the city gets a clearer sense of what these replacements look like in practice and what technical or other obstacles exist to a straightforward swap in some homes. City staff can better understand the labor and equipment costs for the installer as well as learn about the age and efficiency of gas appliances in homes. This is useful information as we evaluate our emission reduction plans and consider future potential pilots (e.g., for electrifying space heating/cooling).

What does the program look like in practice? I spoke with a Palo Alto resident who was one of the first in line. She had seen her neighbor’s water heater start leaking and their subsequent rush to replace it. Her water heater was fifteen years old and she was eager to get a streamlined climate-friendly replacement. “The whole process was very easy,” she said. The contractor and a city representative came out at the scheduled day and time for the assessment, which took 30-60 minutes, then once she accepted the estimate, the permitting was taken care of and the installation happened on time, complete within a day.

The new HPWH is in a closet in the garage, next to an older radiant boiler.

The resident is happy with the quality of the work. “The electrician found a really nice way to connect the conduit on the roof to the water heater, so it doesn’t go through the roof and is barely visible. The plumber was also very helpful when I wanted to use the old heater’s water in my garden. Both workmen were very nice and did good work.”

The conduit on the roof is nicely connected to the water heater in the garage.

The resident observed that Synergy’s scheduling service could have been better. They seemed confused about a few things (e.g., when scheduling a follow-up visit and then the inspection), but Abendschein says after some early learning, the team is better prepared now to handle requests. The resident also felt bad that the electrician had come all the way from Sacramento, and hopes that more local people are available going forward.

The heater itself is working well. The homeowner chose a 50-gallon heat pump water heater to replace the old 50-gallon gas water heater. That works out well for her family and saved a little bit of money. It heats their water nicely, even when set at 130 degrees. (2) She likes the easy Vacation mode on the water heater, and the ability to set it in Hybrid mode if there are many people at the house. (That mode will use both heat pump and electric resistance heat as needed.) She said she can hear a hum from the appliance when she is in the garage and it’s running, but it doesn’t seem to run often. In the kitchen, if it’s quiet, she will sometimes hear it as if the refrigerator is running. She has not noticed her garage being any cooler.

One surprise for her was that there is more condensation than she expected. It drains onto their patio, and for now she has put a small cup there to catch it, which she occasionally empties into the yard.

Homeowners use a small cup to capture condensate from the water heater

One thing that I heard from this homeowner, which I have heard from others and which was my experience as well, is that it makes sense to think through all of your electrical needs when running conduit. When I installed an EV charger, I didn’t think ahead to other electrical needs I would have, and ended up needing to redo the conduit (make it larger) and put in a subpanel. Similarly, the conduit that this home had in place for an EV charger would not handle the additional load of the HPWH, so they had to put in a second line. That was an extra $2000 charge, since it runs all the way across the roof of the house. To prevent that from happening again, the contractor offered to put in larger-than-needed conduit and space for a future connection so they can easily electrify their boiler when the time comes.

In general, the resident is happy with the new water heater, grateful that the city’s program made the conversion very simple, and encouraged to have made a dent in her home’s use of gas and prepared to make more.

The gas that we burn in our homes and our cars contributes to the warming that our planet has been experiencing over the past decades. It is only going to get more expensive relative to electricity over the coming years because of the damage it is causing. It is great that our city is stepping up to help us reduce our gas use. This program, focused on water heaters in single-family homes, is something that I hope many of you will take advantage of. You can sign up here.

Temperatures in North America have warmed quickly over the past few decades. Source: #ShowYourStripes

Notes and References
1. Some installations will incur extra costs, such as if a panel upgrade is needed or a very long conduit is needed to connect the water heater to a distant panel. These electric upgrades can be done in such a way that they make it much easier to later install an EV charger, an electric heat pump, and/or other electric appliances.

2. Initially the residents had the temperature set to 140, but on a return visit the contractor said that was probably too hot and so they settled on 130.

Current Climate Data (April 2023)
Global impacts, US impacts, CO2 metric, Climate dashboard

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What is it worth to you?


Posted by Bystander, a resident of Another Palo Alto neighborhood,
on May 28, 2023 at 7:16 am

Bystander is a registered user.

Until or unless our power supply is more efficient and reliable, I don't think many want to even contemplate this.

We are being told that this summer, due to the high rainfall, we are unlikely to lose power. But that is only part of the story. We have just had a winter with more storms than I remember in Palo Alto. Every storm caused outages all over town, some lasting for days. Our heroic line workers battled each outage in all types of weather and did a wonderful job, but how much did all that cost in overtime and replacement costs of power poles and equipment? If these continued stormy winters cost the same, how will that pan out in our utilities budget?

All of us are using more electricity than we did even a decade ago. We all depend on our devices that need to be charged and as for the number of Ebikes and similar high electrical skate boards or whatever. And don't forget the number of EV cars which need charging and the charging stations in places like Piazzas parking lots which are said to be built all over town.

This means that our supply has to be more efficient and reliable. This means that it has to be there when we get home in the early evenings when we want to charge, to cook dinner, to do laundry, and all the other things that we do in our homes during the evening. All the restaurants need power to get them through the busy evening hours when they have the most customers. All this idea of using less power between the hours of 5 - 8 pm is pointless when that is the time of day most of us need to use power at home.

I see very little California effort to increase the power infrastructure and even less for Palo Alto Utilities for improving service.

Touting a change when it is a poor choice for reliability makes very little sense.

Posted by KOhlson, a resident of Old Palo Alto,
on May 28, 2023 at 10:31 am

KOhlson is a registered user.

Thanks for revisiting this.I'm glad the HPWH program seems to be working, at least for some. They came out and assessed our house in early April. After a few questions by email, radio silence. And the price point, at least from my estimate and that of a friend, seems squishy. I'm sure thee are early-in-cycle problems, and I will get a HPWH from someone else, if not through the city.
In past posts you've written of different "types" of HPWH (3, I think), including 120v versions. In my experience, that's not what the CPAU program is working with. Part of my after-visit correspondence with the city and with the contractor was what type of WH they were talking about. I feel this is an area that CPAU could be more helpful with.
I feel for Bystander. He must live in a different part of Palo Alto than we do. I've lived here for decades and been pretty happy with utility reliability, including electricity.

Posted by Eddie, a resident of Fairmeadow,
on May 28, 2023 at 5:12 pm

Eddie is a registered user.

Sherry - I read through the website, and it's not clear to me that there is not some kind of commitment, or at least somewhat of an expectation, that the resident will follow through with the installation after the assessment.
I've commented on this blog before that we really don't have room for a tank (we currently have a tankless heater). So if we were to replace our tankless heater, we would possibly (probably?) shop around and not use the city installers.
So with that in mind, it's not clear to me that the city wants us to sign up for the assessment if we have reservations about following through with their services (at least from reading through the city's website). But perhaps you've heard something to the contrary?


Posted by Sherry Listgarten, a Almanac Online blogger,
on May 28, 2023 at 9:08 pm

Sherry Listgarten is a registered user.

Thanks for the great questions.

@KOhlson, there are a few things that can increase the price, such as if a panel upgrade is needed or really long conduit. If you don't have those, then I'm surprised if the price isn't as promised. I would love to learn more.

The program director, Jonathan Abendschein, says that they are considering several models of heat pump water heaters. He specifically said they are including 120 volt models when it makes sense, for example to avoid a panel upgrade or long conduit. But they do have longer recovery times so they want to use them judiciously. I would expect they are also including both 15-amp and 30-amp models. What was interesting to me is he also said they are thinking about how to include the two-part SanCo water heaters, which are much more expensive but can be a good replacement for water heaters in very small interior closets (for example). They are definitely open to a variety of technologies, but need to make sure the economics work for the contractor. Alternatively, as you say, it's possible to use your own contractor and just take the $2300 rebate.

Re reliability, yes, I've also lived here for decades and have no issues with the reliability. When I asked the resident in the blog post about it, she said: "Not worried about power outages at this point, since they rarely happen here. We don’t have kids, and can deal with cold water and whatever else no electricity brings." I hope to see a report from the utility every year (or more often) that details the outages across the city to get a sense of whether outages longer than (say) six hours are indeed uncommon.

@Eddie: If you have an installer that you like, or don't believe the city has a solution for you, then it doesn't make sense to get an assessment. (You will apply for the rebate and they will learn about your installation that way anyway.) But the city seems to be pretty flexible as far as technology goes, as described above, so I wouldn't proactively rule out your use-case until you talk with them.

I hope this is helpful, and I look forward to more questions. The city really wants this program to be successful, and they want the contractor to be busy, so they are trying to be flexible wrt installations while also investing a lot of time and money in the program.

I want to emphasize again that while there were some very long waits in the beginning, now they should respond within a week to schedule an assessment.

Posted by Ole Agesen, a resident of Menlo Park: Allied Arts/Stanford Park,
on May 29, 2023 at 8:10 pm

Ole Agesen is a registered user.

Hello Sherry, all:

Contrary to previous commenter's claim ("I don't think many want to even contemplate this") I think a lot of us (the rest of us) would like to switch to clean electric appliances to give the next generation and their (grand-)children a better future, less diminished by climate pollution, droughts, wildfires, sea level rise, climate refugees, and Mad Max-like dystopia.

As California reaches 100% emissions-free grid by 2045, electric appliances will (1) be healthier in our homes (2) cause no climate pollution, unlike methane-fueled appliances that will remain unhealthy in our homes (NOx, benzene, asthma, cancer) and continue to worsen climate pollution.

The wrong feedback cycle:
- global warming causes wildfires and heatwaves
- wildfires cause grid safety-shutoffs
- heatwaves cause grid overload and load-shedding
- since the grid is unreliable, I want to keep my gas appliances
- my gas appliances will continue to fuel global warming
- repeat.

The right feedback cycle:
- I switch to electric appliances
- this increases demand on the grid so new investment is needed
- new investment is applied to build a grid that can handle a
climate-polluted world (unlike the grid built 100 years ago for
a different climate)
- more people realize that putting our investments into a reliable
grid, rather than continuing to pump money into a climate-polluting
gas distribution system and gas appliances, is the path to the future.
Don't cling to the gassy past. The future is electric. The future is now.
- repeat.

I live in a 100 year old house and it has no gas. I'm more than happy.

Ending gas can be done, and now is the time to do so. AT OUR HOME.

If you are in Palo Alto, use the City's programs. If you are in Menlo Park, reach out to BlocPower. If you work in tech... tech leads; now is the time to show leadership. Convert your home away from methane. Pave the road for others to follow.

Ole, no gas regrets

Posted by BobH, a resident of Palo Verde,
on May 30, 2023 at 12:36 pm

BobH is a registered user.

I filled in the form, I want to see how much it would cost to have a hybrid water heater installed. Besides the installation costs, I hope this includes how much the operating costs will be compared to my gas water heater.

A significant issue with the "all electric" program is that while installing hybrid electric water heaters is nice, I am not sure there is a similar plug in replacement for home heating. Especially for all of the houses in Palo Alto with gas forced hot water systems like mine. I did a little research on this, it's not clear there is a solution.

Posted by KOhlson, a resident of Old Palo Alto,
on May 30, 2023 at 1:59 pm

KOhlson is a registered user.

A friend lives nearby. Both our water heaters are in a basement.
- $1065 to install 220V outlet. My 200A panel is 5 feet from the existing WH. I have an existing 110v outlet next to my existing WH
- Both estimates had an extra-cost warranty for $405 added. I asked for that to be removed.
- My estimate had an extra $200 to swap the existing recirc pump.
- His estimate included an extra $835 for a condensation pump, which was not included on my estimate.

For my estimate, my total payout is $2900 (2700 + recirc pump). My friends was $600+ more.

CPAU has not been very responsive. They must be very busy and perhaps one day they will get back to me.

I support CPAU's concept on "onboarding" service companies to learn how to efficiently install HPWH. I acknowledge that HPWH installation, even with CPAU support and government rebates, is not less expensive than replacing a gas WH. But in my experience so far, there is a ways to go with respect to cost and service.

Perhaps one suggestion is for CPAU to make publicly and easily available installation costs. Maybe on a giant spreadsheet, similar to what you did. No personally identifiable information, and perhaps a column for extenuating circumstances.

Posted by James, a resident of Midtown,
on May 30, 2023 at 9:29 pm

James is a registered user.

I filled in the CPAU form for HPWH in early May. I got a reply email on May 18th saying they're backed up and working through their backlog. I still haven't heard from CPAU or Synergy. I also contacted two contractors on the CPAU website. One quote was very high (much more expensive than Synergy). The second was more of a discussion, his recommendation was to go with Sanco because my panel is close to maxed out. I also tried to get some quotes to upgrade the panel to 200. Overall I'm not impressed with the contractors on the CPAU website. We'll see what Synergy comes up with.

Posted by Sherry Listgarten, a Almanac Online blogger,
on May 30, 2023 at 10:21 pm

Sherry Listgarten is a registered user.

@BobH: Operational savings depends on a few things: the relative cost of electricity and gas, the relative efficiency of your gas and heat pump water heaters, and the amount of hot water your household uses. Here is a calculation, assuming that EffG is the efficiency of your gas water heater (e.g., 0.7), EffHP is the efficiency of your heat pump water heater (e.g., 3.7), PrE is the per-kWh price of electricity (e.g., 0.21 in Palo Alto), and PrG is the per-therm price of gas (e.g., $2.00).

Electric vs Gas Ratio = (EffG / EffE) * (PrE / PrG) * 29.3

For the sample numbers given above, the ratio is 0.58. In other words, the cost of running the heat pump would be 0.58 times the cost of running the gas water heater. A gas water heater uses around 30% of the annual gas bill for many homes. So if your total annual gas use is 600 therms, or about $1200, then around $360 of that is for the water heater, and you would save 0.42 * $360 = $152 per year if you switched to a heat pump water heater.

I believe that gas will only get more expensive relative to electricity, so the savings will go up as the rates evolve. Every year it gets a little sketchier to install a long-lived appliance that relies on increasingly expensive gas.

You are right that home heating is different from water heating, but I’m curious what you mean by a “gas forced hot water system”. Can you clarify?

@KOhlson: I love your idea of price transparency. Otherwise, yes, it’s hard to build trust when there’s a $200 extra charge here, a $400 extra charge there, and seemingly little consistency. It’s a great idea. I will forward it to Jonathan A, and feel free to send him your thoughts directly as well.

@James: I had a similar problem when I was installing an EV charger and contacted the people on Palo Alto’s website. They were all very expensive. FWIW, an electrician I like is Chris Gray of Gray Electric. You might ask him about a panel upgrade and/or getting your home configured for a HPWH and/or efficient electric heat. He does this kind of work all the time.

If your panel is almost maxed out, I would consider a few things. (a) A smart meter might well indicate that in fact your panel is not almost max’d out. But not sure how soon you/we are getting these. People in PG&E territory have these already. (b) Splitters exist where you can share a 240V circuit between two appliances (e.g., EV charger and HPWH, or dryer and HPWH, or …). No panel upgrade needed when those are used. (c) 120-volt HPWHs exist, and the city will install them when it makes sense. (d) The Sanco uses 15 amps, but so do some of the standard Rheem hybrid water heaters. So no need to go to the more expensive Sanco just for that.

I hope that the city gets back to you soon. I’d love to hear how your experience goes. I know that the city wants the program to be successful.

I love all of these questions and comments, thanks!

Posted by Donald, a resident of South of Midtown,
on May 31, 2023 at 2:56 pm

Donald is a registered user.

I signed up for the assessment and many months later someone came by to do it. I never got the report or the cost estimate. I got nothing from them. In the meantime my old water heater broke and I had to get it replaced by another gas heater. Sigh.

Posted by Mondoman, a resident of Green Acres,
on May 31, 2023 at 7:48 pm

Mondoman is a registered user.

Re: "The assessment in and of itself is a valuable free service."

Yes! It would be great if this could be essentially a stand-alone "readiness for all-electric home" evaluation that identifies (or not) significant cost choke points to installation. I'm thinking overall service capacity, panel capacity, need to install or rewire circuits, and physical space considerations for the appliances. Even if a house's current setup won't support an electric appliance without a significant cost, it would be great to know what type of capacity upgrade to keep in mind for the near future so work doesn't have to be done twice.

Re: "[gas] is only going to get more expensive relative to electricity over the coming years because of the damage it is causing."

I'm not sure I understand the reasoning there - I would have thought if nothing else that lower demand for gas would lead to lower prices. Also, it seems that CA's planned electricity supply increases are from sources more expensive than the current ones (e.g. batteries instead of big hydro).

Posted by Sherry Listgarten, a Almanac Online blogger,
on May 31, 2023 at 8:20 pm

Sherry Listgarten is a registered user.

@Donald: That is terrible. I would strongly encourage you to contact Palo Alto's Home Efficiency Advisor and asked to be referred to the program managers, Scott Mellberg and Jonathan Abendschein. They need to hear this and to be able to ask you questions about your experience.

Phone: (650) 713-3411

Speaking of which:

@Mondoman: The Home Efficiency Genie can (I think) provide that information. Give them a call.

Regarding the price of gas, you are forgetting the fixed costs of maintaining the gas infrastructure, which are significant. (Not to mention the externalities ("social cost") of burning fossil fuels, which keep getting bigger the longer we delay.)

Batteries are expensive, though when paired with solar less so. (We are planning to build more solar than battery, and don't forget wind, etc.) IMO the things that exacerbate climate change will (and must) get more expensive, and the things that mitigate it will get cheaper. I think if bad things stay/get cheaper, then it will lead to a worse outcome, and an ever-increasing number of politicians and policy makers are seeing the wisdom in avoiding that. Not to mention insurers, who we can see are already acting on risk and cost.

Posted by Mondoman, a resident of Green Acres,
on May 31, 2023 at 10:10 pm

Mondoman is a registered user.


Thanks for the pointer to the Genie:

"The Genie's Home Electrification Readiness Assessment, which is included in your virtual or home assessment, helps residents determine if their old appliances and equipment are ready to be replaced, and if their electric panel can support new, efficient, electric alternatives. The HERA includes:
An evaluation of your home's electric panel
Examination of existing appliances and equipment
Your own Home Electrification Readiness Report

Posted by Archer, a resident of Leland Manor/Garland Drive,
on Jun 7, 2023 at 7:43 am

Archer is a registered user.

I recall in the 1980s when someone had a great idea for new hones to have electric heating & hot water. The result was higher utilities bills than the mortgage. Next idea?

I just received my water price increase from the PA utilities. Thank you. This is after a good winter rainfall, not a record, but good nonetheless. California does a poor job in managing water resources so power will be there also.

So today's question is - How quickly will we electrify our homes? I'll choose 2065. Why? The prerequisite of choosing a specific power type for a home or industrial building is that the origination of the power is well planned for. This we do not have in California as our state has a power grid comparable to a third world country. We need smart people running this state to build the power plants necessary for innovative deployment of power to the last mile.

Posted by Karl A, a resident of Another Pleasanton neighborhood,
on Jun 7, 2023 at 3:01 pm

Karl A is a registered user.

Those of you that live in the older areas of the Bay Area (most of Palo Alto) may want to study the power outage history of your area before going 100% electric. Your infrastructure is old and unreliable. The outage maps from this last winter and summer demonstrate this point. Seems the focus should be updating infrastructure first (and also investing in technical advances in batteries, etc) before spending loads of money on the purchase of EVs and the replacement of gas appliances / furnaces / hot water heaters. Without reliable infrastructure to deliver electricity, a lot of people will be really hot in the summer and really cold in the winter. They will also have to get used to cold showers.

Going 100% electric is a good long term plan, but a great deal of infrastructure work really needs to be done first.

The other point is we can spend trillions of dollars to fight climate change, but until China and other developing countries stop building and using coal power plants, our efforts will have minute impacts on climate change.

By all means take action to ease your conscience and feel better about yourself. Just realize in the big scheme of things, the impact of what you are doing and spending will have no real impact.

I'm not a climate change denier. I believe in minimizing my carbon footprint as must as possible. But spending lots of money without any real impact on climate change is just a waste. I'd rather spend the money on eliminating homelessness and world hunger.

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jun 7, 2023 at 9:39 pm

Sherry Listgarten is a registered user.

@Archer: You seem to make a lot of inflammatory assertions without much evidence. In what way is Palo Alto's power like a third-world country? By what metrics? You imply that we do not have smart people thinking about our power. Have you been to any of the CEC or CPUC meetings or read any of their reports? And how is a new power plant going to impact "innovative deployment of power to the last mile"? Regarding 2065, I would hazard a bet that there will be no residential gas delivery by then, so buy some warm clothes for your kids and grandkids.

@Karl, Palo Alto's distribution grid does need updating. But heat pump water heaters (for example) use only as much electricity as a few incandescent light bulbs. There is a lot we can do incrementally -- we can walk and chew gum at the same time. But more importantly, I cannot fathom why you say that people without a gas water heater will "have to get used to cold showers", and that a lot of people "will be really hot in the summer and really cold in the winter". The point of heat pumps is the opposite. In fact, they would provide summer cooling that many don't have now. So you must be predicting widespread, long duration failures. On what basis?

As I've said before, I do not understand the argument that since an individual action, or a country-wide action, isn't big enough to solve a problem, it's not worth doing. By extension, none of us should do anything. This blog is pointless. Your vote is pointless. As is any money you could possibly contribute to homelessness or world hunger.

I am excited that the city is doing the work needed to understand the labor and cost and time to electrify homes. I hope that you and others will sign up.

Posted by Mondoman, a resident of Green Acres,
on Jun 13, 2023 at 11:53 pm

Mondoman is a registered user.

I think Karl may be referring more to impedence-mismatch types of situations. For example, while the average energy use rate of a heat pump may indeed be only a few hundred watts over time, short term it needs much more, as the minimum electrical cirsuit requirements for hpwh's show. It's that extra/upgraded circuit capacity that often causes practical cost issues.

They also tend to have slower recovery times, so maybe the real takeaway is that the water or air heating system needs to be considered as a whole, with component functionality chosen to allow it to work successfully in various environmental conditions. I think your excellent articles on real-world installations have pointed this out; I worry that the too-short message from programs like the City's hpwh pilot is that it's just a drop-in replacement situation, whereas really building insulation, air flow, water use patterns etc need to be considered and perhaps modified for proper overall performance.

Older systems like gas-fired ones could often power through edge conditions by just throwing more BTUs at the problem, but heat pumps and other modern systems seem to have less high-power surge capacity as part of their designs.

I also interpret Karl's comments about China as referring to opportunity cost rather than an action being worthless. As he wrote "I'd rather spend the money on eliminating homelessness and world hunger."

Posted by Sherry Listgarten, a Almanac Online blogger,
on Jun 14, 2023 at 2:02 pm

Sherry Listgarten is a registered user.

@Mondoman: A few points just to make sure you understand how these operate.

Almost all retail heat pump water heaters have two heating units (which is why some manufacturers call them "hybrid"). One is a heat pump, which runs at a few hundred watts, and the other is an electric resistance unit, which runs at a few thousand watts. When you get a 30-amp heat pump water heater, that resistance unit is twice as powerful as when you get a 15-amp heat pump water heater. If you get a 120-volt heat pump water heater, there is no resistance unit.

If you have sized the HPWH properly, the resistance unit will rarely kick in. Just so you can see what that is like, here is a typical day and week of my heat pump water heater, which has a circuit monitor. The resistance element never runs.

But a few months ago, after I turned the HPWH off when I went away, when I turned it back on, the (15-amp) resistance kicked in. Here is what that looks like.

Hopefully this will help you understand how these work. It’s not about the “average” being several hundred watts. That is the power at which the heat pump runs. The resistance element runs at much higher power but rarely.

Every HPWH installation has to look at electrical, air intake/outflow, condensation draining, and recirc pumps. There are plenty of options. They are installed in homes all over the world every day.

But, I’m not here to convince you to change your water heater or even to spend less cycles thinking and worrying about the possibility of changing it. Just as some people are eager to change, some people are very reluctant. And some installations are easier than others. The city's program will provide some facts about installation complexity, which is great.

If Karl can eliminate homelessness and world hunger, more power to him. As he is looking at those issues, he may find that he cares about climate change after all. And he may come around to the fact that standing on the sidelines after having wrought more damage than any other country is no way to encourage action.

Posted by Paly Grad, a resident of Leland Manor/Garland Drive,
on Jul 8, 2023 at 7:44 pm

Paly Grad is a registered user.

I've been thinking about the costs to upgrade from a 100 amp service to a 200 amp service. If someone currently has underground service it would likely cost significantly more compared to a homeowner who has above ground service and is considering a similar upgrade from a 100 amp service to a 200 amp service. The extra costs would be related to the cost of trenching, conduit and then restoring the landscaping or hardscaping when the trench is filled in. It's possible that the cost difference would be substantial!

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