E-mail Sherry Listgarten About this blog: Climate change, despite its outsized impact on the planet, is still an abstract concept to many of us. That needs to change. My hope is that readers of this blog will develop a better understanding of how our climate is evolving a...  (More) About this blog: Climate change, despite its outsized impact on the planet, is still an abstract concept to many of us. That needs to change. My hope is that readers of this blog will develop a better understanding of how our climate is evolving and how they want to respond, and will feel comfortable asking questions and exchanging comments on the topic. It is important that we develop a shared understanding of the basic science and impacts of climate change, to make sense of our actions and policy options going forward. My background is not in climate science, and I'm not even particularly green; my hope is that helps to make this blog more relatable. I studied math and neurobiology on the east coast before moving out here in 1987 for grad school in computer science. After working in the tech industry for about 25 years, I retired a few years ago to better align my time with my priorities. I love spending time outdoors, and feel deeply our responsibility to this incredible planet that we call home.  (Hide)

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I installed a heat pump water heater a few months ago. I would have liked to use American-made Rheem, but I had heard there were noise issues, and when I called them it was "Noise? What noise?" That was a red flag for me. I chose a Stiebel Eltron (after waiting a couple months--not sure if supply chain issues have been resolved) that I bought online. I'm happy with the noise level, and performance. Fuse Service installed for me--I was happy with them, as they were about the only contractor/installer out there that didn't try to gouge me for installation. A couple notes about temperature settings. My Stiebel manual says "Never reduce the set temperature below 122F to reduce problems with legionella." And I've gotten confusing/mixed messages about higher set temperatures: the manual also says that higher set temperature lowers efficiency; however, the City's "energy genie" consultant advised me, if I remember correctly, that a relatively high set temperature is more efficient...

Here, btw, verbatim is a message from Palo Alto's "efficiency genie" consultant. I can't vouch for the accuracy of its contents but have to believe he knows what he's talking about: "Now thinking about the unit as a theoretical device and optimizing the efficiency, the hotter you can keep the water, the better. This is simply because it can hold the temperature easier and allows you to remove less hot water when coupled with a mixing valve like you mentioned you have. The idea being that if you want the water to exit the tank at 120 degrees or 125 degrees which is pretty standard, you can keep the tank at 140-160 degrees which means that the tank will lose less than 1 gallon when the hot water is used. This allows the cold water entering the tank to replace the heated water that was used, to be lessened and reduce the amount you need to heat the water. If done properly, having the tank set to a higher temperature can increase the efficiency of the unit and reduce the need to heat the water as often."

We had a 10 year old GE, which was pretty noisy, but it was tolerable (small cellar under the kitchen). We bought a new AO Smith recently, and it may be a *little* quieter, but I think it's still around 60. I agree with the "microwave analogy"... maybe put one where you plan to install your heater, and see if you can stand it. We watched on of the videos mentioned, and it seemed that that unit had a "hum" which was much louder than either of ours... I would say the fan noise "overwhelmed" the hum... Another thing we found out is that the AO Smith units they sell at the big box stores are not the same as one you would buy from a plumber... the plumber took the part no. from ours, and said that a duct-kit was not available! Caveat Emptor!

Just a couple more notes about (my) Stiebel Eltron: They do tend to be more expensive than most other models. I was also warned off them by a local, experienced contractor for three reasons (two of which turned out to irrelevant or wrong): 1) They have "nonstandard" size water connections; 2) it is hard to change the settings on it; and 3) it wouldn't be compatible with Palo Alto's future smart metering system. The first two "warnings" proved to be nothingburgers--Fuse Service had no problem with connection sizes (if you do get a Stiebel you may want to first get the installation manual online and forewarn an installer); and the "settings" are not hard to change at all (this "warning" was a head scratcher). I don't fully understand what the future smart metering will offer, but it is apparently true that the Stiebel will not be capable of that, according to Stiebel support. And I should note that I, as far as I can tell, cannot do time-of-day/scheduling of different temperatures as Sherry apparently can do with her Rheem.

Hi. Thanks for the comments. I agree that a good setup is a smaller tank with a mixing valve. Then you can heat the water up hotter and mix it to a lower temperature, gaining the benefit of a larger tank without needing the size. And maybe there's a health benefit too wrt legionella. I've always had our tank at 120, and it's the default setting, so that's what I went with, plus I don't have a mixing valve... BTW, someone asked if the noise is related to the unit being 15 amps. It's not. The 15 amps just means the resistance unit uses less power. That wouldn't make it noisier, and anyway my heat pump never uses it anyway because it's enormous. (In retrospect, I would have been fine with a 65 gallon one.) Anyway, thanks for the comments.

I want to share this comment that a reader emailed to me: > I was thinking about replacing my gas water heater with one, > but was concerned that since my water heater is mounted in a > utility closet in our family room noise would be a factor. The > closet door is also about 4-ft from my favorite chair, which I > use when reading or watching TV. I recall you mentioned that > the units were quiet, which based on your article is no longer > the case. > > 55-60 dB is the same volume as my old Bosch washing machine > when its on high-speed spin, which though relatively quiet in > the world of washing machines is still quite disturbing. > Fortunately it is a room that we can close off to reduce the > noise to a whisper and we don't do laundry several times a day. > > Thank you for writing this update addressing the noise issue. I > think the HPHW technology is not quite ready for prime time. > This is especially true for those of us whose water heaters are > in the home and not in a garage away from living quarters. > > De-carbonization is important, but so is quality of life, > especially since excessive noise is unhealthy. So for now, no > HPWH for me. > > Noise abatement isn't rocket science. But it seems that Rheem > and Ruud appear not to give a damn. > > So there won't be any heat-pump water heater in my future until > the manufacturers up their game. I want to share a few thoughts. 1. 55-60 is noticeably louder than 50-55. The decibel scale is logarithmic, so small changes are noticeable. I'd suggest listening to one. I shared some videos. Hopefully you can find someone who has one, or just email me if you'd like to listen to mine. 2. Many of these are perfectly quiet. My contractor just installed two that were whisper quiet. Consider checking the date when you buy. 3. There are some straight-forward ways to dampen the sound. We all used to wrap our water heaters in blankets way back when. The suggestion now is to just wrap the top (minus the air intake/outtake and display) in a double layer of soundproofing mats. 4. As I mentioned, you can set a schedule to impact when it runs if you are still sensitive to any remaining hum. These only run 4-8 hours per day in most households. Obviously I anticipated this sort of response when I wrote this post, but still it makes me sad. There are many reasons not to adopt cleaner technologies and to continue to burn fossil fuels. Change is not easy and it is imperfect. We each have to decide for ourselves where we want to be on the curve of this change. I try to choose actions that would make my daughter/nephews/grandkids proud.

I'm glad, Sherry, that you noted that in retrospect you would have been fine with a 65 gallon model. That is another way that people can cut down on energy use--get the right size? Our house when we moved in had 2 80-gallon heaters (!) (one "dedicated" to the master bathroom) which I'm sorry to say we used for years; then we took one out. My new hpwh is just 58 gallons (though with the mixing valve it effectively may be more). Two of us here have had no problems with that size; and my brother and family just visited--two teenage girls taking Midwestern-length showers--and we apparently had no problem (unless they were too polite to say something). Lesson? Take a hard look at how big you really need.

Sherry, thank you for the informative and impartial post. I look forward to switching over to a HPWH once the kinks are worked out. It is odd that Rheem/Rudd is not addressing nor being transparent regarding this seemingly obvious issue. Rheem has historically a good track record. Perhaps the issue is on the Rudd side? Regardless, I appreciate you and the other contributors helping to inform the community and indirectly contribute to lower emissions.

We installed an Eco2 heat pump because our contractor warned us about the noisiness of the Rheem heat pumps (which they install in garages to mitigate the noise issue). The Eco2 heat pump is more expensive but we didn't want the noise and it was not possible to put a heat pump in our garage. A nice bonus: the Eco2 refrigerant is CO2, not Puron.

@ljse: Yes, the contractors I've spoken with all speak highly of the Eco2 heat pump water heater (which used to be called Sanden). It is powerful and quiet. As you say, it costs 50-100% more than these other options and you need a space for the outdoor unit, so it's not for everyone. But it's a great option. Thanks for mentioning it, and glad to hear you are happy with it. BTW, there are some great bills being proposed to encourage more development of heat pump tech in the US (outside the US it's much farther along). You can read more here and here. It can't happen too soon!

FYI, I have updated this blog post with information about a relatively simple but effective fix. See "Update!" above. Thank you to the contractor who provided the description and pictures!

I bought Ruud, but according to the advertisement, the machine works smoothly and does not make noise. But that's the opposite of me. It is too loud, affecting my daily life.

@kate19: I'm sorry to hear that. I hope you can use some of the tips in this post to reduce the sound.

We installed a Ruud 65 gallon HPWH last year, and it's much louder than I expected from the research I did prior to installation. I tried to measure the actual sound level using an iPhone app (Sound Level Analyzer LITE). While the app seemed to be precise and sophisticated, I couldn't figure out how to calibrate it to the ambient sound level. The unit is in our garage, but adjacent to the master bedroom, so the noise is a problem when we're trying to sleep. We mitigated it by using the schedule to turn it off at night. This has worked pretty well, and the 65 gallon unit is sufficient for our small family. We set the temperature to 122F. I will probably try the “Update" fix recommended by SunWork that you included. One other problem I have had is the Econet app that controls the system is buggy and sometimes turns the heater off for a day or two. I have to monitor it closely and reset the system when it goes off. And calling for service can be a problem, because the Ruud water heater and the Econet app seem to be different companies. When you call one of them, they blame the problem on the other.

@Brian, please let me know if the sound mats help! I haven't heard of any issues with the Econet app, but I'll keep an eye on it. Thank you for adopting a HPWH early and pushing the industry to keep getting better.

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