Talk to me about switching to an electric water heater
November 11, 2018 9:59 AM   Subscribe

We need a new water heater, and are considering a switch from natural gas to electric. What do we need to know?

Our water heater needs to be replaced. Our current one is natural gas, but we're considering switching because (1) our utility is offering rebates on high-efficiency heat pump electric water heaters, and (2) we recently got solar panels and are producing more electricity than we use.

Is this a good idea? What should we be thinking about to make the decision?
posted by medusa to Home & Garden (12 answers total) 3 users marked this as a favorite
How often do you have power outages? I always had electric water heaters and recently moved to a place with gas. I am so, so happy to be able to have hot showers when the power is out (due to e.g. hurricanes). It makes a long power outage that much less awful. I would prioritize a gas water heater for that reason alone. But other factors may outweigh that for you.
posted by snowmentality at 10:23 AM on November 11, 2018 [2 favorites]

Heat pump hot water heaters make some noise, they have an air filter that needs to be cleaned, they blow cold air, and they need a minimum volume of air to pull heat from.

You'd need to check models, but I think all heat pump hot water heaters also have standard hot water heating elements. If the heat pump can't keep up the heating elements come on. You might have to get new wiring installed to power the heating elements.

In my area both the electric company and the gas company offer pretty good incentives.
posted by gregr at 10:32 AM on November 11, 2018

Where will the water heater be located, and where do you live?

If you live in a hot area, heat pump water heater is great to have inside the house because it will help cool it. If you live in a colder area, it should be outside of the living space (garage).
posted by Diddly at 10:34 AM on November 11, 2018

Good suggestions. Power outages are rare where we live, which is hot in the summer and cool in the winter. The heater would be in finished living space.
posted by medusa at 10:38 AM on November 11, 2018

If you already have solar panels, you might as well. You might have to arrange for the appropriate outlet. I would look beyond whatever models your utility offers just to know what your options are. Even in an outage, a good heater will hold the temp for a very long time, and if you have solar, that's probably not your biggest concern anyway. Maybe I just hate gas appliances (yes, have had both gas and electric), but I don't see a downside in this case.
posted by sageleaf at 10:52 AM on November 11, 2018 [1 favorite]

Do a LOT of research on costs and reliability of long term ownership of RC water heaters. They have a poor rep here, possibly as a result of one manufacturer in particular. However the fact of the matter is that they are relatively complex electro-mechanical devices compared to a resistive or gas water heater. If you can get 'free' electricity from your panels consider using one of the sophisticated timers to control the heater's operation, whether resistive or RC.
posted by GeeEmm at 1:30 PM on November 11, 2018

Gas water heaters cost nearly nothing to run. Electrics do cost more to run. You can have a large, well insulated gas water heater to bold a large supply of clean emergency water, as long as it is installed so it won't easily fall over in unstable conditions.
posted by Oyéah at 2:06 PM on November 11, 2018 [1 favorite]

Medusa, that is an excellent idea and in fact the company I work for absolutely loves to sell a combination of solar and heat pump water heaters, because they complement each other so well and help customers transition off of fossil fuels while saving money at the same time. The main barrier is that heat pump water heaters are rather expensive up front, but if you can get a solid rebate and are already producing excess PV then it sounds like a really good deal. They also dehumidify your basement, by the way.

Other complementary (to PV) technologies include air source heat pumps (aka "mini-splits") and electric vehicle chargers. What do you currently use for heating and cooling? Do you, or would you like to, drive a PHEV or BEV? Depending on how much excess PV you're making, you could potentially do a lot here.

The main thing to bear in mind if you start loading up on this stuff is what your house's service capacity is. If you're only on a 100A service, you'll hit limits pretty quickly if you move from fossil fuels toward an all-electric setup. Depending on your house's baseline energy needs, it's not inconceivable that you might need a 400A service at some point. However, in my experience, 200A is still enough for most households' needs at this time.

Anyway, those are some things to think about but overall if you're making excess PV and you can get one for a good price, go for it. If you have other questions, I can try to answer them.
posted by Anticipation Of A New Lover's Arrival, The at 3:42 PM on November 11, 2018

Or sorry, dehumidify your living space I guess. I'm not sure I'd put one in a living space as they do make some noise. I might use a conventional electric water heater instead, because they're silent. Even though they are less efficient, if you have the spare kWs it may not really matter.
posted by Anticipation Of A New Lover's Arrival, The at 3:44 PM on November 11, 2018

Another factor I forgot to consider above: are you sure you're making excess PV? Due to the regulatory environment in most states, it's not normal for a solar company to build someone a system that's significantly larger than they actually need unless the customer specifically intends to increase their electricity consumption in the near future. Stop me if this is something you're already thinking about, but I've found that many customers don't have a firm grasp on the fact that their system is designed to overproduce in the summer months in order to build up a credit that can be used during the winter months (like, starting now) when short days mean that the array will underproduce relative to the customer's power consumption.

You've lived with your array for a few years now and are confident that it's overproducing on a full-year basis, yes? That would point to possible sloppy design (or maybe just greedy design, since larger systems cost more) by your installer, although it would suggest that increasing your consumption by shifting fossil-fuel-derived energy to PV-derived energy would be a good idea.
posted by Anticipation Of A New Lover's Arrival, The at 2:12 AM on November 12, 2018

Your PV system is really irrelevant to your hot water heater decision assuming that your utility is buying back any excess electricity at a reasonable rate. If a gas hot water heater costs less to install and operate than the equivalent electric heater, you should use gas and sell the electricity. This cost tradeoff will depend on the gas vs electricity costs and the efficiency of the gas vs heatpump models you compare.

If you want to think about it in terms of carbon, you are sending your carbon-free electricity to someone else who is using an electric water heater because they don't have the option of gas.
posted by JackFlash at 9:10 AM on November 12, 2018

I went from a regular electric water heater to a hybrid heat pump heater. The rebates were fantastic so it paid off in one year. One month after I purchased it, the manufacturer quit making them.

I like the system. It's reliable, well designed and works as mentioned by others in this thread. It cools the space it's in and needs some elbow room for air supply. Also needs a drip/condensate drain outlet.

If the machine breaks for any reason, I'm pretty much out my investment. There are no 'certified' repair people in my county or probably state so GE won't give me any support or parts without one. The 10 year warranty is pretty much worthless. When I've called the support line, they pretty much just stonewalled and gave no help.

It's a great machine but the market just wasn't buying efficiency.
posted by diode at 2:07 PM on November 12, 2018

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