New Heat Pump Hot Water Heater = All Electric Home
 

I've been looking at Heat Pump hot water heaters for a few years now but couldn't see spending the money to swap out our gas water heater. Well that was taken care of for us when it decided to fail in a spectacular fashion. The plastic drain valve failed, shot across the room, and the water heater sprayed gross water full of mineral deposits all over my BMW. (It took 3 washes with the last using a diluted vinegar to get the deposits off the bike)

So this weekend I spent our anniversary swapping out a water heater. The hardest part was finding fittings that would work for the condensation drain.

The new Rheem Protera 50 gallon water heater will work out to be $700 after incentives. ($1700 - $700 from electric utility - $300 Federal tax credit. The energy star label says it will use $117 of electricity a year vs the $330 a year on the label for the old water heater. (We actually spend $209 a year for natural gas)

Failed plastic drain:
https://ecomodder.com/forum/attachme...5&d=1684729958

My motorcycle after the rupture:
https://ecomodder.com/forum/attachme...6&d=1684729992

New water heater:
https://ecomodder.com/forum/attachme...7&d=1684730016

I had a heat pump hot water heater.
Won't make that mistake again.

Care to expand on that? Small details like how long ago this was and the problems you experienced.

Gotta wonder what brand, early models were very expensive and like all new things needed expensive maintenance and repairs off book.

In this area any device that makes cold air also generates boatloads of mold after a few months unless you locate a $200 UVC light that fits your condenser.

My question is does your “heat pump” water heater provide the side benefit of AC during operation?

Some just vent cold outside (a consideration in areas that get hot and cold)

Yes, like all heat pumps it exhausts cold air when heating. Mine is in a 400 sq ft garage so I don't expect that to be an issue - A friend has been using the same basic model for 5 years in a single stall garage without a problem. In the summer I'll take as much side effect A/C in the garage as I can get.

There are vent kits and if there was a problem I have an exhaust vent right above it left over from the natural gas water heater and old gas furnace.

This Rheem water heater has a one year labor / 10 year part warranty. If things go as planned we will be selling this house in summer 2024. I could have saved $150 or so by going with a super cheap conventional water heater but that would be incredibly short sighted. I will likely break even in that year and this water heater will save the next owner thousands of kWh.

EDIT:

A Rheem 50 gallon regular electric water heater with a 9 year warranty is $679 - or $21 cheaper

A Rheem 50 gallon gas water heater with a 9 year warranty is $809 - or $109 more expensive.

A natural gas heater wouldn't use any KwH and are usually at least 80% efficient.

No, a gas water heater doesn't use any electricity - just $17.50 a month in natural gas. (At least that was my monthly average).

That is the equivalent of 115 kWh of electricity a month. Time will tell with the new water heater but the energy star label says 837 kWh per year or 70 kWh per month. I'm guessing I'll be closer to 650 - 700 kWh for the year.

80% or even 95% efficiency sounds good until you compare it to a heat pump at 250% to 300% efficiency.

EDIT: Again - care to share what problems you had with your old heat pump water heater?

First time I heard about similar all-electric setups was in 2008, yet I have never seen one. Gas-fired and even wood-fired boilers OTOH are still common in my region.

Our current house in Oregon is the first I've lived in that has natural gas. My houses in Virginia, Tennessee, and Alabama were electric only.

In my country, a built-in heater element (replaceable) right at the shower head is more usual than central water heating, yet in regions with a colder weather it's more common to resort to central heating. Hotels and hospitals may also resort to central water heating more often.

I've seen those units in various places around the world. The B&B we stayed at in Scotland had an on-demand electric water heater right in the shower.

Have to wonder what the reasoning is behind encouraging more people to use more electric applies when the power grid clearly can't handle unusually hot or cold periods.

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Did you get rid of the old tank ?

If you haven’t, put a plug in the drain hole and build a pre heater for your new unit.


https://i.postimg.cc/Zv531QCM/72-F8-...-AB9-BE5-F.jpg

https://i.postimg.cc/8sphJ7tm/F1-FCE...F0747-F474.jpg



:turtle:

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Not a bad idea in the right location. I don't really have the room for a glass coffin around a water heater in my small urban lot nor do I believe a homebrew water preheater will add value to my home or make it sell faster.

Then there is the climate. That kind of simple solar preheater works in mild climates where freezing isn't an issue. In colder climates that drop below freezing you have to either use coolant with a heat exchanger or drain back systems for 4 season use. For a simple system it could be plumbed in parallel and only used in the summer.

That's what the house my parents built in 1980 had.

The solar preheater was in the top of a sunroom, regular electric heater, and an on-demand heater (but it was in the kitchen, not at the shower).

But they got a solar installer out of Dallas, OR, that wore a ten-gallon hat with a little fan of feathers on the front. I didn't trust the guy, he borked the installation and the subsequent owners removed it, and the skylight.

The 80’s had a lot of sketchy thermal solar companies. My parents were talked into a thermal collector on their roof that was supposed to save them huge amounts of money on heat. It worked but the savings were minimal. We tool it off about 10 years later when we replaced the roof.

I'd run that before a heat pump hot water heater.
But I would have to drain and isolate it during the winter.

Else one could install it vertically, and put two rotating sleeves around it; each half transparent sheet arcrylic Fresnel lenses out of old big screen TVs. The other half insulated

One sleeve moves to follow the Solar cycle*, the other the day/night cycle. Turned against each other it's an insulated box.

The result is optimized gain and loss.

Edit: I think that's wrong. Would work if horizontal. One fixed, one rotating in either orientation?

I thought at the time the fancy hat was a tell.

Coincidinkly; this posted today:

1936 Solar Energy - The Poor Man's Cousin

A general backgrounder with an interesting perspective: Solar was kilt by coal, and then nuclear, but it's coming back again.

Maybe nobody noticed #18 (permalink)?

As I was walking home from the grocery store, I realized that I have a $10 8-gallon water heater I was going to test for watertightness. If I can find a Fresnel lens it would make a good test case.

In my country solar panels exclusively for water heating (without electricity, or resorting to a backup electric heater just for extreme weather circumstances) are not unheard of, yet they're not so cheap. Had i been living in a house instead of an apartment, maybe I could consider such setup.


You mean anything (at least conceptually) similar to this?
https://www.leroymerlin.com.br/chuve...zetti_86213043

Same concept but a bit different:

https://ecomodder.com/forum/attachme...7&d=1685484749

Preliminary efficiency results are in. In my first week the hot water heater used 11.94 kWh ($1.79) of electricity. That is less than 1/2 the cost of running the old natural gas water heater.


That was just holding water temperature at a steady 125F - time to use some of the "smart" features on the new water heater. Yesterday I started a time of day usage schedule. I set the water temp to 125F at 5 am so we will have plenty of hot water for showers and then at 7 am it drops and holds at 120F for the rest of the day.

Similar to what I usually see in motorhomes, serving both as a shower and as a tap for the sink.

You can also use the heater for a localized AC unit. Got one in a converted breezeway that we have to turn off in the winter

How long is recovery from ambient? Until I retired and was home all day, I turned mine off until two hours before I returned, and ditto for wake up. Couple extra insulation batts and it wouod stay around 100f

It took about 2 hours after filling the water heater with cold water to heat up to the stock setting of 120 F.

The instructions on this water heater specifically say not to add additional insulation to the outside of the water heater. I suspect they are concerned that people will cover the intake and exhaust vent. It also has a pretty thick stock Styrofoam jacket. The top insulation is about 3 inches thick.

More than 20 years ago, I remember some studies meant to use the serpentine of a fridge as a water heater for a shower. It didn't succeed AFAIK.

I guess it depends on what you mean by not succeeding. Heat from an A/C condenser absolutely will warm water. However, there likely isn't enough heat produced by an A/C to warm water enough for a comfortable shower. You would need to use the waste heat to warm a preheat tank and then send that preheated water into a continuous water heater for the final warming.

Wasn't clear enough then, insulation jacket on a conventional electric WH only. Afaic, not so efficient on gas fired, cant prevent heat loss through chimney to outside.

SO the issue becomes, does restoring power to the new WH after bringing it back from off for 8-10 hours cost more than maintaining 120f? I would think not, that would be the useage scenerio for the compressor heater

It never costs more to heat or cool a thing as needed than to maintain a continuous temperature, at least from an energy consumption standpoint. That's why turning the thermostat off when everyone leaves the house saves energy compared to maintaining a continuous temperature.

The law of entropy causes heat to disburse, and the greater the temperature differential, the more rapidly that occurs. Allowing temperatures to drift towards equilibrium when not needed means less continuous heat transfer.

My water heater has both the heat pump and 2 regular electric elements. The water heater has 4 modes that blend the use of those heat sources. Anything from only using the heat pump to only using the resistant elements. Between those extremes are 2 modes that blend the use with the trade-off that the more eco mode has slower recovery time.

It would be possible to use more electricity with a schedule vs steady 125F hold depending on how the schedule was designed and the usage mode for the water heater. If I set the water heater for fast recovery and then let the water temp drop to something like 110 degrees only to be heated each morning with the electric elements I'm sure that would use a lot more electricity than holding the water at a steady 125F all day using the heat pump. (Which is roughly 3x more efficient than the element heaters.

In the end it didn't save much on the electricity bills when I last saw anything about that.

No it wouldn't save much money because refrigerators don't use much electricity - especially small to medium size ones that are used in most of the world. The 74L fridge I bought for the ambulance has used 1.14 kWh in 4 days of testing. Even if someone could recover all of that energy as waste heat it would be pennies a week.

Recovering waste heat from A/C doesn't make much sense on a small scale. It could have reasonable savings at a commercial scale. For example some server farms are heating hot water with some of their waste heat from running their huge A/C units. They are also experimenting with using that waste heat to provide heating for other buildings.

The claims I found were that using the serpentines of the fridge to heat water rendered it more difficult for the heat to dissipate, increasing the load on the compressor in order to mantain a low temperature inside. So, compared to the electrically-heated shower heads more usual in my country, maybe the only economy would be not having to replace a heating element inside the shower head again :turtle:

You can still buy a fridge with the serpentine coils?

I assume you've cancelled gas service to save on the monthly meter fee?

I go the opposite direction and try to gasify everything I can. Ran a line out to the back deck so my BBQ is on natural gas. Used a Y adaptor to plumb in a patio heater. Bought a used natural gas dryer using OfferUp app. I've got a natural gas dryer in the Vancouver house, and in my current house now, both bought used for $50, and both running perfectly years later. They dry much faster than an electric dryer.

The range is natural gas, as well as furnace and 2 fireplaces.

Only thing not natural gas is the oven, which is built in with the microwave above.

I need to complete the carburetor conversion on one of the gensets to utilize NG so that next outage I have unlimited cheap electricity, and don't have to be concerned with stale gas gumming up the carb.

You have natural gas available. The trench alone for me would be 15 large plus whatever it took to plumb and vent the house and buy all new appliances

I don't recall exact prices, but my parents got electricity, gas, and cable run about 170ft to their new (used) mobile home for extremely cheap. I want to say one company charged $1, the other was free, and the other might have been $100.

Trenching is easy if there's not too many boulders.

... I inquired about running gas to a particular house once, and the gas company would have to extend their line along the road and they quoted me $50k to do that. Then everyone else would get cheap access to the line I would have paid to run.

Yes, I called and cancelled service and had them come out and physically turn off the gas to my house. (They didn't want to do that initially.) We were paying more for the connection charge than for gas.

For me it was all about dollars and cents.

When we bought the house it had a decades old gas furnace. Inefficient and likely to fail at the most inconvenient time and force me into a rushed and expensive replacement. I originally planned to replace it with another gas furnace but even a base inefficient model was several thousand more than the ductless heat pump that we ended up installing. A new furnace + central A/C would have been about $7K more than the heat pump. So it was thousands cheaper up front to go with the heat pump.

Then there are the operating costs which are much less heating with electricity. With the gas furnace my December bill was $209 ($135 for gas +$74 for electricity). After we switched to a heat pump that dropped to $131 ($113 for electricity + $18 for gas) We also keep our house warmer because of the savings. With the gas furnace the heat was set to 68F. Now we keep the house at 72F when we are home and awake. (The heat pump is on a schedule)