Heat Pump water Heaters

[onokai]

First let me explain my whole system so you can see the whole picture.
I have since 1983 had 2 4x8 solar hot water panels south facing on my roof is what's know to us old timers as a drain back system . That is when its gets cold or in my case nearly every night on a timer its drains down so it cannot freeze. This system is direct system meaning the water is in the copper tubes in the panel and gets it heat from the black painted flat copper panels that the tubes are soldered to . This water is pumped down on a differential thermostat when it gets hot enough . This heater water goes into a 80 gallon Ream solar tank with 4 fittings directly.its just a storage solar tank.The solar tank feeds my 40 gallon natural gas water heater. I know this system very well and have spares to keep it active ( I even have a spare tank)and like it very much-thanks Jimmy Carter for paying for it in the 80s.I installed three such system back then.

Now in 2020 I installed a 9.6 KW solar panel system (24 400 watt) ground mount system that feeds a 22.5 kilowatt lithium battery bank. I have a sol-ark 12k inverter that works the whole system. I did the entire install my self and am still connected to the grid and still use some small amounts of power now and then (I do not have a contract with the power utility ) None of our power backfields the grid as I have limiters on the inflow wires to house service.
We live in a rainy mild climate in Nor-cal near the coast in the redwood forest area north of Eureka Ca.. We do get lots of sun 5 miles inland in 8 months and it's a bit cloudy and rainy in winter months with some shading on system Nov-Dec-Jan-Feb.
I also have a hot water smart pump that taps into bottom of said gas water heater that provides instant hot water at all taps (grundfuss smart pump) a super simple system. The only way hot water from solar tank gets to water heater is when demand draws it into gas water heater (you turn oil hot water in house-that the demand)
Now this whole tank system is on the north side of house in outside shed built for this stuff (central vac and water filters and calcite system from well is also in this two door larger 4x8 attached shed to home wall.
I'm thinking of relapsing my gas water heater with a new heat pump style which just used electric as we have plenty 8 months of the year . I think it will cost us the 4 months when we buy power and we live in the second most expensive power rates in the country other than Maine.
I know these heat pumps are best in heated areas and ours will not be as its north side but our climate is mild year around with only some minor freezing now and then winter wise. One thing on note is now my excess power is counter to a 220 stinger water heater element in solar tank now which I would have to turn off if I got the heat pump water heater. I have read up on these units and am on the fence whether this makes sense or is my gas unit cheaper to run. I still need the smart Grufus pump on water heater drain line for hot water loop . The climate is warm summers here with lots of 80 degree days and a lot of mild 60s in split seasons
The last note is we have 3 Mr cool mini splits for heating and cooling now I installed over the past 3 years as well. The water heater is the last step
any thoughts on is this a good move over the gas water heater now. I need to crunch the gas numbers still
any thoughts I'm missing?

 

[NIFE]

First let me explain my whole system so you can see the whole picture.
I have since 1983 had 2 4x8 solar hot water panels south facing on my roof is what's know to us old timers as a drain back system . That is when its gets cold or in my case nearly every night on a timer its drains down so it cannot freeze. This system is direct system meaning the water is in the copper tubes in the panel and gets it heat from the black painted flat copper panels that the tubes are soldered to . This water is pumped down on a differential thermostat when it gets hot enough . This heater water goes into a 80 gallon Ream solar tank with 4 fittings directly. The solar tank feed my 40 gallon natural gas water heater. I know this system very well and have spares to keep it active and like it very much-thanks Jimmy Carter for paying for it in the 80s.I installed three such system back then.

Now in 2020 I installed a 9.6 KW solar panel system (24 400 watt) ground mount system that feeds a 22.5 kilowatt lithium battery bank. I have a sol-ark 12k inverter that works the whole system. I did the entire install my self and am still connected to the grid and still use some small amounts of power now and then (I do not have a contract with the power utility ) None of our power backfields the grid as I have limiters on the inflow wires to house service.
We live in a rainy mild climate in Nor-cal near the coast in the redwood forest area north of Eureka Ca.. We do get lots of sun 5 miles inland in 8 months and it's a bit cloudy and rainy in winter months with some shading on system Nov-Dec-Jan-Feb.
I also have a hot water smart pump that taps into bottom of said gas water heater that provides instant hot water at all taps (grundfuss smart pump) a super simple system. The only way hot water from solar tank gets to water heater is when demand draws it into gas water heater (you turn oil hot water in house-that the demand)
Now this whole tank system is on the north side of house in outside shed built for this stuff (central vac and water filters and calcite system from well is also in this two door larger 4x8 attached shed to home wall.
I'm thinking of relapsing my gas water heater with a new heat pump style which just used electric as we have plenty 8 months of the year . I think it will cost us the 4 months when we buy power and we live in the second most expensive power rates in the country other than Maine.
I know these heat pumps are best in heated areas and ours will not be as its north side but our climate is mild year around with only some minor freezing now and then winter wise. One thing on note is now my excess power is counter to a 220 stinger water heater element in solar tank now which I would have to turn off if I got the heat pump water heater. I have read up on these units and am on the fence whether this makes sense or is my gas unit cheaper to run. I still need the smart Grufus pump on water heater drain line for hot water loop . The climate is warm summers here with lots of 80 degree days and a lot of mild 60s in split seasons
The last note is we have 3 Mr cool mini splits for heating and cooling now I installed over the past 3 years as well. The water heater is the last step
any thoughts on is this a good move over the gas water heater now. I need to crunch the gas numbers still
any thoughts I'm missing?

It depends on how much you spend per year heating the water with gas. One downside to anything heat-pump is they work the best when you need them the least. I have considered one to get a dual benefit. In the summer, the heat pump water heater gives some cooling to the space they are installed in. In the winter this goes against you. You end up spending money to reheat the area the heat pump water heater just cooled off. If your unit is in an enclosed outdoor building, as it heats the water it will cool the space it is installed in. As the space gets cooler, the unit becomes less efficient just when you need it the most. Unless your gas cost is exceptionally high, I think you will miss that gas water heater when it is gone. Like the old saying goes, if it isn't broke don't fix it. Your knowledge of the current system and the spare parts is a plus.

 

[onokai]

Yes I'm aware they cool the space which does me zero good-If I could fit inside our small house I would but alas that not happening space wise .
I'll gather my 12 months of gas bills annd see what gives vs buying 4 months worth of power on the non solar months midwinter.

I should I add I am a potter past 50 years and also have a separate mondo large gas meter for that business as its a semi industrial flate rate -but this water heater is on our house meter and the rates are not as good

 

[hwy17]

The hot water circulation system might be adding a lot of standby heating load that would affect the calculation, although I get the feeling from your description that maybe you've actually insulated all the pipes for that very well.

 

[onokai]

The hot water circulation system might be adding a lot of standby heating load that would affect the calculation, although I get the feeling from your description that maybe you've actually insulated all the pipes for that very well.

All hot water pipes are fully insulated and that smart pump moves water extremely slowly or any speed when needed (7$ a year to operate)
can be installed on any water heater with a drain.

 

[Zwy]

I just purchased a hybrid heat pump water heater and will be installing it this weekend time permitting. I am leaving my propane power vent in place and will be running the heat pump water heater ahead of the gas. It will be at a higher temp than the propane water heater.

With a hybrid, you can run the heating element if desired. I plan to use it as a dump load in winter months and probably run mainly off the propane water heater in winter if endless cloudy days like this year occur.

 

[Ampster]

In the winter this goes against you. You end up spending money to reheat the area the heat pump water heater just cooled off.

My heart pump water heater is in the garage so it does not use conditioned air. I also run a duct to my nearby attic which is typically warmer than my garage from sunlight hitting my roof or occasional leakage through the attic insulation from my house.

 

[onokai]

Ok I totaled up my gas usage in dollars for the last year-it was $1,400,
Thats split between
cooking (gas stove and oven)
forced air heating -Low use as wek have mini splits and a pellet stove but do use it on cold mornings to take the chill off
water heating (as noted have a solar asset system that feeds the 80 gallon solar holding tank feeeding the 40 gallon gas water heater)
cloths drying (gas dyer)
my guess is water heating is at most 50% of this cost=$700 a year.
I think the heatpump/ electric water heater will cost more than that during the 4-5 winter months in power usage at our .43cent per kilowatt that our UTILITY charges off peak ,when solar power is much less avalible for us in winter.
Looks like another gas water heater makes the most sense. This Rheem has 11 years on it now.

 

[Zwy]

Ok I totaled up my gas usage in dollars for the last year-it was $1,400,
Thats split between
cooking (gas stove and oven)
forced air heating -Low use as wek have mini splits and a pellet stove but do use it on cold mornings to take the chill off
water heating (as noted have a solar asset system that feeds the 80 gallon solar holding tank feeeding the 40 gallon gas water heater)
cloths drying (gas dyer)
my guess is water heating is at most 50% of this cost=$700 a year.
I think the heatpump/ electric water heater will cost more than that during the 4-5 winter months in power usage at our .43cent per kilowatt that our UTILITY charges off peak ,when solar power is much less avalible for us in winter.
Looks like another gas water heater makes the most sense. This Rheem has 11 years on it now.

It probably costs me about $450 a year for propane to heat water. The heat pump cost me less than $1600 with sales tax but I will receive a 30% tax credit so net cost will be about $1100. Less than 3 years payback. If I end up running the gas water heater in the middle of winter, it still won't be much more than 3 years payback as there are days of excess PV and a large amount of hot water storage.

At $0.43/Kwh and $700 per year, I know what I would be using. My cost is under $0.20/Kwh.

 

[onokai]

It probably costs me about $450 a year for propane to heat water. The heat pump cost me less than $1600 with sales tax but I will receive a 30% tax credit so net cost will be about $1100. Less than 3 years payback. If I end up running the gas water heater in the middle of winter, it still won't be much more than 3 years payback as there are days of excess PV and a large amount of hot water storage.

At $0.43/Kwh and $700 per year, I know what I would be using. My cost is under $0.20/Kwh.

Our 3 mini spits in winter are what we heat with ,with all our solar power and extra batteries. I'm a bit worried at .43cents a KW we will eat up that gas cost pretty fast and start paying big tome for power in winter .Any leftover power now goes to the 80 gallon solar preheat tank in a heat/stinger especially in summer. Gas is slowing going uo but power cost really went up 30% in January with PG&E power company.
I could use the 30% credit as I used that on last years heat pump mini split but It need to pencil out inthe the long run.Your 20cent a kw sounds great.

 

[gotbeans]

any thoughts on is this a good move over the gas water heater now. I need to crunch the gas numbers still

Yea might as well, gas is like the worst one for efficiency and really just depends on your actual gas prices vs electric.. but if you get a heat pump then it's easy

Make sure to get the HYBRID hot water heat pump because they're 240 volts and they're cheaper.
From my research all of them can be set to "heat pump only" mode which won't run the elements or "eco" mode which will extremely rarely do the elements (only if you run all the hot water gone)

The others are more expensive and 120volts (more expensive and less efficient)
and of course balancing the load of the inverter is a good thing too.

I have emailed them asking why the worse heat pumps with less features are more expensive, their automated system responded saying they received it but no human has responded yet.

 

[pollenface]

I have a 250L heat pump hws. It replaced an instantaneous gas hws. It is programmed to only run between 8am & 5pm while the sun is out. It still consumes about 0.5kwh over night with it's standby power. Using grid-tied solar power to heat water, I couldn't be happier and it never runs out of hot water at night with sometimes 7 people in my household.

 

[jpimlott]

I have a rheem heat pump water heater for a year now. There are 2 of us in the house.
I have a bunch of solar panels up 7kw worth. Our normal use is between 700 watt hours and 2.5 kilowatt hours
for the power reported from the device as it is on wifi.
It has a high demand mode for fast recovery from large loads ( bath or laundry and 2 showers)
I find it works great and cost the same amount of power as the gas was before but with solar it is prepaid for,

i am in nor cal with pacifc graft and extortion.