Tracking Heat Pump Water Heater Power Consumption (1 Year)

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Location
Athens, GA
April 10th marks the 1 year anniversary of installing a Rheem 50 gallon 'Hybrid' water heater in the house. I've posted on it before, but to recap.

I have, what I feel, is a 'best case' scenario for one of these. My water heater is in the garage, I live in Georgia, and my garage faces the afternoon sun.

I have a single day, in the past, where I was the only one home, the HVAC was off, and other than LED lighting, the only thing I did that day was taking a shower and heat water with a standard resistive water heater. The result of that, was approximately 4KWh used for that day, so keep that number in mind with the HP data.

The WH is locked into heat pump mode and does not run the elements....EXCEPT. On December 23rd of 2022, GA had some of the coldest temps I remember in years (11* low, 7* the next day) and , and the garage went from its usual above freezing temps, to well below, I think it may have been in single digits for a while. It was cold enough to freeze my condensate line from the water heater, so it was cold. Rheem has the unit programmed to run the elements in that case(the compressor did not run at all, I suspect either because it would be of no use or to protect it from damage), and it is very apparent that they ran, racking up 9KWh for that day.

Some points:

Average usage over 370 days: 3.676685 KWh/day
Highest day: 9.95 KWh
Set temp 136* (57.77c)
People in the house: 3 (all adult)
The dishwasher in use and clothes get washed warm/hot.

Most days there are a minimum of 2 showers and usually, a load of laundry or dishes is done in the house. Sometimes more, but usually never less.

The economics of the unit are.

$1100 Paid for the unit. Figure another $150 in install stuff (PEX, Fittings, Crimpers, Pump, Etc)
Local EMC Rebate - $500
US Gov Rebate - $300
A very rough estimate is that I've saved around $300 so far in a year in power, so that leaves me with just around an 18-month payback on the unit. I'll admit, I bought it for the right price, and the rebates knocked a big chunk out of it, as well as being able to install it myself helped.

Odd note. If you have one of these, and you go on vacation, kill the power to the unit. For some reason, it will use 1KWh a day just being in 'vacation' mode, which you would think is off. You can see that in my graph where we took a vacation in May of 22 and then again in March this year where I just threw the breaker and left.

I did run with the 'energy saver' mode turned on, and from what I see, it never ran the elements for me, but it did some screwy things with the schedule of when it ran and didn't suit our usage since we both keep odd work hours. I noticed that I sometimes didn't have good hot water when I wanted it, so I switched it back to straight-up heat pump mode.

We never really run out of hot water, although with a back-to-back run of showers, you can feel it get low, and of course, it does take longer to recharge, but never to the point of wanting to turn the elements on to make up for it. We've always had enough hot water when we need it and haven't really changed our usage pattern. Although, I will tend to wash my clothes earlier in the day rather than in the middle of the night like I used to on my days off to take advantage of warmer garage air temps.

All-in-all, still extremely pleased with the purchase.

The orange line is a 7-day rolling average, you can clearly see the Dec 23rd event.
1681636462857.png


You can clearly see how the COP goes down as outdoor temp drops. (Both Aprils are incomplete months)

1681636400049.png
 
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Based on your graph would you say you are using roughly 1/3 the power of a resistive water heater?
 
Interesting data, there is no question that down South, a hybwid water heater is a wonderful thing. I have a first gen AO Smith 80 gal hybwid water heater in my garage. 2HP 3 stage Goulds jet pump making 90PSI, and 6 shower heads in a 5x9 foot shower. We use the hot water up fast.

The good news is, the unit costs little to run, and the garage is air conditioned when ever the water heater is running.

But, don't tell me that a hybrid water heater, placed in a home up North, is somehow saving significant amounts of energy by pulling the heat from the home.
 
Interesting data, there is no question that down South, a hybwid water heater is a wonderful thing. I have a first gen AO Smith 80 gal hybwid water heater in my garage. 2HP 3 stage Goulds jet pump making 90PSI, and 6 shower heads in a 5x9 foot shower. We use the hot water up fast.

The good news is, the unit costs little to run, and the garage is air conditioned when ever the water heater is running.

But, don't tell me that a hybrid water heater, placed in a home up North, is somehow saving significant amounts of energy by pulling the heat from the home.
define north.
Saves me a bunch and dehumidifies my basement which is needed 8 months out of the year(plus free cold air)
In the winter its not optimal but the gas furnace costs pennies to run.
literally my entire gas usage for the year is about 1/3 the cost with the line connection charge being 2/3 the yearly cost.

of course we dont put them in garages up here.

it is not saving a ton over natural gas.. but I got mine for free after tax credit.. a power vent natural gas heater which I couldnt install myself would have been over 2k.
The real savings come from not running a dehumidifier for me.

IT saves aprox(for me) 20-25 a month on electricity over a resistance electric water heater with real data numbers not just estimating.
A dehumidifier can use that much a month.. in the worst months.
250w-700w x 10hours a day
if on the low end 300w*10 = about 100kwh or $17
it is not a stretch to say it is saving me $400+ a year over running a resistance electric water heater and dehumidifier.
 
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But, don't tell me that a hybrid water heater, placed in a home up North, is somehow saving significant amounts of energy by pulling the heat from the home.

I don't know. I'd imagine it would depend on the source of heat for the home and the cost of that heat.

I know that air sourced HP's are getting to the point where they will still provide over a 1.0 COP down to significantly low air temps, so it's not outside the realm of possibility that the technology will come to a water heater as well. And in a house where the backup source is what it was using before, you could still be ahead of the curve where you use HP's to provide heating and water a good percentage of the time and then fall back to the backup when COP gets too low.

But, that's just me talking, I don't live up there so have nothing to back that up.
 
That was a great review. Thanks for the post. Putting a heat pump water in a warm garage is a great scenario. It actually helps to air condition the space.

I would like to see numbers where it is in a heated space inside the house. Some of the “ free energy” inside the house is actually provided by the house central heating system. In the winter in a northern climate, the unit is providing cooling in the room, but the central heating system has to heat the area back up. So far I have not seen any calculations on that.
 
April 10th marks the 1 year anniversary of installing a Rheem 50 gallon 'Hybrid' water heater in the house. I've posted on it before, but to recap.

I have, what I feel, is a 'best case' scenario for one of these. My water heater is in the garage, I live in Georgia, and my garage faces the afternoon sun.

I have a single day, in the past, where I was the only one home, the HVAC was off, and other than LED lighting, the only thing I did that day was taking a shower and heat water with a standard resistive water heater. The result of that, was approximately 4KWh used for that day, so keep that number in mind with the HP data.

The WH is locked into heat pump mode and does not run the elements....EXCEPT. On December 23rd of 2022, GA had some of the coldest temps I remember in years (11* low, 7* the next day) and , and the garage went from its usual above freezing temps, to well below, I think it may have been in single digits for a while. It was cold enough to freeze my condensate line from the water heater, so it was cold. Rheem has the unit programmed to run the elements in that case(the compressor did not run at all, I suspect either because it would be of no use or to protect it from damage), and it is very apparent that they ran, racking up 9KWh for that day.

Some points:

Average usage over 370 days: 3.676685 KWh/day
Highest day: 9.95 KWh
Set temp 136* (57.77c)
People in the house: 3 (all adult)
The dishwasher in use and clothes get washed warm/hot.

Most days there are a minimum of 2 showers and usually, a load of laundry or dishes is done in the house. Sometimes more, but usually never less.

The economics of the unit are.

$1100 Paid for the unit. Figure another $150 in install stuff (PEX, Fittings, Crimpers, Pump, Etc)
Local EMC Rebate - $500
US Gov Rebate - $300
A very rough estimate is that I've saved around $300 so far in a year in power, so that leaves me with just around an 18-month payback on the unit. I'll admit, I bought it for the right price, and the rebates knocked a big chunk out of it, as well as being able to install it myself helped.

Odd note. If you have one of these, and you go on vacation, kill the power to the unit. For some reason, it will use 1KWh a day just being in 'vacation' mode, which you would think is off. You can see that in my graph where we took a vacation in May of 22 and then again in March this year where I just threw the breaker and left.

I did run with the 'energy saver' mode turned on, and from what I see, it never ran the elements for me, but it did some screwy things with the schedule of when it ran and didn't suit our usage since we both keep odd work hours. I noticed that I sometimes didn't have good hot water when I wanted it, so I switched it back to straight-up heat pump mode.

We never really run out of hot water, although with a back-to-back run of showers, you can feel it get low, and of course, it does take longer to recharge, but never to the point of wanting to turn the elements on to make up for it. We've always had enough hot water when we need it and haven't really changed our usage pattern. Although, I will tend to wash my clothes earlier in the day rather than in the middle of the night like I used to on my days off to take advantage of warmer garage air temps.

All-in-all, still extremely pleased with the purchase.

The orange line is a 7-day rolling average, you can clearly see the Dec 23rd event.
View attachment 150716

You can clearly see how the COP goes down as outdoor temp drops. (Both Aprils are incomplete months)

View attachment 150715
How is the noise?
 
Well thought out post. It threw me off at first because the hot water in our home for the last 15 years until we just moved, cost total, less than $30 a month and that included the actual connection charge, so actual gas cost cost is $10 to 15. But the real cost is up to $30 in actual payment per month.
Then it hit me, you had an Electric hot water heater, we had a 50 gallon NG heater. Gosh, now in a new home, one month so far and its propane. Something tells me to prepare for more than $30 a month in actual payment for propane hot water?

Anyway if you have Natural Gas at your home, at least here in the Carolina's by far that seems to be the cheapest way to heat hot water comparing it to the OP who has to use electric and most likely me who now has propane. :confused:.

Below is an example of our monthly, non heating season NG bill for the water heater of the last 15 years.
Screenshot 2023-04-23 at 11.03.06 AM.png
 
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Well thought out post. It threw me off at first because the hot water in our home for the last 15 years until we just moved, cost total, less than $30 a month and that included the actual connection charge, so actual cost is $15.
Then it hit me, you had an Electric hot water heater, we had a 50 gallon NG heater. Gosh, now in a new home, one month so far and its propane. Something tells me to prepare for more than $30 a month in actual payment?

Anyway if you have Natural Gas at your home, at least here in the Carolina's by far that seems to be the cheapest way to heat hot water comparing it to the OP who has to use electric.

Below is an example of our monthly, non heating season NG bill for the water heater of the last 15 years.
View attachment 152240
Yep, even in Dec at our average of $.13 per KWh it cost us $18ish for the month.
 
My wife and I have a 50 gallon Menard’s brand Richmond (Rheem) and have zero complains. According to the app, we average about 2.75kw a day.

It’s in a farm house basement and is in sub optimal conditions.
 
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