Electric water heater consumption

[wattmatters]

If the climate is mild

This looks perfect for a quality heat pump water heater:





And it seems it is being encouraged:

New Heat Pump Water Heater Incentives Now Available for Californians

California homeowners can take advantage of TECH Clean California incentives starting at $3,100 for new heat pump water heaters, making it easier and more affordable to install clean and efficient water heating equipment.

buildingdecarb.org

 

[CaliSunHarvester]

And it seems it is being encouraged:

New Heat Pump Water Heater Incentives Now Available for Californians

California homeowners can take advantage of TECH Clean California incentives starting at $3,100 for new heat pump water heaters, making it easier and more affordable to install clean and efficient water heating equipment.

buildingdecarb.org

"Incentives range from $3,100 to $5,300"

These incentives are why stuff gets expensive.
EV $7500 tax credit removed? Price for EVs fall.

My new water heater will cost under $2k at Home Depot, and I won't get a permit or hire a $200/hr plumber firm.

These crazy incentives are the reason why homeowners pay $1000 for a new toilet or $2500 for a new (conventional) gas water heater.

 

[Steve777]

Did not see it mentioned, but there are dedicated electric hot water timers made, specifically to turn your HW heater off over night or whenever. Many have a bypass switch, just in case you want to take a shower at 2AM or whatever. One of those may be easier to install, setup and use.

As far as measuring, I picked up one of these (no affiliation):

https://www.amazon.com/DROK-Frequency-Electric-Voltmeter-Multimeter/dp/B07YC1XHKQ/ref=sr_1_3?crid=OAC9AI63LF00&keywords=ac%2Buse%2Bmeter&qid=1708288165&sprefix=ac%2Buse%2Bmeter%2Caps%2C170&sr=8-3&th=1

It will accumulate the power used on the circuit. Quite handy for measuring lots of "appliances", and it uses a CT so no need to pass all the current thru it...

 

[wattmatters]

The water heater, even though it's 80G, comes on when people use hot water. Not instantly, but definitely any time someone showers, it comes on, minimum 15 minutes, and as long as a bit over an hour. Peak is 4pm to 9pm, definitely water use during that time.

Not if the water heater circuit has a controllable contactor to turn the power supply on/off so that it can only consume energy when you wish it to.

And off peak is not much cheaper. 50c vs 60c.

Yeah that sucks. Heat pump for the win.

1/4. Wow. Should have done it last time when I cleaned out the tank.
Better now than next year.

Just make sure it is a quality unit.

What you need to look for is the COP (coefficient of performance) rating for the unit. That tells you how much heat is delivered to the water per unit of electrical energy consumed.

COP varies with ambient temperature and usually it's quoted based on some standard ambient temperature and also temperature the water is heated to (e.g. ~60°C). A COP between 4 and 5 is very good.

I don't know what the industry is like over there but here, heat pump water heaters here earned a poor reputation for reliability/longevity. It's not a concern with the quality units but as often happens when govt incentive money is of offer, bottom feeders enter the market offering crap product and sloppy installations. It is getting better as the public learns, but there are always those who get sucked in by the "$33 heat pump water heater" deals. Only to have it fail within two years.

A unit with a separate compressor located outside would be preferable. Same as you would for an aircon system.

These incentives are why stuff gets expensive.

Yes, they drive me nuts. Same happens here. But may as well use them to your advantage where it makes sense to.

 

[wattmatters]

As far as measuring, I picked up one of these (no affiliation):

Iotawatt is excellent.

IoTaWatt™ Open WiFi Electric Power Monitor

Electric Power Monitor. Residential and Commercial. Single, split and three-phase. Any voltage. Local data storage and analysis and also upload to your cloud service. Economical. Ships worldwide, in use in dozens of countries on four continents.

iotawatt.com

(no affiliation - but I use one).

 

[wattmatters]

My new water heater will cost under $2k at Home Depot,

I implore you to take a little time to research the quality and performance of your heat pump water heater choice.

I know little of Home Depot nor what type of systems they sell (their website is blocked for viewing for me) but if the unit is an all-in-one with the heat pump on the top of the tank, tread carefully. There are some real stinkers.

 

[CaliSunHarvester]

There are some real stinkers

Home Depot sells Rheem. I see some good reviews. The big competitor, Lowe's, sells AOSmith. Supposedly louder. Both have the heat pump on the unit on top.

Ok, I will research alternatives. Helping him with the truck today anyways.

 

[CaliSunHarvester]

.

 

[Bop]

Rheem (at least in Australia) has a quite good reputation (in fact my last place had an electric element Rheem, that was nearly 30 years old, had thermal solar panels added to it in 2002, and was still going like a champ when I moved out in 2020...
(I know thermal solar isn't looked at favorably these days, but ours ran a household with two or three people in it all year around in Brisbane and the electric boost (the original heating element lol) was turned off for almost all the year- it took a week of really bad weather, or if we had visitors staying, to make up go out and turn on the MCB in the fusebox...
Even my 'temporary' solar HWS is thermal- a 400L electric tank, with 50m of black polypipe laying on the ground in the sun lol- doesn't even need a pump- because the polypipe is lower than the tank in the shed, it naturally thermosyphons...

 

[CaliSunHarvester]

Around here, Rheem is so-so. Bradford White is liked by many plumbers. My buddy - a retired plumber - explained it once, to much to write. Something about GE and Rheem, solely sold my HD here. Intentionally lowered quality. Could be paranoia.

My existing unit is a Bradford White from 1994, and still works. Only changed the 2 elements once AFAIK, around 2016. At that time, I cleaned the sediments out too.


All the pipes at the top.. it used to be tied to solar hot water panels. They are gone now.

 

[Crowz]

Our 80 gallon hot water heater doesn't use that much power per day. It handles everything in the house except for the dishwasher which has its own 30 gallon hot water heater.

I think this pretty well shows what I'm talking about.



That is just the hot water heater circuit.

 

[CaliSunHarvester]

One problem is the wife. Refuses to use the dishwasher. Instead hot water runs 15 minutes straight into the drain, down the hill. It's a gray water system. For our fruit trees. The 4" line is 200ft long, has never clogged due to all that hot water.

 

[wattmatters]

Rheem (at least in Australia) has a quite good reputation

Their tanks, yes. Their heat pump units though, not so much.

Our last Rheem tank here was 30 years old when I replaced it (it was still functioning but on borrowed time as I was sure very little maintenance had been done to it prior to our owning the home). I replaced it with a stainless steel Rheem unit, 315 litres. It should outlive me.

This is our daily water heater energy consumption for the last six months:



All but 12 kWh of that was powered by our solar PV (I use a smart PV diverter). Days with low consumption are likely days the tank did not complete a full heat cycle (poor solar PV production days) but it normally makes up for it in the following day or so.

Two person household with occasional friends/family staying. Benefit of a large tank is our system can ride through multiple days of poor solar PV weather yet still supply ample hot water. I have an automation to alert me if it's gone for too many days without a full heat cycle, such that I can choose a manual boost (legionella safety). Never needed to so far.

With our new retail plan having two free windows on weekends, they are now the perfect time for that.

 

[wattmatters]

It handles everything in the house except for the dishwasher

Our dishwasher and clothes washing machine heat their own water. They are mostly run during the day when PV output covers them but if absolutely necessary then the battery can cover their use at night. Rare but can happen when visitors are staying and we have a lot of dishes to get cleaned.

One problem is the wife.

It's a shame when people are unwilling to help with energy efficiency. Particularly when it's not a difficult change to make.

Best of luck turning that around.

Our dishwasher uses less than 7 litres of water and about 0.6 kWh per cycle (most of which is heating the water, once for wash, once for rinse). This was power consumption during yesterday's cycle:

 

[Bop]

Their tanks, yes. Their heat pump units though, not so much.

Our last Rheem tank here was 30 years old when I replaced it (it was still functioning but on borrowed time as I was sure very little maintenance had been done to it prior to our owning the home). I replaced it with a stainless steel Rheem unit, 315 litres. It should outlive me.

This is our daily water heater energy consumption for the last six months:

View attachment 196509

All but 12 kWh of that was powered by our solar PV (I use a smart PV diverter). Days with low consumption are likely days the tank did not complete a full heat cycle (poor solar PV production days) but it normally makes up for it in the following day or so.

Two person household with occasional friends/family staying. Benefit of a large tank is our system can ride through multiple days of poor solar PV weather yet still supply ample hot water. I have an automation to alert me if it's gone for too many days without a full heat cycle, such that I can choose a manual boost (legionella safety). Never needed to so far.

With our new retail plan having two free windows on weekends, they are now the perfect time for that.

The tank at the old place was a 400l as well, and yes- combination of a large tank with the relatively small usage most of the time (teenagers use SOOO much water lol) meant it was basically about a week before we had to turn on the boost element in bad weather...

 

[Bop]

One problem is the wife. Refuses to use the dishwasher. Instead hot water runs 15 minutes straight into the drain, down the hill. It's a gray water system. For our fruit trees. The 4" line is 200ft long, has never clogged due to all that hot water.

Uggh... that wouldn't float at my place lol- I got 30000L/8000 US gallons of water storage in my tanks- which basically get filled in late summer/early autumn, and basically have to last a year until the next 'wet season', we get minimal rainfall during the rest of the year (we can go literally months with zero rainfall at all)
Water is NOT wasted here- if I run out, thats it...
I can go into town and fill the IBC's at the town standpipe at the council yard- but that costs $14 per 1000L, plus fuel for the tilt-tray and my time... and I then have to pump it into the tanks...
(last year we had an abnormal amount at the end of spring in November- usually we get the highest rainfalls in Jan/Feb/March)

 

[CaliSunHarvester]

8000 US gallons of water storage in my tanks

I have 10k Gallon storage (38000 liters) but we are on a well. There is no meter, but I once turned off the well pump and measured how many inches the tanks lost every day. It amounted to 200G (760 liters) a day. Which is actually not wasteful given that 4 to 6 people live on the property. One house is occupied only 25% of the time.

I read that in Southern California, per head consumption is 360G per day. Green turf in the desert. In our county, the number was 95G a few years ago, and has decreased since then.

So 200G for all of us.. 50G per person.

We don't water landscaping, or wash cars.
1 of the houses has no on-site laundry and another house seems to never use it.

 

[zanydroid]

Re: brands and models. AOSmith used to be loud AF (70+DB, you can see videos on YouTube of this, it's pretty insane), but the new version has a specified 45 dBA, while Rheem no longer reports a dBA rating (but based on YouTube sounds like it's in the low 60s).

AFAICT Rheem is a lot easier to add your own Home Automation controls on top of due to more users and more integrations having been built.

Efficiency wise, EnergyStart rates efficiency based on something similar to cycling the whole tank per day. Electric heaters have a UEF in the 0.90s (UEF is like COP for a given cycle, IE standby loss), while HPWH vary from 3.0-4.0. The most efficient HPWH tend to be the 80 gallon ones; I think they win due to better surface area to volume ratio. However, you have to cycle the whole tank to achieve that.

(The fact that electric WH have UEF in the high 0.90s is correlated with exterior insulation not really making a difference. Electric water heaters are pretty well insulated as stock)

Generally in the US you upsize about 15 gallons when going from WH to HPWH to compensate for slower recovery and shrinkflation. Some brands have smaller water volume than the number would imply...

 

[Bop]

I have 10k Gallon storage (38000 liters) but we are on a well. There is no meter, but I once turned off the well pump and measured how many inches the tanks lost every day. It amounted to 200G (760 liters) a day. Which is actually not wasteful given that 4 to 6 people live on the property. One house is occupied only 25% of the time.

I read that in Southern California, per head consumption is 360G per day. Green turf in the desert. In our county, the number was 95G a few years ago, and has decreased since then.

So 200G for all of us.. 50G per person.

We don't water landscaping, or wash cars.
1 of the houses has no on-site laundry and another house seems to never use it.

Wells don't work here- no groundwater...
We can have a bore drilled, but the water at 400m is unsuitable for drinking (for humans or animals) and you have to go down 800m-1200m and have a fully cased bore to get to the drinkable water- thats a fully cased bore drilled down 4000ft...
Expect to pay about $80k-$100K for 'watering the garden' water- and up to quarter of a million for drinkable water...
I can buy a LOT of water tanks for quarter of a mil....
The sheds tanks are just for it currently, when the house itself is finished, there will be another two 22500L/6000 gallon tanks on it as well

I either wash the vehicles in 'the big smoke' if I am there (there's a carwash about an hours drive away from me lol) or if it starts raining, you will often find me standing out in it washing the vehicles lol- otherwise- they just stay dirty...

 

[JRH]

Oh sure, it's not rocket science. Less elegant than gravity drain, and need to do some additional testing of what happens if it fails.

The store above my store had one for their ac unit….and fail they do ….water would overflow and come down my wall …she would not clean it…so I did…!!
A biology lab would be impressed at the goop that can can grow and slime up the tank and gum up the float that operates the pump.
OP needs to mount it in a very visible and accessible place as to monitor and to clean it out easily and periodically … I found goosing the tank with a bit of Clorox weekly helped slow critters from growing in it…
GROSSSSS….
J.