Tankless water heaters are terrible....

[dgpcolorado]

Sounds like yours meets your needs and you use only 2 therms/ month for combined cooking and water heating. That's truly impressive. You are probably in the lowest 1 percentile for energy use in these categories, so A+ for low energy use.

Environmental benefits aside, for the large majority of Americans, though, a HPWH (new property install or upgrade) will probably pay for itself within a few years given EIA data above.

Being energy conscious was a goal in designing my house and using an on demand water heater: it only heats water when the water flows, rather than heating a tank that just sits most of the time. Back then I was on propane and it was expensive and had annoying yo-yo pricing patterns.

Back in 1999 my judgment was that ground source heat pumps, for space heating, weren't ready for prime time, at least in my area. Air source heat pumps weren't "a thing" back then, so far as I was aware. So, I went with an inexpensive forced air furnace. Initially propane, later NG when lines were extended to my remote rural neighborhood (to my considerable surprise).

Keeping energy use down has been a goal for decades, both to save money, since I live entirely on savings, and to avoid waste. Same reason I bicycle commuted for two decades, 43,000 miles, before retiring to the mountains.

To save on energy I designed my house to be "sun tempered": long axis facing due south and windows sized for good solar gain, following a formula for my climate zone that I got from a seminar on the subject at NREL in Golden CO. To keep heating costs down I set the thermostat at 62° mornings and evenings and 52° at night, and dress appropriately in winter (what a concept!).

Before I put in my first solar panels in 2008, my electricity use averaged 4.5 kWh/day, more in winter when the furnace blower is running and less in summer, of course. (No AC needed in the mountains, summer is windows open at night and closed during the day.)

My energy conservation efforts work. Even with NG prices much higher this winter, my bill maxed out at $108 for January. I can afford that. The downside of already being energy conscious is that the truly gigantic cost of going all electric makes zero financial sense. So, I drive my solar- powered electric car, keep the thermostat down in my house and just conserve energy, same as always.

It would be nice to live fossil fuel free but I can't afford it.

 

[dgpcolorado]

That's pretty exceptional if you're really only using ~60kWh (~2 therms) of gas per month. A single 10 minute shower generally uses ~3kWh of heat. My HPWC has paid for itself in connection fees alone. $14/mo so I've saved ~$1500 by not having a gas connection.

Yes, good point. I've been told that my NG connection fee is going up from about $12/month to about $20. So, $144/year to about $240 a year. Would be nice to get rid of that cost.

 

[jerry33]

Yes, good point. I've been told that my NG connection fee is going up from about $12/month to about $20. So, $144/year to about $240 a year. Would be nice to get rid of that cost.

Got rid of the last NG last year. Downside is that there is no longer any use for the CO metre.

 

[iPlug]

Weird twist for ditching NG here in California.

Every spring and fall, millions of California residents receive credits on their electric and natural gas bills identified as the “California Climate Credit.” The California Climate Credit is part of California’s efforts to fight climate change.​

​

California Climate Credit

The "Climate Credit" is distributed through the public utilities. There is one credit for having electrical service and another for having natural gas service.

This month we got a $39.30 credit for being only electric. We ditched NG a few years ago, but perversely don't get the climate credit that is assigned with having that service. If we still had that service, we would have gotten the $47.83 credit this month. Don't know if it has changed in the last few years, but the natural gas connection fee was only a few bucks per month back then.

 

[Dave EV]

Weird twist for ditching NG here in California.

Every spring and fall, millions of California residents receive credits on their electric and natural gas bills identified as the “California Climate Credit.” The California Climate Credit is part of California’s efforts to fight climate change.​

​

California Climate Credit

The "Climate Credit" is distributed through the public utilities. There is one credit for having electrical service and another for having natural gas service.

This month we got a $39.30 credit for being only electric. We ditched NG a few years ago, but perversely don't get the climate credit that is assigned with having that service. If we still had that service, we would have gotten the $47.83 credit this month. Don't know if it has changed in the last few years, but the natural gas connection fee was only a few bucks per month back then.

Yeah, the climate credit needs to be reworked. The credit for gas bills should go away and be added to the electric bill. I still have gas service, despite barely using any gas since swapping out my gas water heater for an electric heat pump unit 2.5 years ago. I have a hybrid (heat pump + gas furnace) whole-house central heating system, but I've only used 17 therms of gas in 2.5 years, and that's not because the heat pump wasn't sufficient, it's just that the temperature switchover point is set to 45* or something (have to check). Only used 1 therm this winter after turning down the temperature switchover point even further - my system provides plenty of heat regardless of the outdoor temperature.

For SDG&E the gas minimum bill is $0.13151 / day or $48/year. I just received a climate credit of $43.06 - so there is basically no financial incentive for me to ditch the gas meter and disable the gas furnace completely. In fact, I'm throwing money away by not using enough gas.

If the goal is to electrify everything (and it should be), the climate credit would be more effective if applied as a discount to electricity rates. This would reduce the cost of electricity and encourage more electricity use, which is what we want to do - more heat pumps, fewer gas burning appliances.

There should be a climate cost for gas - not a credit.

 

[nwdiver]

For anyone is WA state PSE and Seattle City Light are offering a $500 rebate on HPWHs. And it's an instant rebate so it's immediately taken off the sale price.

 

[nwdiver]

This made me feel better. My heat pump water heater is CRAZY efficient at 110F and it's nice being able to just turn the hot tap and the water 'automatically' being the temperature I like it at. Always a little concerned about Legionnaires. I do flush it completely if it doesn't get used for more than ~3 days.

 

[SageBrush]

Always a little concerned about Legionnaires. I do flush it completely if it doesn't get used for more than ~3 days.

Hmm
If you are just opening taps to drain the tank volume, you end up with an admixture of old and new water in the tank.

Google says that 50C kills 90% of Legionella in 2 hours, so I would be more inclined to heat up the tank to 50C for 4 - 6 hours for a 2 fold to 3 fold reduction in bug concentration, and then run the taps to drain the water in the pipes. I think it would be a more effective Legionella measure, and save a lot of energy to boot.

As a matter of routine anti-Legionella maintenance, I like the advice of the video to heat up the water to 50C for a couple of hours once a week, followed by a flush of the pipes.

Home test kits are available. I found most offered are $100+ (per test ?) but C4Hydro via Amazon offers the reading kit for $115 and then under $50 per test.

Other preventive measures can include filtration at the outlet; or per this article , periodic cleaning of the faucet/shower head.

 

[nwdiver]

Hmm
If you are just opening taps to drain the tank volume, you end up with an admixture of old and new water in the tank.

The video seems to reference a study that cycling water was sufficient even it mixed. There's thermal stratification and water heaters are designed to reduce the mixing of incoming cold water so the mixing is probably very minimal.

 

[mspohr]

Chlorine shock treatment should be effective.

Controlling Legionella in Potable Water Systems | CDC

Learn about the routine maintenance of building water and recreational water systems for the prevention of disease.

www.cdc.gov

 

[Dave EV]

This made me feel better. My heat pump water heater is CRAZY efficient at 110F and it's nice being able to just turn the hot tap and the water 'automatically' being the temperature I like it at. Always a little concerned about Legionnaires. I do flush it completely if it doesn't get used for more than ~3 days.

How much efficient is it at 110F / 43C vs say 120F / 50C? How are you measuring that?

Hmm
If you are just opening taps to drain the tank volume, you end up with an admixture of old and new water in the tank.

Google says that 50C kills 90% of Legionella in 2 hours, so I would be more inclined to heat up the tank to 50C for 4 - 6 hours for a 2 fold to 3 fold reduction in bug concentration, and then run the taps to drain the water in the pipes. I think it would be a more effective Legionella measure, and save a lot of energy to boot.

As a matter of routine anti-Legionella maintenance, I like the advice of the video to heat up the water to 50C for a couple of hours once a week, followed by a flush of the pipes.

Home test kits are available. I found most offered are $100+ (per test ?) but C4Hydro via Amazon offers the reading kit for $115 and then under $50 per test.

Other preventive measures can include filtration at the outlet; or per this article , periodic cleaning of the faucet/shower head.

I like the idea of temporarily boosting the temperature once a week to ensure there's no buildup in the tank, but since heat pump efficiency goes down at higher water temp settings, I wonder what the net-result is? Heat pump water heaters with internet controls and scheduling would make it easy to schedule the higher temperature.

Back to nwdiver's comment about being able to just go full hot and get a a nice temp at the shower/faucet, you could install a thermostatic mixing valve at the water heater to get that as well. I think that's a good idea regardless (on my todo list) as it opens up the possibility of super-heating the water to do load shifting.

If you're worried about legionnaires in the shower, are we mostly concerned about it growing in the shower head, pipes or water heater?

Probably not a bad idea to not direct the first blast of water at your head when you first get in and also to run the bathroom fan for some ventilation, but otherwise you should be flushing the pipes and shower head regularly with each use.

 

[SageBrush]

I wonder what the net-result is?

It depends on cycling.

E.g, say one tank a day;
And let's further guess-estimate a COP of 4 from 15C up to 40C 7 days a week, and then a COP of 3 from 40C to 50C one day a week.

The daily heating takes 25*7 heating units a week, and the extra heating takes 10*1.3 = 13.3 heating units. You end up spending (25*7+13.3)/(25*7) = 1.076 = 7.6% more energy

 

[nwdiver]

How much efficient is it at 110F / 43C vs say 120F / 50C? How are you measuring that?

Mostly on how long the heat pump runs for. I've been running it manually for a while with my toy off-grid system. Generally it appears to use ~25% less energy at 110F vs 120F but the resistance backup also seems to kick on fairly often when set to 120F but rarely at 110F.

 

[Dave EV]

Mostly on how long the heat pump runs for. I've been running it manually for a while with my toy off-grid system. Generally it appears to use ~25% less energy at 110F vs 120F but the resistance backup also seems to kick on fairly often when set to 120F but rarely at 110F.

Hmm, can't you disable the resistance heat? FWIW, I feel like on my Rheem, they updated the firmware at some point in time to improve efficiency by keeping resistance heating from turning on as readily. It's usually readily apparent when it does kick on as the energy consumption reported by the app is double to triple for that day what the normal max daily energy usage is.

View attachment 863176

110F - 120F is about 5C difference - so maybe 10% according to the chart above - any extra resistance heating would explain the difference.

 

[CapitalistOppressor]

This is at least partially on topic, so here goes.

I’m going to open a small laundromat in Thailand (because reasons) and I am potentially power limited and am reluctant to use LPG because I am a long time TMC user.

I maybe can’t avoid it with the dryers, but I know heating water can be more efficient with tankless systems and heat pump water heaters.

I included a pic of the default meter that is available. There is an upgraded meter that is 30/100 instead of the 15/45 shown but is otherwise the same I think.

I’m thinking about 10 of the linked 12kg washer/dryer models and I know I can delete the heating system from the washer and provide my own hot water, providing I can do it more efficiently.

The total system would have to work on the 30/100 panel.

So are there efficient heat pump water heaters that are high throughput?

 

[CapitalistOppressor]

This is at least partially on topic, so here goes.

I’m going to open a small laundromat in Thailand (because reasons) and I am potentially power limited and am reluctant to use LPG because I am a long time TMC user.

I maybe can’t avoid it with the dryers, but I know heating water can be more efficient with tankless systems and heat pump water heaters.

I included a pic of the default meter that is available. There is an upgraded meter that is 30/100 instead of the 15/45 shown but is otherwise the same I think.

I’m thinking about 10 of the linked 12kg washer/dryer models and I know I can delete the heating system from the washer and provide my own hot water, providing I can do it more efficiently.

The total system would have to work on the 30/100 panel.

So are there efficient heat pump water heaters that are high throughput?

Just to be clear the machines use around 150L per wash and take about 30 minutes, so there needs to be high throughput.

The machines already include a tankless heating system but I’m concerned they use too much electric and I’m not sure about their efficiency. If I delete them I can install a bank of tankless systems but i can size that such that if there is too much demand it will reduce water flow not blow a breaker.

 

[phigment]

This isn't what you asked about, and I don't know if anything like this exists for easy installation, but have you looked in to a waste water heat recovery system? I imagine you could pre warm the incoming water with the heat going down the drain from the washed loads.

 

[SageBrush]

So are there efficient heat pump water heaters that are high throughput?

No, which is why the solution is bigger tanks

Side note: we wash in cold water.
I don't know how adamant your customers are that hot water be used, but you might be able to offer them a choice, along with a discount for choosing the less energy demanding choice.

Side note #2: Using resistive heating to dry clothes is a *huge* power draw. That is where your focus should be. Off-hand, a couple of thoughts occur to me:

1. Increase spin time to wring the clothes out
2. Find out whether people will take damp clothes home
3. Look into heat pump dryers. The trade-off here is longer drying times and more expensive machines

 

[SageBrush]

This isn't what you asked about, and I don't know if anything like this exists for easy installation, but have you looked in to a waste water heat recovery system? I imagine you could pre warm the incoming water with the heat going down the drain from the washed loads.

Very nice thought, but in general these heat exchangers are designed with gravity in mind.

 

[brkaus]

I wouldn’t delete the built in heaters. I’d just look for ways to pre-heat the incoming water on the hot side. I’d assume (hope) they can provide a variable amount of extra heat.

Heat pump heaters are going to be slower. Just due to the design choices they have made towards efficiency.