Heat Pump Hot Water System vs Gas Hot Water

[@EEVblog2]

Forgot to mention solar hot water. That's not a thing here any more. It was big in the 1980's, but hardly anyone here installs it any more.

[@mrhoogles]

thank you so much, i live in Alabama and its pretty much Alabama minus the humidity and you've helped me so much

[@KriLL325783]

Any idea how solar hot water compares to using electric solar panels connected to an electric heat pump?

[@v.m.a.d.l.e.6972]

How about combining both systems, by preheating the water on a solar circuit, would save even more energy.

[@EEVblog2]

@@KriLL325783 Yep, it's in the slide I put up a few times. The one with the pink bargraphs. Gas=6157kWh/year, Electric=5110, Solar=2300, heat pump=1161. So heat pum is about twice as good as solar hot water. As always, YMMV.

[@EEVblog2]

@@v.m.a.d.l.e.6972 Possible. But at only a few kWh/day for heat pump anyway, is it worth the hassle and complexity?

[@universeisundernoobligatio3283]

In Canada put in a ground source heat pump, went from $3000 propane to $300 electricity. With grants payback was 8 years. Preheats the hot water to 45degC in a storage tank, then an electric hot water tank. Put a timer on the hot water tank to only heat at the lowest electricity rates. Summer air conditioning is almost free since I'm dumping the heat into the cold ground which is around 5degC

[@doigal12345]

If you have a lot of excess solar it’s worth adding resistive hot water into the comparison. The cheaper capex compared to heatpump might more than make up for the higher opex if it’s all solar anyway.

[@davesmith342]

I did resistive heater in Vic on a timer, 2 person, electric only house, 8kw Enphase with 7kw of inverters, split NE NW, 240L hot water tank with a 2.4kw coil, timer run be tween 10:30am and 3pm, this is within my off peat time so 18.5c/kw import and 6.7kw export, uses about 7kw, most days we don't import any power, install cost was $900 for the tank and and $200 for the timer and contactor, expected system lifetime 10 years, been in place for 1 yeah so far Cost me about $220 per year in in power if you include the lost export payment and the odd day when I need to import, there was no math that would make heat pump worth it in my scenario

[@chefgav1]

MC electrical has done the numbers on his channel and HPHWS wins hands down

[@AndyFletcherX31]

I got a 300L tank with an integrated heat pump about 3 years ago replacing a resistive heating tank. I'd say the average COP around the year works out at about 3. I'm off grid in the UK at 53N so the sun only gets to 14 degrees altitude at winter solstice and it made a big difference in how often I had to run the generator to keep the batteries topped up. As you have so much spare solar power one option for you would be to run a solar diverter to direct the power you would have otherwise exported into the hot water. It would certainly be a cheaper option.

[@Lordniksidor]

Imagine if you could have the refrigerant for your hot water heat pump plumbed into your split system for the summer in a setup like the multi split - Keeping cold whilst you heat your water.😀😀 that would be supreme efficiency.

[@landspide]

This is a very good idea, AC systems should dump their heat into the hotwater system while cooling.

[@jasonriddell]

in Canada the heatpump water tanks have the heat pump on the top of the tank so it IS cooling your interior space when running and I imagine one could plumb ductwork off of it for HOT climate areas for a "low cost" method

[@DEEJAY88]

@@landspide There is one mitsubishi with R410 that has heat recovery AFAIK

[@sjcsystems]

Look at Daikin split systems, they do this

[@Kregorius]

@@jasonriddell saw one of those in some random channel. How does this effect the actual energy usage. I would imagine that running it inside the house would cool the house in the winter too. Meaning the house would use exactly same amount of energy to heat up again. That would make the heat pump usage kind of useless in winter.

[@anthonymc76]

I have the Sanden 250l heat pump hot water system (same technology as the Reclaim) installed last August. It runs at midday for 2 hours on the solar energy and consumes 1.1kWh.

[@xjet]

A couple of questions: 1. What's the max water temperature you can generate with a heat-pump? 2. What's the minimum outside operating temperature at which the pump will generate a useful level of temp in the water tank? Heat-pump-based hot water is fine if you live in a climate where there's always enough ambient heat in the air to provide an adequate source but across the ditch here in NZ there are many places where even daytime temps don't make it into double-digits so heat-pump *anything* really struggles to reach the promised efficiencies.

[@EEVblog]

The Reclaim unit operates down to -10degC. Max, not sure, but 59-63C is mentioned as nominal.

[@evensgrey]

@@EEVblog You can still get at least 100% heating efficiency out of a good heat pump system down to a bit below freezing. Where I live, you do have to have a backup system, though. Winter temps can go down to -40C for WEEKS at a time here. Not all that often, but I'm seen it happen.

[@jasonriddell]

@@evensgrey I assume Canada and all the heat pump units I have seen have the whole system ontop of the tank and does NOT see - anything and will be COOLING your inside air

[@evensgrey]

@@jasonriddell There's no actual reason you have to take the heat from the air inside the house. Unless, of course, the heat pump heating the hot water tank doesn't have any backup so you need to take heat from somewhere you know won't be too cold, like inside the living area. In circumstances where you're needing to heat that area, this is undesirable, although it might be more efficient than having the heat pump move heat from outdoors somewhere.

[@76queen]

Fridgy is my trade, older split system, broke into the discharge line from compressor to reversing valve and placed a tube in tube heat exchanger with hot gas up the centre tube. The outer tube is connected into the one of the inlets and outlets on a dual access hot water system. So end result hot water in both summer and winter, condensing unit ( outdoor section had a 8kwR capacity which heated the 250 litre tank quite quickly.

[@jomac2046]

I helped to put one in on my sister's farm NE of Perth about 6 years ago, has worked great without a hiccup since.

[@techalyzer]

Wow those are some insanely low gas prices. Here in Romania we paid even 250 AUD/month during winter months last year, for a 2 room flat (living + bedroom). I just bought our first flat ever, and with all the renovations and cleaning and washing and testing and everything I expect a bill of about 300 dollars this month, if not more.

[@peterevenhuis2663]

The heat pump manufacturers have their calculations based on a 20C outside temperature, when you have 0C outside in the winter it's not so efficient, so I hope it helps in your setup. But do not be surprised if suddenly you don't save money

[@pie314isi]

nope. they frustratingly don't always give figures, but if you dig a bit you can find them. It's common to quote them for A7/W55 (air 7deg, water 55deg).

[@EEVblog]

We don't get 0degC here in Sydney. A really cold winter day will be in the low teens.

[@ottoplichters]

@@EEVblog and your solar panels are naar the equator so it wil make alot of power. so win win 👍

[@peterevenhuis2663]

@@EEVblog , my 0 degree is a example, what I want to point out is not just work with calculations from heat pump manufacturers, they calculate in their own pocket. Somebody can install a heat pump and then suddenly come to the conclusion that it cost more than a standard electric heater, as before I hope it works out for you. Readers be aware of your local climate and calculations

[@nukularpictures]

@@pie314isi and what COP do they specify for that? Can’t be above 4 and yet Dave’s System would mean a COP of greater than 6, closer to 7 even considering losses in the gas heater.

[@WhenTheManComesAround]

I'm definitely interested in this without a doubt! This year I bought qty 40 240 watt solar panels, 15k in LiFePO4 batteries and 2 all in one inverters because I could see energy costs going up. I spent $1.21 per gallon on propane 2 years ago & $1.29 per gallon last year. This year with shopping around to 5 different vendors in my area got it for $2.18 per gallon. So with what I've seen in costs going up I'm doing everything I can to supplement my energy needs with solar solutions. I think a heat pump hot water might be just another way to do exactly that. Thanks for the great vids my friend, and I look forward to more 😁

[@ctechbob]

We came from a regular resistive water heater in our place and went with a same-sized heat pump. Cut energy usage from hot water anywhere from 1/3-1/4 the amount the resistive heater used. I have what I consider to be almost the best case usage for one. My water heater sits in my garage, so it doesn't cool the house (Units here in the US are combined units as opposed to what I'm going to call the 'mini split' style Dave is showing), and I live in the southeastern US, so there is plenty of heat in my garage to pump into the water. Ours is a 'hybrid' that also has normal resistive elements in case you need fast recovery or something happens to the heat pump system, but you have the option of locking those out and not using them, which I have. The unit was around $1100 USD and my local EMC was offering a $500 rebate on the unit. My guestimate of payback on the unit is right around 2 years or less.

[@crfuzz1144]

This is very similar to my costs and estimate. We went from a 10 year old regular resistive WH to a heat pump. Mine is in my basement so it helps keep it a touch drier in the summer months. It does in theory scavenge some heat from the home heating system (older inefficient oil boiler), but that keeps the basement fairly warm as is so it's probably a net benefit. Mine was around 1300 with a 700 rebate, and I installed myself. I estimated around 2 years as well. According to app I use at most ~130kWh/month, though usually around 95-100.

[@electrodacus]

The formula to calculate thermal storage capacity in kWh is fairly simple. So to increase the water temperature by 40C so say from 20C to 60C you have 415 liter * 40C * 1.16 = 19.256kWh And if you ignore losses to ambient from the water tank then this will be exactly what a direct electric water heater will use as it is 100% efficient. For a heat pump will be much less as you pump heat from outside and the COP will depend on the delta in temperature between outside ambient air and water temperature. So since you have a larger water tank than needed and you want it to be as efficient as possible keep the water temperature limit around 55C or 60C and not higher (assuming you can set that). In summer I'm sure it will have a fairly high COP but in winter it will be quite a bit lower so average will likely not be as much as advertised.

[@EEVblog2]

Not quite that easy though. As you use the water more colder water comes in and hot water flows out. So it's continuous flow system, not a system where you extract X amount and then refill makign the calcs simple in practice.

[@mikerowe402]

Yeah very fair comment. While I'm a huge fan and will move to the same unit when my solar hot water system dies you call out a strong variable on the temperature from the mains the water comes in at. South East Queensland is a lot different from say the hills of Adelaide/Sydney/Melbourne (cold!) etc :)

[@liam3284]

required in most states to heat to 59°C

[@EEVblog]

@@mikerowe402 Never measured it, but I don't recall our tap water being that cold in winter. It comes from underground pipes of course.

[@jasonriddell]

@@liam3284 building code? requirement for at least OR MAX??

[@chrismaxny4066]

We have a 50 gallon or 189 liter heat pump hot water heater and it works flawlessly! So far in 2022 it has used $206 USD and 803kWh. There are two of us living in a 1920 sq ft or 178 sq m house and we do have guests every so often. We've bought it in 2018 for the same price as a standard electric water heater due to an instant rebate from our local power company and never run out of hot water.

[@ijacobs333]

Have a heat pump, had it for 2 years now, still grid tied, and in south africa, we have serious power issues, so being able to have hot water , running off a small generator is a huge bonus! but when we do have power from the grid, it barely uses power!

[@devinhedge]

Was talking about this locally and everyone thought I had 3 heads. Thanks for vindicating me! 🎉

[@PaulGreeve]

Dave, a couple of months ago we had to replace our old clothes dryer and got a new one that’s based on a heat pump. I’m intrigued to see all these new heat pump based, home appliances appearing on the market. It’s rather amazing how the dryer works, compared to the expensive, hairdryer style method the old one used. Dave, the way this dryer operates might make an interesting subject for one of your videos. Maybe? Now, thanks to your video, it looks like a heat pump, hot water system is in our future. Also, we still use our solar hot water system, thank you. As we are in Perth Western Australia, it would be stupid not to, though I have a timer on its electric heater so it uses the solar panels at midday, to keep costs down as much as possible in winter.

[@EEVblog]

Mrs EEVblog is also talking about a heat pump dryer. But the number of heat pump boxes it getting silly. We already have 4 separate aircons units plus this new heat pump.

[@PaulGreeve]

@@EEVblog they are self contained. No extra condenser unit. In fact they are excellent for small apartments as the moister is condensed into a removable container or pumped down a sink via a detachable hose. And the hot air remains in the dryer and not vented into the room and waisted. And they are lot more efficient as well, something like 4 or more times depending on the make. As best as I can determine, air is passed through the condenser to heat it, then through the clothes, to extract more moisture and then through the evaporator to cool and dry it. Then the cycle repeats. As the refrigerant absorbs the heat from the hot wet air through the evaporator, the heat is not lost but is immediately returned to the now dry air via the condenser. Very clever design.

[@PaulGreeve]

@@EEVblog also if you make a video you could just after getting the new dryer out of the box, say to Mrs EEVblog, “Don’t turn it on, tear it apart!”. I’m sure she be mightily impressed with you. 😉

[@ericlooewe]

@@EEVblog Don't worry about it and embrace the savings. Had one for like 15 years and the heat pump part of it has always been zero trouble. As a whole, the biggest issue was a crappy bearing for the belt tensioning pulley that gave out earlier this year. Super easy repair and no different from the equivalent vented or condenser models. Around here, the European Commission is somewhat likely to outright impose a minimum efficiency only attainable by heat pump dryers in the coming years.

[@Richardincancale]

Yup - I got one recently and it typically consumes 400-500 watts while drying a big load of sheets and towels for a couple of hours. It’s baking hot inside just like the old thesis ones that took 2-3 kW!

[@sharpx777]

Looking forward for the actual numbers after you installed it, really curious to hear

[@azpcox]

You can put on a water temperature tempering valve and increase your tanks storage temp to higher. Effectively create a 2x size virtual water tank. Love your system discussions!!!

[@dkind82]

Just installed a hphws in south west Sydney- 2.3kwh per day. 2 people, non energy conserving. Used a Shelly 1PM to schedule during solar production after storage is full.

[@PeterMilanovski]

Take note of how much energy is going to go into the new hot water storage system when it's first fired up, you should get an idea of how much energy it's going to need to heat 415 litters of water. Also, maybe it's a Sydney thing but down here in Melbourne, central heating is a thing! Gas fired central heating. You might have been referring to hydronic central heating which is common in many countries outside of Australia...

[@chptech]

The only problem with heat pump water heaters, is during the winter. Whatever you heat the house with has to be figured into the operating cost. We use BTU's in USA. If you remove 1000 BTU's from the room you have to replace the room heat with some other heat source.

[@neonsigns6721]

Upvote if you shower before bed like Dave. Thanks for the comparison. It would be interesting to see how some of the different types of heat pump water tanks stack up. Looking forward to the results

[@jmvanick]

I just installed one of these a few months ago... it was going to cost me just over $10,000 to install a new chimney, the heat pump system not only is saving energy, but was a lot more cost effective, and we've had no issues with having enough hot water. I n the last month, we've used about 8kwh total electricity to heat water (confirmed by both the app and my independent electrical monitoring setup). At our kw/h rates, that's less than $2 for the entire month. it's actually been WAY more efficient than I was expecting.

[@davidunwin7868]

I have a small Midea heat pump HWS. It draws about 500w to run the heat pump, and it runs for about 3 hours a day to heat the water we use. I program it to kick on at about 8.45am and switch off before peak pricing at 3pm, but it is up to temp by 12pm, so it doesn't switch on again until the next day. The solar PV is a 5kw system. I'm about to disconnect the gas ducted heating and install two reverse cycle air conditioners instead. Price is $5700, and the gas heating is $1200/year, so in about 5 years the AC will be paid for, not to mention the savings of running it off solar, and actually having cooling in summer. 😎

[@tomwiles]

My particular rural electric cooperative here in the US does a one for one kWh trade, so in effect it acts like a kWh bank. I currently have an 11,700 kWh credit built up. I’ve just replaced my propane fired central furnace for a heat pump system so I expect to start digging in to my kWh credit.

[@tomgeorge3726]

Hi Dave. Great video, we have a small heat pump HWS unit at work. My brother who lives in a regional town with no piped gas, about 4 years ago had their electric HWS die. He fitted a heat pump system and hasn't looked back, quick to install and compared to electric heat HWS, it is a god send. Even got the gov rebate.👍👍 At 1:55, you mentioned reverse cycle air con, but showed an evaporative unit. We recently moved from a reverse cycle house to an evaporative ducted house, and would reluctantly go back to reverse if we had too. Evap is so much more comfortable, due to the moisture in the air, just need a couple of windows open to let the air out. Power consumption wise it appears to be cheaper. A humid day compromises it a bit, but all you do is turn the water off and run fan to circulate. I live in Central Victoria, so evap works well, t'up north it may be a different kettle of fish. As for solar, were are in the middle of a new housing estate, and most houses have solar hot water panel, possibly pre heater, on their roofs.

[@kissingfrogs]

In Perth evap is supreme most of the time we need cooling and ticks a few other boxes such as quickly airing the house out after kids cooking has set off the fire alarm.

[@Rickmakes]

If a person is currently using a resistive hot water heater and a dehumidifier, a heat pump water heater kills two birds with one stone as it acts as a dehumidifier. I'm not ready to replace my gas water heater with one because I often heat my house with gas. In my case, in the winter, a heat pump water heater would essentially be heating my water with gas.

[@getyerspn]

Looking forward to the follow-up video...I've been eyeing a hot water heat pump system myself.

[@UpLateGeek]

Smart move getting ahead of the price rise. If you were Linux Tech Tips and you had water cooled solar panels, you could probably figure out a way to use the evaporator to cool your solar panels to increase the efficiency too!

[@DrFrank-xj9bc]

Hi Dave, your energy consumption is extremely high, about 5500kWh/yr, 10 times what we use here in Germany. We have a one-family-house, solid construction (not wooden😁 )and well isolated. We have to heat our houses in winter time, so in total we have about 13..15MWh consumption, only 3..4% going into water heating. We 3 people use hot water for shower, typically a few minutes only, 2..3 times a week per person, rarely taking a full bath, and for the daily hygiene, of course. Then I often dish wash manually, what's not going into the machine. That's all of usage. In this country, most living spaces use gas heating. Caloric Value Boilers are meanwhile standard here, i.e. 95% efficiency by a built-in heat exchanger. The 250l water tank @ 60°C and the water pipes are isolated as well. I suspect that your old gas boiler and for sure your water tank are very inefficient and not well isolated, causing that high waste of energy. A closer look at your gas boiler and the water pipes would be interesting. I assume, that your new system will even save much more of energy simply due to its better efficiency and isolation. I guess it might be down to 10..20% consumption only.

[@jasonriddell]

in Canada 30 year old tanks are rated around 60% efficient and NEW "condensing" units are 97% so a MASSIVE savings fitting a NEW tank

[@5Breaker]

In Germany we have the option to have a powerplan to import our exported energy for free. That also means we export for even less than none but we import for the same less than none as long our export is higher than import. It has a decency, we need to have a battery system with all least 10kWh. But it's working wonders.

[@tme2912]

The water temparature delta is important factor because in winter the input water is much colder than in summer. And at the same time the efficiency of heat pump is much lower when outside temperature is low ( less than 5 - 10 degrees C ) . So having a mixed between gaz and heat pump and preheat cold water with gaz when outside temperarure is under a triggered temperature might be an efficient solution.

[@cmssniper]

I am using my heat pump for floor heating in my house. I never wanna go back!

[@jkbrown5496]

It is interesting to see heat pumps moving from the mechanical to electronic controls. The best of the mini splits have a pretty much set refrigeration circuit that is controlled by the electronics with electronic expansion valves and ECM fan/compressors. That's how they get the higher COP. Unfortunately, the having refrigeration people do electronics does not lead to reliability, especially when they see a profit center in selling OEM-only parts. Kind of why Bosch and others are dominating since they had the in-house electronics experience. It'll all settle out eventually, but it's easier to buy a refrigeration circuit and put your electronics experience on it than it is to buy electronic controls and put it on your refrigeration expertise.

[@AmbachtAle]

If you add a tempering valve you can heat the water to a higher temperature in the tank and still safely wash your hands without scalding yourself.

[@dorsetengineering]

Always amazing to see you guys put your hot water cylinder on outside of the house :) You mentioned that you heat and cool the house with a regular reverse cycle air conditioner, you didn't fancy going all-in on a multi-head VRF unit with heat recovery? Pump the heat out of your house in the summer and dump it onto your DHW cylinder?

Looking forward to the results!

[@kissingfrogs]

I want to jam a solar powered immersion heater into our gas water heater just to keep it hot during the day. Set to a few degrees above. Basically to make up for the wasted heat thru the insulation and supply the small demands. Next time we leave the house for extended period I will note the gas reading so we can see just how much is used keeping it warm and a pilot light running,

[@michaelhall4626]

If that's an '80s gas water heater, probably only about 60% of the energy in the gas will go to heating the water. The rest will go up the flue. A modern 95%+ efficiency condensing unit would cost a lot less to run, but still use more energy than the heat pump one. And since you've got the excess solar, electric makes a lot of sense.

[@ArthursHD]

Mixergy heat pump water heater can heat up tank partially. Myenergi Eddi is a smart solar PV diverter.

[@boilerbots]

Your water heater looks very old and might only be around 40% efficient. I have a tankless unit at around 97% efficient. However I did rip the resistive heating element out of my hot tub and installed a heat pump. It just sips the power when necessary and keeps the water hot all year. My measurements and conversions confirm based on the energy in vs temperature rise that on a warm day it outputs about 7 times the heat as energy consumed, it outputs 41C water temp during heating.

[@Anamnesia]

I had a conversation with our Building manager today & he mentioned how the 2,500 person office is going to replace the gas hot water system, to a *_Heat Pump_* system! The reasoning; Using GAS to heat the water is worse for the NABERS rating, than electricity...

[@Lordniksidor]

The gas v conventional electric difference makes a lot of sense if you think about it. Whole bunch of exhaust gas with plenty of heat left in it straight out to atmosphere vs an element heating up in a sealed insulated enclosure dumping all of its heat straight into the water with no wastage bar a bit of resistance in the house wiring. That's half the reason I'm not a fan of gas cooktops, inefficient as you can be with most of the heat ending up in exhaust gas in your kitchen rather than in the pan where you wanted it.

[@kissingfrogs]

maybe, but gas is instant on, adjusts instantly and I can see at a glance exactly how much I have the stove turned on and I can use it to light candles and burn other things that need a flame like soldering copper pipes in the kitchen and it provides an alternative when the electricity is out and emergency lighting to help me find the candles, a touch or my phone.. It also provides for a more humid oven bake which is sometimes preferred and as best as I can tell my gas is charged at almost 1/2 of what I pay for electricity per kWh. 15cents v 27cents. But your point is valid, whole bunch of exhaust gas out the top of the water heater which also loses heat

[@radman999]

The flue pipes on modern gas tanks are PVC plastic. Your analogy doesn't hold up.

[@SpencerHHO]

At a crappy rental I lived at our hot water system used 15KWh per day it had a 5KW element that ran for 3 hours a day. Turns out the shower the landlord refused to fix was leaking hot water in the wall. They tried to pin it on us untill I proved I raised it as a maintenance issue on our first inspection 9 months earlier. The massive power bills didn't hurt so much when their refusal to fix anything resulted in a foundation sinking....

[@joef108]

Hi Dave. I believe you indicated that you were anticipating (hoping for?) your existing gas water heater reaching End-Of-Life soon. Wouldn't the eventual cost of replacing your gas unit with another gas unit shave a couple of years off of the 7.6 year break-even, assuming that it reaches EOL within say 4 or 5 years?

[@heavy1metal]

More so, when you factor in the technology difference 30 years makes. From 80% efficiency to 94%+ as well as better insulation.

[@SupremeRuleroftheWorld]

Hi Dave, hvac tech here. There need to be some corrections in the calculations as they are based on marketing wank. First off the efficincy. In hot water the usual cop is 3.5 when heating to 55c every time. Not 7. Numbers above 5 are reserved for low temp heating systems like underfloor heating. The higher the water temp needs to be the lower the cop is going to be. it depends on outside temperature as well wich is higher in your climate but you will find that the claimed numbers are "overstated" once you look at the actual performance. the only way you will see a cop above 6 is when its full on summer. you can also save a bunch of electricity by not heating up the tank more than you need. if you can manage your daily needs with 50 degrees then use that and put the rest back in the grid. its a waste to heat up more than you need. 5 cents back is still more than having a bunch of hot water you dont need. running at higher temperatures also decreases the lifespan of the refigerant system, most notably the compressor. the most expensive part.

[@kissingfrogs]

thanks for the numbers. My gas bill is in energy units which they convert from cubic meters and say the energy per cubic meter fluctuates as it is natural gas. Recent meter readings 644m3-539m3 = 105m3, which they converted to about 1108 units. So perhaps a 'energy unit' is actually 1kWh and they are suggesting there are 10.5 kWh/m3 and they charge ~ 15cents per energy unit while the electicity company charges ~27cents per kWh

[@SupremeRuleroftheWorld]

@@kissingfrogs email them and ask them flat out what the conversion is and what a unit is to them. It does fluctuate but not much as the source is pretty fixed. If you get cheap russian crap gas for example you wont see more than 8kW from 1 cubic meter, higher grades (non russian) can hit 11 or better.

[@kissingfrogs]

@@SupremeRuleroftheWorld I think its primo quality gas pumped from about 1000kms away from the exquisite gas fields of the Carnarvon Basin so maybe the 10.5 is plausible.

[@izimsi]

If you want to know how efficient that is, just check the temperature before and after it's done the first heating of the whole tank, obviously also measuring the power draw.

[@af8056]

In South Africa , with all The loadsheading and power cuts , it's better to go with a Gas Tankless Turbo Fan Water Heater , gas works out and roughly 1$ USD a Kg , if you buy the 48kg bottle, and normally lasts up to 3- 4 months . A Heat pump is Not idea if you go A Few Days Without Power . Cheapest Cost vs Hot Water Availability is the Factor. As we Can't rely on always having Power like other Countries.

[@rkan2]

Maybe Dave could do a small demo about this? See how hot the same amount of water gets using phototermic & photovoltaic. There are nice demos about it on YT already.

[@jasonriddell]

I have NEVER seen ads claiming GAS was "efficient" but "cheap" so the question is what would an ELECTRIC tank cost to run on AUS power rates for the SAME water usage AND the heat pump maths assuming ZERO solar power I assume it then "looks better" I know in Canada a 30 YO tank would be around 60% efficient and modern "condensing" tanks are around 92% I believe - same with central boilers / furnace units

[@MartinE63]

Missing something here in the energy balance as in MJ of gas supplied, when burnt, does not equate to kWh of electrical equivalent, a percentage goes up the flue to atmosphere.

[@mosfet500]

I'm running ductless HP home heating and cooling with a COP ~3.8 but not HPHW, here's why: First HPHW is very slow to recover ~3 hours, that's why you need 415 L. What happens usually is they do their recovery at night when there's little or not hot water demand so your PV isn't giving you any benefit. Then there's legionella and cryptosporidium so the tank has to heat above the point they grow, over 50C (120F). Usually manufacturers put a heating element in tanks and cycle them to kill bacteria. The element has a COP of 1 and companies like Rheem use the element if the water drops below a specific point because of the slow recovery. Now you have a tank with 415L sitting at 50C so you get standby losses, the greater the temperature differential the greater the losses. Then you have line losses to fixtures, then mixing losses to bring the water down to use temperatures. The extra complexity also means there's more to go wrong, more to install and a 415L tank takes up room space too. I run PV and I run tankless, here's why: No standby losses, no line losses, no bacteria cycling and easier to install and maintain. Because it's so small it can be put closer to fixtures and because you set the temp to use temp and you don't have water sitting in a tank there's no bacteria build up and there's unlimited water 24/7 with no waste losses. When it's off there's no draw and because it comes on when I say it does I can maximize my PV, so things like clothes washing happen on sunny days, dishwashing when there's PV output too. After monitoring my tankless for a year I found it never draws above 5kW's when on if not everyone is using water at the same time, if you want to wash clothes and have three people taking showers it's not going to work for you. HPWH work if you have a lot of hot water usage but if you're careful and conservative tankless is better. Not only does it cost less and less to install it lasts longer. A tankless can last 25 years and with an inexpensive element change if needed another 25 years. HPWH, maybe 15 years and if the tank splits open like most tanks eventually do, you'll have a flood, that doesn't happen with tankless either. Let's say I take a 5 minute shower which is about right for me: 5/60 * 5e3 = 416watts to take that shower, then it's off, no tank to reheat, no standby losses, nothing. It's only two of us here now but my monthly usage is usually under 40 or 50 kWh's, at 20 cents (USA) a kWh that's $10 for the month but most of it is covered by my PV, the key is we control when most of the hot water is used and you set the temp, there's no mixing losses, turn the water fully hot, super efficient even though it's an element and if you have a good system it slow starts. Do the research, see if I'm right. I bought it from Amazon, it came in the mail (16 pounds), I ran in a 240 line and it was done in an afternoon.

[@50Hz]

I got a instant hot water unit. Absolutely love it

[@EEVblog2]

No thermal battery for you.

[@50Hz]

@@EEVblog2 No unfortunately, maybe on the next one. Interested to see the results after install.

[@mosfet500]

@@50Hz Dave read my analysis and why I chose a tankless, I'm pretty much off grid. Check your tank, bet it has an element in it with a COP of 1. It's not exactly a "thermal battery", that's called standby losses and that tank is cooling - entropy, every time it cools past a specific point the systems calls for heat.

[@jasonriddell]

@@mosfet500 everything I have read is for LOW usage households tankless are better but for higher usage environments heat pump TANK types are better Dave is trying to "consume" solar power and NOT back feet to the grid so he wants to "time shift" the supply/demand

[@mosfet500]

​@@jasonriddell I can tell you from living basically off grid for the last several months that the thing you want to control is when you use energy. Here's an example: I have a robotic vacuum that I charge during the day and I can use at night so I'm not using my battery bank to vacuum. I have several things like this and I control when I use energy very well, you pick this up right away when you're watching every watt. The problem with HPWH is that they are very slow to recuperate, about 3 hours so usually people set them to heat during the night so they will have shower water the next morning. With the tankless I have the option when that unit draws energy, clothes washing for example. With a HPWH if you draw the tank down too far the electric element kicks in and you now have a standard tank water heater. I don't know what the break even point is as far as usage preferences for one or the other but you're probably better off with a HPWH if you have a big family, it's just one to two people here most times. I did do the cost breakdown and by the time the HPWH catches up to the tankless you're pretty much at end life. You'd be surprised how much you save just using hot water when you need it, I'm monitoring my usage and for the last two weeks all I used was 19kWh but it was mostly just me as my wife was away. Dave's got four or five people in his house so let's say we multiplied my usage by five and then doubled it to get a monthly total. That would only be $20 for the month at my rate.

[@tracyrreed]

415 liters? That's 91 gallons. That's twice the size of my water heater which happily serves a family of four! They want quite a lot more money here for larger systems.

[@EEVblog2]

Was told the 415L wasn't much more, forget the actual difference, but it wasn't much. So what the heck.

[@eliotmansfield]

Indeed - family of four here and we have a 250L tank which is considered quite big

[@radman999]

Never seen a 90 gallon tank outside of commercial warehouses. That is just insanely huge. 50 gallon gas fired is more than enough here with 3 females in the house.

[@kjlovescoffee]

You should do a yearly update on how much you've saved/how much it has paid for itself, given the increasing energy costs. I have a feeling pay back time will be quite a bit less than 5 years.

[@EEVblog]

Yes, likely less with increased gas and supply prices.

[@Nighthawke70]

What about using geothermal type systems for heating/cooling? It's a proven performer in a variety of regions.

[@eliotmansfield]

My boiler uses 13kWh to heat my 250L tank doing the same with immersion heater uses about 7.5kWh. What has become apparent is the heat loss from the heating loop between the boiler and tank (8-10meters some of it not insulated) All my gas and electricity energy is pulse counted - so all the maths is done automatically every day. I pulse count the water too - so there’s a spoken alert in the house for people taking long showers - and other handy stuff like water leaks etc Would be good to see the actual COP - figures which should be easy with a few sensors and counters

[@connerlabs]

Neither the boiler nor the immersion heater will heat the full contents of the tank to a uniform 60C, or whatever you set the cylinder thermostat to. The water is (should be) stratified with hot at the top and cold at the bottom. The immersion heater typically heats 1/3 to 1/2 of the water, and the boiler about 3/4, which agrees roughly with your measurements.

[@nukularpictures]

This seems way to good to be true. Even if you have a really bad gas heater at 90% efficiency it would mean a COP of 12,8kWh*0,9/1,7kWh=6,7. That just seems way to high for hot water especially as you want to have higher temperatures then for heating heat pumps. The system we just installed has a listed COP of ~5 for a 20°C difference between air and water temperature. So even with the relatively high air temperature I doubt you will reach a COP of > 5 over the entire year.

[@jasonriddell]

OLD heaters can be in the 60% range

[@liam3284]

In fact our prices are going up for a similar reason, other countries want to pay top dollar for our exported gas. That drives up the cost of gas fired electricity, which passes through to our bills thanks to the National Electricity Market's design.

[@SomeMorganSomewhere]

Yeah, this is why WA has a cap on what proportion of gas mined in the state can be exported.

[@janverhave]

Maybe I misunderstood, but why not sticking to a 175-200L tank instead of 415L. You still need the excess energy to warm it all up to a comfortable temperature.

[@MatyasLemberTutorials]

We just discussed this topic with my friend who was about to install solar. Unfortunately our gov decided to not allow net metering, so he cancelled the installation. This could be a great solution though

[@rkan2]

You could also wire solar panels directly to a water heater. Often no need for permitting and absolutely no need for expensive inverters.

[@zxspectum]

Awesome timing will watch this later.

[@justinbrain]

That tank is a funny looking green rectangle that looks like Bob's uncle made it in the garage from a kit.

[@mikerowe402]

Looking forward to seeing the seasonal actuals! Rough feel for the mains water temperature would be good too (some of us are in the cold parts of Aus ;p)

[@EEVblog]

Will take a full year to get good measured results

[@djrenault]

it's a neat concept; more to go wrong in 10 years, though, as you're adding another compressor etc to the list of things that can break expensively. this differs from north american ones in that yours has an outdoor unit and the NA ones pull heat from indoors. how cold can it be outside before it stops working? i'm guessing australia doesn't get as cold as where i am in canada (i've seen -34c in recent years) - the air-to-air heat pumps don't heat at those temperatures, making it tricky to design hvac systems when gas isn't an option.

[@radman999]

Agreed. Have fun with that resistive element burning all winter long. You might as well just hang electric baseboards on the wall, would be much cheaper.

[@Peter_A1466]

Can you dump excess heat from other equipment in this system? Looking forward to follow-up videos!

[@kd1010163]

The heat pump water heaters in the US generally have their evaporator inside on top of the tank. Why would you want the evaporator outside? Take the hot air out of the house and put that energy in the tank. Reducing the load on your AC units.

[@MrShwaggins]

I wonder why the tank is painted white instead of black. It seems like it would be better for it to be black since it can absorb more heat passively. I never thought there would be a heat pump hot water system. TBH, I thought the next fad would be those vacuum glass tubes with the dark pipe inside to be used as a hot water source.

[@heavy1metal]

I would be curious for it to be compared to a modern gas tank instead of a 30 year old one. I suspect the 30 year old tank is ~80% efficiency vs 94%+ on modern ones. I wonder how long the ROI of a heat pump at $5500 vs a modern gas tank at probably $1,000 and an extremely cheap bill. Also what's the estimated lifespan of the heat pump tank - I'm floored your current one lasted 30 years! Currently we use a tankless which provides hot water for laundry, dishes, sink, and showers. My own showers average 15 minutes with a 2.5gpm head, so probably 1.0gpm of hot water.. That's roughly 68 liters for just my hot shower. All this to say, with our modern gas tankless, it uses between 4 and 7 CCF of natural gas a month aka 2.05KWH (For 7 CCF). My tankless was $2200USD to install which included new vents. Might not hurt to quickly compare a tankless (both gas and electric) as well as a normal gas based tank water heater. *Edit - I'm also curious - have you been cleaning out the sediment from the 30 year old one? I wonder if its capacity has been reduced as well as its ability to heat the water because of the sediment. The more I think about an average daily of 12kwh to heat ~ 45 gallons is insane. You're using the equivalent of running a microwave for 12 hours nonstop. Or an oven set to 230C / 450F for 6 hours.... every day... Your water heater is not functioning properly for sure...

[@patrickpalmarella3119]

Ur on the ball, life span versus conventional Rheem my family had in a little cupboard upstairs in the Laundry with little space vented on a Cowl compared to these heat pumps that needs roof space and permits just to save a few dollars... then these people drive big 6 cylinder cars and turn on the house heater and wear t-shirts in wintertime.

[@mariuszsuchenek6047]

it would be good to compare it with a "solar water heater". And in the case of a "solar water heater", you heat the water directly, additionally, water flow is required through the circulation pump. But it is worth comparing the size of solar panels to solar water heaters.

[@dasrue6983]

I'll be super interested to see how you go with this! I have been looking into the numbers myself for NZ, moving from electric hot water to heat pump. Based on my calculations and usage the best payback period would be to get the absolute cheapest model, which can only run in heat pump mode down to 7°C and only gets a COP of 2. The reclaim unit is super efficient and will run in heat pump mode all winter, but in NZ they cost around $8000 so you have to use a lot of hot water to make the payback time reasonable. Also I think the reclaim heat pump unit is made by chofu in Japan

[@EEVblog2]

Yeah, would cost a lot to ship. None made local in NZ?

[@dasrue6983]

@@EEVblog2 There are at least a couple - Ecoenergy HP4000LT and BDT Hydrobox were what I found, but they cost a decent bit more than the cheapo Midea unit

[@kissingfrogs]

My reluctance to move from gas to this is there are so many moving parts and things to go wrong compared with the simple robust design of a gas heater. Dave himself has said that he was hoping the thing would die but still soldiers on after 30 years,

[@weeeeehhhhh]

@@kissingfrogs would be worth downloading the maintenance manuals for the unit and training yourself up. You need a professional gas installer to service a boiler. Anyone can do a heat pump.

[@mrzon9344]

That gass efficiency seems low but could also be a product of the age of the unit. I see the Reclaim Heat pumps are use CO2 refrigerant. What is the highest temperature you can get the water to?. I would think easy 80°C. and they should work to sub zero. The air source heat pumps I worked on reached COP 1 @ -5°C and COP 6 @ 42°C ambient they were R134A. Just a little gripe I have with some explanations - A heat pump is not a 'reverse cycle' AC you are just using the oposite sides of the cycle ie the condenser to heat the water and the evaporator to cool the air or ground water.

[@poormanselectronicsbench2021]

You have "muddied the waters" a bit in your comparison by converting your MJ usage to electrical KWH costs right away, and then calculating your cost in the price of electrical KWH, without calculating your ACTUAL cost of the natural gas MJ's you used to begin with, and thereby changing your actual cost per day, ( or breaking it down from your providers billing statement for those cycles). According to Google, the avg price cost of natural gas in Australia in Mar 2022 was 0.070 U.S. Dollar per kWh. 3200 MJ's converts to 30.337 Therms (100 cubic foot units) Your claim of 889 KWH converts to 30.341 Therms, which closely agrees with the 30.337 Calculation above. The avg cost of natural gas in AUS in Mar 2022 was $0.07 USD / per KWH ( Per Google) , which multiplies out to $62.23 USD, multiplied by today's conversion rate of AUS /USD of 1.58/1 = $98.32 AUS D, divided by 94 days = $1.05 AUS D per day, not counting any delivery fee, pipeline maint fees, tariffs taxes, ect. This is QUITE a bit different from your calculated $1.54 AUS D / day, but it also cannot be argued that the cost of natural gas, and it's delivery, is going to constantly increase over the years, and you do directly benefit from converting your solar power to the task of heating your water. The bottom line, is, SHOW US THE GAS BILLS!!

[@Turbochargedtwelve]

I bet his connection fee is almost as high as his usage fee. Mine always has been when not using gas for heat three season a year

[@Swenser]

Got mine month ago. Cost 350 installed with gov rebate. The main thing is with solar panels you literally get free hot water. Gas however isn't available free from any source. Disconnected gas altogether. I have stopped using the term "cooking with gas."

[@rockpadstudios]

I was thinking the same thing. In the US installation is x2 the equipment cost (on average). I asked how much to put in a mini-split and the number was $9k so it is true since the mini was $3k. I'm going to buy the tools I need since even if they cost $1k it beats handing over $6k.

[@USNEM]

Everything in the U.S. is a scam. Installing solar is extremely expensive, installing a hybrid water heater is also extremely expensive.

[@rockpadstudios]

@@USNEM The only option is to DIY. Start slow, I put some panels ($150 used, 300 Watts) over my deck and it shades me during the summer. I buy LiFePo batteries and the controllers to setup mini systems and I use them when the power goes out to run my computer and heat a microwave. Each Year I add more and I hope to use it soon to power daily. TouTube has anything you need to fix appliances like leaky toilets' etc. Buy tools and learn how to use them.

[@lackinggravitas6751]

I got one of these a couple years ago. Between a screaming deal from the retailer, a chunky rebate program from the power company, and self-installation, it was only a couple hundred when everything was said and done. Massive power savings compared to the old resistive water heater we had previously.

[@jeffm2787]

Had 80 gallons of solar hot water. Cost about $35 a year to run the pumps to move the water through the solar panels. At one time I had solar hot water with solar powered pumps as well. That cost nothing to run.

[@jbar6618]

Wow i had no idea what an advantage heat pumps have over natural gas. Your electric supplier could save a bundle by using heat pumps to boil water for their generators instead of natural gas.

[@HughMungoose]

How's the noise from these units? Some neighbours love to complain about people's AC, I imagine this would be similar?

[@EEVblog]

37dB

[@tasman1340]

I've I have had one for 10 years they are pretty good the heat pump hot water service Australian built 1 and I don't cost much to run either

[@MatthewSuffidy]

Using water in place of a battery in applications where the solar heating replaced grid electricity is definitely a good idea. The only problem is that the heat will eventually bleed out of the tanks, and they have a maximum capacity. I would expect it is usually cheaper to heat with gas than electricity, not that that is relevant here.

[@tracyrreed]

I've got a heat pump system sitting here waiting to replace my gas water heater too!

[@EEVblog2]

Let us know what consumption numbers you get.

[@soniclab-cnc]

meanwhile here in BC,Canada... its 2.9c and wet. I have both mini split and a few small heaters running. Lol, the hot water tank outside is not a thing here.

[@EEVblog2]

Outside is normal for free standing houses here. My house when I grew up it was in the roof.

[@jasonriddell]

@@EEVblog2 was young in southern California and the tank was outside but in Canada it is INSIDE as it NEEDS TO BE

[@henke37]

I think Dave missed to factor in the lost income from selling the excess electricity that is insted used by the pump. He did mention that the pay was poor, but a quick calculation of how little it is would've been good.

[@everTriumph]

And what is the performance going to be with high humidity cold outside temperature (

[@maxbutton9996]

I assume your aware of the government subsidies in Australia Dave? (I’m 4 minutes into video if you mention it.) I got a Midea 170L unit installed for only $33 total.

[@terry6131]

I wonder what the payback time would be if you had no solar / storage and decided to go full in. I looked at solar panels at the beginning of this year as prices were creeping up. For a 4Kw with battery based on my consumption, it was 15 years before break even (based on various online calculators). Given my age and likelihood of another house downsize, it wasn't worth pursuing. In the end I was able to make internal cost savings and whilst the cost has done up, I still pay around the same per month.

[@TheSir2005]

First of all you have a very inefficient gas system if you use over 10kWh a day for 175L (on average a 5 minute shower is about 50 liters of hot water which is/should be about 2kWh). You wanna do the math on that first, a 175L tank doesnt say much about how much water you actually use. So either you have a very inefficient gas system of you use a lot more hot water than 175L. Its probably both seeing how old your system is and 175L a day for a household is pretty low. Ok to the heatpump and 415L tank/boiler (depends where you live what you call the bloody thing). You can take off (on average) 20% of that. Thats 332L thats actually usable and will be actually hot (around 55/60°C normally). (S)COP for tapwater aint going to be 5 or 6, on average its about 2.5. Now you need to know the temp of your mains waterline (usually around 10°C on average) calculate the difference and the amount of energy it takes to heat it etc etc. My calculations for you new system, with a 5kW heatpump, 415L, a Delta of 45°C, 2.5 COP and 4180 J/kgK (energy to heat up 1L water): 17,5 kWh to heat 415L (80/85% usable) and 3,5 hours to heat up. Now of course there's a lot of variables there, which i dont know, you would need to factor in to be 100% exact. You can half it with the silly COP of 6 they have in their specs (32.6°C ambient / 21.1°C cold water inlet) and not come close to 1.7kWh. So my mind would be blown if your heatpump with a 415L tank would only use 1.7kWh a day, i would even be shocked if its less than 10kWh a day on average through the year. 3 kWh to heat 315L .... Thats simply aint happening and well nonsense. I looked into getting rid of my gas connection and using electricity for heating (house and water) last year and talked to a lot of guys who install heat pumps, cause i run into them often at sites, but no matter what, it doesnt make sense financially for me. Even not when i have 20 solar panels on top of my roof.

[@BAMBAM5476]

30 years old waterheater is not as efficient as a modern one . We have central heating with radiators and a flow boiler is build in no big boiler. When we got the new one the gas bill dropped quite a bit. So newer models gas heaters are better than old ones

[@markjacksonpulver3546]

I've think doing this for the pass few weeks. But we have 2 inline gas heaters, so we have to plumb in a tank. Also we don't have much excess solar. Only a 3kW of panels (10 years old), 2.9kW battery (6 months) old. I see it I can work out hot water consumption from the bills. Probably do it anyways. My wife wants to get off gas.

[@galileo_rs]

If not for the same reasons why is the gas price in Australia rising?

[@haywirekwek]

My current home is a single storey dwelling. We have a standard gas HWS. One side of the house always has hot water much much slower than the other side where it's nearer to the HWS. With heat pumps, do you think it works the same way? Meaning, do you think 2x 40 (or 50) gallon heat pump HWS is better than just 1x 80??

[@JimmyLLL]

We had a cheaper heat pump in QLD that ran on the off peak electricity. It had its own meter and used only 1.5kwh per day. Hot water was virtually free.

[@GertvandenBerg]

Interesting that the gas one does not heat the water as it flows through... It seems like centralising heat pumps might work - the aircon's warm side is wasted and the water heater's cold side is wasted...

[@pr5991]

I live in Melbourne, have gas water heater, but was told that upgrade and rebate is available only for electric water heater and not for gas water heater. But in your case it was gas water heater. Which company should I contact to get heat pump?

[@MegaBCAD]

Dose this system recharge as the system is used I imagine is dose as most do to supply the pressure it would be interesting to see how much useful hot water you get with out actively adding heat to the system while you’re diluting it with fresh cold water

[@123mjolie]

Thanks !! This was so interesting and informative!!

[@petersage5157]

What happened to the installation video on your main channel? YT is telling me it got set to private.

[@markushahnenkamm]

So dave wants to replace 12.8 kWH Gas with 1,7 kWh Electricity - i highly doubt that. If i assume a Gas efficiency of really bad 80%) than the water has received 10,24kWh. With 20°C outsde and 60°C target for the water i would assume a COP of 3,2 vom 30-->60°C maybe 4,1 . So you will neeed 3,2 to 2,5kWh/ day