Heat Pump Hot Water System vs Gas Hot Water

Comparing gas hot system to a heat pump hot water system before I install a Reclaim 415L heat pump hot water system at home in Sydney Australia to utilise my excess solar energy.

Support the EEVblog on:

Buy anything through that link and Dave gets a commission at no cost to you.

Donate With Bitcoin & Other Crypto Currencies!

#ElectronicsCreators #heatpump #solar

[EEVblog]

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.

[doigal]

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.

[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.

[AndyFletcherX]

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.

[anthonymc]

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.

[universeisundernoobligatio]

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

[jomac]

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.

[devinhedge]

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

[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.

[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 😁

[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.

[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.

[ijacobs]

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!

[cmssniper]

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

[peterevenhuis]

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

[dkind]

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.

[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.

[tomgeorge]

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.

[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!!!