Gas Hot Water Services just don’t stack up to a Sanden Heat Pump
Are you aware that when you use gas a substantial amount of heat energy that you have paid for is lost during combustion? This is not the case with a Sanden Heat Pump
If we consider an ideal world where gas is 100% efficient and there are no heat losses, we know that it takes #13,761Mj/Yr of energy to heat water from 15C to 60C. But in the real world there are heat losses and the burning of gas does not achieve 100% efficiency.
The Gas Star Rating System uses the ideal world scenario and that is 13,761Mj/Yr of energy to heat water from 15C to 60C as a basis to show the efficiency of the gas hot water system
If we look at a 3 star rated gas hot water service, it consumes #24,854Mj/Yr of gas. Now if it takes 13,761Mj/Yr of energy to heat water from 15C to 60C then where has the 11093Mj gone or to put a dollar value on it what happened to ^$210 of my hard earned cash?
Even if we look at the 6 Star Rated gas hot water service at #18785Mj/Yr, where has 5024Mj/Yr gone or ^$95
Remember gas will not give you 100% efficiency you will always lose heat energy during combustion
So how does this compare to a Sanden Heat Pump? A rule of thumb to determine the efficiency or COP of a heat pump is the amount of input electrical energy compared to the output heat energy.
In the case of a Sanden Heat Pump, it uses a nominal 1Kw of electrical energy to produce *4.5Kw of heat energy or a COP of 4.5 or it is said to be 450% efficient..
If we divide 13761Mj/Yr by 3.6, it will give us the equivalent in Kw/Yr which is 3822.5Kw. We now know that it takes 3822.5Kw to heat water from 15C to 60C/yr. If we then divide the 3822Kw/Yr by the Sanden Heat Pump efficiency of 450% or COP 4.5 or let’s be conservative and say in the real world an average of 400% or COP of 4 we get 955Kw/Yr.
So instead of taking 3822Kw/Yr to heat the water from 15c to 60C it has only taken the Sanden Heat Pump 955Kw/Yr and heat losses are kept to an absolute minimum because no combustion has taken place to release heat energy into the atmosphere.
Now here is the clincher: 955Kw/Yr@^.23cents/kw equals $219/yr. This how much it will cost to run if you installed a Sanden Heat Pump. Your 3 Star gas water heater will cost you 24,854Mj/Yr@^.019cents/Mj equals $472/yr. The difference is $472-$219 a saving of $253.
If your gas boosted hot water service is 10 plus years old then there is a good chance you will need to replace it. Let’s say your new gas boosted hot water service is $1300 installed.
If you choose to install a Sanden Heat Pump instead, it will cost you about $3700 installed including gst and STC rebate plus electrical of about $250 so call it $3950 installed. To ascertain the true cost of the Sanden Heat Pump we need to deduct the cost of the gas boosted unit because you were going to have to pay for a HWS anyway. So, $3950-$1300 equals $2650. This is the real cost of the Sanden Heat Pump
The Sanden Heat Pump really comes into it’s own for property owners who have PV’s (photovoltaics) and still have gas boosted hot water services.
Drawing a nominal 1Kw, most PV system will generate enough power for the Sanden Heat Pump to heat hot water. This means instead of paying $472/yr for your 3 Star gas HWS you will be paying ZERO for your hot water and the payback for your investment into a Sanden Heat Pump will be $2650 divided by $472 equals 5.6years.
Lets look at C02 emissions.
To produce 1kw of electricity from brown coal you release 1.2Kg of CO2.
To produce 1kw(3.6Mj) of electricity from natural gas you release .4Kg of CO2.
This simply means that if you continue to use the 3 Star gas HWS system you will be releasing .4kg by 24854Mj(6903kw) equals 2.76 tonnes/year of C02.
Compare that to a Sanden Heat Pump with an average winter run time of 3.5Kwhrs for a 4 person family the C02 will be 3.5Kwhrs x 365days x 1.2Kg equals 1.53 tonnes/year .
If you have PV’s on the roof and install a Sanden Heat Pump then your C02 emissions to run the heat pump would be ZERO
Clearly the winner in this is you and the environment.
^prices for cents/Kw and cents/Mj where based on my own rates
*1 Ambient temp. (Dry / Wet) 16oC / 17oC, Inlet water temps. 17oC, Outlet water temp. 65oC Sourced from Sanden Installation manual version 4.1
# Sourced from Elgas