Save money on your energy bill by doing your research into energy efficient hot water systems that will save money in the long run. If your hot water water service 10 – 14 years old you should be thinking about replacing it.
Replacing a Gas Hot Water System
Replacing your gas hot water system
Here’s what you need to consider if you are going to replace your gas hot water service.
If you have solar panels (PV’s) on your roof, say a 3kw system, then you should consider installing a highly efficient heat pump.
The high efficient cold climate heat pumps only consume 1kw of electrical energy to produce 3-3.5 kilowatts* of heat energy.
If you set the heat pump timer to operate during the day, when your PV’s are producing electricity, then it is very likely that you won’t be paying anything for your hot water.
Even if you don’t have PV’s on the roof you still should consider a high efficient heat pump because gas is not as cheap as it use to be.
If you do your home work by doing the simple arithmetic, and ignoring the natural gas marketing hype, then you might be surprised to find how well a high efficient heat pump stacks up against a gas hot water system.
And here is one of the reason’s why
Heating water with electricity is 100% efficient. For every 1Kw of electricity you consume to heat hot water, you get one unit of heat energy. Not so for gas. The best condensing gas boilers only provide 94-96% efficiency.
That means that for every 1Mj of energy you use to heat hot water, you only get 94-96% of one unit of heat energy. This means it costs you 4-6% more energy to heat the same amount of water using gas compared to electricity.
And if you compare the heat pump to a gas hot water system. The heat pump is 300-350% efficient at say 7-9 degrees C or a Coefficient of Performance (COP) of 3-3.5.
If I look at my own experience between 20/2/14 and 23/4/14, over two months, I used 1861Mj of energy.
While we cook with the gas cook top, most of the gas consumed would be for generating hot water.
I pay .019ents/Mj for gas x 1861Mj = $35.35.
To convert Mj to Kw divide by 3.6.
So 1861Mj divided by 3.6 = 517Kw. Lets say the heat pump is 350% efficiency or COP of 3.5.
So 517Kw divided by 3.5 = 147Kw.
I pay 26 cents/Kw. So .26/Kw x 147Kw = $38.22
Basically we are looking at a $3 difference between gas and electricity for the same period. “So what’s your point I hear you say?”
My first point is my hot water service is a high performance open circuit gas instantaneous boosted solar unit and yet it only saved me $3 and I know for the expense of buying and installing the solar unit it is not worth it compared to the heat pump. My second point is that if you have a stand alone gas hot water service then I would expect good savings to be made if you installed a high performance heat pump not to mention that if you have say a 3Kw PV system on the roof it is very likely that you will pay nothing for your hot water.
In fact, if my hot water service was the only appliance on gas, I would remove the gas meter and save having to pay the the service supply charge, which was $37 for the two months, and would save me $215 for the year.
Replacing a gas hot water storage system with an instaneous gas unit
If you replace a gas storage unit with a gas instantaneous unit, there’s a good chance that you will be faced with a gas line upgrade. This is to cope with the demand for increased gas supply by the new gas instantaneous.
In most cases you wouldn’t get much change from $1000 for the gas upgrade.
Again, a high efficient heat pump should be considered because as in the above paragraph at .019cents/Mj the running costs between a gas boosted solar HWS and a high efficient heat pump is about the same and the running costs are even greater when comparing a stand alone gas instantaneous to a high efficient heat pump, so you might as well pocket the $1000 or put it towards your other bills.
Replacing an electric hot water service
Here’s what you need to consider if you are going to replace your electric hot water service.
Replacing your old electric hot water service with a high efficient heat pump should be one of your first considerations.
Why?
Because the efficiency of a high efficient hot water heat pump is equal to, or greater than solar boosted electric.
The Small scale Technology Certicficates (STC’s) values given to a hot water system is indicative of it’s efficiency performance.
For example, a 315L squat tank Sanden heat pump gets 35 STC’s compared to a Rheem solar 270L loline with three Panels which gets 31 STC’s.
The other big issue is labour costs.
A heat pump can be 1/3 of the cost to install and the reason is there are no labour costs to install panels on the roof, nor are there any labour costs to install insulated copper flow and return lines between the tank and solar panels.
Also don’t be afraid of heat pump technology. Your fridge uses the same technology and ask yourself how long does a fridge last?
For more information about replacing your current hot water system with a energy efficient, cost saving hot water heat pump system, contact Joe Walkerden 0418 124592
*winter COP