Hi. So just curious, what is going to cost more to run, a 180L cylinder that will most likely never be emptied, so will probably just be maintaining temp most of the time OR a 45L cylinder that just MIGHT run out of water. and will be topping up and heating from cold iykwim :) Thanks
trade4us2,
Mar 20, 3:03am
The small cylinder will have less heat loss, so use that.
lythande1,
Mar 20, 12:50pm
The cylinder will not have heat loss - all modern cylinders are insulated now. Touch one - they are not warm on the outside like they used to be.
The heating cold water will use more power. why not go in between? 135l?
carter19,
Mar 20, 2:26pm
It would be helpful to know what use the cylinder is having. eg are you expecting 3 showers, hot wash and dishwasher? or is it just for a sink?
mm12345,
Mar 20, 2:33pm
Of course they still have heat loss - and a larger cylinder more heat loss than a smaller one - all other things being equal. For a typical size modern insulated HWC, I believe it's about 2kwh/day - so $15 or so per month for hot water heating even if you don't use any hot water.
loose.unit8,
Mar 20, 2:42pm
Big cylinder, small cylinder it costs the same amount to heat x amount of water by y number of degrees.
Positives for the big one The big one will probably get up to temperature faster due to a bigger element and, as you say, won't run out as easily.
Positives for the small one Given the same amount of insulation for each, the small one would lose less heat due to having less surface area to permeate that heat.
mm12345,
Mar 20, 2:57pm
Another positive for the bigger one is that if total electricity and hot water use patterns suit, a larger cylinder has more chance of keeping up with hot water use if you switch to day/night electricity plan.
jane310567,
Mar 20, 3:19pm
135l is ok for two people - a good shower each and dishes.
goldgurl,
Mar 20, 3:23pm
Thank you very much people :) The cylinder will service 2/3 people in a 2brm sleepout. I think I'll go with the big one.
5425,
Mar 20, 4:46pm
on demand gas would be cheaper again , [no storage] also if proper lagging of the hot water pipes.
loose.unit8,
Mar 20, 5:18pm
Depends on the price of the gas.
Hot water heat pumps are (usually) even cheaper to run than gas, even if the gas price is pretty cheap.
mm12345,
Feb 28, 11:53pm
Problem with many of these things is that calculating energy use patterns isn't easy, potential energy savings even harder, as that depends on use patterns and what you're installing, then trying to guess a "payback period" depends on anticipated lifespan of the equipment, and a random guess as to how much future energy prices will increase. Great source of entertainment on forums - many wildly optimistic claims get made.
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