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Energy efficiency with hot water

Currently most of out hot water heating is done by electricity although we are are working on a number of strategies to reduce this component. One part of the approach is to keep the thermostat set so that the water is just hot enough.

I was having a conversation with someone about energy efficiency and hot water heating and what was the best temperature setting for the hot water cylinder.

The friend was operating under the incorrect assumption that it was better to have the cylinder as hot as possible so that when water was taken out, for a shower say, there was less cold water entering that required heating. There is a certain surface logic to this but it seemed to me that it doesn't matter what temperature the water is, when you have a shower or do the dishes you are extracting the same amount of energy (in the form of hot water) from the tank and so the energy needing to be replaced is the same.

The issue with keeping water extra hot then, is more to do with the extra energy that is required to maintain a greater temperature  differential between the temperature inside and outside the hot water tank.

According to one website:
"The ideal setting is 60°C. It is important that the water in the cylinder is this hot to kill bacteria such as legionella but higher temperature settings only increase your power bill."
June 17, 2011  energy  hot water  electric  temperature  efficiency 
Solar - third time lucky

Solar - third time lucky

After several failed attempts to create a low cost, low tech solar water heater I gave in and purchased a complete kit off the shelf. It's only August but we've been having some nice fine days and the temperature has been getting up to high 50's. This unit has 20 evacuated glass tubes with some kind of antifreeze that exchanges heat with water that is pumped through the header. While I would have preferred a passive system I do like the modular nature and programmable smarts of the control centre.August 21, 2013  solar  energy  water  technology 
Pumping with free energy

Pumping with free energy

Using water to pump water, now that is cool! I have been building a small ram pump for lifting water. The design uses off the shelf components assembled and then cast in concrete.

Overview: Water from a small creek enters a screened intake and is carried via 32mm polythene piping. This has a drop of perhaps a meter over about 70 - 80 meters. This connects to 18 meters of rigid steel 25mm pipe which drops a further 10 meters to the pumping unit. The outlet from the pump delivers water via 15mm poly tubing up to an elevation of around 30 - 40 meters.

While the device works technically it has a number of drawbacks:
  • The water delivery is very slow, perhaps 1 litre every 2 - 3 minutes. This is a result of the various measurements. More water in, dropped from higher or delivered lower would improve the situation.
  • The pump unit stops every day or so due to (I believe) air accumulating at key points in the delivery line. This can be improved by eliminating high points from the line.
  • Pump stops when river drops too low
August 15, 2015  energy  water  technology