Comments on: Is Your Energy Bill Getting You Into Hot Water? DIY and Home Improvement Hints, Tips, Help and Advice from The DIY Doctor Thu, 28 Aug 2014 12:26:26 +0000 hourly 1 By: Padge Fri, 04 Oct 2013 15:13:36 +0000 Hello,

Great entry! I’m just curious, how did you calculate the energy used?
Did you use a smart meter with everything else turned off at the time of this experiment? Or, did you just time how long the immersion had been on and multiple and calculate the kw hours from that to get how much energy was used?
The reason I ask is because, I have after reading this interesting entry, I noticed that you(maybe to keep it simple) didn’t make any reference to these two very important factors:

A) Thermostat in the immersion heater.
B) Insulated cylinders don’t just keep hot water hot, they also keep cold water cold.

A. Immersion heaters don’t constantly use 3KW, they have a thermostat inside that cuts off the electricity when the water reaches the temperature it’s set to and doesn’t kick back in(turn on again) after the water has dropped 5-10 degrees below that.
Therefore it uses a hell of a lot less energy than an appliance constantly using 3KW, especially if the cylinder is insulated, which leads me on to the other factor.

B. Insulation works both ways, i.e. it keeps our houses warm in the winter(once we get the house warm inside) and it keeps them cool in the summer(it keeps the heat outside from coming in), despite what you may think, you’re better to have ac circulating cool air in your house than to open a window if it’s really hot outside.
In hot countries near and south of the equator, they open their windows early in the morning before sun rise to let some cool air in, then they close the windows and pull their curtains/blinds during the day.

-My point being here is that if you have let the water in your insulated cylinder drop completely, to say 15 degrees(or whatever your hotpress room temperature is), it will take a lot longer for your immersion heater to heat up that water than in a non-insulated cylinder, because on an insulated cylinder, the cold water will not have the benefit of dissipating it’s cold while being heated, like on a non insulated cylinder.

I believe also, this ‘myth’ is to keep the sink/basin element of a dual element immersion on all the time. It’s shorter, uses only about 2KW of electricity and heats the water at the top of the cylinder mostly.

I have not tried an expereiment to calculate it because me and the misses always just time it well and use just what we need but I think it’s really cool to see someone made the effort of doing this and recorded the results as well. Well done.

If I was to try out a technique, I personally would, initially adjust the stat on the immersion down to just below 60 degrees, turn on the long bath element for about 2 hours to make sure the water on the bottom is good and hot too, stack as many towels, blankets on top of it to keep the heat in(as heat rises) and would have just the short sink element come one say 15 minutes every morning, maybe use the bath one for half an hour to 1 hour once a week top top up the cold water at the bottom.
If we had kids to bath every other day, this would obviously increase a bit.

I am open to getting thorn a new one so if anyone has their own 2 cents, I’ll hear them.