FWIW my thoughts are that, as you say, the current arrangement only has to replace the heat you have used + any that's esacaped into your dwelling so it probably isn't too wasteful.Snorvey wrote:So that's fine, but I was just wondering about the tank of water we heat up every night (and have done for years). After we fit the shower, we'll definitely not need to heat up 120 (I think) litres of water, more like 4 sink fulls a day. Could we get a smaller tank and save a bit of cupboard space or even an 'on demand' water heater like the shower for example? Or are the costs likely to outweigh and potential benefits. The tank is well insulated and the water is nice and hot even 24 hours later, so I guess there's not that much electricity used in getting the tank up back up to temeperature again.
The most convenient instant water heaters are usually electric so the cost per litre might be more. I imagine tiny gas boilers for sinks are still available though.
I feel an experiment is in order involving your gas meter or your immersion heater. Maybe a measurement too of how much water you actually use from the hot taps in one day. I'm sure someone of your abilities could get to the bottom of this.
Regards,
Chris