Point-of-use water heating

paieye

We have got oil-fired central heating, and water-heating to 4 bath-rooms and kitchen. However, even in the winter we seldom use any central heating at all, and, now that the family have grown up and moved away, for weeks and weeks we need only 1 bathroom.

We are therefore considering point-of-use water heating, and should welcome any advice.

dogshome

Assuming you have a reasonably large Hot Water tank that's foam insulated, a 3/4 hour boiler run with 'Hot Water only' selected on the controller will fill the tank with enough hot water for a couple of showers and Kitchen/Hand washing use for an entire day.

rogerblack

Argh - long reply accidentally lost.
In brief.
You pay 7p/kWh or so to heat the watertank with oil.
You're probably wasting at least 2kWh/day keeping the tank hot.
I would be extremely surprised in a large property if most of the hotwater (other than perhaps for showers) is not wasted in running the tap to get it hot. (use a jug to measure your water use into for a day - measure the amount of wasted cold and hot you use)

It does not take much for a point of use heater at (say) 12p/kWh to be a notable saving.

However - http://www.screwfix.com/p/triton-t30i-bq3a3034i-handwash-3kw-oversink-water-heater/92436 - even assuming it saved you 20% (more may be realistic) - you'd need to recover £300 or so to make it pay.
However - http://www.screwfix.com/p/triton-t30i-bq3a7074i-handwash-7kw-oversink-water-heater/28781 - for example - if it saves you 30% - and needs

paieye

Thank you all, most helpful.