Cheaper to heat water continually or when needed?

longwalks1

we have a 3 bed semi with a boiler downstairs (old, about 12 years old) with a copper cylinder (with red jacket on) and 2 water tanks in the loft. Had a new valve fitted to the cylinder when we moved in to switch between hot water and heating (it was faulty). I asked the plumber about setting the timer up, he said as only 2 of us live here, its probably cheaper to leave the hot water on continually, so it switches on and off lots of times a day to just keep the cylinder up to temperature, instead of only heating it when we need it (every morning). As it would mean heating a full cylinder of cold water, does this make sense?

I'm unsure of whats more cost effective?

Thank you

macman

Your plumber is entirely wrong, the longer the tank is heating, the more it will cost you. A properly lagged tank will not lose too much heat in a day, and that heat is not 'lost', but warms the house in the heating season.
Would you keep your kettle 'on' all day on the chance that you wanted a cup of tea? It's no different.
A modern CH system should have a proper digital programmer controlling both the CH and the hot water, so if you have one, use it.
The norm would be to set the DHW to come on early in the morning and then again at night, the tank 'stat will then call for heat as required.

JJ_Egan

Problem is tank full of hot water you use some and replace it with cold water .
Do you really need hot water 24 hours a day .