Heating up the hot water in the tank

(8 Posts)
sparkle9 Sat 12-Jan-13 23:21:27

I posted previously about the heating in my new house and have got the hang of that now.

So I need some help with the hot water now. My previous house had a condenser boiler in the kitchen - no large tank - so it was hot water on demand. My new house is a new build and has a boiler in the kitchen and a large tank upstairs. I believe, from replies to my last post, that it is a modern, high-spec pressurised system. The hot water can be programmed to be on always, off always or to come on and off once, twice or three times a day. It also has a boost function.

So please help. I'm clueless. How many times a day should I set it to go on/off in a day, and for how long? We are a couple, no children. We only use hot water for showers, baths and hand washing etc. We have cold feed dishwasher and washing machine. We usually have either 1 bath and 1 shower or 2 showers in the each evening and sometimes daytime showers.

Any advice?

sparkle9 Sat 12-Jan-13 23:26:02

I just realised what a dull post this is for a Saturday night....

PigletJohn Sat 12-Jan-13 23:47:11

If your cylinder is a white one, it will probably supply two of you with water all day if you run the boiler HW cycle for half an hour or so, morning and evening. Each cycle will probably be enough for one bath and one modest shower. If you can time it to be still running while the bath is run, it will reheat itself while you're splashing about. There is very little to be saved by restricting the timings, but avoid letting it be on all day, as the boiler will tend to run for a few minutes every time you use a sinkful of hot water, which is uneconomical for the boiler. If you find half an hour twice a day is not enough, try an hour, especially if you can overlap onto the main usage times.

This depends on it being 200 litres or so, which they usually are. The capacity may well be printed on the side or on a maker's plate. If not, how tall and how fat is it?

An ordinary copper cylinder, insulated in yellow, green or blue, is typically only about 120 litres, which is about enough for one bath, but if the boiler is on a HW cycle while you run the bath, it will be hot again in about 20 minutes, if the boiler and cylinder are both quite modern.

sparkle9 Sun 13-Jan-13 12:02:13

Thank you for the brilliant answer! It is a white tank and it is 200L. I will try it for just an hour in the morning and evening and see how we get on.

Fluffycloudland77 Sun 13-Jan-13 14:46:37

I'd do half an hour at first, it's not cheap to heat water.

We turn our water stats down to 60, 75c seems to be a standard setting.

PigletJohn Sun 13-Jan-13 14:59:51


but a white cylinder is very well insulated, and as soon as it reaches the set temperature, the thermostat will stop calling for heat and making the boiler fire, even if the timer is still on.

an ordinary modern cylinder, heated by a modern boiler, is hot in 20 minutes, but this white cylinder is about twice the size, and I don't know how big a coil it has.

Agree that 60C is normally adequate, and is hot enough to prevent growth of warm-water legionella. 75C would be scalding

sparkle9 Tue 15-Jan-13 18:23:49

Ooh now how do I set the actual temperature??

The cylinder has a white plastic dial on it and I was told that controls the temperature the water actually comes out the taps. Is this the one?

PigletJohn Tue 15-Jan-13 19:42:29

probably, but you would do best to look at the maker's name and model number on the cylinder, and either download the user instructions from their website, or ask them.

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