How long should I have my hot water coming on a day?

[BrianCox]

I guess it all depends on the number of people living in a property and whether you have a shower everyday etc. But what's the recommended time I should have my hot water coming on a day. My local plumber stated an hour in the morning and an hour in the evening - seems excessive to me. Any thoughts?

 

[ShaunCorbs]

Yes I would agree with him but it’s what’s best for you even if you put it on and the hot water is hot the boiler shouldn’t come on

 

[king of pipes]

The simple answer is experiment ? and hour twice a day is not excessive in my view , once your cylinder is satisfied the boiler will turn off anyway

 

[Chuck]

If you've got a reasonably modern well-insulated cylinder its losses are a small fraction of the cost of producing hot water so there is no point trying to overthink this problem. Any hot water you don't use on one day will cause the cylinder thermostat to shut the boiler down before the next programmed period is complete.

If you get up at 0700 and have your heating coming on at 0630 I'd start with the programmer coming on for an hour at 0530 to flatten the demand on the boiler. If you find you're short of hot water in the evening then programme a top up period in the late afternoon.

 

[Ric2013]

Ideally heat the water before you make your greatest demand on it for the day, but as Chuck says, with an insulated cylinder it doesn't really matter what time of day you heat. (Depending on the system, it might be argued to be better to choose a time when the boiler is already running due to having the heating on, but some systems won't heat both radiators and cylinder at the same time, so in that case, this isn't a possibility.)

Personally, I'd suggest to set the programmer to heat water once a day for however long it takes for the system to heat a cylinder from stone cold to fully heated (the time it takes for the boiler to switch off). That way, if the cylinder is already part-warm from the previous day, the system will just switch off a bit earlier but you're heating the water through to an hygienic temperature every 24 hours and any more than this is usually overkill.

Unless you are regularly running out of hot water, this is enough. If you have visitors and you run out of hot water on those occasions, then perhaps you need an extra heating period just when you have visitors.