how long to programme hot water for?

mr_mitch

So we have a traditional style boiler with a hot water tank that you set on a timer to heat up water at certain times of the day.

Anyway, I was just wondering how long it needs to be set to come on for?

3 adults, we have 2 power showers and a large bath that is used once in a blue moon.

Also how exactly does the hot tank work? Does it just keep heating water until the tank is full? Or does it it simply keep heating water until the timer switches the hot water setting off?

Additionally, would it be more economical to programme the hot water to heat us at times that the boiler is working anyway (for the heating), to have the hot water and heating on at separate times, or does it not make any difference?

matelodave

It depends a bit on the configuration of your heating system. Most relatively modern heating systems have a diverter valve which steers the hot water from the boiler between the tank and the heating system. Some can share the water between the two and others can heat either the tank or the heating but not both at the same time.


Ideally time your hot water heating for when you need it so if you shower in the morning that's when you need hot water. Try it for an hour before you get up and if that's not enough add another half hour.
There's no advantage it keeping the tank hot all day but make sure it's well insulated, put another jacket around it and insulate the pipework between the boiler and the tank to minimise heat loss.


The best way to reduce your water heating costs is to reduce your consumption of it by having shorter showers and not wasting hot water by letting it run down the sink when washing. Wash your hands in cold water rather than hot, short run-offs waste water and leave a gallon or two sitting in the pipework to get cold.

Pincher

Ideally, you want to heat the water up, then use it all up within hours. When heating the cylinder up from cold, the efficiency is very good, because the boiler can output at 60 degrees, and return cold, producing lots of condensation.


If you keep topping up from 60 degrees to 65 degrees, the boiler has no choice but to output at 80 degrees, which returns at 65 degrees-ish, with no condensation at all.


I would heat a whole tank around 4am, and don't heat it again unless the water becomes lukewarm, by stabbing at a BOOST button.

mr_mitch

Thanks both.

We currently have it on for an hour before we get up, obviously for showers in the morning.

Its then on file an hour in the afternoon, because I like to have a shower before bed, and also for the water for washing up, etc.

We never really find ourselves in a situation where we run out of hot water, (unless it's a rare occasion when we fill the bath)... Then the boost button might get a jab!

But I think the tank and pipes are quite well insulated because it stays hot for hours after the timer goes off.

So I was just wondering if reducing the time down in the afternoon a little would save us any money? Or would it just leave us short of hot water?

We seem to be using tonnes of gas, and I can't really understand why! (Besides the obvious cold temperatures)

jbainbridge

You could reduce the time you have it on in the afternoon and see how you get on.

Ours comes on for about an hour before we get up and that's it. We'll have 2 adult showers, general washing up and then a bath for the kids in the evening.

Pincher

If you think about it, you never use the water at 65 degrees.
It is more energy efficient to heat the water up to say 45 degrees, which means you always get condensation during heating.
In this scenario, topping up frequently is not an issue.

The problem is germs. The reason that all plumbers set the cylinder stat to around 61 degrees or more is because there is a chance of germs growing if it's not hot enough.

bnegative

are you sure you need to pre heat the water before taking a shower?

mr_mitch

bnegative wrote: »

are you sure you need to pre heat the water before taking a shower?

Yeah. Fairly sure. It runs off a pump that draws from the hot water tank.

PS, what's all this talk of condensation during heating? Is that a good thing, or bad?

Also, I'd rather have it hot to kill germs. And I like my showers fairly hot!

Pincher

bnegative wrote: »

are you sure you need to pre heat the water before taking a shower?

Love to hear what you are proposing as an alternative.

mr_mitch

Pincher wrote: »

Love to hear what you are proposing as an alternative.

Well the shower we had previously used to heat its water on the fly, so maybe he was thinking it may have been one of those.

It isn't.

System

What you need, if you haven't got one already, is a cylinder thermostat. Basic thermostats wrap around the tank and you can set the maximum temperature (usually 60C). When the tank reaches the set temperature it tells your boiler to shut down irrespective of the timer settings.


http://www.screwfix.com/c/heating-plumbing/cylinder-thermostats/cat831450?cm_mmc=Google-_-Plumbing%20%7C%20Central%20Heating%20Controls,%20Pumps,%20Treatments%20and%20Valves%20%7C%20Generic-_-Cylinder%20Stats%20%7C%20Exact-_-cylinder%20thermostat&gclid=CLTZzM7UxsMCFYXLtAod9VkARA