Hot water tank - efficient use?

penyjen

Hi, newbie so please be kind!

I’ve just moved in to a rental house with a hot water tank and I’d be grateful for any advice on the most efficient way to use it.

How long should I set the boiler to come in for to heat the whole tank? And how long will the tank stay hot for? At present I’ve got it set to come on 6am - 6:30am and 4pm - 4:30pm.

We’re a family of 2 adults, 2 short showers 6:45am, 1 shower 6pm, hand washing dishes.

I’ve lived in houses with a combi-boiler for a decade now so this is a step backward in money saving!

penyjen

Test: just worked out how to set up thread notifications I think.

Robin9

Do you run out of hot water ? Are you on E7 - if so don't bother with the afternoon setting but extend the early morning to say 0500 -0700.

If on E7 use as much at night as you can.

How is the house heated - storage rads ?

penyjen

House is heated with standard radiators but the heating programming is completely separate (and indeed the central heating is off for the next few months!). This is just for the hot water.

Forgive my ignorance but wouldn’t hearing the hot water tank for 2 hours in the morning (05:00-07:00) be more expensive than heating it for half an hour morning and half an hour afternoon as I currently have?

Blackbeard_of_Perranporth

I have run our hot water twenty minutes in the morning and ten in the evening pretty well for thirty years. Never run out!

Takmon

penyjen wrote: »

House is heated with standard radiators but the heating programming is completely separate (and indeed the central heating is off for the next few months!). This is just for the hot water.

Forgive my ignorance but wouldn’t hearing the hot water tank for 2 hours in the morning (05:00-07:00) be more expensive than heating it for half an hour morning and half an hour afternoon as I currently have?

Robin9 is assuming you are on an E7 tariff and have an electric boiler. If that is the case then heating in the morning will be cheaper due to the lower electricity rate and also heating and maintaining the temperature for 2 hours could be cheaper than heating from a lower temperature twice a day.

But it sounds like you have a Gas Boiler to me?

Robin9

Takmon wrote: »

Robin9 is assuming you are on an E7 tariff and have an electric boiler. If that is the case then heating in the morning will be cheaper due to the lower electricity rate and also heating and maintaining the temperature for 2 hours could be cheaper than heating from a lower temperature twice a day.

But it sounds like you have a Gas Boiler to me?

My presumption re Electric and E7 is wrong - it looks like a conventional gas boiler.

Mister_G

OP - it really will depend on you use and how well insulated your hot water cylinder is.

If it is well insulated then any hot water not used in the morning will still be there for later use (to a certain extent).

I suggest you try it for the shorter times and see if you run out. If you do, then just extend the time.

penyjen

Yes, gas boiler.

I’ll give it a try on shorter heating time and see how we get on. I hate wasting money but I also hate cold showers!

Biggus_Dickus

penyjen wrote: »

Yes, gas boiler.

I’ll give it a try on shorter heating time and see how we get on. I hate wasting money but I also hate cold showers!

In agreement with ‘Mister G’ post #8,... It depends greatly on how well your hot-water tank is insulated and where in the property (warm/cool/cold) it’s situated.

There is little value in heating too much water in the morning (or evening) just for it to go cool or even cold during the day (or night). If you are not wary your hot-water tank could become, in effect, an unwanted radiator that loses heat (money!) in an area of the house that doesn’t benefit from that radiated heat.

It’s probably a case of trial and error to see which heating regime best suits your lifestyle.

However, by far the most important thing is to have a well insulated hot water cylinder/tank. Modern tanks have a hard-foam insulating layer that is applied to the entire outer surface of the tank during the manufacturing process. Older tanks may have ‘jacket’ type lagging/insulation which is generally not as efficient as foam but if properly fitted is still quite good.

As for the cost of heating your hot water tank as compared to a combi:...I reckon that if you manage your hot-water heating regime efficiently then it needn’t be more expensive than running hot-water from a combi,...indeed it may work out cheaper! :money:

WobblyDog

In my house the gas boiler is only started once per day, in the morning, to heat the hot water cylinder, but I don't use a lot of hot water. I think that's slightly cheaper than running it twice per day like I used to, and the cylinder still gets hot enough to kill bugs.

I do sometimes wonder if it would be cheaper to set the boiler to run in the afternoon, when the air drawn into it is likely to be warmest, but I suspect the saving would be small.