Conventional Boiler: What is the most efficient approach to heating the water?

Macano

We have just moved into our new home and inherit a conventional boiler. We also inherit the previous settings which means the heating of the water seems to be more or less ongoing. My question is about the efficiency of this: should we have it set 'on' for much of the day, whereby we maintain the temperature at target levels, presumably using regular but smaller bursts of heating to maintain temperatures, or should we turn it off and then use more gas to boost the temperature of the water ahead of the evening. Just really want to ensure we don't get stung when the first bill hits!

Alnat1

It really depends when you need the hot water, how big the tank is and how many people live there.

A family with a couple of teens who shower in the morning, dad after work and mum likes a bath later on, might need the constant top ups or perhaps an hour heating in the morning and again in the afternoon would be enough.

A couple who both have a quick shower after work could probably get away with heating the water for an hour in the afternoon.

You also need to consider how hot you need to heat the water, turning down the temperature will save ££

Macano

Alnat1 said:

It really depends when you need the hot water, how big the tank is and how many people live there.

A family with a couple of teens who shower in the morning, dad after work and mum likes a bath later on, might need the constant top ups or perhaps an hour heating in the morning and again in the afternoon would be enough.

A couple who both have a quick shower after work could probably get away with heating the water for an hour in the afternoon.

You also need to consider how hot you need to heat the water, turning down the temperature will save ££

So confirm that turning down the water would be done on the boiler itself? It's damn hot at present.

RavingMad

There should be a temperature dial on the tank.

I have the water set to come on twice a day (half an hour each time) for our family of 4.  Uses about 8kwh in the winter 

matelodave

As suggested above, you need to work out when you need hot water and adjust the settings to suit. We can get away with heating our tank for an hour or so once a day in the mornings ready for ablutions (two of us at home all day)

There is then enough hot water to last through to the next mornings heating.  TBH there's no benefit in keeping the tank hot all day or all night if you aren't using it.(assuming that you have a tank and its not a combi boiler)

If I leave my hot water on all day, the short   top up boosts double our daily electricity consumption compared with one heating session in the morning (we are all electric with a heatpump so easy to measure). I guess a gas boiler will be similar as they tend to go flat out every time they start up.

If necessary have an evening boost if you are into night time showers/baths as well.

You can also save energy by ensuring that the tank and pipework around it are well insulated. Avoid short draw offs of hot water, especially if you have long pipe runs, letting half a gallon or more of water run down the drain until the hot water arrives leaves the same amount of expensive hot water sitting in the pipes to get cold. - Rinse stuff (including your hands) in cold water. It can also help to fit an eco shower head and take shorter showers or shallower baths to save both water and energy.

Chrysalis

I dont think is a need to heat water all day.  You have 3 choices.

1 - On all day, careless attitude towards cost, but always as hot as possible.  How much more expensive it will be, dont know, but it will be the most expensive route. 
2 - On a timer to fit the usage of the household, so maybe hour or two a couple of hours before people use shower in morning.  Maybe similar in evening if need for baths. 
3 - On demand, no automation, just turn it on an hour or two manually before you know you need it, cheapest but least convenient.

QrizB

During heating season, I run my hot water timings to match the heating ones. If the boiler is going to be running anyway, pumping the water through the coil in the tank isn't going to need any extra electricity and the heat lost from the tank will mostly end up reducing the heating demand.

Out of heating season, I set it to heat the tank once, in the evening, to let people bathe, shower and wash dishes. If the tank runs cold during the daytime I'll advance the programmer for an hour or two manually.

FreeBear

Chrysalis said: 3 - On demand, no automation, just turn it on an hour or two manually before you know you need it, cheapest but least convenient.

This is what I used to do with my vintage Baxi back boiler. Also turned the gas off at the meter during the summer months so that I didn't have the pilot light running 24/7.

If @Macano has a modern boiler, there shouldn't be any need to go to the lengths I went to. Assuming it is a fairly recent condensing boiler that can vary the flow temperature on the fly, it would be worth looking to see if it is set up for priority domestic hot water - This allows the boiler to run at a lower flow temperature for central heating (good for efficiency), and ramping up just for hot water.

Reed_Richards

Macano said:

Alnat1 said:

It really depends when you need the hot water, how big the tank is and how many people live there.

A family with a couple of teens who shower in the morning, dad after work and mum likes a bath later on, might need the constant top ups or perhaps an hour heating in the morning and again in the afternoon would be enough.

A couple who both have a quick shower after work could probably get away with heating the water for an hour in the afternoon.

You also need to consider how hot you need to heat the water, turning down the temperature will save ££

So confirm that turning down the water would be done on the boiler itself? It's damn hot at present.

The temperature control might be on the tank or it might be a function of the controller you use for your heating.  If your boiler has a temperature control that will be the output water temperature so primarily for your central heating.

Macano

Thank you to everyone for the feedback. At one stage, I thought it was a combi boiler with a redundant water timer switch, but realised it didn't have a pressure gauge, and then I managed to find the tank. Access was actually via a door on the side of the house which we didn't have a key for. Talk about a detailed hand over from previous owners! Amazingly the timer for the water heating was set for about 12 hours a day when we moved into the house, and I have calibrated to two hours in the morning and two in the evening as this is when showers, general use would cover.  I have also turned the temperature right down.