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Original poster

Please help clueless me understand if i’m wasting money on heating water

67 replies

Brokenbuttercup · 31/08/2022 18:03

Sorry if this is a stupid question but I’m a but clueless when it comes to house stuff (stbxh always sorted such things and I really don’t want to ask him!)

I have a system boiler with a gas boiler in the kitchen, a large water tank in the airing cupboard and a digital thermostat in the hall. It’s a new build house, and as such it’s pretty warm and doesn’t need a lot of heating. I’ve set the thermostat to standby meaning the central heating is essentially off but will guard against frost damage. Hoping to keep this off until we get to the real depths of winter.

The bit I’m struggling to understand is the hot water. My boiler is permanently on and I therefore always have a full tank of hot water. The tank is massive and I really don’t need that volume of hot water. Should I be setting a timer for my hot water? Is it constantly using gas to keep the tank full and heated or does it just top up hot water once I have used some? I’m not sure if not using any of the water to heat the radiators actually makes any difference to the amount of gas I use if it’s in the tank already and constantly being heated??

I have tried Google but it’s hurting my head. Can anyway explain how it works in layman’s terms please??

OP posts:
DahliaMacNamara · 31/08/2022 18:07

It sounds like mine, though mine's pretty old. You need the water on a timer if it's heating up a water tank.

SamLane · 31/08/2022 18:08

Thank you for asking this - sorry I'm no help. I got to thinking the same when I realised id turned the hot water off when we were away for two nights, hadn't turned it back on and have been washing/showering in warm water for a day.

I never know whether the water heating should be on all the time, kept at temp. through intermittent heat or just heated at the times when it is used ( morning and night)

Littlepies · 31/08/2022 18:10

My set up is similar to yours and it’s a new build. I must admit I’m confident in the heating system but have no idea about the hot water. Earlier in the week I set hot water on a timer for four hours a day instead of being on all of the time. So far that gives me enough hot water for our daily needs… although I’m not sure if there are cost savings in doing this, perhaps if it’s on all the time it’s not using much electricity because it rarely drips under the required temperature in the tank?! Following with interest!

Pootle40 · 31/08/2022 18:11

Brokenbuttercup · 31/08/2022 18:03

Sorry if this is a stupid question but I’m a but clueless when it comes to house stuff (stbxh always sorted such things and I really don’t want to ask him!)

I have a system boiler with a gas boiler in the kitchen, a large water tank in the airing cupboard and a digital thermostat in the hall. It’s a new build house, and as such it’s pretty warm and doesn’t need a lot of heating. I’ve set the thermostat to standby meaning the central heating is essentially off but will guard against frost damage. Hoping to keep this off until we get to the real depths of winter.

The bit I’m struggling to understand is the hot water. My boiler is permanently on and I therefore always have a full tank of hot water. The tank is massive and I really don’t need that volume of hot water. Should I be setting a timer for my hot water? Is it constantly using gas to keep the tank full and heated or does it just top up hot water once I have used some? I’m not sure if not using any of the water to heat the radiators actually makes any difference to the amount of gas I use if it’s in the tank already and constantly being heated??

I have tried Google but it’s hurting my head. Can anyway explain how it works in layman’s terms please??

We have same system also fairly new home. We just had both tank and boiler replaced after 14 years since house built. I have just changed it over to a timer for the hot water as like you I had it 'on' all the time. We have a huge tank so I now have hot water on for 1 hour around waking and 1 hour at night. Going to see how that goes but figure it must cut back gas use slightly !

FusionChefGeoff · 31/08/2022 18:15

I'm no use I'm afraid but worth thinking about the energy needed to take something from cold to hot (a lot!!!) vs to keep something warm.

The same argument applies to heating the house and I've never found a solid answer if it's better to keep a steady 19 degrees or drop to 5/10 overnight then reheat the whole house...

icantworkout · 31/08/2022 18:17

FusionChefGeoff · 31/08/2022 18:15

I'm no use I'm afraid but worth thinking about the energy needed to take something from cold to hot (a lot!!!) vs to keep something warm.

The same argument applies to heating the house and I've never found a solid answer if it's better to keep a steady 19 degrees or drop to 5/10 overnight then reheat the whole house...

I was about to say this - ours is set to come on twice a day but it only comes on for about half an hour max to bring it back up to temperature. What you can do to save energy is make sure you're not heating it up too high (sounds obvious but you don't need boiling hot water as you just add cold to make it useable for showers etc)

Damnautocorrect · 31/08/2022 18:17

Is your tank well insulated?

Damnautocorrect · 31/08/2022 18:18

It’s not advisable to turn the water down too much with tank systems as you need it to kill legionnaires etc

Original poster
Brokenbuttercup · 31/08/2022 18:19

@SamLane interesting that you still have even warm water after 2 days. Makes me think i can probably just have it on in the morning and still get a hot bath for my ds in the evening

@Littlepies thats exactly what I don’t get! Gut instinct tells me it must be cheaper to be on less but maybe it burns more getting it back up to temp

its reassuring to know I’m not the only one who doesn’t know this stuff 😂

OP posts:
Original poster
Brokenbuttercup · 31/08/2022 18:21

@Damnautocorrect i think so. Not sure how I would check other than turning it off and seeing how quickly the water goes cold. It’s only 3 years old so I would Imagine it is

OP posts:
BattyChatelaine · 31/08/2022 18:22

Ours used to be set to come on for a couple of hours in the morning and the same in the evening. We've recently changed it to just mornings and not noticed a difference in water temperature in the evening although maybe that will change when clubs start again and my DC are showering in the evenings more.

Nolongera · 31/08/2022 18:22

Do you have a handbook for it?

isthismylifenow · 31/08/2022 18:23

I have a hot water geyzer which runs off electricity. Not in UK so it's not linked to any heating system, for hot water only.

There has been a lot of discussion lately over whether it works out cheaper to run it on a timer, or leave it on all the time. It turns out it costs more in electricity to have it on a timer, it uses more power to heat the water from cold (or even warm) over the thermostat kicking in every now and then to keep it at the same temp.

On top of that, turning it on and off all the time puts so much more wear on the element. So the advice to us is to lower the temp of the water to 50 degrees and leave it on.

Original poster
Brokenbuttercup · 31/08/2022 18:26

@Nolongera good question. Will have to take a deep breath and have a hunt around in the cupboard of crap, aka my filing system

OP posts:
CatNamedEaster · 31/08/2022 18:27

We have ours timed for 30 mins in the evening. That gives us enough for washing up and a bath (don't bath every night obviously, but on a night when I've had one, it's been hot enough after having done washing up.)

If I need to use a sink of water in the morning for wash, it will still be warm enough from the night before.

Hugasauras · 31/08/2022 18:27

Yep, timer! We have ours on for an hour a day and just boost it if we think we will need more.

FormerlySpeckledyHen · 31/08/2022 18:29

Our’s is on for 2 hours from 5-7am and we never run out of hot water. Enough for 2 showers/baths in the morning, one bath in the evening and all normal daily use.
We cook with gas too and the bill this month was £42.20

Read your meter for a few days and make a note. Then set the timer for a couple of hours and monitor again to establish the difference.

Original poster
Brokenbuttercup · 31/08/2022 18:30

I think I might just have to test it out for a month and see if it makes a difference. I guess there is probably a few different factors at play

OP posts:
bigbluebus · 31/08/2022 18:37

Our hot water is on for 2 hours in the morning and 2 hours in the evening. We usually shower in the mornings and even if we get up early before the hot water comes on there is still enough hot water in the tank from the previous day's heat. Our hot water tank is well lagged. Tbh I was thinking if reducing the time on the clock for the hot water as we don't really use a full tank - no one has a bath now - which was the only thing that used up all the hot water.

Lottsbiffandsmudge · 31/08/2022 18:43

Our upstairs socket electric went off due to a fault recently and I didn't realise it had also affected the hot water timer until we ran out of got water after 2 days! Modern hot water tanks have excellent insulation.

ValerieDoonican · 31/08/2022 18:46

Re the question of keeping hot rather than intermittent heating, with a hot water tank heated by gas, its definitely worth heating on a timer, because you can fine-tune (by trial and error) to heat just the hot water you need.

If the tank is always fully hot (as now), you are heating water that you aren't going to use, that slowly cools down, letting heat into the house, so you have to replace that heat (that in summer in particular, you don't want!) by burning more gas.

If your boiler has a temperature dial (on the boiler, not the thermostat on the wall) then if you turn that to about 60* your water will be hot enough (ie too hot unless mixed with cold, but also legionella safe) and the boiler actually burns gas more efficiently than if it's set hotter.

*You might need to tweak the knob up a degree or two more if the boiler keeps repeat firing in its 'on' period, as the water tank will be set to heat to 60 for legionella protection, and if the tank is only at 59 it might keep hassling the boiler for more heat...

Franca123 · 31/08/2022 18:50

1 hour in the morning for our showers. Then 30 mins early evening for kids bath and washing up. We boost for an hour if we have guests or are doing lots of cooking.

Darkness22 · 31/08/2022 18:58

Literally just had British Gas engineer here and asked him the same question! He said few hours in the morning and a few in the evening.

Middledazedted · 31/08/2022 19:03

Have moved ours to heat for two hours a day - has saved me a fortune. Largely through this one change my fuel bill has reduced in comparison to the norm - and that’s after the first increase!

mumda · 31/08/2022 19:03

Reduce time until it's not enough.