Combi boiler hot water costs

[Deeebs]

I've always had the hot water set to off on my boiler as the hot water works regardless. After the £367 invoice I received this morning, I'm thinking is this energy efficient? We don't use the hot water at set times, it's very random.

Are you sure you don't have something else heating up your water if it's hot even when turned off, maybe an old hot water tank in the loft instead?

I had both my hot water and heating turned to the minimum temperatures between May and November as we use a dishwasher or an electric show and my bill was less than £10 a month, this included when I occasionally turned the hot water and ran it above 60 degrees to avoid legionnaires etc. Even with the heating on now my bill isn't more than £80 for 4 radiators on when we are home.

electric shower

No tanks... I don't have a loft as it's a room, so definitely nothing up there.
My boiler is a Worcester and it's only a few years old. It's always been set to off and the hot water always comes on when I turn the hot tap on, so I thought I'd just keep it set to off!
After this month's ridiculous bill I'm determined to not put my heating on at all this month, and use as little hot water as possible.

I think you’re referring to the comfort mode where a small amount of hot water is kept in the boiler to supposedly come out of the tap warm straight away. I tried it once and it doesn’t really seem to make much difference to how quickly you get hot water if it’s a tap far from the boiler. I think it’s more economical to have it turned off (which is called eco mode on our boiler).

Hmm not sure it's this as I can run a full boiling hot bath. It has never run out.

Any boiler experts out there? @pigletjohn ?

Cost of hot water with a modern gas boiler is very low, I doubt it would cost £367 over an entire year.

Cost of heating a house is much more.

Please post photos of your boiler with closeup of the knob you are setting to "off"

Thank you @PigletInABlanketJohn

I have no idea why I'm getting hot water when it's permanently set to off

But that’s with it set to off? That just means it functions as a normal combi boiler and heats the water on demand when you turn the tap on.
If it didn’t do that your boiler would be broken.
I don’t think you can turn hot water off on a combi boiler , just the comfort setting that I described above.

That's says the boiler is on the Eco setting

www.worcester-bosch.co.uk/support/troubleshooting/faqs/all-faqs/why-might-i-want-to-programme-hot-water-times-with-my-combi-boiler

The eco setting is heating I think?

The link implies your boiler is fancier than mine. When the hot water is off it fires only when tap is turned. But you can programme the pre-heat time to only be on at certain times of the day (eg when you are in and using hot water more often) or to be on all the time. We can only have our pre-heat setting on or off.

I'm just wondering whether it's more cost efficient to have the hot water on a timer, as opposed to heat as you go.

Good to know that hot water isn't the main culprit though @PigletInABlanketJohn
I think I need to just not use my heating. £367 per month will total me!

I think it’s cheaper to heat as you go. The cheapest is just to use cold water for washing hands etc as it takes ages to heat the water enough to wash in warm water when you only wanted warm water for a very short period.
however in the summer our gas bill was only £15 a month so I don’t think hot water contributes that much to the bill compared to heating.

Thank you @User963 That's what I was hoping to hear. Thought I'd stitched myself right up for the past few years!

Our gas bill was also very low in the summer, little more than standing charge, we have no other gas appliances

That's not off, that's set to cool, which is 40C which is why you're still getting hot water. That means your boiler isn't running hot enough to kill of legionnaires disease etc. it's a bad idea.

Last month was very cold all over the country so you will have used more gas if you used your heating.

October and November was warmer than normal in a lot of places. If you were in one of those places your gas usage would have been lower than normal for that time of year.

Added with the price increases over the last 18 months it means your gas bill in the colder period would be larger than would you would normally have.

All the advice is that if don't have a hot water tank you can go down to 60-55 degrees C

energysavingtrust.org.uk/should-i-turn-boilers-flow-temperature-down/

There isn’t a risk of legionnaires with a combi boiler and no water tanks.

@pigonalipstick I only turned it down today when I received my bill this morning! Its usually set a lot higher. I will whack it back up again then.
To be fair, the water is still very hot when it's turned right down.