CH or gas fire?

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The problem with trying to work out the running cost of CH is that outside temperature and prevailing wind are key factors and they change all the time. You would need to work it out for all temperatures and adjust accordingly, which is not really feasible.

One interesting thing I discovered a while back. My hot water was always on for an hour in the mornings. I decided to drop it by 15 minutes to see what happened? In theory, not much should happen - the cylinder is high quality with V low standing loss - but in fact there was a definite drop in gas usage. Initially I thought I'd reduce it by another 15 minutes, but in the end I thought sod it, I'll reduce it to the minimum - 15 minutes - and put it back up if anybody complains about the hot water. Well, no complaints and the gas usage dropped again. That was about four months ago and gas usage went from an average of £1.15 per day to 60p per day. That is checked by energy monitor and there is nothing else in the house using gas, so is pretty accurate. That's two hundred quid a year saved. There are three adults in the house.
 
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The problem with trying to work out the running cost of CH is that outside temperature and prevailing wind are key factors and they change all the time. You would need to work it out for all temperatures and adjust accordingly, which is not really feasible.

One interesting thing I discovered a while back. My hot water was always on for an hour in the mornings. I decided to drop it by 15 minutes to see what happened? In theory, not much should happen - the cylinder is high quality with V low standing loss - but in fact there was a definite drop in gas usage. Initially I thought I'd reduce it by another 15 minutes, but in the end I thought sod it, I'll reduce it to the minimum - 15 minutes - and put it back up if anybody complains about the hot water. Well, no complaints and the gas usage dropped again. That was about four months ago and gas usage went from an average of £1.15 per day to 60p per day. That is checked by energy monitor and there is nothing else in the house using gas, so is pretty accurate. That's two hundred quid a year saved. There are three adults in the house.
surely the boiler only uses gas to heat the water up to temperature, and doesn't stay on after it has done that, regardless of whether it takes 2 , 5 15, 30, 45 or 60 minnutes?
 
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One interesting thing I discovered a while back. My hot water was always on for an hour in the mornings. I decided to drop it by 15 minutes to see what happened? In theory, not much should happen - the cylinder is high quality with V low standing loss - but in fact there was a definite drop in gas usage. Initially I thought I'd reduce it by another 15 minutes, but in the end I thought sod it, I'll reduce it to the minimum - 15 minutes - and put it back up if anybody complains about the hot water. Well, no complaints and the gas usage dropped again. That was about four months ago and gas usage went from an average of £1.15 per day to 60p per day. That is checked by energy monitor and there is nothing else in the house using gas, so is pretty accurate. That's two hundred quid a year saved. There are three adults in the house.

The only way that hangs together, is if the boiler is frequently firing up to replace hot water which is actually used, or if your cylinder is particularly badly insulated.
 

JohnD

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Unlike Freddy, I generally wear natural fibres.

The last woollen garment I bought was last Thursday, though it does have a lining made from cellulose.
 
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JohnD

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The problem with trying to work out the running cost of CH is that outside temperature and prevailing wind are key factors and they change all the time. You would need to work it out for all temperatures and adjust accordingly, which is not really feasible.

One interesting thing I discovered a while back. My hot water was always on for an hour in the mornings. I decided to drop it by 15 minutes to see what happened? In theory, not much should happen - the cylinder is high quality with V low standing loss - but in fact there was a definite drop in gas usage. Initially I thought I'd reduce it by another 15 minutes, but in the end I thought sod it, I'll reduce it to the minimum - 15 minutes - and put it back up if anybody complains about the hot water. Well, no complaints and the gas usage dropped again. That was about four months ago and gas usage went from an average of £1.15 per day to 60p per day. That is checked by energy monitor and there is nothing else in the house using gas, so is pretty accurate. That's two hundred quid a year saved. There are three adults in the house.

I think that will be top-up. It's very inefficient to heat a hundredweight of boiler, pipes and water for five minutes every time you run a tap ( combis are worse) and then let it go cold. Modern cylinders are usually big enough that they only need to be heated once or twice a day, with one sustained firing of the boiler. In this house, Summer gas usage is HW only. My last gas bill was less than 50p a day. Pipes are short and well-lagged.
 
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As JD says, the only possibility is the boiler firing occasionally to top the temperature up. Cylinders always have some standing heat loss - the loss for good quality cylinders is stated in the specification. Mine is a good one and the standing loss is low, but there is always some loss. The pipework also dives under the floor and the floor is always warm - the cat loves it. The boiler is therefore firing occasionally to top up the loss - what is surprising is the amount of gas used in an hour to do that. As I said, I wasn't really expecting a measurable difference but it definitely is.
 
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Gas usage.jpg
 
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Dont forget the cold water entering your cylinder will be far warmer in the summer than it is in the winter so more gas required in winter to heat it which will eat into the savings you think you are achieving
 
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I've asked this before, but some time ago. Living room gas fire is almost unused and I'm wondering whether this winter I should make more use of it, and limit use of CH as a way to save on gas consumption?

CH heats nine radiators, in nine spaces, all but one fitted with TRV's, with a compensated controller. Gas fire is an old triple radiant type giving a choice of 3 lit or just 1, and the place is well insulated.
If you only want to heat the room containing the fire, then use the fire. It can be up to 85 - 90% effucient, but drops a bit when on low.

Dependant on room dize, it will jor be on 3kw for long, most will drop it down towards the lowest setting after z reasonably short period.

I use to have customers complaining complaining that low was too high - although that tended yo be coal effects
 
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If you only want to heat the room containing the fire, then use the fire. It can be up to 85 - 90% effucient, but drops a bit when on low.

Dependant on room dize, it will jor be on 3kw for long, most will drop it down towards the lowest setting after z reasonably short period.

I use to have customers complaining complaining that low was too high - although that tended yo be coal effects
Still having trouble with your eyesight ;)
 
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If you only want to heat the room containing the fire, then use the fire. It can be up to 85 - 90% effucient, but drops a bit when on low.

Dependant on room dize, it will jor be on 3kw for long, most will drop it down towards the lowest setting after z reasonably short period.

I use to have customers complaining complaining that low was too high - although that tended yo be coal effects
Old 3 radiant fire at 90% eff? Has someone put a flagstone in place of the pot lol.
 
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Old 3 radiant fire at 90% eff? Has someone put a flagstone in place of the pot lol.

I've managed to find a manufacturers spec. for the fire and it suggests 84% which is much higher than I would have expected. I'm sort of thinking in terms of nudging the CH program down a couple of notches, combined with making use of previously never used radiant gas heater. I've run it on low for a couple of evenings, during the week - I always as a matter of habit read and log in a spreadsheet, all of my meter readings and it's use made absolutely no increase in gas consumption, beyond what was used for the boiler running the water heating.
 
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I've managed to find a manufacturers spec. for the fire and it suggests 84% which is much higher than I would have expected. I'm sort of thinking in terms of nudging the CH program down a couple of notches, combined with making use of previously never used radiant gas heater. I've run it on low for a couple of evenings, during the week - I always as a matter of habit read and log in a spreadsheet, all of my meter readings and it's use made absolutely no increase in gas consumption, beyond what was used for the boiler running the water heating.
What model is it?
 
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