# Heating hot water Immersion, electric vs gas



## Susie2017 (18 Oct 2017)

Hi. I have a hot press immersion which I switch on at night time for about an hour on night rate to have hot water for the morning. It has broken down three times in the last 11 years since I bought the the house new. Anyway I'm thinking of getting a valve installed so I can use the gas instead. Recently I have seen someone getting a new zoned gas system in their apartment for heating hot water and it seems a faster way of heating water. Is gas cheaper than electric ? Sorry If this is a basic question, I thought I read somewhere that gas is more efficient? I'm not keen on handing over 2 k for the zoned version but how much would it cost to do the valve approximately ? Fed up of electric immersion failure in the morning and impossible to get an electrician where I live.


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## Leo (19 Oct 2017)

Gas is a lot [broken link removed] than electricity.


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## Grizzly (19 Oct 2017)

During the winter we would have our central heating on a few hours a day. It is gas.  This heats up our water. Unfortunately our system does not let us heat up our water boiler separately.

During the summer we have to put the immersion on, to heat up the water.

In ten minutes we have enough hot water for washing. My problem is forgetting to turn the immersion off.


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## Delboy (19 Oct 2017)

On a related note, I have 2 options with my gas heating system...1 for water and 1 for heating the rads. Someone said to me recently that when you have 1 on, you might as well have the other as it won't cost extra to run both- they're both running off the same boiler.
Is that true?


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## Delboy (19 Oct 2017)

sahd said:


> Whoever said that was talking rubbish. Heating the radiators as well as the water tank will use more gas - it's obvious.


Bear with me here as I know nothing about boilers, heating systems etc. So it's not obvious to me.

If the boiler is running for 1 hour to heat the rads, would it not make sense to have the water heating also? Both are coming off of the 1 boiler at the same time.


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## SparkRite (19 Oct 2017)

Delboy said:


> Bear with me here as I know nothing about boilers, heating systems etc. So it's not obvious to me.
> 
> If the boiler is running for 1 hour to heat the rads, would it not make sense to have the water heating also? Both are coming off of the 1 boiler at the same time.



There is no such thing as " a free lunch" as the saying goes, so it stands to reason if you are putting more load on the boiler by heating more water, whether in the rads. or in the cylinder then it stands to reason that more fuel must be used within the given time.

However the extra fuel used to heat the cylinder along with the rads. is smaller than the other way round, ie. if only hot water is required, heating the rads. along with it would use a LOT more, assuming a standard 3 bed with approx. 7 rads..

NB.: This question has "been done to death" in the past here, so a little search will give you loads to peruse.


To the OP, an immersion element should last way way longer than what you are getting out of one, especially if its only on for an hour a day. I have seen them last over twenty years, within family homes, make sure you buy a decent brand. Gas is NOT more efficient for heating water as immersions are in excess of 97% efficient, however the cost per KWhr of gas is definitely cheaper than electricity.


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## shweeney (19 Oct 2017)

re: the relative costs. I pay 4.4c per kW/h for Gas and 14c per kW/h for Electricity, so gas is much cheaper per unit. 

However a gas boiler is unlikely to be more than 80% efficient, and you are also heating the pipes between the boiler and the tank; whereas electricity is more or less 100% efficient and heating the water directly so the difference is slightly less than the unit costs would suggest - gas is still less than half the price though. I think we've used the immersion once in the last 5 years.


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