Hot water - immersion heater v oil boiler
Discussion
Smallish cottage, heating and hot water currently supplied by oil fired system boiler. Oil fired AGA for cooking but the Aga also keeps the house warm and we only put the heating in the cold winter months. We turn the Aga off 3 or 4 months of the year and use air fryer, micro combi oven and electric hot plate to cook. I have an EV and decent tariff with EDF that gives 7 hours of low cost electricity at 5.5p/kwh each night.
With the alarming cost of heating oil I’m doing my best not to buy any, so looking at options. Man is coming to talk to me in ten days about solar installation, electric Aga, batteries, etc.
However, just as a stop gap is there anything to be gained by not using oil for hot water but using the immmersion heater on a timer, during off peak hours? Is there any way of comparing costs and efficiencies between the two? 5.5p/kWh v £1.15/litre.
With the alarming cost of heating oil I’m doing my best not to buy any, so looking at options. Man is coming to talk to me in ten days about solar installation, electric Aga, batteries, etc.
However, just as a stop gap is there anything to be gained by not using oil for hot water but using the immmersion heater on a timer, during off peak hours? Is there any way of comparing costs and efficiencies between the two? 5.5p/kWh v £1.15/litre.
How much hot water do you use?
If you have a mega turbo powa showa, then you might use lots of hot water if you stand in it for 20 minutes a day.
OTOH, if your shower is not so vigorous and you're fairly quick, the amount of hot water is a whole lot less.
People's hot water consumption varies hugely.
Hot water costs 30p per kWh or so from an immersion, maybe 12 or 15p from oil heating.
But in the summer, firing up the boiler to heat water may be less efficient?
If you have a mega turbo powa showa, then you might use lots of hot water if you stand in it for 20 minutes a day.
OTOH, if your shower is not so vigorous and you're fairly quick, the amount of hot water is a whole lot less.
People's hot water consumption varies hugely.
Hot water costs 30p per kWh or so from an immersion, maybe 12 or 15p from oil heating.
But in the summer, firing up the boiler to heat water may be less efficient?
JoshSm said:
Easy enough to convert both to the same energy units then slap on an efficiency adjustment.
Does depend slightly on where the immersion is - topup or low mounted as one will heat the whole cylinder and the other, well, won't.
Fairly modern Joule unit, low mounted 3kw heater.Does depend slightly on where the immersion is - topup or low mounted as one will heat the whole cylinder and the other, well, won't.
What is the day rate though?
Ours is about 28p/kWh day rate, making the oil cheaper (we have oil heating).
My parents have an electric AGA (and oil CH), it sits in slumber mode which gives a nice background heat, and is then boosted in the morning and evening for cooking. Their electricity bill is huge. They are old and enjoy a warm house and can afford it, but it is huge.
ASHP will give >100% efficiency, but generally gets worse when it is colder.
You will probably need new radiators for ASHP. When I have looked, I have always come to the conclusion installation costs will pay for a lot of oil..
Ours is about 28p/kWh day rate, making the oil cheaper (we have oil heating).
My parents have an electric AGA (and oil CH), it sits in slumber mode which gives a nice background heat, and is then boosted in the morning and evening for cooking. Their electricity bill is huge. They are old and enjoy a warm house and can afford it, but it is huge.
ASHP will give >100% efficiency, but generally gets worse when it is colder.
You will probably need new radiators for ASHP. When I have looked, I have always come to the conclusion installation costs will pay for a lot of oil..
OutInTheShed said:
How much hot water do you use?
If you have a mega turbo powa showa, then you might use lots of hot water if you stand in it for 20 minutes a day.
OTOH, if your shower is not so vigorous and you're fairly quick, the amount of hot water is a whole lot less.
People's hot water consumption varies hugely.
Hot water costs 30p per kWh or so from an immersion, maybe 12 or 15p from oil heating.
But in the summer, firing up the boiler to heat water may be less efficient?
90% of the time there’s only two us in the house, we reckon there the best showers in the world, lots of water, lots of pressure. Wife showers quickly, me not so much. I could measure the flow rate and report back.If you have a mega turbo powa showa, then you might use lots of hot water if you stand in it for 20 minutes a day.
OTOH, if your shower is not so vigorous and you're fairly quick, the amount of hot water is a whole lot less.
People's hot water consumption varies hugely.
Hot water costs 30p per kWh or so from an immersion, maybe 12 or 15p from oil heating.
But in the summer, firing up the boiler to heat water may be less efficient?
CubanPete said:
What is the day rate though?
Ours is about 28p/kWh day rate, making the oil cheaper (we have oil heating).
My parents have an electric AGA (and oil CH), it sits in slumber mode which gives a nice background heat, and is then boosted in the morning and evening for cooking. Their electricity bill is huge. They are old and enjoy a warm house and can afford it, but it is huge.
ASHP will give >100% efficiency, but generally gets worse when it is colder.
You will probably need new radiators for ASHP. When I have looked, I have always come to the conclusion installation costs will pay for a lot of oil..
Pete, peak rate is approx 23.5p kWh. Ours is about 28p/kWh day rate, making the oil cheaper (we have oil heating).
My parents have an electric AGA (and oil CH), it sits in slumber mode which gives a nice background heat, and is then boosted in the morning and evening for cooking. Their electricity bill is huge. They are old and enjoy a warm house and can afford it, but it is huge.
ASHP will give >100% efficiency, but generally gets worse when it is colder.
You will probably need new radiators for ASHP. When I have looked, I have always come to the conclusion installation costs will pay for a lot of oil..
ASHP is a non starter, installation costs too high. I’m thinking of covering the roof in solar panels and using them to run an Aga conversion. Might be nonsense but renewable energy man coming will be able to advise.
Seems sensible to use the cheap rate electricity to run your immersion based on your electricity tariff and current price of oil.
Obviously keep an eye on the respective cost per KWh and choose accordingly. Be careful not to make any expensive/irreversible changes based on the current peak oil prices - longer term averages are obviously much lower.
Edit - pretty exceptional figures on your electricity tariff btw, can't get anywhere near those here.
Obviously keep an eye on the respective cost per KWh and choose accordingly. Be careful not to make any expensive/irreversible changes based on the current peak oil prices - longer term averages are obviously much lower.
Edit - pretty exceptional figures on your electricity tariff btw, can't get anywhere near those here.
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