Domestic hot water, immersion heater versus oil boiler

Mikex

Currently experiencing dramatic increase in price of Kerosine. Apart from the price increase there is a waiting list for deliveries.

I am wondering with the rising cost of kerosine (currently about £1/litre) when does it become more cost effective to use the immersion heater to heat our domestic hot water.

Please if anyone can help with the calculations I will supply additional information upon request.

My boiler is a Worcester Bosch Danesmoor 15/19 recently serviced so hopefully running quite efficiently. It is fitted with the 17 burner nozzel and according to the manual will use 2.05 litres/hour.

Thanks

Mike

YORKSHIRELASS

Hi, I cant help you with exact calculations but we did this through the summer. We didnt buy any oil from May till November because we switched the boiler off and used the immersion heater.

We didnt notice any increase in electric but we dont use much hot water. We have an electric shower and rarely have baths. We also have a dishwasher so dont do much washing up.

Not sure how it would work in winter, we have got to have the heating on quite a bit anyway with temperatures as they are.

Mikex

Thanks Yorkshirelass,

I thought there might be a boffin or two out there willing to have a go at the calculations. It does seem to be a pretty common sence thing for me to determine bearing in mind the cost of kero & the uncertainty in the supply chain.

The bit of kero we have left is just been used for central heating. We also have a couple of log fires & 20 tons of logs so not panicing yet.

Any offers of help with the calcs?

Thanks

Mike

HappyMJ

Mikex wrote: »

Currently experiencing dramatic increase in price of Kerosine. Apart from the price increase there is a waiting list for deliveries.

I am wondering with the rising cost of kerosine (currently about £1/litre) when does it become more cost effective to use the immersion heater to heat our domestic hot water.

Please if anyone can help with the calculations I will supply additional information upon request.

My boiler is a Worcester Bosch Danesmoor 15/19 recently serviced so hopefully running quite efficiently. It is fitted with the 17 burner nozzel and according to the manual will use 2.05 litres/hour.

Thanks

Mike

Let me see....47kwh in each gallon of kerosene. £1 per litre. Boiler is 85% efficient. Or you could do 19kwh/2.05litres = 9.3kw/litre. That works out at about 10-11p/kwh so if your electricity rate is less than 10/11p then it's cheaper using the immersion.

And to confuse you here's a link....
http://www.nottenergy.com/energy-costs-comparison3

Mikex

Thanks HappyMJ & sorry I have not made my original post clear enough.

When I said the boiler has the 17 burner nozzle fitted this means it is producing 17 Kwh. The boiler output can be altered between 15, 17 and 19 by changing nozzles.

I will try to understand the calcs in due course but if you could refresh them using the new figures I would be most obliged. Also could you advise if you have allowed for the losses due to the inefficiency of the boiler?

Thanks

Mike

Mikex

Right I think I have got my brain into gear.........

2.05 litres of kero produces 17kw

therefore 1 litre of kero produces 8.29kw

However the boiler is only say 80% efficient so....

1 litre of kero actually provides 6.63kw

We pay 13.5 pence for our electricity

13.5p x 6.63 = 89.5p

Therefore if kero is less than 89.5p use kero. (if I can get it)

If more than 89.5 use the immersion heater.

Mike

Cardew

Normal oil for CH contains approx 10.2kWh per litre IIRC.

I thought oil was around 47p a litre??

So for an 80% boiler it would cost just under 6p/kWh

Mikex

Thanks cardew,

Our last delivery of kerosine was around the price you suggest. Up until about 3 weeks ago I could have bought it for around 60 pence/litre.

Now I understand it is around £1/litre. There is a 3 week waiting list for deliveries. As a result of the 3 week delay in deliveries some companies will not quote a price. You just place your order & pay the going rate on the day of delivery. On top of that I doubt the oil company will risk another wagon down our farm track unless the weather improves significantly. They put a wagon in the ditch a few years ago.

It is interesting your quoted figure for kWh from a litre of kerosene varies from the one quoted by HappyMJ.

Mike

HappyMJ

Mikex wrote: »

It is interesting your quoted figure for kWh from a litre of kerosene varies from the one quoted by HappyMJ.

Mike

It's the quality of the kerosene. It could be anywhere around those figures. I got my figure from a table that lists it in gallons. Cardew's is probably closer to the UK average it's very close. I was quite amazed when you said nearly £1 so I did google it and found boilerjuice says the wholesale price is around 70p to 80p...eeek..and excluding VAT too.

http://www.boilerjuice.com/heatingOilPrices.php

Oh...your boiler output is 17kw you don't need to alter it for efficiency so 13.5 * 8.29 = £1.12 per litre or less then use kero rather than electric.

Mikex

Thanks HappyMJ,

I have been mulling it over whether the rated output of the boiler had taken into account its efficiency. It was going to be the subject of another post/thread. Well spotted.

Mike