Cheaper to use electric immersion heater ?

w50nky

I believe cardew is correct. When my oil boiler was serviced the airflow and pump pressure are adjusted. The engineer stated that the "burner" was operating at its best efficiency for complete combustion according to his gas analyzer.
I suppose then it comes down to how well this heat is transfered into the surrounding water in the boiler water jacket and what escapes via the flue.

Mickyp

I heat my water with an immersion heater, tank size is 210 litres, I recon it costs about £1 a day to heat the tank.

Incidentally, I was origionally on E7, but it worked out cheaper to be on a normal tariff as the use during the day was that high. Must be the 50" TV!

SD-253

My electric tarrif is
Online Energy Reward from ScottishPower
Unit prices
Electricity 19.56p per kWh (day) for the first 900kwh per year but charged per quarter IE first 225 kwh per quarter
6.72p per kWh (day) above 900 kWh p.a
3.16p per kWh (night)
All prices shown are inclusive of V.A.T. at 5%
Therefore the standing charge equivalent is £9.63 per month (19.56p - 6.72p = 12.84p x 900 = £115.56 divide by 12 = £9.63 per month)

This does not include the Online energy rewards of £63 paid to everyone who took out this tarrif NO MATTER HOW MUCH YOU USED. As my bill is £21 a month that means you have to reduce all charges by 25%. Clearly a loss making tarrif (at least in my case).
This last till July. If I changed now the day rate would rise to over 10p but the night rate is almost identical as is the standing charge (equivalent).
My LPG is 47p a litre assuming my 4 year old boiler is giving me 90% efficency then I am looking at 7.34p KwH while electric is 3.16p per kWh (night) Electricity a clear winner. But I only use E7 for environmental reasons (large amounts of electricity are unused/wasted at night) Therefore as it is said that you need to use 20% of electricity at night and I rarely manage that then I am on loss maker? Not of course true as the replacement tarrifs shows.
Note this does not take into account that there are so many tarrifs available at each company that at times the day rate can actually be cheaper on E7 than without E7. IE you cannot lose by being on it. You would of course still be on a winner if it was the same?
Now I have in fact failed to mention that I do not actually use any hot water electric or otherwise (LPG boiler is not a combi) as everything I have is cold water fill IE Shower washing machine and my rarely used dishwasher. If I did use my E7 to heat the immersion then I would definatly be above 20%

Below is a site for a new type of system called an Accumulator hot water tank this allowes you to put any amount of hot water sources onto the same system ie solid fuel, gas, oil, solar thermal panels and as it is in a hot water tank E7 electric. The loss of heat is 2 degrees centigrade per 24 hours or as you are actually going to use it before the 24 hours is up then probably only 1 degree C. I am looking into it as I am on LPG and eventhough 47ppl is good E7 is a lot cheaper.

NOTE LPG GIVE YOU 7.11 KwH PER LITER AND OIL 10.35 PER KwH BOTH ASSUMING THE IMPOSSIBLE 100% EFFICIENCY
ALSO IF YOU ARE ONLY USEING ELECTRIC (HEATING ETC) THEN YOU WOULD HAVE TO REMOVE THE STANDING CHARGE FROM YOUR CALCULATIONS AS THAT WOULD BE DOUBLE COUNTING (IF YOU HAD OIL GAS ETC YOU WOULD STILL HAVE AN ELECTRIC STANDING CHARGE)
http://www.stovesonline.co.uk/wood_burning_stoves/Accumulator-hot-water-tanks.html

PS best value should take into account how much heat you lose before you use. IE if you don't use most or any heat till night time then a standard insulated tank will have lost a lot of heat. Therefore my 3.16p per kWh is not accurate......the same you could say as a boilers lack of 100% efficency?

http://www.stovesonline.co.uk/wood_burning_stoves/Accumulator-hot-water-tanks.html

Cardew

SD-253 wrote: »

My electric tarrif is
Online Energy Reward from ScottishPower
Unit prices
Electricity 19.56p per kWh (day) for the first 900kwh per year but charged per quarter IE first 225 kwh per quarter
6.72p per kWh (day) above 900 kWh p.a
3.16p per kWh (night)
All prices shown are inclusive of V.A.T. at 5%
Therefore the standing charge equivalent is £9.63 per month (19.56p - 6.72p = 12.84 x 900 = £115.56 divide by 12 = £9.63)

This does not include the Online energy rewards of £63 paid to everyone who took out this tarrif NO MATTER HOW MUCH YOU USED. As my bill is £21 a month that means you have to reduce all charges by 25%. Clearly a loss making tarrif (at least in my case).
This last till July. If I changed now the day rate would rise to over 10p but the night rate is almost identical as is the standing charge (equivalent).
My LPG is 47p a litre assuming my 4 year old boiler is giving me 90% efficency then I am looking at 7.34p KwH while electric is 3.16p per kWh (night) Electricity a clear winner. But I only use E7 for environmental reasons (large amounts of electricity are unused/wasted at night) Therefore as it is said that you need to use 20% of electricity at night and I rarely managed that then I am on loss maker.
Note this does not take into account that there are so many tarrifs available at each company that at times the day rate can actually be cheaper on E7 than without E7. IE you cannot lose by being on it. You would of course still be on a winner if it was the same?
Now I have in fact failed to mention that I do not actually use any hot water electric or otherwise (LPG boiler is not a combi) as everything I have is cold water fill IE Shower washing machine and my rarely used dishwasher. If I did use my E7 to heat the immersion then I would definatly be quids in IE well above 20%
Below is a site for a new type of system called an Accumulator hot water tank this allowes you to put any amount of hot water sources onto the same system ie solid fuel and gas oil and as it is in a hot water tank E7 electric. The loss of heat is 2 degrees centigrade per 24 hours. I am looking into it as I am on LPG and eventhough 47ppl is good E7 is a lot cheaper.

NOTE LPG GIVE YOU 7.11 KwH PER LITER AND OIL 10.35 PER KwH BOTH ASSUMING THE IMPOSSIBLE 100% EFFICIENCY
ALSO IF YOU ARE ONLY USEING ELECTRIC (HEATING ETC) THEN YOU WOULD HAVE TO REMOVE THE STANDING CHARGE FROM YOUR CALCULATIONS AS THAT WOULD BE DOUBLE COUNTING (IF YOU HAD OIL GAS ETC YOU WOULD STILL HAVE AN ELECTRIC STANDING CHARGE)
http://www.stovesonline.co.uk/wood_burning_stoves/Accumulator-hot-water-tanks.html

Be interesting to know where you live as that same tariff in my area(Midlands) is much more.

Tier1(up to 900kWh pa) we pay roughly the same(19.56p to 19.85p)

However the other rates for me are way higher.

Night rate You pay 3.16p; I pay 4.351p so 38% more

Day rate You pay 6.72p; I pay 9.023p so 34% more.

Discounts are the same.

I hadn't realised there were such regional variations - it aint fair!

Below is a site for a new type of system called an Accumulator hot water tank this allowes you to put any amount of hot water sources onto the same system ie solid fuel and gas oil and as it is in a hot water tank E7 electric.

That statement implies you can input any amount of heating sources at the same time.

I am pretty sure you couldn't put feeds from both, oil/gas/lpg and solid fuel at the same time. There are serious safety issues combining solid fuel with gas etc.(and other issues) This can be overcome but it is very expensive and I didn't see anything on the website to say these were built in; I may be wrong but it would need to be checked. It looked like a normal thermal heat store to me.

You can of course combine any single heating source with an Immersion heater.

Certainly agree with your financial logic at your prices.

SD-253

Cardew wrote: »

Be interesting to know where you live as that same tariff in my area(Midlands) is much more.

Tier1(up to 900kWh pa) we pay roughly the same(19.56p to 19.85p)

However the other rates for me are way higher.

Night rate You pay 3.16p; I pay 4.351p so 38% more

Day rate You pay 6.72p; I pay 9.023p so 34% more.

Discounts are the same.

I hadn't realised there were such regional variations - it aint fair!
.

LN13 0 you will have to make the rest up as I don't want to give it out online. LincolnshireWolds though. When did you take out your tariff remember tariff have changed Dramatically!

Cardew wrote: »

That statement implies you can input any amount of heating sources at the same time.

I am pretty sure you couldn't put feeds from both, oil/gas/lpg and solid fuel at the same time. There are serious safety issues combining solid fuel with gas etc.(and other issues) This can be overcome but it is very expensive and I didn't see anything on the website to say these were built in; I may be wrong but it would need to be checked. It looked like a normal thermal heat store to me.

You can of course combine any single heating source with an Immersion heater.

Certainly agree with your financial logic at your prices.

"I am pretty sure you couldn't put feeds from both, oil/gas/lpg and solid fuel at the same time."

The ability to put 2 feeds on the same system has existed for years. I looked at a few house who had it. But adding in via a tank would allowe any amount as the page/site says.
Read the page again

"The accumulator also lets you link up different heating systems, most notably it lets you link in a stove with a backboiler. A woodburning stove with a backboiler is the perfect companion for solar thermal panels because"

And also

"You can of course plug in just about anything else to the the accumulator tank: another stove, a conventional boiler for backup, electric heating elements (again as a backup source of heat), ground or airsource heat pumps, etc. The accumulator tank is the central point in your heating and hot water system - all your heat sources connect to it and all your heating is taken from it"

If you want you could call it a "normal thermal heat store" The point I was making is where I live we often have, as I do 2 sources of heat IE a wood burner and an LPG/Oil fired boiler. It would not be practical to add E7 radiators as (never mind the expense) while this seems to sort that problem out. Also as a friend is about to check out the accumulator a heating engineer is about fit one near him. Now he is thinking of Oil and Wood combo which the heating engineer is fitting. I am not going to change my wood burner for 1 with a back boiler I am just interested in the E7 benefit??

Cardew

SD-253 wrote: »

"I am pretty sure you couldn't put feeds from both, oil/gas/lpg and solid fuel at the same time."

The ability to put 2 feeds on the same system has existed for years. I looked at a few house who had it. But adding in via a tank would allowe any amount as the page/site says.
Read the page again

Sorry you are correct, somehow I missed that part of the page - too busy watching the cricket I suppose.

I was well aware that it was possible to have two feeds to a CH system as I have had such a system for 23 years(and wish I hadn't bothered) Mine is a solid fuel Baxi open fire with a back burner fed into a Gas CH system.

I had my house built, and wanted an open fire in one of the rooms and it seemed 'something for nothing' to have a Baxi back boiler.

The problem is that a plumber(understandably) could not put in a valve to shut off the water from the fire when it is not lit. The reason was that if somebody ever forgot that the valve was shut off and lit the fire, the water in the back burner would boil and you would stand a risk of a serious explosion.

This presents a problem in my system that there is always a 'back-path' from the HW cylinder to the back boiler and even in summer I have a warm back boiler - an unwanted small radiator. There are also other problems that involve sensors and electrical relays - but I won't go into these now.

I contacted Baxi and other plumbers but was told nothing could be done.

http://www.esse.com/pdfs/Centraliser.pdf

The Centraliser was not around(or nobody knew about it) 23 years ago. I did look at geting one fitted but the cost to retrofit was just too much.

It would be interesting to see how 'your' thermal tank prevents a similar 'backpath' to mine.

SD-253

Cardew wrote: »

The Centraliser was not around(or nobody knew about it) 23 years ago. I did look at geting one fitted but the cost to retrofit was just too much.

It would be interesting to see how 'your' thermal tank prevents a similar 'backpath' to mine.

I assume the centralizer is another name for accumulator? Anyway I think it is a brilliant idea absolutely fantastic........but you are probably right retro fit maybe too expensive as in you need to get your money back in a reasonable period of time. If I was starting again I would actually consider it as the sole means of heating using E7. The loss of heat of 2 degrees per 24 hours is fantastic. If I was on oil I would consider it but as I am on LPG and I am not sure I would get away with not using my LPG (the tank belongs to the supplier) pity. As I am retired on a small pension I am always looking to save. IE no car (3 bikes) get free pheasant, rabbit or anything that else that is killerable (is that a word) made 34gallons of cider last year etc etc.
So am happy to invest for a long term saving (I think money back in 10 years is what you should aim for????). I may consider getting or creating a better more insulated tank. As I would prefer to use a non electric shower and will eventual have to renewing my bathroom. (They say you can buy from B&Q a wash basin sink combo that puts the water from your sink into the toilet cistern). Any ideas on improving tank insulation? Not really going to go for the fiberglass but if I boxed in my tank and poured some ball type thingy mejigs in??? Thanks for your time JB

PS the feed in tariff for renewable is 40p per kilowatt and they sell electric at 10p.........how long is that going to last for????????

bernithebiker

Just to add my experience of this;

Electricity is definitely cheaper for heating our hot water. I turn off our oil boiler in the summer (the log boiler is shut down too) and just use an immersion.

In France we have an interesting tarif called 'Tempo'. You have 3 types of day in the year, Red, White and Blue. About 22 Red, 40 White, and the rest Blue.(300ish)

Blue is attractive - about 6p day and 5p night. White is normal, about 10p day and 9p night. Red is OUCH!, 40p day, and 18p night.

The idea is to reduce load on the grid when demand is high (in cold weather). Anyone with a Tempo tarif does their best to reduce consumption on Red days as it's so expensive!!

As far as boiler efficiency goes, our 45kW oil boiler has to heat up it's whole body to 80'C to get the water to 60'C. This residual heat is then lost after the water is heated. A waste in the summer.

Pincher

It's occurred to me that the return flow should be as cold as possible to pick up the latent heat by condensation, so what if we cool the return flow?

Normally, a combi would take in cold mains water, at say 10 degrees, but if this water is warmer, we burn less gas. So we put in a mains pressure cylinder which feeds the combi. A diverter valve is triggered by a temperature sensor, so if the return flow is too warm to cause condensation, e.g. 40+ degrees, we cool it by passing it through the buffer tank in a coil. This boosts the efficiency in two ways:

1. More heat is recovered through condensation
2. The combi burns less gas when delivering hot water.

Potentially, we can use a lower rated combi for the same house.

There needs to be a proportional thermostat and an integrated controller, otherwise the boiler can interpret the cold return flow as a very cold house and turn up the flame in error.

SD-253

Any ideas on improving tank insulation? Not really going to go for the fiberglass but if I boxed in my tank and poured some ball type thingy mejigs in??? Anyone