I realise this has been aired before but didn't really get the full
answer I was hoping for. Any input very welcome:

What's the cheapest way to heat my water during the summer? I've a
regular oil fired boiler system that heats water in a hot water cylinder
and also does the central heating when required.

My oil is about 38p/l, electricity roughly 5p/kWh plus a standing charge
but that's kinda irrelevant since I'll pay that either way.

I've read lots of heated (sorry) discussions about efficiency of heating
the water tank with the oil burner vs. the electrical immersion heater.
I'm happy to assume that electrical is more efficient than oil method but
not by a massive amount. Obviously the oil method has to heat the pipes,
loses some energy out the flue and needs electricity itself to drive the
pump.

I guess the question is roughly how much energy does an average oil
boiler get from a litre of oil?

The interweb figures I've found suggest 11.5kWh from a litre of oil, or
3.3p/kWh.

So oil energy is roughly 2/3 the cost of electricity energy.

So my oil boiler would have to be better than 66% efficient at converting
the energy from the oil into energy directly heating the water?

It sounds like oil method should be better, anyone feel like wading in?!

Mark.

Mark wrote:
I realise this has been aired before but didn't really get the full
answer I was hoping for. Any input very welcome:

What's the cheapest way to heat my water during the summer? I've a
regular oil fired boiler system that heats water in a hot water cylinder
and also does the central heating when required.

My oil is about 38p/l, electricity roughly 5p/kWh plus a standing charge
but that's kinda irrelevant since I'll pay that either way.

I've read lots of heated (sorry) discussions about efficiency of heating
the water tank with the oil burner vs. the electrical immersion heater.
I'm happy to assume that electrical is more efficient than oil method but
not by a massive amount. Obviously the oil method has to heat the pipes,
loses some energy out the flue and needs electricity itself to drive the
pump.

I guess the question is roughly how much energy does an average oil
boiler get from a litre of oil?

The interweb figures I've found suggest 11.5kWh from a litre of oil, or
3.3p/kWh.

So oil energy is roughly 2/3 the cost of electricity energy.

So my oil boiler would have to be better than 66% efficient at converting
the energy from the oil into energy directly heating the water?

It sounds like oil method should be better, anyone feel like wading in?!

Mark.

sounds about right


NT

In article ,
Mark wrote:
What's the cheapest way to heat my water during the summer? I've a
regular oil fired boiler system that heats water in a hot water cylinder
and also does the central heating when required.

My oil is about 38p/l, electricity roughly 5p/kWh plus a standing charge
but that's kinda irrelevant since I'll pay that either way.

I've read lots of heated (sorry) discussions about efficiency of heating
the water tank with the oil burner vs. the electrical immersion heater.
I'm happy to assume that electrical is more efficient than oil method
but not by a massive amount. Obviously the oil method has to heat the
pipes, loses some energy out the flue and needs electricity itself to
drive the pump.

Since you've done the sums and have answered yourself I'll add a rider.
Switching off a boiler fed system totally during the summer months often
results in seized components - valves and pumps, etc. Running it every
day for hot water helps prevent this. So it's even more heavily weighted
on using the boiler.

--
*Husband and cat lost -- reward for cat

Dave Plowman London SW
To e-mail, change noise into sound.

On 07 Aug 2006 12:35:49 GMT someone who may be Mark
wrote this:-

What's the cheapest way to heat my water during the summer?

Solar.

Zero energy cost. Obviously one has to pay for the capital cost, but
that was excluded from your figures for oil and electric.

I've read lots of heated (sorry) discussions about efficiency of heating
the water tank with the oil burner vs. the electrical immersion heater.
I'm happy to assume that electrical is more efficient than oil method but
not by a massive amount.

Ignoring the standing losses in the cylinder (which will be similar
for oil, electric, or solar) electricity is 100% efficient (assuming
a suitably sized cable). Oil is not.

It sounds like oil method should be better, anyone feel like wading in?!

It sounds like you assume that cheaper is the same as better. If so
then it is probably better to heat the water on White Meter
electricity (they have another term for it in England and Wales) in
the summer. Assuming your cylinder is properly lagged and sized then
it should provide enough water for a day's use.

Topping up the water may well be better done by oil, rather then
full price electricity.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

Mark wrote:
I realise this has been aired before but didn't really get the full
answer I was hoping for. Any input very welcome:

What's the cheapest way to heat my water during the summer? I've a
regular oil fired boiler system that heats water in a hot water cylinder
and also does the central heating when required.

Use the oil.


My oil is about 38p/l, electricity roughly 5p/kWh plus a standing charge
but that's kinda irrelevant since I'll pay that either way.

I've read lots of heated (sorry) discussions about efficiency of heating
the water tank with the oil burner vs. the electrical immersion heater.
I'm happy to assume that electrical is more efficient than oil method but
not by a massive amount. Obviously the oil method has to heat the pipes,
loses some energy out the flue and needs electricity itself to drive the
pump.

I guess the question is roughly how much energy does an average oil
boiler get from a litre of oil?

More than the average power station does.


The interweb figures I've found suggest 11.5kWh from a litre of oil, or
3.3p/kWh.

So oil energy is roughly 2/3 the cost of electricity energy.

So my oil boiler would have to be better than 66% efficient at converting
the energy from the oil into energy directly heating the water?

It sounds like oil method should be better, anyone feel like wading in?!

Yes, it is, but don;t bust a gut over it.

In winter we burn getting on for 500 quid of oil a month, in spring and
autumn we burn maybe 200 a month. In the three summer months the boiler
fires up generally twice a day for about half an hour. i.e. about 10
unit of electricity (we have a 10KW boiler)..domestic water heating is
the least of MY worries, cost wise.



Mark.

Last time I looked I thought electricity was approx 7p per kWH,
and we got approx 10 kWH out of a litre of 28 second oil.

I amnot sure if that is net or gross - assuming gross, that's about 8 kWH
into the water and say 7 kWH into the hot tank.

If oil is 38 p / litre, that makes a kWH from oil cost about 5.6 p....
I suggest you re-visit the Electricity bill and check that price per unit.

Please let us know - I am sure my standard rate is around 7 to 8 p / unit

Nick

Please let us know - I am sure my standard rate is around 7 to 8 p /
unit

Nick

I grabbed the figure from my last bill from Scottish Power which showed
4.89p/kWh plus a 17.57p/day standing charge. 5% VAT needs to be added and I
got a modest reduction for taking gas & electric and being on an internet
tariff. I think it was capped too. I've since moved (hence the talk about
oil) so have lost the capped rate benefit.

Maybe you're on a all-in rate without the standing charge? The equivalent
price for my last bill if it was without standing charge would have been
6.26p/kWh before vat.

I need to get out more...

Thanks all for input. I'll stick with firing up the boiler for 40 mins a
day which seems to cover the days needs. Solar panels and wind turbines are
likely to become a more serious proposition the way energy prices are
going.

On 07 Aug 2006 19:16:50 GMT, Mark wrote:

I grabbed the figure from my last bill from Scottish Power which showed
4.89p/kWh plus a 17.57p/day standing charge.

That's good if still current. Our Scottish Power, NORWEB area, online,
single rate, electric only: 7.191p/kWh 12.39p/day standing charge. Just
gone up (again) on the 10th July from 6.85p/kWh. Only have to use about 2
units/day to make up the standing charge increase by the cheaper unit
cost, not a problem we use 22 units/day...

I guess the higher standing charge is because of the combined
gas/electric aspect or do you have a seperate gas standing charge?

Maybe you're on a all-in rate without the standing charge?

They normally only increase the first X units above the standard rate,
once the standing charge has been recovered the cost/unit is the standard
rate.

--
Cheers
Dave. pam is missing e-mail

and geothermal if you have a bit of land and don't mind doing the trench
yourself

The rest of the kit is really not too expensive, although under floor
heating would make it more efficient, else radiators would have to be a lot
bigger

Nick

Mark wrote:

Thanks all for input. I'll stick with firing up the boiler for 40 mins a
day which seems to cover the days needs. Solar panels and wind turbines are
likely to become a more serious proposition the way energy prices are
going.

Theyre already an easy payback if you understand how to design to
maximise return/cost ratio, and treat it as a hobby ie value your
labour at zero.


NT

Nick wrote:
Last time I looked I thought electricity was approx 7p per kWH,
and we got approx 10 kWH out of a litre of 28 second oil.

I amnot sure if that is net or gross - assuming gross, that's about 8 kWH
into the water and say 7 kWH into the hot tank.

If oil is 38 p / litre, that makes a kWH from oil cost about 5.6 p....
I suggest you re-visit the Electricity bill and check that price per unit.

Please let us know - I am sure my standard rate is around 7 to 8 p / unit

Nick


More like 10-13p

Nick wrote:
Last time I looked I thought electricity was approx 7p per kWH,
and we got approx 10 kWH out of a litre of 28 second oil.

I amnot sure if that is net or gross - assuming gross, that's about 8 kWH
into the water and say 7 kWH into the hot tank.

If oil is 38 p / litre, that makes a kWH from oil cost about 5.6 p....
I suggest you re-visit the Electricity bill and check that price per unit.

Please let us know - I am sure my standard rate is around 7 to 8 p / unit

Nick



Here is a good site to answer these questions

http://nep.gngateway.org.uk/renewabl...sts-comparison

However I query their 90% efficiency figures for a boiler. Probably
60-70% nearer the mark.

On Tue, 08 Aug 2006 11:57:39 +0100 someone who may be The Natural
Philosopher wrote this:-

Here is a good site to answer these questions

http://nep.gngateway.org.uk/renewabl...sts-comparison

However I query their 90% efficiency figures for a boiler. Probably
60-70% nearer the mark.

There are two major flaws with the figures they present:

1) they have not included a figure for off-peak electricity. It is
undoubtedly cheaper to heat water using off-peak electricity rather
then run an old boiler with a long pipe run to the cylinder.

2) it is not just the efficiency of the boiler. A long run of
uninsulated pipes between boiler and cylinder will lose a fair
amount of heat and thus reduce system efficiency.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:
On Tue, 08 Aug 2006 11:57:39 +0100 someone who may be The Natural
Philosopher wrote this:-

Here is a good site to answer these questions

http://nep.gngateway.org.uk/renewabl...sts-comparison

However I query their 90% efficiency figures for a boiler. Probably
60-70% nearer the mark.

There are two major flaws with the figures they present:

1) they have not included a figure for off-peak electricity. It is
undoubtedly cheaper to heat water using off-peak electricity rather
then run an old boiler with a long pipe run to the cylinder.

2) it is not just the efficiency of the boiler. A long run of
uninsulated pipes between boiler and cylinder will lose a fair
amount of heat and thus reduce system efficiency.


Points well made and accepted. HOWEVER I suspect that even off peak
electricity is barely a match for a decent oil burner, and many of peak
charges include standing charges as well.

As far as the long runs go, if the pipes are well lagged its not a huge
loss for the very short periods that the boiler is in fact heating water.

On Tue, 08 Aug 2006 13:42:13 +0100 someone who may be The Natural
Philosopher wrote this:-

HOWEVER I suspect that even off peak
electricity is barely a match for a decent oil burner, and many of peak
charges include standing charges as well.

As far as the long runs go, if the pipes are well lagged its not a huge
loss for the very short periods that the boiler is in fact heating water.

It is a matter of the specific against the general. It's easy to
construct systems under various charging regimes where each is
better in terms of various costs. However, for the typical systems
seen in houses I don't think off-peak water heating is that
expensive. I have done the sums a few times.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:
On Tue, 08 Aug 2006 13:42:13 +0100 someone who may be The Natural
Philosopher wrote this:-

HOWEVER I suspect that even off peak
electricity is barely a match for a decent oil burner, and many of peak
charges include standing charges as well.

As far as the long runs go, if the pipes are well lagged its not a huge
loss for the very short periods that the boiler is in fact heating water.

It is a matter of the specific against the general. It's easy to
construct systems under various charging regimes where each is
better in terms of various costs. However, for the typical systems
seen in houses I don't think off-peak water heating is that
expensive. I have done the sums a few times.





Trouble is after a day of washing up, and laundry, there is nothing left
for an evening shower or bath.

On Wed, 09 Aug 2006 11:01:56 +0100 someone who may be The Natural
Philosopher wrote this:-

Trouble is after a day of washing up, and laundry, there is nothing left
for an evening shower or bath.

Then the hot water storage has not been sized properly.

Anyway, washing up and laundry can usually be done overnight. In
summer the off-peak period runs until 08:00-08:30 depending on meter
and location. This means breakfast, washing and so on can be done
and there is still time for the storage to be warmed up before the
end of the off-peak period.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:
On Wed, 09 Aug 2006 11:01:56 +0100 someone who may be The Natural
Philosopher wrote this:-

Trouble is after a day of washing up, and laundry, there is nothing left
for an evening shower or bath.

Then the hot water storage has not been sized properly.

I put in a 700 lite tank. After a few showers, washing machines and She
leaving the sink running whilst she does her makeup, there is bugger all
left mate.


Anyway, washing up and laundry can usually be done overnight. In
summer the off-peak period runs until 08:00-08:30 depending on meter
and location. This means breakfast, washing and so on can be done
and there is still time for the storage to be warmed up before the
end of the off-peak period.


Try telling that to my wife.

Or indeed alleged;ly to teenage kids.

Christ, turning the radiators up full and opening a window is standard
practice innit?