Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler, controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in the
evening.
The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

In an earlier contribution to this discussion,
Stewart wrote:

Now that the warmer weather is here we are not using the central
heating, just the hot water.
I am heating the domestic hot water cylinder from the gas boiler,
controlled by a cylinder stat and timed for 2 hours in the morning
and 2 hours in the evening.
The cylinder also has an immersion heater and I am wondering if that
would be a more economical method of getting hot water. As well as
the comparative cost of gas versus electricity the immersion would be
on all the time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

To do a *real* comparison, you'd have to do it both ways and measure the
actual electricity and gas consumption over (say) a week, and then work out
the costs. Measuring the gas is easy if that's *all* you're using gas for -
more difficult if you also cook by gas. Measuring the electrical consumption
is harder, because immersion heaters are usually hard-wired. You'd probably
have to temporarily rewire it to a 13A plug and use one of these plug-in
meters.

Having said all that, bearing in mind that the unit price of on-peak
electricity is about three times that of gas, I very must doubt whether
electricity would work out cheaper. I always use gas throughout the summer -
with the immersion heater being just for emergencies.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Wed, 21 May 2008 09:40:11 +0100 someone who may be "Stewart"
wrote this:-

Now that the warmer weather is here we are not using the central heating,
just the hot water.

Just the time of year for solar water heating. DIY kits at
http://www.navitron.org.uk/zen/index.php?main_page=product_info&cPath=71_86&produ cts_id=208

The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all the
time (no clock) but of course controlled by a thermostat.

Electricity is 3-4 times the price of gas. Your boiler and pipework
would have to be very inefficient to make electricity cheaper than
gas. Are the pipes between boiler and cylinder insulated?

How well insulated is the cylinder and hot water pipework? Leaving
an immersion heater on all day and night with poor insulation is
throwing money away. Far better to fit a time clock and only have it
on when hot water is likely to be required.

If you have cheap electricity overnight then the comparison is more
difficult. In some circumstances it can be cheaper to use an
immersion heater overnight, as long as the water stays hot so little
boosting is necessary.


--
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

Stewart wrote:

Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler, controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in the
evening.
The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

Gas is a fraction the price. There are inefficiencies but not that
large. The only time elec would work out cheaper is if you had an
old cast iron exchanger boiler, low efficiency plus cycling that
would waste a whole lot of heat.


NT

Stewart wrote:

Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler, controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in the
evening.
The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


NT

wrote in message
...


fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

Thanks all, from the comments it appears that we are doing the right thing.
I have 2 jackets on the hot water cylinder so any heat is retained.


"Stewart" wrote in message
...
Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler,
controlled by a cylinder stat and timed for 2 hours in the morning and 2
hours in the evening.
The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all
the time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

Stewart wrote:
Thanks all, from the comments it appears that we are doing the right
thing. I have 2 jackets on the hot water cylinder so any heat is
retained.

If you're talking about loose jackets on a bare cylinder, I think you'll
find that "any heat" is a bit of an over estimation. Foam insulated
cylinders are a *lot* better at retaining the heat. I dunno what the
payback period is but you might want to think about changing your cylinder.

Tim

"David Hansen" wrote in message
...
On Wed, 21 May 2008 09:40:11 +0100 someone who may be "Stewart"
wrote this:-

Now that the warmer weather is here we are not using the central heating,
just the hot water.

Just the time of year for solar water heating. DIY kits at
http://www.navitron.org.uk/zen/index.php?main_page=product_info&cPath=71_86&produ cts_id=208

Pinched my thunder!


How well insulated is the cylinder and hot water pipework? Leaving
an immersion heater on all day and night with poor insulation is
throwing money away. Far better to fit a time clock and only have it
on when hot water is likely to be required.

Whatever the source of heating everything should be more insulated than
you'd think necessary.

Mary

On Wed, 21 May 2008 15:07:52 +0100 someone who may be "Mary Fisher"
wrote this:-

Just the time of year for solar water heating. DIY kits at
http://www.navitron.org.uk/zen/index.php?main_page=product_info&cPath=71_86&produ cts_id=208

Pinched my thunder!

Sorry. I will go and hide now:-)



--
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

On Wed, 21 May 2008 14:38:37 +0100 someone who may be "Tim Downie"
wrote this:-

If you're talking about loose jackets on a bare cylinder, I think you'll
find that "any heat" is a bit of an over estimation. Foam insulated
cylinders are a *lot* better at retaining the heat.

Indeed. Even standard thickness sprayed on insulation is a lot
better than jackets. Double or triple thickness insulation is even
better.

In addition the pipes should be properly insulated.



--
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

wrote in message
...
Stewart wrote:

Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler,
controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in
the
evening.
The cylinder also has an immersion heater and I am wondering if that
would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all
the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.

And rust up the burners as when the boiler stat is set far too low,
condensing occurs.

"dennis@home" wrote in message
...


wrote in message
...


fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.

It would be as most boilers are less efficient run like that.

They are not. The lower the temperature and the wider the delta T the more
efficient.

"Tim Downie" wrote in message
...
Stewart wrote:
Thanks all, from the comments it appears that we are doing the right
thing. I have 2 jackets on the hot water cylinder so any heat is
retained.

If you're talking about loose jackets on a bare cylinder, I think you'll
find that "any heat" is a bit of an over estimation. Foam insulated
cylinders are a *lot* better at retaining the heat. I dunno what the
payback period is but you might want to think about changing your
cylinder.

Yep. Get a stainless steel ACV tank-in-tank cyinder.

dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

And experience with doing it on space heaters has given
impressive results. At full power there's stacks of heat coming out
the back, whereas at at low power hardly anything comes out
exteriorly, whereas internal heat output is still good.

Re rusting, bear in mind iron exchangers rust in normal use, but if
set _too_ low it could condense and thus rust faster. Even if it did
though it would take many yrs to eat through an iron exchanger -
and you'd soon notice condensate running out where it shouldn't.

Not recommending it, but it seems to add up.


NT

wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

And experience with doing it on space heaters has given
impressive results. At full power there's stacks of heat coming out
the back, whereas at at low power hardly anything comes out
exteriorly, whereas internal heat output is still good.

Uh! ???

Re rusting, bear in mind iron exchangers rust in normal use, but if
set _too_ low it could condense and thus rust faster. Even if it did
though it would take many yrs to eat through an iron exchanger -
and you'd soon notice condensate running out where it shouldn't.

Liker rusting the burner box and burner. Which was quite common, as stupid
manufacturers allowed the temperatures to go too low on the boiler stats. I
think deliberately so.

If you had a blending valve on the return pipe to the boiler set to 58C, any
lower and condensation occurs, and the boiler stat set to max, the boiler
will run very efficiently and a 80% non-condensing boiler will return near
condensing efficiencies.

"Doctor Drivel" wrote in message
...

"dennis@home" wrote in message
...


wrote in message
...


fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.

It would be as most boilers are less efficient run like that.

They are not. The lower the temperature and the wider the delta T the more
efficient.

Wrong.
You are assuming that by running with a lower flame more heat is transferred
to the water, this depends on boiler design, not some idea you dreamed up.

wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions, the designers
will have decided where that optimum point should be and it probably isn't
at the low end.
Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger, flow rates, etc. all of which will have an effect
on efficiency and may not be best at low outputs.


And experience with doing it on space heaters has given
impressive results. At full power there's stacks of heat coming out
the back, whereas at at low power hardly anything comes out
exteriorly, whereas internal heat output is still good.

Re rusting, bear in mind iron exchangers rust in normal use, but if
set _too_ low it could condense and thus rust faster. Even if it did
though it would take many yrs to eat through an iron exchanger -
and you'd soon notice condensate running out where it shouldn't.

Not recommending it, but it seems to add up.


NT

"Doctor Drivel" wrote in message
...


If you had a blending valve on the return pipe to the boiler set to 58C,
any lower and condensation occurs, and the boiler stat set to max, the
boiler will run very efficiently and a 80% non-condensing boiler will
return near condensing efficiencies.


You don't even need blending valves, just zone everything and run it at full
output all the time.
The boiler will only fire if it needs to unlike these cra@py TRV controlled
systems.
My non condensing boiler system is easily more efficient than next doors
condensing boiler and mine is more than 20 years old (and no cast iron to
worry about either).

wrote:
Stewart wrote:

Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler, controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in the
evening.
The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

Gas is a fraction the price.

Not for much longer.

There are inefficiencies but not that
large. The only time elec would work out cheaper is if you had an
old cast iron exchanger boiler, low efficiency plus cycling that
would waste a whole lot of heat.


Or if gas exceeds nuclear energy costs by a factor of three, which it
looks set to do.


NT

dennis@home wrote:
wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions, the designers
will have decided where that optimum point should be and it probably isn't
at the low end.
Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger, flow rates, etc. all of which will have an effect
on efficiency and may not be best at low outputs.

I've yet to meet a simple passive exchanger that would do that, but
I'll accept I've not seen them all.


And experience with doing it on space heaters has given
impressive results. At full power there's stacks of heat coming out
the back, whereas at at low power hardly anything comes out
exteriorly, whereas internal heat output is still good.

Re rusting, bear in mind iron exchangers rust in normal use, but if
set _too_ low it could condense and thus rust faster. Even if it did
though it would take many yrs to eat through an iron exchanger -
and you'd soon notice condensate running out where it shouldn't.

Not recommending it, but it seems to add up.


NT

wrote in message
...
dennis@home wrote:
wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions, the
designers
will have decided where that optimum point should be and it probably
isn't
at the low end.
Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger, flow rates, etc. all of which will have an
effect
on efficiency and may not be best at low outputs.

I've yet to meet a simple passive exchanger that would do that, but
I'll accept I've not seen them all.

Never seen a Thorn Apollo in your life?
They are more efficient if you set them to max than to min, not that they
modulate as it isn't needed.

On Thu, 22 May 2008 01:34:52 +0100 someone who may be The Natural
Philosopher wrote this:-

Or if gas exceeds nuclear energy costs by a factor of three, which it
looks set to do.

Most unlikely.

Gas is an increasingly rare material which has a small amount of
processing before it is sent by pipe direct to houses.

Nuclear fuel is an increasingly rare material which has an enormous
amount of processing before it is taken to a large power station.
The electricity is then taken by cable to houses. We'll leave aside
what happens after the fuel leaves the power station.



--
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

"dennis@home" wrote in message
...


"Doctor Drivel" wrote in message
...

"dennis@home" wrote in message
...


wrote in message
...


fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.

It would be as most boilers are less efficient run like that.

They are not. The lower the temperature and the wider the delta T the
more efficient.

Wrong.
You are assuming that by running with a lower flame more heat is
transferred to the water, this depends on boiler design, not some idea you
dreamed up.

Your knowledge on thermal transfer is sadly lacking.

"dennis@home" wrote in message
...


wrote in message
...
dennis@home wrote:
wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather
thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions, the
designers
will have decided where that optimum point should be and it probably
isn't
at the low end.
Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger, flow rates, etc. all of which will have an
effect
on efficiency and may not be best at low outputs.

I've yet to meet a simple passive exchanger that would do that, but
I'll accept I've not seen them all.

Never seen a Thorn Apollo in your life?
They are more efficient if you set them to max than to min, not that they
modulate as it isn't needed.

You made that up.

"dennis@home" wrote in message
...


"Doctor Drivel" wrote in message
...


If you had a blending valve on the return pipe to the boiler set to 58C,
any lower and condensation occurs, and the boiler stat set to max, the
boiler will run very efficiently and a 80% non-condensing boiler will
return near condensing efficiencies.

You don't even need blending valves, just zone everything and run it at
full output all the time.

You need the bending valve to ensure the non-condensing boiler does not
condense and ruin the boier. On commercial boiler it is called "back end
protection". In this case it is to improve thermal expansion.

My non condensing boiler system is easily more efficient than next doors
condensing boiler and mine is more than 20 years old

If the system is designed properly and the return runs at 58C, and the
condensing system is poorly designed and commissioned that can be the case.
However in your case I doubt it as you only have half a clue at most.

"The Natural Philosopher" wrote in message
...
wrote:
Stewart wrote:

Now that the warmer weather is here we are not using the central
heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler,
controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in
the
evening.
The cylinder also has an immersion heater and I am wondering if that
would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all
the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

Gas is a fraction the price.

Not for much longer.

What do you know we do not?

There are inefficiencies but not that
large. The only time elec would work out cheaper is if you had an
old cast iron exchanger boiler, low efficiency plus cycling that
would waste a whole lot of heat.

Even then with an old cast iron boiler gas is still cheaper.

Or if gas exceeds nuclear energy costs by a factor of three, which it
looks set to do.

You made that up. The government is giving grants to people who change over
from electric to gas CH.

"dennis@home" wrote in message
...


wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions,

Or more likely setting with a "range".

the designers will have decided where that optimum point should be and it
probably isn't at the low end.

Isn't it?

Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger,

If the burner is designed to modulate this is not an issue.

flow rates, etc.

Through the heat exchanger? That is a point.

all of which will have an effect on efficiency and may not be best at low
outputs.

In a non-condensing boiler with set rate burner, having the return at 58C
and the flow through the heat exchanger to give the highest temperature rise
(highest delta T) will give maximum efficiency. The heat exchanger has to
cope with the delta T. Finned copper tube heat exchangers are generally
suitable as they are all one piece.

The system can be engineered to give this by sizing the rads to suit 58C
return and 82C flow. 24C delta T. Ensuring the rad circuit pumps around on
itself to give a return of 58C is the way to do it. The blending valve only
opens to allow heat into the rad loop and at the same time ensuring a return
back to the boiler of 58C.

It is easy once you know what you are doing.

"Doctor Drivel" wrote in message
...

"dennis@home" wrote in message
...


wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions,

Or more likely setting with a "range".

the designers will have decided where that optimum point should be and it
probably isn't at the low end.

Isn't it?

Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger,

If the burner is designed to modulate this is not an issue.

Of course its an issue.. modulating the boiler means compromising somewhere.

"David Hansen" wrote in message
...
On Wed, 21 May 2008 14:38:37 +0100 someone who may be "Tim Downie"
wrote this:-

If you're talking about loose jackets on a bare cylinder, I think you'll
find that "any heat" is a bit of an over estimation. Foam insulated
cylinders are a *lot* better at retaining the heat.

Indeed. Even standard thickness sprayed on insulation is a lot
better than jackets. Double or triple thickness insulation is even
better.

In addition the pipes should be properly insulated.

That's VERY important.

I'm off for a bath in a few minutes, water temperature 57C, it's been cloudy
today so not so hot but far warmer than I need for a tub full
:-)

Mary

"dennis@home" wrote in message
...


"Doctor Drivel" wrote in message
...

"dennis@home" wrote in message
...


wrote in message
...
dennis@home wrote:
wrote in message
...

fwiw with cast iron you can greatly improve the efficiency by
modulating it manually. Turn it down to the needed heat output
for the summer, which isnt very high for hw only. But I gather thats
frowned on now.


It would be as most boilers are less efficient run like that.

How would that be so? You're running less power through the same
exchanger, thus using more exchanger area per kilowatt, which
strikes me as a recipe for greater efficiency. AIUI this is one of
the
advantages of modulating boilers.

The boiler will have an optimum set of operating conditions,

Or more likely setting with a "range".

the designers will have decided where that optimum point should be and
it probably isn't at the low end.

Isn't it?

Reducing the flame will effect all sorts of things, like the turbulence
across the heat exchanger,

If the burner is designed to modulate this is not an issue.

Of course its an issue.. modulating the boiler means compromising
somewhere.

You really just don't know. The most common is pneumatic ratio-control
burners. This compensates for weather conditions such temperature and
barometric pressure. The speed of the fan acts on a venturi. Based on this
pressure difference the gas valve opening is adjusted to match the air.
They are highly efficient pre-mix burners and can modulate efficiently over
a wide range.

There is a slow transition from the metallic pre-mix burner to flameless
ceramic burners, which give out far more radiant heat, 35% to 5% to 15%, and
much cooler flue gassess, under 1,000C to 1,300C. If the flameless burners
are advanced more condensing technology will be reversed. Only when the
condensing plumes become a full nuisance and emissions are tightened will
this happen, like eliminating all SEDBUK band B boilers. Then a plumeless
boiler will be needed for flats - flameless burner boilers can do this and
still give high efficiencies..

The Natural Philosopher wrote:
wrote:
Stewart wrote:

Now that the warmer weather is here we are not using the central heating,
just the hot water.
I am heating the domestic hot water cylinder from the gas boiler, controlled
by a cylinder stat and timed for 2 hours in the morning and 2 hours in the
evening.
The cylinder also has an immersion heater and I am wondering if that would
be a more economical method of getting hot water. As well as the
comparative cost of gas versus electricity the immersion would be on all the
time (no clock) but of course controlled by a thermostat.
Has anyone done a comparison of the relative costs?
Thank you.

Gas is a fraction the price.

Not for much longer.

Electricity has always cost more than raw fuels, as it has the
added costs of power stations plus considerable conversion
inefficiency. Short term variations only change that short term.


There are inefficiencies but not that
large. The only time elec would work out cheaper is if you had an
old cast iron exchanger boiler, low efficiency plus cycling that
would waste a whole lot of heat.


Or if gas exceeds nuclear energy costs by a factor of three, which it
looks set to do.


NT

If it climbed that high people would already have quit using it for
nearly all apps. And again I dont see it happening.


NT