I have a 20 years old Glow-worm Spacesaver wall boiler which works fine,
providing pumped CH and gravity DHW.
B/Gas 3 star engineers keep telling me the they can "no longer guarantee to
be able to source spares"...ie a sales ploy to sell a new boiler.
Our local council are supplying discounted high efficiency boilers as a
greening initiative, but I reckon the bill will be £2k with fitting and
maybe mods to the exisiting system.
Any of you experts got any impartial advice ?
My gut instinct is to try and source spares for my existing boiler to keep
it going as long as possible.
What do you think.?

In article , Roger wrote:
Our local council are supplying discounted high efficiency boilers
as a greening initiative, but I reckon the bill will be £2k with
fitting and maybe mods to the exisiting system.
Any of you experts got any impartial advice ?
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

It really depends on how much you are spending on gas. You can
probably reckon on your existing boiler being 65-70% efficient at
best, against 90% for a new condensing boiler so if you do the swap
your bills will probably drop by about 25%. Do the arithmetic and
you'll see what the likely payback period is.

Your best way of saving money is probably to ditch the BG *** and
find a local guy who will sort out any problems if needed.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

Absolutely right. I just fell into the trap and had a Worcester HE40
installed. Subsequently I found I could get spares for the old Gloworm
and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have been.

Jim A

On Sat, 8 Jan 2005 09:48:04 -0000, "Jim Alexander"
wrote:


"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

Absolutely right. I just fell into the trap and had a Worcester HE40
installed. Subsequently I found I could get spares for the old Gloworm
and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have been.

Jim A


It depends on what you started with and the weather.

I replaced a 65% SEDBUK efficient piece of GlowWorm crap with a 90%
efficient condensing boiler and the savings average 25-28% for periods
of time of equivalent outside temperature.

This was done by making weekly gas meter readings and continuously
logged outside temperature readings and the results are quite
consistent.






--

..andy

To email, substitute .nospam with .gl

In article ,
Grumpy wrote:
Absolutely right. I just fell into the trap and had a Worcester HE40
installed. Subsequently I found I could get spares for the old Gloworm
and as for 25% savings with a condensing boiler dream on.

Only direct experience I've heard of and can trust is that of my brother.
He had a 20 year old FS RS 80,000 BTU boiler replaced with a condenser,
and reckons on a 20% saving in gas usage.

However, had he had to pay for repairs - he's got a service contract, as
he had before - the costs would have wiped out any savings and then some.
Then there's the question of how long it will last before BG says it's no
longer serviceable - as they did with the last one. Doubt it will be 20
years

--
*'Progress' and 'Change' are not synonyms.

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

"Roger" wrote in message ...
I have a 20 years old Glow-worm Spacesaver wall boiler which works fine,
providing pumped CH and gravity DHW.
B/Gas 3 star engineers keep telling me the they can "no longer guarantee
to
be able to source spares"...ie a sales ploy to sell a new boiler.
Our local council are supplying discounted high efficiency boilers as a
greening initiative, but I reckon the bill will be £2k with fitting and
maybe mods to the exisiting system.
Any of you experts got any impartial advice ?
My gut instinct is to try and source spares for my existing boiler to keep
it going as long as possible.
What do you think.?

You have an outdated boiler and system. I reckon it is getting 55%
efficiency. If you can get a good deal on new high efficient boiler then
go for it. The bills will noticeably drop. Also DHW recovery, using a
quick recovery cylinder will be zippo. It may work out more in total
running costs to keep the old boiler as you may be nickel and diming it.

"IMM" wrote in message
...

Also DHW recovery, using a
quick recovery cylinder will be zippo. It may work out more in total
running costs to keep the old boiler as you may be nickel and diming it.

Err... where exactly did you go on holiday?

Jim A

I like the Buderus condensing range, the system boilers are very reasonable cost, and the combis are excellent. Slight problem with size (BIG) and they are more noisy than most but beautifully engineered and a dream to service/repair. They've been at the condensing game over 20 years on the continent where it took off a lot sooner.

For a good condensing system boiler pay £700 or so, for a combi a little over a grand. Should be a days labour, maybe a day and a half in certain circumstances. If someone in your area is trying to get £1,000 out of you for a days work give me a call I'll travel anywhere in the country for a days work at half that pay. I charge £300 for a combi swap in my area but I'd need more to travel a long way.

"Paul Barker" wrote in message
...

Roger Wrote:
I have a 20 years old Glow-worm Spacesaver wall boiler which works
fine,
providing pumped CH and gravity DHW.
B/Gas 3 star engineers keep telling me the they can "no longer
guarantee to
be able to source spares"...ie a sales ploy to sell a new boiler.
Our local council are supplying discounted high efficiency boilers as
a
greening initiative, but I reckon the bill will be £2k with fitting
and
maybe mods to the exisiting system.
Any of you experts got any impartial advice ?
My gut instinct is to try and source spares for my existing boiler to
keep
it going as long as possible.
What do you think.?

I like the Buderus condensing range,
the system boilers are very
reasonable cost, and the combis
are excellent. Slight problem with size
(BIG) and they are more noisy than
most but beautifully engineered and a
dream to service/repair. They've been
at the condensing game over 20
years on the continent where it took off a lot sooner.

I thought they were British from Ipswich. They are mainly know for oilers,
not gas. Not a big player in the UK. I know they have been bought out by
Bosch and the Ipswich plant is moving production to Worcester's factory. I
asume they wanted the oil boiler range, not the gas range.

I like the ease in which even the heat exchangers can be changed. They
virtually clip in and out, so no ditching the boiler if the heat echanger
fails.

"Jim Alexander" wrote in message
...

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have been.

Installed November 04. I'm looking at 7% but its early days I suppose. I
have
no experience of maintenance costs.

I like the ease in which even the heat exchangers can be changed. They
virtually clip in and out, so no ditching the boiler if the heat echanger
fails.[/quote]

Yes me too. Also the pcb is in a plastic module, you just undo one big screw and the whole thing pulls off. No taking pictures of all the edge connectors with your digital camera necessary.

The 28kw combi has a small amount of storage; the practical DHW performance is the best I have come across from a 28kw combi. Of course it's only a shaddow of the 40kw Worcester condensing combi, but it's a close second, though maybe ahead in the repair situation.

One gripe, I had to buy sensetive equipment (Kane 400) just to comission this boiler properly. That bugged me, but that's the future, we'll be required to set up gas and air ratios by quite a few more manufacturers in the days ahead.

On Sun, 9 Jan 2005 10:17:28 -0000, "Grumpy" wrote:


"Jim Alexander" wrote in message
...

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have been.

Installed November 04. I'm looking at 7% but its early days I suppose. I
have
no experience of maintenance costs.

Too short a time.

You really need to compare with average temperature data as a minimum
to get a meaningful comparison. If the weather is colder than at the
equivalent time with the previous boiler then the gas use would be
higher anyway. It's no use just comparing quarterly bills.



--

..andy

To email, substitute .nospam with .gl

"Paul Barker" wrote
| If someone in your area is trying to get £1,000
| out of you for a days work give me a call I'll travel
| anywhere in the country

Unst? ;-)

| for a days work at half that pay. I charge £300 for
| a combi swap in my area but I'd need more to travel
| a long way.

And would you want your ferry fare and sandwiches additional? :-)

Owain

"Andy Hall" wrote in message
...
On Sun, 9 Jan 2005 10:17:28 -0000, "Grumpy" wrote:


"Jim Alexander" wrote in message
...

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have
been.

Installed November 04. I'm looking at 7% but its early days I suppose. I
have
no experience of maintenance costs.

Too short a time.

You really need to compare with average temperature data as a minimum
to get a meaningful comparison. If the weather is colder than at the
equivalent time with the previous boiler then the gas use would be
higher anyway. It's no use just comparing quarterly bills.

Its useful feedback as input to my planning. Monitoring my return temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain. My gas is less than £200/year, not all of it heating, saving £30/year
say. The Vokera/Vaillant/Worcester condensing models are £300 more
expensive discount. Even factoring in zero DIY installation costs that's
10ish years payback assuming equivalent maintenance costs which may or may
not be true. Sorry condensing just doesn't payback for a lot of small
system replacement. My advice is get a replacement non condenser while you
can.

Jim A

"Jim Alexander" wrote in message
...

"Andy Hall" wrote in message
...
On Sun, 9 Jan 2005 10:17:28 -0000, "Grumpy" wrote:


"Jim Alexander" wrote in message
...

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have
been.

Installed November 04. I'm looking at 7% but its early days I suppose. I
have
no experience of maintenance costs.

Too short a time.

You really need to compare with average temperature data as a minimum
to get a meaningful comparison. If the weather is colder than at the
equivalent time with the previous boiler then the gas use would be
higher anyway. It's no use just comparing quarterly bills.

Its useful feedback as input to my planning. Monitoring my return temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain. My gas is less than £200/year, not all of it heating, saving
£30/year
say. The Vokera/Vaillant/Worcester condensing models are £300 more
expensive discount. Even factoring in zero DIY installation costs that's
10ish years payback assuming equivalent maintenance costs which may or may
not be true. Sorry condensing just doesn't payback for a lot of small
system replacement. My advice is get a replacement non condenser while
you
can.

Most homes do have £200 a year gas bills for full heating and DHW. The
average home does benefit from a condensing boiler if changing boilers.

"Paul Barker" wrote in message
...

The 28kw combi has a small
amount of storage; the practical DHW
performance is the best I have come
across from a 28kw combi. Of course
it's only a shaddow of the 40kw
Worcester condensing combi, but it's a
close second, though maybe ahead in
the repair situation.

What's the prices these days? And who is a big stocker? Parts should become
easy as they are merging into Bosch. I fear they may drop these gas boilers
in favour of the Worcester range. If they do, vested interest triumphs
over superior design and make yet again.

There are lots of small makers turning out boilers these days, even Johnson
& Starley have a boiler range now.

One gripe, I had to buy sensetive
equipment (Kane 400) just to comission
this boiler properly. That bugged me,
but that's the future, we'll be
required to set up gas and air ratios
by quite a few more manufacturers
in the days ahead.

For DIY I try to avoid recommending these types of boilers simply because of
the commisioning equipment and knowledge required.

"IMM" wrote in message
...

"Jim Alexander" wrote in message
...

"Andy Hall" wrote in message
...
On Sun, 9 Jan 2005 10:17:28 -0000, "Grumpy" wrote:


"Jim Alexander" wrote in message
...

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have
been.

Installed November 04. I'm looking at 7% but its early days I suppose.
I
have
no experience of maintenance costs.

Too short a time.

You really need to compare with average temperature data as a minimum
to get a meaningful comparison. If the weather is colder than at the
equivalent time with the previous boiler then the gas use would be
higher anyway. It's no use just comparing quarterly bills.

Its useful feedback as input to my planning. Monitoring my return temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain. My gas is less than £200/year, not all of it heating, saving
£30/year
say. The Vokera/Vaillant/Worcester condensing models are £300 more
expensive discount. Even factoring in zero DIY installation costs that's
10ish years payback assuming equivalent maintenance costs which may or
may
not be true. Sorry condensing just doesn't payback for a lot of small
system replacement. My advice is get a replacement non condenser while
you
can.

Most homes do have £200 a year gas bills for full heating and DHW. The
average home does benefit from a condensing boiler if changing boilers.

Don't necessarily disagree. My gripe is the forthcoming "compulsory
condenser" replacement for homes that don't economically benefit.

Quite like to see your calculation for condenser replacement with £200/year
heating. Perhaps you are suggesting compulsory combi?

Jim A

"Jim Alexander" wrote in message
...

"IMM" wrote in message
...

"Jim Alexander" wrote in message
...

"Andy Hall" wrote in message
...
On Sun, 9 Jan 2005 10:17:28 -0000, "Grumpy" wrote:


"Jim Alexander" wrote in message
...

"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing
boiler
to keep it going as long as possible.

and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have
been.

Installed November 04. I'm looking at 7% but its early days I
suppose.
I
have
no experience of maintenance costs.

Too short a time.

You really need to compare with average temperature data as a minimum
to get a meaningful comparison. If the weather is colder than at the
equivalent time with the previous boiler then the gas use would be
higher anyway. It's no use just comparing quarterly bills.

Its useful feedback as input to my planning. Monitoring my return
temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain. My gas is less than £200/year, not all of it heating, saving
£30/year
say. The Vokera/Vaillant/Worcester condensing models are £300 more
expensive discount. Even factoring in zero DIY installation costs
that's
10ish years payback assuming equivalent maintenance costs which may or
may
not be true. Sorry condensing just doesn't payback for a lot of small
system replacement. My advice is get a replacement non condenser
while
you
can.

Most homes do have £200 a year gas bills for full heating and DHW. The
average home does benefit from a condensing boiler if changing boilers.

Don't necessarily disagree. My gripe is the forthcoming "compulsory
condenser" replacement for homes that don't economically benefit.

Quite like to see your calculation for condenser replacement with
£200/year
heating. Perhaps you are suggesting compulsory combi?

Missed out a not.

"Most homes do nothave £200 a year gas bills for full heating and DHW. The
average home does benefit from a condensing boiler if changing boilers."

If you look around condensers are now not much more than regular. B&Q are
now sell codnesners for around £400 or so. And when most are codensers,
maybe they will be more expensive. Regular can be fitted, but a special
form explaining why not has to be made out. The guide is pretty strict.

Average payback on an average house with average bills is/was around 3
years. That calculation will change come April.

On Sun, 9 Jan 2005 16:12:26 -0000, "Jim Alexander"
wrote:



Its useful feedback as input to my planning. Monitoring my return temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain.

It's hard to do a meaningful comparison using a conventional boiler
for this because the whole principle of control is different.

In the conventional boiler environment, the room thermostat will cause
the boiler to fire up and the temperature to rise to the design 82
flow, 70 return or thereabouts. One control loop is the boiler
cycling on and off to maintain approximately those temperatures.

With the condensing boiler, the boiler modulates and is striving to
maintain the operating temperatures as low as possible consistent with
providing adequate heat for the radiators.

Also, the condensing boiler doesn't have to be operating in condensing
range to obtain an efficiency increase relative to most conventional
boilers.


My gas is less than £200/year, not all of it heating, saving £30/year
say.

Obviously this depends on the size of property and the heat loss
through the fabric and air changes.

The saving will also depend on the type of old boiler being replaced.

For example, a really old cast iron one may have an efficiency of 50%
or possibly even less if in a poor state of repair.

A low water content type of 20 years or so might have 65%.

A conventional boiler purchased today will have 78-80% or so.


The Vokera/Vaillant/Worcester condensing models are £300 more
expensive discount. Even factoring in zero DIY installation costs that's
10ish years payback assuming equivalent maintenance costs which may or may
not be true. Sorry condensing just doesn't payback for a lot of small
system replacement.

This would assume no increase in energy cost over the lifetime of the
boiler. We've had typical price rises of 15% in the last year.
You are comparing good quality products. This is fine, but the
lifetime would be expected to be more than 10 years, probably 20.



My advice is get a replacement non condenser while you
can.

That would be a bit short sighted as I see it.....



--

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
You really need to compare with average temperature data as a minimum
to get a meaningful comparison. If the weather is colder than at the
equivalent time with the previous boiler then the gas use would be
higher anyway. It's no use just comparing quarterly bills.


I have a record of the units used back to 1989 which show an average of
1440.2 per year. Given a year or two I will be able see quite clearly
any savings showing up. External temperature excursions are only
relevant when trying to make a short term evaluation. However I
should benefit quite a lot since the previous system was gravity fed
with no tank stat whilst the new system is a Y plan. with better control.
I do miss the "kettling" :-)

As far as maintenance is concerned I have only had 2 shut downs with the
old Gloworm both due themocouple failure and 1 pump failure
during the period.

On Sat, 08 Jan 2005 09:48:04 +0000, Jim Alexander wrote:


"Grumpy" wrote in message
...

"Tony Bryer" wrote in message
...
In article , Roger wrote:
My gut instinct is to try and source spares for my existing boiler
to keep it going as long as possible.

Absolutely right. I just fell into the trap and had a Worcester HE40
installed. Subsequently I found I could get spares for the old Gloworm
and as for 25% savings with a condensing boiler dream on.

That's interesting. Can you put a figure what the gas savings have been.

I would say from the customers I have asked and from my own experience
that 25-30% is achievable but will require best case/worst case upgrade to
acheive.

I.e. previously:
permananent pilot, conventional flue, simple time switch
no seperate control of HW, plain tank with tatty jacket.

afterwards:
condensing boiler: Programmable thermostat, Part L compliant tank
for S-plane controls and TRVs. and full control of HW.

Have a fan assisted boiler or electronic ignition in the old kit and the
savings will be much less.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

"Andy Hall" wrote in message
...
On Sun, 9 Jan 2005 16:12:26 -0000, "Jim Alexander"
wrote:



Its useful feedback as input to my planning. Monitoring my return temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain.

It's hard to do a meaningful comparison using a conventional boiler
for this because the whole principle of control is different.

In the conventional boiler environment, the room thermostat will cause
the boiler to fire up and the temperature to rise to the design 82
flow, 70 return or thereabouts. One control loop is the boiler
cycling on and off to maintain approximately those temperatures.

With the condensing boiler, the boiler modulates and is striving to
maintain the operating temperatures as low as possible consistent with
providing adequate heat for the radiators.

I'm talking mainstream domestic condensing system boilers that would be used
for replacement in a smallish system. Yes they modulate just like combis
have for a few years but your explanation is misleading. Fixed pump speed
is the norm in the smaller boilers. The set point is the same old
temperature limit as in older boilers, a limit which Potterton for example
says set to max in winter. The modulation can only try to keep the
temperature at the setpoint, not down to a lower setpoint. The boiler has
to achieve the heat requirement of the radiators or heating effectivness is
poor. The radiator system may reduce the flow as a result if TRV action.
Perhaps that's why some condenser advocates now recommend removal of TRVs.
A flow reduction causes the return temperature to rise, the modulation only
goes so low, typically 50% of rating. Crucially in a system boiler the
setpoint has to be high enough for safe DHW. In the mainstream domestic
system boilers there is not currently a separate control loop for DHW. Yes
if there was things would be better.

I'm not arguing against bespoke condensing design, only the dubious
economics of compulsory replacement in some small systems.


The Vokera/Vaillant/Worcester condensing models are £300 more
expensive discount. Even factoring in zero DIY installation costs that's
10ish years payback assuming equivalent maintenance costs which may or may
not be true. Sorry condensing just doesn't payback for a lot of small
system replacement.

This would assume no increase in energy cost over the lifetime of the
boiler. We've had typical price rises of 15% in the last year.

Well it was a very simple response which assumed zero installation cost.
There is a comment in the installer magazine at the merchants that if the
rules had allowed 20% exceptions unscrupulous installers would have used
this to undercut. I think that is a rounabout way of saying condenser
installation is more expensive.

You are comparing good quality products. This is fine, but the
lifetime would be expected to be more than 10 years, probably 20.

Ideally but spares are only guaranteed for ten.
My advice is get a replacement non condenser while you
can.

That would be a bit short sighted as I see it.....

I have to agree with that statement.

Jim A

On Mon, 10 Jan 2005 15:36:03 -0000, "Jim Alexander"
wrote:


"Andy Hall" wrote in message
.. .
On Sun, 9 Jan 2005 16:12:26 -0000, "Jim Alexander"
wrote:



Its useful feedback as input to my planning. Monitoring my return temps
don't think I will get much condensing so I'm assuming 15% efficiciency
gain.

It's hard to do a meaningful comparison using a conventional boiler
for this because the whole principle of control is different.

In the conventional boiler environment, the room thermostat will cause
the boiler to fire up and the temperature to rise to the design 82
flow, 70 return or thereabouts. One control loop is the boiler
cycling on and off to maintain approximately those temperatures.

With the condensing boiler, the boiler modulates and is striving to
maintain the operating temperatures as low as possible consistent with
providing adequate heat for the radiators.

I'm talking mainstream domestic condensing system boilers that would be used
for replacement in a smallish system. Yes they modulate just like combis
have for a few years but your explanation is misleading.

Not really.

Fixed pump speed
is the norm in the smaller boilers.

True on many system boilers, but a number even in smaller capacity
have at least a switched pump.

If a self adjusting pump such as the Alpha is used then variation as a
result of TRV behaviour is accounted for.

The set point is the same old
temperature limit as in older boilers, a limit which Potterton for example
says set to max in winter. The modulation can only try to keep the
temperature at the setpoint, not down to a lower setpoint. The boiler has
to achieve the heat requirement of the radiators or heating effectivness is
poor.

This depends on the season, the system and what one is trying to
achieve. I wouldn't take anything from Potterton as indicative of
anything. They are living on former glory and not a lot more.

On a conventional boiler, you should not really be turning the boiler
thermostat down below the 82/70 figure too much since it will induce
condensing and in this environment that is deleterious.

In a condensing boiler, the boiler thermostat can be turned down when
the weather is warmer. This is because the heat loss from the house is
lower and required radiator output lower. It's a fallacy to suggest
that the system needs to be run at 82/70 for most of the time unless
the radiators are marginally sized or the weather exceptionally cold.

It's true that more sophisticated condensing models have weather
compensation and take this into account to control the water
temperature, but this does not mean that the manual control that can
be applied to a simpler condensing boiler to operate it in a lower
temperature range rather than having it cycle is not valuable.


The radiator system may reduce the flow as a result if TRV action.
Perhaps that's why some condenser advocates now recommend removal of TRVs.
A flow reduction causes the return temperature to rise, the modulation only
goes so low, typically 50% of rating.

Actually not. If you look at products from Vaillant at the low
capacity end they will modulate from 4.8 to 14.2kW - essentially 3:1
The small Worcester Bosch is similar.



Crucially in a system boiler the
setpoint has to be high enough for safe DHW. In the mainstream domestic
system boilers there is not currently a separate control loop for DHW. Yes
if there was things would be better.

I'm not arguing against bespoke condensing design, only the dubious
economics of compulsory replacement in some small systems.

Since the issue is one of compulsion through legislation, there are
more issues to consider than the cost of your gas bill.

I suppose that a max power level could have been set below which
fitting of condensing boilers was not mandatory (notwithstanding the
other exemptions), but it's then adding another level of complexity to
the whole thing. Since condensing combis, for right or wrong have a
significant market share and in general have a minimum power level of
20-25kW to do anything remotely useful, it would be difficult to
structure and operate rules to specifically exempt just small heating
boilers.





--

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Mon, 10 Jan 2005 15:36:03 -0000, "Jim Alexander"
wrote:


"Andy Hall" wrote in message
. ..
On Sun, 9 Jan 2005 16:12:26 -0000, "Jim Alexander"
wrote:



..

Since the issue is one of compulsion through legislation, there are
more issues to consider than the cost of your gas bill.

I suppose that a max power level could have been set below which
fitting of condensing boilers was not mandatory (notwithstanding the
other exemptions), but it's then adding another level of complexity to
the whole thing. Since condensing combis, for right or wrong have a
significant market share and in general have a minimum power level of
20-25kW to do anything remotely useful, it would be difficult to
structure and operate rules to specifically exempt just small heating
boilers.

Not really, normally building regs only apply to new work or to
modifications. This is an example of a like for like replacement being
virtually prohibited at the component level regardless of system
implications. IMHO that's going too far. Actually I understand that
compulsory condensing is not going to apply in Scotland so my fear of not
being able to obtain a conventional system boiler may not apply.

Jim A

On Mon, 10 Jan 2005 17:25:51 -0000, "Jim Alexander"
wrote:


"Andy Hall" wrote in message
.. .
On Mon, 10 Jan 2005 15:36:03 -0000, "Jim Alexander"
wrote:


"Andy Hall" wrote in message
...
On Sun, 9 Jan 2005 16:12:26 -0000, "Jim Alexander"
wrote:



.

Since the issue is one of compulsion through legislation, there are
more issues to consider than the cost of your gas bill.

I suppose that a max power level could have been set below which
fitting of condensing boilers was not mandatory (notwithstanding the
other exemptions), but it's then adding another level of complexity to
the whole thing. Since condensing combis, for right or wrong have a
significant market share and in general have a minimum power level of
20-25kW to do anything remotely useful, it would be difficult to
structure and operate rules to specifically exempt just small heating
boilers.

Not really, normally building regs only apply to new work or to
modifications. This is an example of a like for like replacement being
virtually prohibited at the component level regardless of system
implications.

It is for other replacements as well, such as windows (unless you go
for other than elemental method for part L1 purposes)



IMHO that's going too far. Actually I understand that
compulsory condensing is not going to apply in Scotland so my fear of not
being able to obtain a conventional system boiler may not apply.


This is from the government that brought you part P when that is
demonstrably unnecessary and unenforceable.

There are other parts of L1 like having a token number of electrical
light fittings that will only accept low energy light bulbs.

If you look at the Regulatory Impact Assessments around part L1, it is
mainly around how to achieve carbon emission reduction and measures
for that. Return on investment to householders does not figure
highly in it.

It's difficult to guess at how prices of condensing and non-condensing
boilers will move after April. It is alleged that there is a higher
manufacturing cost in condensing models , but unless you are comparing
against really simple conventional boilers with mechanical thermostat,
there is not a huge difference in content apart from the arrangement
to remove condensate - perhaps a fiver's worth of plastic bits at
cost.
So one could reasonably conclude that there could be cost differences
that are volume related - i.e. as conventional boiler numbers decline
they become more expensive to manufacture and condensing ones cheaper
with increasing volume. It is hard to assess how amortisation of
development costs will be treated - in other words whether
non-condensers can be considered to have had that written down if they
have been on the market for a while.
Another unknown is how manufacturers will price and take margin on
products, although that's more of a marketing, distribution and
competition issue. It's possible that prices for condensing units
will stay high in the short term, but I suspect that competition will
do something about that ultimately.
At any rate, I would expect that price differentials between
condensing and non condensing will erode or disappear.

It's a pretty safe bet that energy prices will increase, so any
percentage saving on use will have a direct impact.

There's not a great deal more that can be done to improve condensing
boiler efficiency further with today's technology, which is why most
units are grouped around the SEDBUK 90-91% range - and differences are
not statistically significant.
Therefore, the energy use gain, accounting for property size and type
is fairly predictable or calculable.

THese seem to me to be the three economic factors and then one has to
consider the time period.

I don't think that these are the main focus of the government in the
legislation. They are assuming also that you will want to be
sufficiently public spirited, but just in case you are not, they will
help you with legislation which is for your own good :-)














--

..andy

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