Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip upgrades...


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

Ed Sirett wrote:
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
snip
I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip upgrades...

But are they CORGI registered?

On 2006-11-16 23:20:17 +0000, Ed Sirett said:


Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

Why does a dog lick its parts?

The large computer manufacturers did this for years, some may still.
IBM is reputed
to have had a DASD (disk drive to everyone else) upgrade to improve the
data rate.
This consisted of two pullies and a belt and the customer was neither
allowed to see the
upgrade kit or the installation of it "for intellectual property
reasons". Cost was some way into four figures.




I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.
In Hong Kong there is probably someone who sells grey market chip upgrades...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...


Surely the heater exchangers must be different from model to model, as the
flame temperature and loop temperature are fixed? Unless, that is, all the
lower power models have oversized heat exhangers and have an appropriately
restricted gas flow.

Andy.

Ed Sirett wrote:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

Much the same way as a Mini One can be turned into a Cooper with a
software swap and yet the price differential is still maintained. The
average driver/fitter is probably not well enough clued up on these
things to cause a problem for the makers on a large scale.

How is the firmware held on the boiler (i.e. EPROM, Flash etc)?

In Hong Kong there is probably someone who sells grey market chip upgrades...

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In message , John
Rumm writes
Ed Sirett wrote:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

Much the same way as a Mini One can be turned into a Cooper with a
software swap and yet the price differential is still maintained. The
average driver/fitter is probably not well enough clued up on these
things to cause a problem for the makers on a large scale.

How is the firmware held on the boiler (i.e. EPROM, Flash etc)?

In Hong Kong there is probably someone who sells grey market chip upgrades...

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

You think they'd be so stupid as to make the ucontroller programmable?

Thick - not stupid

and Ian - what does a chip pirate want with CORGI registration (smileys
aside) ?

makes me think about that silly woman doctor on breakfast TV, who said
to make sure you buy parts from a CORGI registered merchant

CORGIS install (by definition)

--
geoff

raden wrote:

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

You think they'd be so stupid as to make the ucontroller programmable?

I have seen stranger things... still how much is a blank device?

what sort of procesor/micro do they use for these things?

(I would have though an 8031 or even a PIC type device ought to be able
to hack it)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure. Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

The message
from Ed Sirett contains these words:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I forget which computer firm it was in the 60s(?), perhaps ICL, that had
a simple upgrade to double the speed of your computer. When the firm
paid for the upgrade a technician arrive, took off a panel, snipped one
wire, and put the panel back.

--
Skipweasel
Pay no attention to that man behind the curtain.

On 2006-11-17 09:34:49 +0000, "Fred" said:


I would think it will be a combination of fan speed and burner pressure. Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

Designs vary though. For example, on mine (MAN MIcromat), there are
different sizes of heat exchanger for different rated outputs together
with a different component where gas and air are fixed before passing
through the fan to reach the burner.

The output is then entirely controlled by the fan speed, the fan being
a motor with servo operated by the boiler controller. The gas
pressure, if it were measured at the output of the valve is around
zero. The combustion adjustments are via two controls on the gas valve
which are used for the top and bottom ends of the modulating range.
Adjustment is made against CO2 percentage in the flue gases.

Via this method, the boiler can operate over a 4 to 30kW range.

Viessmann and others use a similar design.

Given that, it's entirely possible to have a single mechanical design
which will operate at up to 30kW or so with soft limits in between.

To some extent, even if there is a larger heat exchanger for larger
models, the difference in manufacturing cost, even multiplied by
margins in the distribution channel does not add up to a £200
difference. If the only mechanical difference were a diffierent
injector, it wouldn't either.

The point is that the products are positioned at the market price for
the capacity and functions of the boiler, taking into account brand
value as well. As a result, Vaillant will make more margin on the
higher end product and less on the higher volume smaller ones.
Production and material costs are only a part of the pie.

Guy King wrote:
The message
from Ed Sirett contains these words:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I forget which computer firm it was in the 60s(?), perhaps ICL, that had
a simple upgrade to double the speed of your computer. When the firm
paid for the upgrade a technician arrive, took off a panel, snipped one
wire, and put the panel back.

I got paid a couple of hundred to do the same thing to a guitar amp I
had designed once.

The customer wanted the chorus to 'sound like a Roland, not like a
Leslie speaker'..it had taken me a week to design it to get rid of the
harshness of the Roland sound..using an all pass phase shifter. I simply
snipped one wire on the capacitor..

raden wrote:
In message , John
Rumm writes
Ed Sirett wrote:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( ?815
versus ?1009) for essentially a firmware difference.

Much the same way as a Mini One can be turned into a Cooper with a
software swap and yet the price differential is still maintained. The
average driver/fitter is probably not well enough clued up on these
things to cause a problem for the makers on a large scale.

How is the firmware held on the boiler (i.e. EPROM, Flash etc)?

In Hong Kong there is probably someone who sells grey market chip upgrades...

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

You think they'd be so stupid as to make the ucontroller programmable?

Thick - not stupid

and Ian - what does a chip pirate want with CORGI registration (smileys
aside) ?

I was assuming 'gas work for a fee'.
This may be incorrect of course.

"Andy" wrote in message
...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...


Surely the heater exchangers must be different from model to model,

Matt, why should they be? Motor makers have done this years. The BMC A
series engine block was used in 700cc to 1300cc engines, although with
heavier cranks and different cly' heads. Same block though. heat exch =
block. Some mods here and there and a new model with different performance
to add to the range.

"raden" wrote in message
...

makes me think about that silly woman doctor on breakfast TV, who said to
make sure you buy parts from a CORGI registered merchant

CORGIS install (by definition)

Maxie, do you need to be Corgi to put back the burners on the hob after they
have been washed in the dishwasher?

"Fred" wrote in message
...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

It modulates but Ed said the maximum is clipped on lower models. You will
most prob find the same instruction manual for all models and the only
different part NO. is the pcb. See if the heat exchanger is the same part
No for each.

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

What is the max kW and fan speed on CH? They have obviously changed matters
for DHW.

Owain wrote:
Ed Sirett wrote:
This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? ...
I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Then ask yourself how long a 28kW unit will last when running at 37kW?

If the only difference is in fact the firmware, as it may be, as long as
the 37Kw stamped one.


Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( ?815
versus ?1009) for essentially a firmware difference.

Intel manage it and AFAIK they don't even change the firmware, just
disable bits of processor. Zap! and the power is gone.

"Doctor Drivel" wrote in message
reenews.net...

"Fred" wrote in message
...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

It modulates but Ed said the maximum is clipped on lower models. You will
most prob find the same instruction manual for all models and the only
different part NO. is the pcb. See if the heat exchanger is the same part
No for each.


So if all else is equal you can upgrade for the modest cost of a PCB!

Reminds me of an early Amstrad satellite receiver. There were 16 and 48
channel versions with a substantial price difference between them. Yet the
price, until Amstrad got wise, of the relevant IC was a few pounds! Most
independent retailers would happily modify your receiver!

"Doctor Drivel" wrote in message
reenews.net...

"Andy" wrote in message
...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...


Surely the heater exchangers must be different from model to model,

Matt, why should they be? Motor makers have done this years. The BMC A
series engine block was used in 700cc to 1300cc engines, although with
heavier cranks and different cly' heads. Same block though. heat exch =
block. Some mods here and there and a new model with different
performance to add to the range.


You're actually partly right here. The Mini (and variants) used 2 blocks
which were rather different. The lighter one was used for the 850 to 1100
cc varieties and the other for 1275 and Cooper engines.

There were other A series engines such as 803cc but they were inline engines
and slightly different again.

On Fri, 17 Nov 2006 09:40:04 UTC, Guy King
wrote:

The message
from Ed Sirett contains these words:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( ”¬Ãº815
versus ”¬Ãº1009) for essentially a firmware difference.

I forget which computer firm it was in the 60s(?), perhaps ICL, that had
a simple upgrade to double the speed of your computer. When the firm
paid for the upgrade a technician arrive, took off a panel, snipped one
wire, and put the panel back.

IBM. ICL wouldn't have had the nous.

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

On 2006-11-17 11:10:33 +0000, The Natural Philosopher said:

I got paid a couple of hundred to do the same thing to a guitar amp I
had designed once.

The customer wanted the chorus to 'sound like a Roland, not like a
Leslie speaker'..it had taken me a week to design it to get rid of the
harshness of the Roland sound..using an all pass phase shifter. I
simply snipped one wire on the capacitor..

I once worked with an engineer who had been involved ina previous life
in the design of TV sets at Plessey/Philips/Pye (I think the place was
each of these at one time or another). At any rate, the chief
engineer would go round with his wirecutters looking at the proper
designs and would snip out components until the set stopped working....
Apparently, considerable cost savings were made this way.

On Fri, 17 Nov 2006 00:12:00 +0000, Andy wrote:

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...


Surely the heater exchangers must be different from model to model, as the
flame temperature and loop temperature are fixed? Unless, that is, all the
lower power models have oversized heat exhangers and have an appropriately
restricted gas flow.

That latter description is exactly how they work, AISI, because they are
condensing units the greatly over sized heat exchanger for the lower end
models is not a problem.

The matter was a particular irritation to me as I bough the 24kW unit the
other month mainly as a heating unit with the HW side just for an adjacent
WC basin. I was vexed to discover the heating side is pegged to 19kW
although the HW goes to 24kW. The setup parameters allow you to further
restrict the heating but not to increase it.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 00:21:35 +0000, John Rumm wrote:

Ed Sirett wrote:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

Much the same way as a Mini One can be turned into a Cooper with a
software swap and yet the price differential is still maintained. The
average driver/fitter is probably not well enough clued up on these
things to cause a problem for the makers on a large scale.

How is the firmware held on the boiler (i.e. EPROM, Flash etc)?

In Hong Kong there is probably someone who sells grey market chip upgrades...

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

Once they are out of the guarantee period the only obstacles would be
legalities of making such a mod.
Setting that matter aside there would be changes in the maximum permitted
flue lengths (almost certainly not an issue) and the sizing of the gas
supply pipes (almost certainly an issue in most places).

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 00:46:12 +0000, raden wrote:

In message , John
Rumm writes
Ed Sirett wrote:

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

Much the same way as a Mini One can be turned into a Cooper with a
software swap and yet the price differential is still maintained. The
average driver/fitter is probably not well enough clued up on these
things to cause a problem for the makers on a large scale.

How is the firmware held on the boiler (i.e. EPROM, Flash etc)?

In Hong Kong there is probably someone who sells grey market chip upgrades...

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

You think they'd be so stupid as to make the ucontroller programmable?

Thick - not stupid

and Ian - what does a chip pirate want with CORGI registration (smileys
aside) ?

makes me think about that silly woman doctor on breakfast TV, who said
to make sure you buy parts from a CORGI registered merchant

CORGIS install (by definition)

This is OT but the issue is a real one every time I go to a house and find
a fancy fireplace installed by one of the several 'frieplace' shops round
here.

Invariably the prime offence is a damper plate which can fall down
easily into a position that blocks the flue. Turns out the fireplace
_company_ is indeed registered and proudly puts orange shield logo on shop
front etc. But they don't actually have any registered 'operatives' so the
actual installers are unqualified.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 00:40:31 +0000, Owain wrote:

Ed Sirett wrote:
This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? ...
I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Then ask yourself how long a 28kW unit will last when running at 37kW?

In principle as long as a 37kW unit would.



Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

The only way to bring a sense of competition into the matter would be
simply to buy other makes when needing higher powered units, but they of
course apply the same marketing strategy, although possibly not to such an
extent.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 09:34:49 +0000, Fred wrote:

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure. Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

The manual and spares list is common to all models.

The gas valve acts more like a carburettor on this sort of boiler the
faster the fan moves the air the more gas that is injected.

The fan speed is altered by the PCB changing the voltage to the fan motor.
It is checked and fed-back to the PCB by a tachometer on the fan shaft.

The units modulate over a wide range by altering the fan speed.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 15:42:39 +0000, Fred wrote:

"Doctor Drivel" wrote in message
reenews.net...

"Fred" wrote in message
...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

It modulates but Ed said the maximum is clipped on lower models. You will
most prob find the same instruction manual for all models and the only
different part NO. is the pcb. See if the heat exchanger is the same part
No for each.


So if all else is equal you can upgrade for the modest cost of a PCB!

That would probably be worth it for changing a 824 into an 837.
But not for the other models.

Reminds me of an early Amstrad satellite receiver. There were 16 and 48
channel versions with a substantial price difference between them. Yet the
price, until Amstrad got wise, of the relevant IC was a few pounds! Most
independent retailers would happily modify your receiver!




--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 13:58:51 +0000, Doctor Drivel wrote:

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

What is the max kW and fan speed on CH? They have obviously changed matters
for DHW.

Off the top of my head (and I can't remember if these are input or output
rates - although as it's condensing they are very close).

HW (MAX) CH
824 24 19
828 28 22 ?
831 31 24
837 37 ?

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

"Ed Sirett" wrote in message
...
On Fri, 17 Nov 2006 00:46:12 +0000, raden wrote:

In message , John
Rumm writes
Ed Sirett wrote:

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

Much the same way as a Mini One can be turned into a Cooper with a
software swap and yet the price differential is still maintained. The
average driver/fitter is probably not well enough clued up on these
things to cause a problem for the makers on a large scale.

How is the firmware held on the boiler (i.e. EPROM, Flash etc)?

In Hong Kong there is probably someone who sells grey market chip
upgrades...

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

You think they'd be so stupid as to make the ucontroller programmable?

Thick - not stupid

and Ian - what does a chip pirate want with CORGI registration (smileys
aside) ?

makes me think about that silly woman doctor on breakfast TV, who said
to make sure you buy parts from a CORGI registered merchant

CORGIS install (by definition)

This is OT but the issue is a real one every time I go to a house and find
a fancy fireplace installed by one of the several 'frieplace' shops round
here.

Invariably the prime offence is a damper plate which can fall down
easily into a position that blocks the flue. Turns out the fireplace
_company_ is indeed registered and proudly puts orange shield logo on shop
front etc. But they don't actually have any registered 'operatives' so the
actual installers are unqualified.

I trust you reported them.

"Ed Sirett" wrote in message
...
On Fri, 17 Nov 2006 15:42:39 +0000, Fred wrote:

"Doctor Drivel" wrote in message
reenews.net...

"Fred" wrote in message
...

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the
last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional
to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just
go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Part of me is truly impressed with the design which makes a whole
range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained (
£815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else
who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner
pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume
it's
not a modulating boiler.

It modulates but Ed said the maximum is clipped on lower models. You
will
most prob find the same instruction manual for all models and the only
different part NO. is the pcb. See if the heat exchanger is the same
part
No for each.


So if all else is equal you can upgrade for the modest cost of a PCB!

That would probably be worth it for changing a 824 into an 837.
But not for the other models.

Last time I bought one a Valliant pcb was silly money. £150 to £170 or so,
if my memory is right.

"Ed Sirett" wrote in message
...
On Fri, 17 Nov 2006 09:34:49 +0000, Fred wrote:

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

The manual and spares list is common to all models.

The gas valve acts more like a carburettor on this sort of boiler the
faster the fan moves the air the more gas that is injected.

How about injector size? same?

The fan speed is altered by the PCB changing the voltage to the fan motor.
It is checked and fed-back to the PCB by a tachometer on the fan shaft.

The units modulate over a wide range by altering the fan speed.

Ideal do the same.

"Ed Sirett" wrote in message
...
On Fri, 17 Nov 2006 13:58:51 +0000, Doctor Drivel wrote:

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

What is the max kW and fan speed on CH? They have obviously changed
matters
for DHW.

Off the top of my head (and I can't remember if these are input or output
rates - although as it's condensing they are very close).

HW (MAX) CH
824 24 19
828 28 22 ?
831 31 24
837 37 ?

If there is an injector I suspect to upgrade the pcb and injector (small
item) would need to be changed as well. The big stuff may be the same. The
devil may be in the detail.

"Owain" wrote in message
...
Ian Stirling wrote:
raden wrote:
and Ian - what does a chip pirate want with CORGI registration (smileys
aside) ?
I was assuming 'gas work for a fee'.
This may be incorrect of course.

Why, the microcontroller isn't even a "gas carrying part"?

If it involved in the control of gas on site then CORGI.

"Ian Stirling" wrote in message
...
Owain wrote:
Ed Sirett wrote:
This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? ...
I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Then ask yourself how long a 28kW unit will last when running at 37kW?

If the only difference is in fact the firmware, as it may be, as long as
the 37Kw stamped one.

It is a matter of goping through part numbers on prime points. You may find
only two differences: the pcb and injector.

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...


--
Ed Sirett - Property maintainer and registered gas fitter.



I think this is fairly common practice in many product lines.

It makes sense for a mfr who wants to produce a range of products to
minimise inventory and create the range artificially by having one base
hardware configuration, and disabling features to create the lower-end
models.

I had a sinclair scientific calculator at school, cheaper than the one my
friend had. It apparently had less functions. However, if you performed
the same key-presses on mine and his, they both actually had the same
functions! The only difference was the sticker on the keypad! If you
just wrote the other 'missing' functions on with a pen, hey presto, instant
upgrade.

--
Ron

"Ron Lowe" wrote in message
...
I think this is fairly common practice in many product lines.

It makes sense for a mfr who wants to produce a range of products to
minimise inventory and create the range artificially by having one base
hardware configuration, and disabling features to create the lower-end
models.

I had a sinclair scientific calculator at school, cheaper than the one my
friend had. It apparently had less functions. However, if you performed
the same key-presses on mine and his, they both actually had the same
functions! The only difference was the sticker on the keypad! If you
just wrote the other 'missing' functions on with a pen, hey presto,
instant upgrade.

I know an automotive engineer or two. About 12 years ago I recall them
saying that it cost more to install a single point fuel injection system on
an engine than multi-point - most cars had gone over to multi-point. I said
"why aren't all car multi-point as it is better?". They said the marketing
levels strategy dictate that lower end models must have less than the levels
above. Otherwise people would go for the lower end of the range most of the
time. They gauge generally by the bottom line profit of the whole range.
More money was made per car on the top end of the ranges (leather seats etc)

In message , John
Rumm writes
raden wrote:

I was thinking more like a quick download from the 31kW one! ;-) (at
least that way they could not say you were not using genuine firmware)

You think they'd be so stupid as to make the ucontroller programmable?

I have seen stranger things... still how much is a blank device?

what sort of procesor/micro do they use for these things?

(I would have though an 8031 or even a PIC type device ought to be able
to hack it)



IF you could copy the program

and what of the legal / insurance implications ?


--
geoff

In message , Fred
writes

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

It modulates but Ed said the maximum is clipped on lower models. You will
most prob find the same instruction manual for all models and the only
different part NO. is the pcb. See if the heat exchanger is the same part
No for each.


So if all else is equal you can upgrade for the modest cost of a PCB!

In the central heating industry, the words "modest cost" and "PCB" are
not comfortable bedfellows



--
geoff

On Fri, 17 Nov 2006 21:07:51 +0000, Doctor Drivel wrote:

"Ian Stirling" wrote in message
...
Owain wrote:
Ed Sirett wrote:
This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? ...
I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Then ask yourself how long a 28kW unit will last when running at 37kW?

If the only difference is in fact the firmware, as it may be, as long as
the 37Kw stamped one.

It is a matter of goping through part numbers on prime points. You may find
only two differences: the pcb and injector.

What injector. These are forced premix burners all the same.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 17 Nov 2006 20:59:59 +0000, Doctor Drivel wrote:

"Ed Sirett" wrote in message
...
On Fri, 17 Nov 2006 09:34:49 +0000, Fred wrote:

"Ed Sirett" wrote in message
...
Hi all,

This week I put a 31kW Vaillant Condensing Combi in. The other month I
put
in a 24kW unit. As I was doing the job, I started to think is there
_anything_ in the boiler that's different between the two units? I had
sort of assumed they would be _almost_ identical but with perhaps a
bigger
fan, gas valve or burner/heatX.

Well I was showing my apprentice how you could find out about all the
different settings.
We looked up the fan speed when it was doing HW and it was 499 rpm, I
was
fairly sure when I commissioned the 24kW unit the fan speed was 395 on
HW.
Then the penny dropped, they are physically identical units to the last
nut
and bolt, except for a couple of bits in the firmware! The power is
proportional to the air flow rate which is more or less proportional to
the fan revs. 499:395 is very near 31:24.

I strongly suspect the 37kW unit is also the same (the fan will just go
yet faster). I did a 28kW unit about 12 month ago and that ran to the
mid
400s on HW.

Part of me is truly impressed with the design which makes a whole range
of
models from the same production line. Part of me is wondering by
what mechanism can a the huge price differentials be maintained ( £815
versus £1009) for essentially a firmware difference.

I suppose some people would say buy a 30kW boiler from someone else who
could potentially be cheaper for the higher powered models.

In Hong Kong there is probably someone who sells grey market chip
upgrades...



I would think it will be a combination of fan speed and burner pressure.
Is
everything else identical? One way of checking would be to look at the
spares list - I assume they have one.

What sort of fan motor is it? What determines fan speed? I presume it's
not a modulating boiler.

The manual and spares list is common to all models.

The gas valve acts more like a carburettor on this sort of boiler the
faster the fan moves the air the more gas that is injected.

How about injector size? same?

They use a "zero-governor" type gas valve. No injector in the usual sense,


The fan speed is altered by the PCB changing the voltage to the fan motor.
It is checked and fed-back to the PCB by a tachometer on the fan shaft.

The units modulate over a wide range by altering the fan speed.

Ideal do the same.


....
and Keston and Worcester and all the other that use forced premix burners.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards