Peter Woodhouse wrote:
I'm considering a WB combi boiler to replace an exisiting boiler.

Could someone tell me the basic differences between the various series that
they manufacturer.
....

24i Junior

compact lightweight unit different from:

24i
24CDi BF or OF or RSF (or are these the same - different flues?)

Yup, flue options. I think the the i and CDi are mechanically similar
but different controls (clock/programmer?)

The latter types are 'conventional' combis having one gas-water heat
exchanger and a diverter valve & (plate type) water-water heat
exchanger for DHW.

The Junior has no diverter valve or plate exchanger, but both primary
and DHW are heated in the gas-water exchanger assembly. Someone (Ed?)
said Ferrolis are like this too.

On Wed, 29 Sep 2004 07:43:34 GMT, "Pete"
wrote:

..

Thanks for the reply John.
Space is not really an issue so it makes no a compact unit has no real plus
points
over a non-plus one. Given this, should I be looking at the 24i/24CDi? Does
the fact that
they have 2 exchangers make them a better unit or is the 1 exchanger of the
Junior a new idea?
Maybe this is a cost cutting measure which means a weaker product?
I'll check out the controls of the i and CDi and see if I can see where they
differ.

FYI, I had a quote from an installer yesterday. They said that the Junior
has a smaller expansion
vessel and they recommended adding an additional, external vessel to the
system to ensure it
supports the radiators satisfactorily (we have 8 which he said was "border
line"). He also said he could
try and get hold of the older 24i which has a larger vessel. It seems a bit
daft to get a non-compact one
which needs "extras". Can anyone comment on this?

Yes.

The Junior has an expansion vessel of 6 litres which is pretty small.
At the normal operating pressure of 1.5bar, that would allow a system
capacity of 30 litres, so I think that your installer is probably
right - it would be marginal at best. You would have to calculate
radiator volume from the radiator manufacturer datasheets to be sure.
Obviously volume depends on the radiator sizes and number of panels.
50-80 litres for a system is pretty typical

The 24i has an 8 litre vessel and the 24CDi has 10. You can scale up
the capacity of system that these will support linearly.

If you have to add an additional expansion vessel to the system it can
go anywhere that is convenient.

You can download all the information from the web site if you go to
the installer area.





As you can tell, I'm a bit of a novice when it comes to combis!

Any additional comments most welcome.

Pete

..andy

To email, substitute .nospam with .gl

On Wed, 29 Sep 2004 00:41:09 +0000, John Stumbles wrote:

Peter Woodhouse wrote:
I'm considering a WB combi boiler to replace an exisiting boiler.

Could someone tell me the basic differences between the various series that
they manufacturer.
...

24i Junior

compact lightweight unit different from:

24i
24CDi BF or OF or RSF (or are these the same - different flues?)

Yup, flue options. I think the the i and CDi are mechanically similar
but different controls (clock/programmer?)

The latter types are 'conventional' combis having one gas-water heat
exchanger and a diverter valve & (plate type) water-water heat
exchanger for DHW.

The Junior has no diverter valve or plate exchanger, but both primary
and DHW are heated in the gas-water exchanger assembly. Someone (Ed?)
said Ferrolis are like this too.

And "Fer" which is a badge of some Ferrolis.
I suspect the down side is that due to hot spots you could get a big
limescale build up in the DHW heat exchanger.
I guess for a soft water area it might be a good choice, although ideally
you would then want a s/s heat exchanger.

--
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

"John Stumbles" wrote in message
...
Peter Woodhouse wrote:
I'm considering a WB combi boiler to replace an exisiting boiler.

Could someone tell me the basic differences between the various series
that
they manufacturer.
...

24i Junior

compact lightweight unit different from:

24i
24CDi BF or OF or RSF (or are these the same - different flues?)

Yup, flue options. I think the the i and CDi are mechanically similar
but different controls (clock/programmer?)

The latter types are 'conventional' combis having one gas-water heat
exchanger and a diverter valve & (plate type) water-water heat
exchanger for DHW.

The Junior has no diverter valve or plate exchanger, but both primary
and DHW are heated in the gas-water exchanger assembly. Someone (Ed?)
said Ferrolis are like this too.

Some Ravenheats are like this, but being crap they also use a 3-way valve.