Combi boiler flue. Size options.
 

Hi.

I'm looking at ordering a new combi on monday, but the maker offers
two flue pack options, a four inch and a five inch. Can anyone tell
me why there is a difference and which would be the better option to
choose? And maybe why? :)

The boiler is a Worcter Bosch Greenstar, combi condensing...

URL:http://www.worcester-bosch.co.uk/Ran...?ProductType=5

.... and I'm thinking of going for the 35 model for the 14l/min DHW
flow. (Don't need a big boiler for the heating, just DHW.)

Thanks.

--
Regards from Mike Barnard
South Coast, UK.

[To reply by email remove ".trousers" spamtrap from email address]

Combi boiler flue. Size options.
 

"Mike Barnard" wrote in message
...
Hi.

I'm looking at ordering a new combi on monday, but the maker offers
two flue pack options, a four inch and a five inch. Can anyone tell
me why there is a difference and which would be the better option to
choose? And maybe why? :)

The boiler is a Worcter Bosch Greenstar, combi condensing...

URL:http://www.worcester-bosch.co.uk/Ran...?ProductType=5

... and I'm thinking of going for the 35 model for the 14l/min DHW
flow. (Don't need a big boiler for the heating, just DHW.)

RTFM :-)
I think you'll find the 125mm flue is necessary for longer runs.

Combi boiler flue. Size options.
 

On Sat, 13 Mar 2004 11:24:39 -0000, "John Stumbles"
wrote:

RTFM :-)

I HAVE read the flippin' manual. :) PDF format from worsters site.
It gives the options in sizing, the runs they allow etc, but not WHY.

I think you'll find the 125mm flue is necessary for longer runs.

Yes, I guess it's to do with frictional loss on the sides of the flue
pipes.

Thanks anyway.

--
Regards from Mike Barnard
South Coast, UK.

[To reply by email remove ".trousers" spamtrap from email address]

Combi boiler flue. Size options.
 

In article , Mike Barnard
wrote:
I'm looking at ordering a new combi on monday, but the maker offers
two flue pack options, a four inch and a five inch. Can anyone tell
me why there is a difference and which would be the better option to
choose? And maybe why? :)

Haven't checked the tech info myself, but at a guess the 5" allows a
longer total flue length.

--
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

Combi boiler flue. Size options.
 

"Mike Barnard" wrote in message
...
On Sat, 13 Mar 2004 11:24:39 -0000, "John Stumbles"
wrote:

RTFM :-)

I HAVE read the flippin' manual. :)

Ahhh: "flippin'". And there was me thinking the F stood for something else.

Like "Friendly" ;-)


PDF format from worsters site.
It gives the options in sizing, the runs they allow etc, but not WHY.

ISTR there was a table somewhere showing the runs allowable with different
dia flues. Maybe it was in the flue manual. Incidentally did you find the
manuals for the current models on their website? They used to only have them
for last year's models.

Combi boiler flue. Size options.
 

In article , Tony Bryer
writes
In article , Mike Barnard
wrote:
I'm looking at ordering a new combi on monday, but the maker offers
two flue pack options, a four inch and a five inch. Can anyone tell
me why there is a difference and which would be the better option to
choose? And maybe why? :)

Haven't checked the tech info myself, but at a guess the 5" allows a
longer total flue length.

Much longer. The Vaillant Ecomax 824E manual (for example) shows the max
length of a 4" flue to be 9 metres (vertical) but a 5" flue is good for
26 metres (vertical). Woster Bolshi will be similar. Don't forget to
allow for 90 and 45 degree bends which reduce the overall limit.
PS If you are going condensing then 26 metres of 5" flue is going to
cost a *lot*, one reason why people go for Keston or Man-ecotec which
use much cheaper 2" plastic kitchen waste. The latter is available as
a combi, and is expensive but if you are staying put for 20 years
cheaper in the long term.
--
Andrew