I am making some changes to my kitchen and adjoining dining room (no door
between them), and as my CH boiler is situated in the kitchen thought I
would just check the ventilation requirements. I have the installation
instructions for the boiler (Potterton Kingfisher, CFL70 - conventional
flue) and this states that the free area should be 84 cm sq.

Now when I did math at school, 84 cm sq meant a square measuring 84cm x
84cm, whereas 84 sq cm is only a little over 9cm x 9cm, a big difference. I
hope that the instructions actually mean the latter? If not I might just as
well take the back door off its hinges and freeze in the winter!

Just as an aside, the boiler is currently ventilated via openings at the
back to the underfloor space (between 5ft and 2ft all over the house) and
from there via 7 air bricks around the walls. This would be well in excess
of the 84 sq cm, but is there anything in the regs that disallow this?
BGas/Transco have a couple of times shut the boiler off cos they didn't
realise where the ventilation came from, and I wasn't home when they visited
to explain things.
David.

"DavidM" wrote in message
...
I am making some changes to my kitchen and adjoining dining room (no door
between them), and as my CH boiler is situated in the kitchen thought I
would just check the ventilation requirements. I have the installation
instructions for the boiler (Potterton Kingfisher, CFL70 - conventional
flue) and this states that the free area should be 84 cm sq.

My boiler is a conventionally flued Potterton C70 (early 1980s) so probably
similar in size to yours.
It's sited in its own under-stairs boiler room to which the house builders
supplied ventilation air through a ~ 4" diam pipe, at ceiling level,
nothing at low level. When the domestic extension to CORGI kicked in it was
condemned until I'd put ventilation panels in its door at both low and high
level. In addition, I had to have a permanently open vent in one of my
lounge windows off which the boiler room is sited. (All vent sizing details
are in the appropriate BS - viewable at your local library.)

So I now get cold draughts in the winter from the window vent, but I guess
I'm not going to die from CO poisoning etc. Another downside is that we can
now clearly hear the boiler firing whereas before its door was ventilated,
the firing was normally inaudible.
Prior to CORGI intervention I kept open the considerably larger chimney
opening above the open fire space where my TV has always sat. That's now
closed off with minor vent holes...

84 cm sq does seem rather large compared to anything I've got here which
certainly satisfied the CORGI fitter.
--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

DavidM wrote:

Now when I did math at school, 84 cm sq meant a square measuring 84cm x
84cm, whereas 84 sq cm is only a little over 9cm x 9cm, a big difference. I
hope that the instructions actually mean the latter? If not I might just as
well take the back door off its hinges and freeze in the winter!

In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was
at school, too!)

David

"Lobster" wrote in message
...
DavidM wrote:

Now when I did math at school, 84 cm sq meant a square measuring 84cm x
84cm, whereas 84 sq cm is only a little over 9cm x 9cm, a big difference.
I
hope that the instructions actually mean the latter? If not I might just
as
well take the back door off its hinges and freeze in the winter!

In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was at
school, too!)

David

So Lobster, in your book, what does 84 sq cm mean ?

In article ,
says...
In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was
at school, too!)

But but but... 9 x 9 = 81!

--
Hedgehog

In uk.d-i-y GlintingHedgehog wrote:
In article ,
says...
In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was
at school, too!)

But but but... 9 x 9 = 81!

Burn him! He's an alien, with 9.1 fingers.

On Sat, 06 Aug 2005 14:40:30 +0000, DavidM wrote:

I am making some changes to my kitchen and adjoining dining room (no door
between them), and as my CH boiler is situated in the kitchen thought I
would just check the ventilation requirements. I have the installation
instructions for the boiler (Potterton Kingfisher, CFL70 - conventional
flue) and this states that the free area should be 84 cm sq.

Now when I did math at school, 84 cm sq meant a square measuring 84cm x
84cm, whereas 84 sq cm is only a little over 9cm x 9cm, a big difference. I
hope that the instructions actually mean the latter? If not I might just as
well take the back door off its hinges and freeze in the winter!

Just as an aside, the boiler is currently ventilated via openings at the
back to the underfloor space (between 5ft and 2ft all over the house) and
from there via 7 air bricks around the walls. This would be well in excess
of the 84 sq cm, but is there anything in the regs that disallow this?
BGas/Transco have a couple of times shut the boiler off cos they didn't
realise where the ventilation came from, and I wasn't home when they visited
to explain things.
David.

They mean 84 square cm.

In the absence of instruction to the contrary....
Provided the air is direct from outside.
Provided there are no other conventionally flued heating appliances
(including a solid fuel grate).

The 70 kBTU/hr that 20.5kW (but boilers of this period tended to quote
output rating so it's likely input rating is c. 25kW) The first 7kW is
free provided it's in a room not a cupboard. This leave ventilation for
18kw which can be provided with 4.5 cm^2 per kW. I.e about 81cm^2

There are rules for ventilation from under floor spaces.
Off the top of my head
1) Not for terraced or semis unless partition walls to ground level
(usually the case)
2) Air bricks have tapered holes so take the minimum they can be much
smaller than you might think.
3) They must be 300mm over ground level (to prevent snow and leaves
trouble).
4) The connecting hole between below and the room for the boiler must
have at least twice the area for the direct vents.

HTH

--
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

Lobster wrote:
In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was
at school, too!)

Have you tried multiplying 9 by 9 recently?

9cm x 9cm = *81* cm^2, which is read as '81 square centimeters'.

The phrase '84 centimeters squared' is ambiguous to me. If I heard it I
would probably presume the source is unreliable, or at least confused.

Rem

"Ed Sirett" wrote in message
news
On Sat, 06 Aug 2005 14:40:30 +0000, DavidM wrote:

I am making some changes to my kitchen and adjoining dining room (no
door
between them), and as my CH boiler is situated in the kitchen thought I
would just check the ventilation requirements. I have the installation
instructions for the boiler (Potterton Kingfisher, CFL70 - conventional
flue) and this states that the free area should be 84 cm sq.

Now when I did math at school, 84 cm sq meant a square measuring 84cm x
84cm, whereas 84 sq cm is only a little over 9cm x 9cm, a big
difference. I
hope that the instructions actually mean the latter? If not I might just
as
well take the back door off its hinges and freeze in the winter!

Just as an aside, the boiler is currently ventilated via openings at the
back to the underfloor space (between 5ft and 2ft all over the house)
and
from there via 7 air bricks around the walls. This would be well in
excess
of the 84 sq cm, but is there anything in the regs that disallow this?
BGas/Transco have a couple of times shut the boiler off cos they didn't
realise where the ventilation came from, and I wasn't home when they
visited
to explain things.
David.

They mean 84 square cm.

In the absence of instruction to the contrary....
Provided the air is direct from outside.
Provided there are no other conventionally flued heating appliances
(including a solid fuel grate).

The 70 kBTU/hr that 20.5kW (but boilers of this period tended to quote
output rating so it's likely input rating is c. 25kW) The first 7kW is
free provided it's in a room not a cupboard. This leave ventilation for
18kw which can be provided with 4.5 cm^2 per kW. I.e about 81cm^2

There are rules for ventilation from under floor spaces.
Off the top of my head
1) Not for terraced or semis unless partition walls to ground level
(usually the case)
2) Air bricks have tapered holes so take the minimum they can be much
smaller than you might think.
3) They must be 300mm over ground level (to prevent snow and leaves
trouble).
4) The connecting hole between below and the room for the boiler must
have at least twice the area for the direct vents.

HTH

--
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


Thanks all for the replies. I will assume that 84 cms sq is equivalent to
9.2cms x 9.2cms and work from there.

Thanks also to Ed for the comments on underfloor ventilation, I will check
the air bricks and stick a big notice on the front of the boiler for the
benefit of visiting gas engineers.

Now I just need tofind a Corgi plumber who will reconnect the gas and do
all the saftey checks after I have reinstalled the boiler. Any offers (mid
Herts)?
David.

I guess that there is a difference between 84 cm square ...and 84 sq cm.

84 cm square = 7056 cm sq
84 sq cm = 84 sq cm ........................or 9.1651513 cm sq

If there is still any confusion I would ring potterton and ask which one
they are defining. for your boiler.
Sometimes this sort of detail is written for the USA market and they do use
different phrases to define their "math "

Barry

--


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"DavidM" wrote in message
...

"Ed Sirett" wrote in message
news
On Sat, 06 Aug 2005 14:40:30 +0000, DavidM wrote:

I am making some changes to my kitchen and adjoining dining room (no
door
between them), and as my CH boiler is situated in the kitchen thought I
would just check the ventilation requirements. I have the installation
instructions for the boiler (Potterton Kingfisher, CFL70 - conventional
flue) and this states that the free area should be 84 cm sq.

Now when I did math at school, 84 cm sq meant a square measuring 84cm x
84cm, whereas 84 sq cm is only a little over 9cm x 9cm, a big
difference. I
hope that the instructions actually mean the latter? If not I might
just
as
well take the back door off its hinges and freeze in the winter!

Just as an aside, the boiler is currently ventilated via openings at
the
back to the underfloor space (between 5ft and 2ft all over the house)
and
from there via 7 air bricks around the walls. This would be well in
excess
of the 84 sq cm, but is there anything in the regs that disallow this?
BGas/Transco have a couple of times shut the boiler off cos they didn't
realise where the ventilation came from, and I wasn't home when they
visited
to explain things.
David.

They mean 84 square cm.

In the absence of instruction to the contrary....
Provided the air is direct from outside.
Provided there are no other conventionally flued heating appliances
(including a solid fuel grate).

The 70 kBTU/hr that 20.5kW (but boilers of this period tended to quote
output rating so it's likely input rating is c. 25kW) The first 7kW is
free provided it's in a room not a cupboard. This leave ventilation for
18kw which can be provided with 4.5 cm^2 per kW. I.e about 81cm^2

There are rules for ventilation from under floor spaces.
Off the top of my head
1) Not for terraced or semis unless partition walls to ground level
(usually the case)
2) Air bricks have tapered holes so take the minimum they can be much
smaller than you might think.
3) They must be 300mm over ground level (to prevent snow and leaves
trouble).
4) The connecting hole between below and the room for the boiler must
have at least twice the area for the direct vents.

HTH

--
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


Thanks all for the replies. I will assume that 84 cms sq is equivalent to
9.2cms x 9.2cms and work from there.

Thanks also to Ed for the comments on underfloor ventilation, I will check
the air bricks and stick a big notice on the front of the boiler for the
benefit of visiting gas engineers.

Now I just need tofind a Corgi plumber who will reconnect the gas and do
all the saftey checks after I have reinstalled the boiler. Any offers (mid
Herts)?
David.

"bs" wrote in message
...
I guess that there is a difference between 84 cm square ...and 84 sq cm.

84 cm square = 7056 cm sq
84 sq cm = 84 sq cm ........................or 9.1651513 cm sq

Whatever definitions you have, I don't think you can be so inconsistent from
one line to the next.

My definitions, for what it's worth:

84 sq cm = 84 cm sq

An 84 cm square = 7056 sq cm = 7056 cm sq

You are of course quite right........its good to see that some people do
read things carefully.
At least we seem to agree on the principal.

Barry
..----------------------------------
--


I guess that there is a difference between 84 cm square ...and 84 sq cm.

84 cm square = 7056 cm sq
84 sq cm = 84 sq cm ........................or 9.1651513 cm sq

Whatever definitions you have, I don't think you can be so inconsistent
from
one line to the next.

My definitions, for what it's worth:

84 sq cm = 84 cm sq

An 84 cm square = 7056 sq cm = 7056 cm sq

"Rembrandt Kuipers" wrote in message
...
Lobster wrote:
In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was at
school, too!)

Have you tried multiplying 9 by 9 recently?

9cm x 9cm = *81* cm^2, which is read as '81 square centimeters'.

The phrase '84 centimeters squared' is ambiguous to me. If I heard it I
would probably presume the source is unreliable, or at least confused.


Or does it mean 84 centimetres square (i.e. a square 84cm x 84cm) which is
substantially larger, the point the OP was trying to illustrate.
--
Keith Willcocks
(If you can't laugh at life, it ain't worth living!)

Keith Willcocks wrote:
"Rembrandt Kuipers" wrote in message
...
Lobster wrote:
In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it
was at school, too!)

Have you tried multiplying 9 by 9 recently?

9cm x 9cm = *81* cm^2, which is read as '81 square centimeters'.

The phrase '84 centimeters squared' is ambiguous to me. If I heard
it I would probably presume the source is unreliable, or at least
confused.

Or does it mean 84 centimetres square (i.e. a square 84cm x 84cm)
which is substantially larger, the point the OP was trying to
illustrate.

That's what 'ambiguous' meant, he didn't know.

Largely this one comes about because '84 centimetres squared' and an '84
centimetre square' sound almost exactly the same unless you are very
careful.

Usually you can tell by context which is meant. Square Centimetres removes
all confusion though.

On Sun, 07 Aug 2005 10:55:20 +0100, Rembrandt Kuipers
wrote:

Lobster wrote:
In my book, 84 cm sq (=84 cm^2) is unequivocally 9cm x 9cm (and it was
at school, too!)

Have you tried multiplying 9 by 9 recently?

9cm x 9cm = *81* cm^2, which is read as '81 square centimeters'.

The phrase '84 centimeters squared' is ambiguous to me. If I heard it I
would probably presume the source is unreliable, or at least confused.

Rem


Possible, although we don't have "coffee shops" in the UK and Meneer
van Rijn was not a native of these shores.




--

..andy

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