On 07/05/2015 08:09, Jim GM4DHJ ... wrote:
"Jim GM4DHJ ..." wrote in message
...

"Bod" wrote in message
...
On 07/05/2015 07:49, Jim GM4DHJ ... wrote:
Why do people insist on fitting air admittance valves outside? ... are
they
mad?...you see them everywhere...!


They look much better than having a long 4" vent pipe going all the way
up and 2ft above gutters.

what if they freeze up?...I know it is unlikely due to hot air in the
system .......I'll have to have another look at fitting instructions .....


perhaps not a good idea .....

'It is not permitted for valves to be fitted externally'

http://www.polypipe.com/cms/toolbox/...stallation.pdf


Yes, but many do fit them externally and have no problems.