You absolutely do not need to plumb the condensate pipe outside.
In fact have a read of the following:
http://www.centralheating.co.uk/sys...ENSATE_DRAINAGE_PIPE_INSTALLATION__FINAL_.pdf
The is the official position of the heating and hotwater council
Secondly read this
http://www.viessmann.co.uk/etc/medi...402.File.File.tmp/Frozen condensate pipes.pdf
Thirdly read section 1.14 on page 13 of Section H of the Building Regs:
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf
Its says you can definitley connect to internal pipes.
Now read the advice from corgi expert:
http://www.atmos.uk.com/core_files/productDoc(102).pdf
Almost all of the above (the experts/guidance) are saying it saying it can and should be plumbed internally.
And finally and this already posted in an alternative thread:
http://www.dailymail.co.uk/sciencetech/article-1342357/Central-heating-break-big-freeze-Heres-.html
In fact have a read of the following:
http://www.centralheating.co.uk/sys...ENSATE_DRAINAGE_PIPE_INSTALLATION__FINAL_.pdf
The is the official position of the heating and hotwater council
Secondly read this
http://www.viessmann.co.uk/etc/medi...402.File.File.tmp/Frozen condensate pipes.pdf
Thirdly read section 1.14 on page 13 of Section H of the Building Regs:
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf
Its says you can definitley connect to internal pipes.
Now read the advice from corgi expert:
http://www.atmos.uk.com/core_files/productDoc(102).pdf
Almost all of the above (the experts/guidance) are saying it saying it can and should be plumbed internally.
And finally and this already posted in an alternative thread:
http://www.dailymail.co.uk/sciencetech/article-1342357/Central-heating-break-big-freeze-Heres-.html