On 30 Aug 2005 05:59:40 -0700, "mmccar"
wrote:

Thanks everyone for your replies.

Andy, so if my 22mm pipe drops to 15mm within 1m of the boiler I may be
ok - I'm thinking the pipe change may be in the wall as opposed to the
under floor - any ideas what the standard practice is, is it even
permissible to lay concreate on a 15mm pipe? Can I get a Corgi
engineer measure the pressure to see if the 15mm pipe will suffice?

This is a bit difficult to do since the existing boiler is running at
a lower gas rate than the combi would. The point would be the pressure
drop from meter to boiler which must be no more than 1mB. However
that has to be measured under load conditions.

You can calculate based on the guidelines at

http://www.cda.org.uk/megab2/build/pub124/default.htm

Generally, if the 15mm run is about 1m, it should be OK as long as the
rest is 22mm.

It is common to use iron pipe in concrete, but the internal diameter
is only slightly more than 15mm copper, unfortunately.

Perhaps you could excavate near the boiler and see what the pipe is?

Copper pipe can be run in concrete provided that it is sleeved in some
way to prevent corrosion of the copper - a material issue not a size
one.




--

..andy

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