Hi, I'm installing a central heating / domestic hot water (solid fuel
Rayburn multiburner range) vented/gravity feed system. I intended to
use plastic piping except for the 28mm circuit and hot water takeoff
from cylinder, however on checking pipe leaflets max service
conditions for them are 92deg c with short term overload of 114degc.
Occassionally in the past with a former system the water in the
pipework would be heard boiling during cooking, remedied by turning on
the central heating to cool the water temp; because of this
possibillity am I correct in thinking that plastic is'nt suitable
either for hot water or c/h in this relatively uncontrollable
situation?

On 07/05/2011 12:23, rog wrote:
am I correct in thinking that plastic is'nt suitable
either for hot water or c/h in this relatively uncontrollable
situation?

Doesn't sound like it... certainly, the last time I had a (gas) boiler
installed it came with warnings not to use plastic plumbing within X
distance of the boiler. Don't the Rayburn installation instructions or
website have similar specs? Would be surprised if not.

David

"Lobster" wrote in message
...
On 07/05/2011 12:23, rog wrote:
am I correct in thinking that plastic is'nt suitable
either for hot water or c/h in this relatively uncontrollable
situation?

Doesn't sound like it... certainly, the last time I had a (gas) boiler
installed it came with warnings not to use plastic plumbing within X
distance of the boiler. Don't the Rayburn installation instructions or
website have similar specs? Would be surprised if not.

David

I would use copper for the gravity serks 28mm, but you should also have a
"heat leak", normally the bathroom radiator
to take all the extra "heat" that the cylinder cannot take.
For the heating you need to come off the boiler in copper for a certain
distance "might be 2mts" then you can use plastic
but I personaly would use copper, as plastic looks horrible going up the
wall and into the rads.
Plastics ok where you cannot see it like in the loft or under floorboards,
but also it can get you out of difficult pipe runs occasionally.
You will need a class 1 flue, and if it's internal, fire breaks where it
goes through the upper floors.