PEX ?

[webmaster]

PEX pipes typically range from 10mm–22mm cross-linked polyethylene pipes they can be run direct off the boiler circuit direct, or via a thermal store. On the first floor if of the larger sizes they are usually attached to heat diffuser plates and these plates fixed to the joists. Or if they are the smaller diameter they can be fixed direct to the underside of the deck.
The smaller diameter pipes are a lot easier to route, not quite as simple as cable but certainly a lot easier than 15mm and greater diameter pipes, which can have a habit of fighting back, and want to lay anything other than straight.
One of the alternatives is to use a series of plastic heating plates instead of the PEX pipe, which is akin to laying radiators under the floor deck.
Some PEX pipes run without the need for a thermal store and run at higher water temperatures. The pipes themselves are capable of running at comparatively high temperatures & pressure, but it must be borne in mind that higher temperatures can lead to less comfort on walking surfaces.

Typical designs use larger bore pipes to distribution manifolds, and then radiate Pex pipes from that, for some designs there are further sub manifolds all to assist ease of distribution.

This manifold system also allows grouping and control of zones simpler.

The following is a link to a pic of the authors distribution manifolds, which may give a better understanding:
http://uk.groups.yahoo.com/group/UK_Selfbuild/files/Rick%27s selfBuild/Optiflo.JPG


Do I need an Oxygen barrier in my PEX/BUTYL pipe?
This depends a lot on the system design; if you have non-ferrous materials in the thermal store & pipes then there is not really a problem.
However if you have any ferrous material then it is important to avoid oxygen ingress, which will cause oxidation – exacerbated by the temperature, which in addition to slowly eating away your system – can also cause problems with sludge build up.


Regards, Webmaster
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Regards, Webmaster