SNIP
Looking at the BES site (thanks Ed and why isn't it in the FAQ?), is the
Differential By-Pass Valve (12161) the approiate part?

Looking at the diagrams the bypass valve should be fitted from the flow
to the return between the boiler and the zone valves. But according to
the Keston installation instructions the flow/return temperature
differential should be 10 to 15 C. In the layout I was planning the zone
valves are only about a meter from the boiler. I can't see that short
run of pipework producing that much of a differential. Any thoughts?

Any other thoughts/observations would be welcome.

Thanks

Paul

Thanks for your reply , Fred.

I've now mailed and spoken to Keston and I'm still not clear about how
to deal with this issue. What is normal practice since Part L came in?
Are installers simply ignoring the boilers requirement for a temperature
drop across the by-pass circuit? Or are they creating an (artificially)
larger loop for the by-pass circuit? Or are they still using a rad as a
by-pass?

Thanks for your responses.

Paul