In message , Dave Fawthrop
writes
Can one temporarily short out, with a pipe, the central heating circuit of
a combination boiler, so that I can get the DHW working first, and do the
central heating later? Clearly in summer the hot water will work OK with
the central heating not working.

The cylinder has to go first before I can fit the combination boiler, can
be fitted.

No, not usually, but then you didn't say what boiler it is

Most combi boilers expect to see pressure in the central heating circuit
as this is what is directly heated - which then heats the hot water



--
geoff