I had to part drain a combi system today (well, depressurise it and make
enough space to fit in a litre of inhibitor - see my post of about a week
ago!). Unfortunately I find I'm out of PTFE tape which I want to use on the
cap on the towel rail which I had to remove; decided to buy some Monday
morning and finish the job then; with no CH in the meantime. However, now
the boiler won't deliver any HW. Is that normal; should I expect that?
Isn't it possible to use HW without CH?

Boiler is a Friendly Format 100E - I have no instructions for the beast
though.

Thanks
David