HI all,

I have a Worcester 24cdi RSF combi boiler which I think is "short
cycling" Once the rads have to got to required heat, the boiler will
fire for 40 seconds and then shutdown for 4 mins. 7 Rads in total with
6 having TRV's and a rad in the bathroom which is the bypass radiator
(without a TRV) and the only thermostat is on the boiler itself.

The other symptom, which I don't know whether it is related, is that I
have bled the bypass radiator every fortnight and a substantial amount
of air has been vented. All other radiators haven't required bleeding
at all and they all get hot.

The only change to the system in the last 12 months was that a
radiator was removed and replaced whilst a wall was being plastered.
The system was drained and refilled at the same time.

I read on another website that there may be to much by-pass flow which
could be a cause of short cycling? Would the system need balancing and
if so, do I treat the by-pass radiator the same as the rest? Would I
need to get a room thermostat and if so, can this be easily wired into
the boiler replacing the on-board stat?

Sorry for all the questions, but you can probably guuess that I
haven't a clue

Any advice or guidance would be much appreciated.

Thanks

Steve