Apologies in advance this could go on a bit!
Since installation a year ago, the blue warning light on my Worcester Bosch
24Ri had occasionally been flashing intermittently.
This is in a "standard" s plan plus system - 2 heating and one HW zones -
As it was a rare occurrence, I procrastinated having loads of other projects
to attack (you know how it is).
Decided to phone WB to query the cause of this and the first thing he
mentioned was pump over-run and to check that the system had been wired
correctly to allow this.
So I started investigating whether the pump did over-run and found that when
HW demand was set, the pump did over-run by 3 minutes.
Tried the same with the CH but the pump just continued to over-run with the
piping around the pump staying hot.
After some deliberation it ocurred to me that the by-pass valve was probably
So the call for heat is turned off, but, as the solenoid valves are closed
and the by-pass isn't working, the boiler experiences no flow and overheats
(presumably this causes the flashing light). As the boiler isn't being
cooled by any water flow, it simply continues to run the pump which is
effectively working against closed valves.
So finally the questions are:
Will the boiler have been damaged in any way by being allowed to sit with
over-hot water content? I do not believe that it would have fired in this
state, just sat there!
Similarly will the pump have been damaged by being allowed to pump against a
closed valve arrangement (I am fairly certain that the pump was actually
generating heat when left running in this state)? The pump over-run that
occurred on my CH test continued for over 20 mins. But this state would
only exist at the end of a heating or hot water time period.
Any informed comment appreciated
- posted 12 years ago