Ideal Mini fault

[diamondgas]

Totally forgot until now an issue I have with the above boiler! Ordered a load of possibilities to be honest but anyone here had more experience and can shed more light I'd appreciate it! These boilers are the old Biasi's I believe ... mini C24

Scenario is this ... main green on light flashes 4/sec ... Issue was no hot water ...

The flat has been empty 4 months ... the pressure was on zero so topped it up ... pump seized but fortunately got that away!

Issue is that I can get the hot water to work as normal as long as theirs a demand for heating. The pcb recognises a call for water, heating on, moves the diverter across and goes to full fire as it should. Turn the demand for heating off and the sequence of events is pump on, pump off, pump on again a few seconds later, pump off repeatedly! Boiler never starts ignition sequence! What's throwing me is that as soon as you call for heating only then hot water the water heats and works perfectly modulating to keep the water hot!

Clutching at straws maybe but wondered if anyone has had anything similar? Any guidance would be appreciated ...

 

[diamondgas]

An update for you regards the above fault!

Turned out to be a stretched pump flow diaphragm! The differential pressure was slightly less across the hot water than the heating meaning that the flow spindle moved out but quite enough to make the microswitch! Weird that it stayed out once maid on central heating! I suspect the plate hex is maybe gunged up a bit too but replacing the diaphragm has done the trick!!!

 

[BLOD]

Hi Diamond,
I have a similar one to this on a C28 where the HW only works when heating on.
When switching between hw & CH could you notice a difference in how far the flow switch pin came out?
On the one Im looking at I can't notice a difference so am staring to think maybe there's a fault in the microswitch itself.

thanks

 

[zeebeedee]

An update for you regards the above fault!

Turned out to be a stretched pump flow diaphragm! The differential pressure was slightly less across the hot water than the heating meaning that the flow spindle moved out but quite enough to make the microswitch! Weird that it stayed out once maid on central heating! I suspect the plate hex is maybe gunged up a bit too but replacing the diaphragm has done the trick!!!

How did you test the differential pressure across both sides?