Biasi Garda HE - intermittant d.h.w. fault when c.h. is on

[DJKELECTRICAL]

Hi Guys,

Biasi Garda HE M96.28. Intermittantly no d.h.w. when c.h. is on. Indicator lamps show "no primary flow" - this is due to the pump switching off. I've witnessed the fault occuring and the sequence looks like this:

1. c.h. running
2. d.h.w. demand
3. burner shuts off
4. pump stops and does not restart*

*When c.h. is on the pump always stops momentarily on d.h.w demand but is uninterupted when changing back from d.h.w. to c.h.

I've had the PCB out and thought I'd struck gold when I found a dry joint on the pump relay but the fault is still there.

It mostly happens in the morning after c.h. has been running for an hour and just as the wife steps under the shower - you can see my problem.

Any help would be appreciated.

Cheers,
Dave

 

[Agile]

You need to remove the pump pressure switch and feel how hard the pin pushes out. It should be difficult to push back with a small finger.

If thats firm then look at the switch. If its turquoise on one side then you can SLIGHTLY bend the operating arm to give about 1.0 mm bend towards the pin.

Tony

 

[DJKELECTRICAL]

Hi Tony,

The problem is that in fault condition the pin doesn't extend at all - I thought the pump provided the pressure to push the pin out?

For some reason the pump isn't switching on. Also, I've measured the resistance of the temp probes and the readings seem to be in line with what's stated in the manual.

Regards,
Dave

 

[Agile]

If the switch is not activated within five secs the pump is turned off!

Activate it manually when the poin pushes.

Tony