Biasi 24S classic lack of DHW but perfect CH.

[andy123456789012]

Referring to old, but very useful bit of dhw troubleshooting for biasi 24s.........

//www.diynot.com/forums/viewtopic.php?p=819406#819406

8. If I disconnect the hydraulic actuator housing and move it to one side (leaving small bore pipes connected) and manually push the pin (manually doing what the actuator is supposed to do) the dhw operates perfectly and to temp

Obviously this sounds stupid but I am going to presume that this does not cause any water leakage or not enough to worry about in the short term. However, presumption is not always good.......hence why I'm double checking.
NOTES:
1) CH works fine
2) DHW does not work....DHW (behind gas valve) microswitch does not get clicked (due to lack of pin-out from right side of Diverter valve) with all "hot" taps turned full.

On a side note, as per the service manual, I used a multimeter to check the CH vs DHW flow switch voltages behind the service panel.
I checked the 2 far right pins on the Left side row of 10 pins.....
It said 11.80 volts when boiler was on, (as it should for CH on)
When I turned on all hot taps, it was still 11.80 (which shows as wrong..)



I would like to check no 8. before taking it apart and checking diaphragm.

Anything I should watch out for, for instance, will moving the actuator housing cause any issues to the 2 connected microbore pipes?

 

[Agile]

It sounds like a classic case of the hydraulic actuator have failed.

I surmise this because you seem to have included a lot of irrelevant information.

The diaphragm is probably failed.

Tony