no hot water

[robhill]

hi i need help with my boiler
i have a biasi 28s its about 6 years old

the dhw does now work unless the ch is on
but if you open the tap without the heating on the boiler tries to start i think its the flue fan i can hear but will not fire and after a few seconds it goes into fault mode (flashing green light). if i turn the power off and on again it goes back to normal. i have checked the dhw flow switch according to the manual and led lights when tap us opened so all is fine with that.
any help would be much apreciated

 

[ChrisR]

Is the HW "normal" if the CH is already on?

 

[robhill]

yes chris works fine

 

[ChrisR]

Can't find anything about a green light, but suspect secondary heat exchanger blocked.

See manual - from their web site.
Check the operation of the System Flow Switch - how far the pin comes out to operate the microswitch. It's possible that there's enough flow on CH to operate it but not on HW, but the stickiness of the switch means that if you put iit on CH first, it stays out just enough.

Could also be a tired pump - same reasoning.
Tony should know he's a Biasi agent, if he comes on tnight. Meantime check that pin.

 

[robhill]

chris you are a star !!!!!!!!!!
cleaned off mechanism and now works fine

thanks a lot