Alpha CB28 boiler help needed!

[getthekettleonthen]

My boiler is not giving me HW or CH. Lamp A & B are flashing together. The boiler fired up for a couple of minutes this morning then it sounded like the fan wound down (like it came under load) and the flame went out. I have followed what the flow chart in the installation instructions says to do for fault finding. This is where I am lost. After saying that it is a fan or Flue fault, it gives a few voltage checks that you can make according to your symptom (lamps). For mine it says to check two volages at the PCB for the air pressure sw. One fails, saying to replace the sw. it also says to check a voltage again at the PCB for the fan, which also fails. 0v when it should be 240v. On checking back along the circuit, I cannot even get 240v at the main terminals of the PCB or the Boiler (yet I am getting 26v at my previous check from somewhere)!
What have I failed to see! HELP! Is there a cut off switch that I need to reset or something?

Thankyou for your time.

 

[Paul Barker]

If I were in front of the boiler I would start by switching off fully at the wall for a few seconds and then on. If it last finished in a lockout it would first show you this again, so would need to be reset.

Then I would listen to the fan performance. This is a two leed aps and just one pressure tube, it works by starting the fan then momentarily stopping the fan and then starting it again. The pcb when it is happy that the fan has stopped will start it again. So it is normal to hear the fan start up faulter and then restart.

From the sound of it though you might have a power supply problem. Only yesterday I found this was the main fault on a right old Eurocombi. I measured just 80v ac at the input. A new fused switched connection unit fixed that.

So make sure that the supply is not the problem, run it again and see if it still happens.