Worcester 28CDi Whining when CH operating

[RichardJones]

My 28CDI has just started whining when the CH is running. It was serviced 2 weeks ago and a few days prior to that the I disturbed the Relief Valve when repositioning the overflow (required for the service). Anyway after blowing off the valve half a dozen times, the valve eventually stopped leaking and the boiler held its pressure. Now I can only presume that the whine I'm getting now is an airlock. The boiler sounds a little rattly (not a metallic noise) and the whine comes and goes at regular intervals. The top air bleed is open.
Is it likely to be an airlock and if it is, is there any other way of clearing?
Is it best left alone to clear itself or is it a case of call out the service engineer?

 

[clf-gas]

Who did the service you or a corgi engineer?.

 

[RichardJones]

British Gas annual service

 

[clf-gas]

Then I dodn't understand how you disturbed the PRV, anyway sounds like your fan, £70+

 

[RichardJones]

I had disconnected the overflow many moons ago and not reconnected it. The engineer during the previous service had stated that it should be reconnected to comply with the service requirements. When I reached up to reconnect the overflow I knocked the PRV, this started it dripping. After the pressure repeatedly dropped due to the leak, I felt the only option was to pressurize the system and then blow off the PRV to reseat the seals. This did work after a few attempts and the pressure has kept constant. The boiler normally idles with 1 bar and rises to around 1.4 under full heat. However, recently it rises to 2.0 bar so my presumption is that the draining and the refilling of the system might have encouraged an airlock that is just being a little stubborn.

 

[clf-gas]

Have a read here then //www.diynot.com/forums/viewtopic.php?t=37170

 

[RichardJones]

Thanks for that...not sure how to read it yet though. I'll have to sit down and apply it to my scenario and see if it makes sense.

Thanks again

 

[bengasman]

If you do have an airlock in a sealed system, it is extremely poorly installed. I can not recall having come across it.

 

[nickso]

repressurise the expansion vessel and see if that cures the pressure problem. if you do phone BG out dont mention that you have touched the boiler or you will get charged for the visit, well you would if i turned up.