To all those who helped with my air flow problem, thank you. Upon taking off the front seal it was apparent that the fan was the problem. One of the small blades on the fan had come off not sure how, but I suppose it could have been age. Anyway, have looked for replacement part and it seems I need to buy a complete new unit as the little plastic fan can't be bought seperately, is this correct? It seems the replacement fan unit is £70.00 - £80.00 plus vat, but I only want a small bit of plastic rather than the whole unit. Is there anyway of just getting the little plastic fan (seems so small compared to size of the boiler) or do I need to get a whole replacement fan unit? If I do need to buy a replacement fan unit can I fix it (fairly competent) or is it an engineer/plumber job?

Any advice or help gratefully received, thank you

Wendy, October 2008

I have had a similar problem with Keston fan unit. The unit has a small plastic fan just to cool the motor but the main fan is located within the main two peice alloy housing unit. The fan is located on the motor spindle and held in place by splines on the spindle and fan boss, what happens is that the plastic splines strip out so there is no longer drive to the fan.
Separate the two halfs of the alloy casing, carefully remove the metal tension clip from the centre boss and the pull off the fan. Lightly roughen the inside of the centre hole and remove all plastic remains from the motor spindle. I then used Araldite to 'glue' the fan back onto the spindle and replaced the metal clip. Make sure that the spindle is pushed fully back into place !! Reassemble as before....note best left for 6 - 12 hours to make sure that the Araldite has fully hardened before starting up. This repair lasted me around two years before the fan finally fell apart, the repair, however was still intact.

Steve, January 2012

Never use spray oil on a boiler fan ,the original bearings are lubed for life bearings ! if you have a speed problem on the fan or it squeals its shot BUT...Most fan units can be repaired quite easily DIY. Read my other post on this question .. Explosion can occur or burning of fan motor using spray lubricant . A gas engineer who serviced my old boiler insisted on using a dry lube spray on the flue fan smelled lousy for days and reacted with wire insulation with heat involved causing cracking don't know why but within 3 weeks the wiring was replaced..
Will post full topic on repairing/replacing fan bearings in future
Thanks

STUCH, May 2011

Hi rather than fan replacement REPAIR IT less than £6 and 1 hour of your time . Its easy to do for those with some engineering skills ,Simply remove the fan unit after taking photos with camera or as i do mobile phone,( Saves wondering which wire went where cuts confusion ) check the bearing number on the bearing edge normally 626Z NSK .Please note... make sure that the new bearings say Z it denotes metal shielding seals, ie..plastics no good.
Remove the motor/bearing cooling fan very carefully by rotating it on its shaft to break the push fit as pulling off . Relace bearings and replace cooling fan using either a good metal lock compound or even superglue and a small centrepunch to dimple the pressed metal fan . Ive repaired several of these for a local plumber some been running 2 years even with superglue on fan...

These are only basic instructions, if anyone interested in more details leave a response will be willing to help

STUCH, May 2011

Hi, i have a used but in excellent condition fan unit if you still require one for a reasonable price?

Colin dyson, February 2009

Hi jp here. I have got the same boiler and yesterday it stopped. I believe the fan is about to go because it makes a squely noise, speed fluctuate and then it stop cutting off the burner. What oil could I spray to make it last a bit longer?

Jp, December 2008

wendy it is not neccessary for you to change the fan because of the broken plastic blade.that is just a cooling blade for the fan motor itself.i have run these units with blades missing without a problem many times.they get brittle with age and just fall to bits.the main fan blades are concealed within the fan casing it is important that the fan performance is adequate for the fan to deliver enough air pressure to satisfy the pressure switcth and so allow ignition to take place,

mr knowitall, October 2008

You will have to change the fan even if it is oiled it will last no longer than 6 months the oil will wax and stiffen the fan
If you turn the spindle that the cooling fan is attached to does it spin if not try turning
It is not good practice to take the cover off make sure it is replaced and sealed

yas, October 2008

Hi C and iain, yes the fan with the broken blade is a small plastic fan that is on the front of the boiler near the top and is visible once the sealed metal casing from the front of the boiler has been removed. I can't see any other fan though to either oil or check to see if its working

Wendy, October 2008

is the fan turning freely? if so the fan is fine. i think you talking about the front plastic bit of the fan..is this correct

c, October 2008

Ok, now I'm confused, if the little plastic one is the cooling fan, where is the fan that I need to spray the oil on, am I being really dense? Didn't use WD40 on the colling fan as it said on the tin that it was flammable so was worried about that in the boiler.

Wendy, October 2008

the little plastic one is just a cooling fan and wouldnt impair boiler performance, like mrknowitall says, try some spray oil on fan (i dont believe in wd40) and see how it goes for a bit.

iain, October 2008