Hi ive been looking through the archives on the above subject and
believe my system needs a Power Flush.

Ive a 28KW Vokera Excell 80 SP Combi, with 7 Rads. Weve been in the
house 6 years and done no maintenance to the system, just fire fighting.
We purchased flush agent and inhibitor from whikes but never used it.

Last year i discovered a problem with diverter valve in that for the
shower to warm through the rads needed to warm through as well (i think
my diagnosis was correct). I purchased the service kit drained the
system fitted the new orings etc, filled with tap water, ran the system,
its seemed ok but 6 month later back to sq 1. Boiler flue fan bearings
are shot now as well.

I now also get air in top rad when bled i sometimes get black water with
wiffy smell. When the system warms up in the morning theres plenty of
knocks and bangs.
More recently ive been hearing high pressure creaking noises from the
boiler.
The only symptom thats not present is that the rads get hot evenly ie no
cool triangles at the bottom or at the top, they warm up evenly.

Due to boiler condition i was going to buy a new boiler but having read
the archives ill just be pumping crap through a new pump and heat
exchanger. So i thought a power flush may be in order.

But before a fork out on a power flush i think ill try the old Whikes
flush agent. Im going to drain a little water from the top rad, then
using a funnel and small bore tube pour the agent in through the bleed
point at the top corner of the rad. Leave that for 24 hrs then drain the
system completely. Then add the inhibitor when i finally refill. If that
dont work then ill go for power flush.

Im not the type for removing rads, to much scope for disaster.

Please confirm if the above is logical.

thank you

Michael