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