Just finishing off adding a rad. and other jobs on the CH system, then do a simple service on the boiler.
It's a Vaillant EcoMAX 824E, about 11 years old. The manual doesn't mention any sort of treatment to put in to the system and the installers said that it wasn't necessary, but there was a small amount of black stuff in the rads (I took them outside and shook the s**te out of them). The drined of water was clear and colourless.
Just wondering if there should be anything put in and, if so, what to use.
Also, I've had little luck in looking for a source of spares so don't want to go too far as there's a major gasket that almost certainly won't survive dismantling.
OK, 11 years of use is a goodly time, but it's off for 5 months a year and v. little use of DHW so not much used by normal standards.
Any info. gratefully received.