Hi Glen. Dave Walton is the name. Just retired after 44 years in plumbing and heating, 35 of them running own company and being one the early CORGI members.
I would say that flushing out system every 18 months is a bit excesive. But what ever you find works for you.
The idea of X400 is that it breaks down any contamination in the system and keeps it water born until dumpted to drain. An average house done correctly usually takes between 6-8 hours to do.
X100 is not a cleanser it is a inhibitor which is supposed to prevent any further corrosion.
Combi's squealing is quite often caused by pump starting to fail thus the flow of water is not fast enough through the heat exchanger.
I would think your engineer will of opened the By Pass valve to increase the flow of water through the boiler, you could find as a result that some of your radiators furthest away run a bit cooler.
|