Hi all I normally drain my system down every November and then refill and add an inhibitor.
Is it a good idea to first put a cleaner if for maybe 5 days then do the drain down and inhibitor
System is a 4 year old main combi boiler
Changing the system water annually may be counterproductive as you are introducing dissolved air every time you do it, though I admire your proactive approach to maintenance. Would I be right to assume you already have a system filter?
It will be interesting to see what others on here say. My feeling on the cleaner is that freeing off potential dirt and putting it into circulation is probably not especially helpful unless you flush the system after using cleaner to actually get the dirt out of the system.
I'd suggest limiting annual intervention to using a cheap turbidity tube (see if you can get one at a reasonable price) and, if all is well, testing the inhibitor concentration and topping that up if need be.
I normally drain some out by flushing through the magnetic filter so the level in the upstairs radiators is low enough to pour some inhibitor in, then fill up and bleed them.
Water is always clean even when I have taken a radiator off.
Combi boiler and I also get it serviced after by a RGI.
Refilling every year is a bad idea for lots of reasons (for starters, adding o2, adding scale, cost of chems and time). Adding cleaner even worse as its a right pain to get all of it out, except with a powerflush (which is a days work in itself) it will eat your system.
No. You're doing more harm than good. If it's a sealed system is shouldn't need draining until the boiler is next replaced. It won't hurt to check the inhibitor concentration once in a while, say every 5 years, but if it's a sealed system that isn't leaking and hence being topped up frequently even this is probably unnecessary.