New boiler, plumber says system doesn't need chemical or power flush

[ScreamingBeans]

He's generally very good and I broadly trust him, but I want to get opinions on this.

He says the way he does it is to just use water, which gets rid of everything (I think he says he takes the radiators off and drains them then puts them back) as chemicals sometimes cause problems and power flushing is overkill.

What's the general view on this, is this insane or OK?

I think most boiler manufacturers require a chemical flush as part of their installation instructions. The boiler warranty won't be valid if its not installed to manufacturers instructions.

I've just googled my boiler installation instructions and it looks like a simple water drain/re-fill is NOT sufficient:

It is a requirement of the Building Services
Compliance Guide which is a second tier document
to the Building Regulations to flush and inhibit the
primary water system in accordance with BS 7593.

Have had two plumbers out this week to quote for a new boiler and both said they do a chemical flush but not a power flush, as power flush pushes a lot of pressure through and can cause leaks etc.

I'm in the thick of boiler replacement at present (which has been beset by so many problems, I now feel qualified as a plumber!)

I agree with the above.

The answer is, it depends! If there was never a power flush done, it probably is needed. If you've ever had one done, it's probably not needed (indeed the power flush I had done this time has put in train a whole host of problems though I always needed a new boiler regardless).

I hadn't even thought of the warranty angle on this.

If he takes the radiators off and (presumably) flushes them with a garden hose while bashing them with rubber hammer or similar, that likely does a better job of removing crud than any power flush would anyway.

Hubby a plumber - has been for 40 years almost- and says that’s fine OP x

From plumber DP: You have to go with manufacturer instructions or boiler warranty is invalid …. The thing is they wouldn’t know if you chemical flushed it or not if the inhibitor is put in the system when filled back up !!
I have a mate who works for a boiler manufacturer and they do a water test from 1 radiator to make sure there is a trace of inhibitor !!
Powerflush is only needed if it is really not working i.e like warm radiators or big cold spots in them ….. if you put a hose pipe on a radiator u are cleaning the radiator but not the pipe work etc. …..
i would say if all the radiators heat up fine but it’s just the boiler playing up then it’s best to just give it a chemical flush …. It doesn’t take long and you know it’s done to manufacturers instructions

Main thing is to make sure there's inhibitor in the system and there's a suitable filter/air separator fitted on the flow or return pipe to the boiler.

We had a chemical treatment put through but not a power flush when we got our boiler replaced

What's an inhibitor @johnd2 ?

Have you got a 'magnaclean' next to the boiler OP? It's a big red thing (2 mug size) that collects the sludgey magnetic goop and you can open it periodically yourself and clean it. That helps the system.

Inhibitor is a 15 pound bottle of liquid that is added to the radiator water and it basically reduces the risk of radiators from rusting from the inside