Would a powerflush work? One-way valves?

[lm713]

Summary:

Old/traditional central heating system (had F&E tank)

Old boiler was set to gravity as oppose to "fully pumped" (rightly or wrongly I don't know - the system did have a pump as well which seemed to be working at least when the heating was on).

New combi boiler installed in a new location; system obviously drained, F&E tank removed, etc.

Unfortunately the plumber installed the new boiler without first doing a chemical flush of the system as directed in the instructions.

I want to have the boiler taken down and do a power flush of the system through the flow and return pipes on the boiler frame.

Questions:

1. The radiators may have one-way valves: indeed the pipes connecting the "newer" radiator in the downstairs extension bathroom have joints/connectors(?) (at floor level) with arrows on them. (Not sure what these joints/connectors are called - the plumber said 'something'-fixes I think.)

All the older radiators in the house have no visible arrows on the connectors.

Would a power flush be pointless if the radiators have one-way valves?

2. Is it ok to power flush the boiler itself, isolated? This is probably OTT, but it's quite an expensive boiler and I would like to clean out the heat exchanger in case some of the dirt from the old system has already got trapped in there. I am a bit disappointed the plumber did not flush the system properly before connecting and I would like to mitigate the situation as much as possible.

Notes:

We did "flush" (fill and empty) the system via the new boiler with mains water several times before switching it on. The plumber assures me that when filling at the filling link, the water travels both ways: up the CH return pipe as well as through the boiler, so I'm hoping that the worst of the dirt run through the boiler.

The water in the system wasn't terrible I suppose: the viscosity seemed fine always, but it did have a brown colour (especially the first couple of times of filling to 2 bars and draining). Now the water is see-through, slight colour (like pond water). Am I over-reacting? We'll fit a filter to the system on CH return as well - maybe that would be enough (along with an inhibitor of course)?

...

I was hoping to keep things brief. It seems I failed. Sorry :/

Any advice would be GREATLY appreciated

 

[Gas2Air]

What do you mean by one way valves? If it is a twin pipe system, then it will not matter.

I can't see if there was a cleanse done on a cleanish system that it would harm the boiler. Powerflush/cleanse is different. If you've paid for a flush and haven't had it it get them back.

 

[Agile]

I expect he means unidirectional TRVs.

They will not make any difference to power flushing.

But I don't see any need to do any power flush if the water is clean anyway!

Tony

 

[lm713]

Thanks so much for the quick replies!

I think we're before the age of TRVs!

A picture paints a thousand words...

Untitled

• lm713
• 26 Nov 2013
• 1

 

[Agile]

That's an isolating valve!

They work in both directions!

They just withstand higher off pressure one way round.

Tony

 

[lm713]

If it is a twin pipe system, then it will not matter.

Sorry, not sure what a twin pipe system means?

I can't see if there was a cleanse done on a cleanish system that it would harm the boiler. Powerflush/cleanse is different.

By cleanse in the first instance, do you mean what we did (fill up with mains, drain, repeat) or do you mean to run the system with a flushing agent for a week or two? My concern with the latter is that the agent might dislodge a load of stuff that would then be taken into the boiler. Is it valid or am I talking nonsense?

 

[lm713]

That's an isolating valve!

They work in both directions!

They just withstand higher off pressure one way round.

Tony

Thank you Tony. That's great news! So a power flush should still be effective.

 

[Agile]

Yes, if done properly, but I don't think that you need one!

Tony

 

[Gas2Air]

Yes as Tony says they're isolation valves. Not good practice to fit them on pipework to rads. But a Powerflush can be done.

Yes a cleanse is basically a drain, flush, hot/cold, add inhibitor. Powerflush use a machine to pump chemicals to erm flush the system. Probably not needed unless you have blocked pipework.

 

[lm713]

Thanks so much for the advice guys.

Not good practice to fit them on pipework to rads.

Yes, there appears to have been some shoddy work done in this bathroom extension. (It was done some time ago.)

Have I got this right: Radiators don't need isolation valves fitted because you would always drain the central heating before removing a radiator?

Yes a cleanse is basically a drain, flush, hot/cold, add inhibitor.

Sorry to be a pain, but what do you mean by hot/cold?

..

So you reckon I should just add the inhibitor, fit the filter on CH return and be done with it. The radiators are a tad colder in the bottom-middle, but the difference isn't major.

Relieved that you guys aren't telling me the boiler will pack it in next year. It's true that instructions can sometimes over-exaggerate things.