New boiler coming flush 8mm or renew

[silver50]

Hi folks,

Bit advice please. Got 8mm from manifold/s ran in my 3 bed circa 1900 flat, 8 radiators. Been in 18 years.

I was thinking of changing rads and pipework but don’t want to make worse mess of already poor floorboards and of course it’s much more costly and involved.

Maybe a powerflush and new radiators rather than renewing pipework? Thoughts please.

Thanks

 

[ianmcd]

not advisable to power flush 8mm as you can push all the crap into the manifolds, but have hear of a few that have done it successfully , if everything is working well I would leave it as it is, change the rads if you want but as said if its working dont fix it

 

[silver50]

Cheers. Aye contrary to my plans I’m starting to wonder if that’s best.

Just took one rad off and quite black sludgy at bottom of it. But that’s maybe not overly surprising or concerning. And a good reason to change them.

 

[Madrab]

If you have the option, change the pipework.

IMO 8mm microbore is a problem waiting to happen, especially if you are changing things on the system, you run the danger of crud getting moved around the system and causing restrictions.

 

[Terrywookfit]

If you have the option, change the pipework.

IMO 8mm microbore is a problem waiting to happen, especially if you are changing things on the system, you run the danger of crud getting moved around the system and causing restrictions.

There is fook all wrong with a properly installed microbore system. ( In copper with no twin entry valves )
We fitted hundreds of systems in the 70 / 80s which are still working properly.

 

[silver50]

Thanks for replies. Seems opinion maybe will be a bit split on it.

Going to get two or three estimates. Would ideally like floors sanded so might see if any fitters would work in tandem with a joiner to sort floors when putting boards back. This needs done anyway.

 

[Madrab]

There is fook all wrong with a properly installed microbore system. ( In copper with no twin entry valves )
We fitted hundreds of systems in the 70 / 80s which are still working properly.

And sorry to say i've probably pulled as many that don't any more. Did one last week actually, 22mm f&r into 8mm splitters that just couldn't heat the rads any more, lousy circulation all, gunged up. Upped to 15mm, customer couldn't believe how much warmer and how much faster the systems heated up, has never been as warm.
Personally I wouldn't use 8mm, 10mm at a push on a small system in a flat maybe. I'm currently living with a 10mm system that can't heat anything larger than a 1400mm rad, that'll be pulled out of the walls this summer.

.... But each to their own

 

[silver50]

Hmm it’s tricky. I’ll need to decide which way to go. Certainly the system is working fine at the moment.

Do others agree a power flush isn’t a great idea incase crud in manifolds were to clog pipes? Sounds possible but this was a bit disappointing to hear as I’d hoped a good flush though might’ve been a plan.

 

[ianmcd]

Hmm it’s tricky. I’ll need to decide which way to go. Certainly the system is working fine at the moment.

Do others agree a power flush isn’t a great idea incase crud in manifolds were to clog pipes? Sounds possible but this was a bit disappointing to hear as I’d hoped a good flush though might’ve been a plan.

Its the other way around, the crud in the pipes accumulates in the manifolds and blocks them, if it was me I would just chemically flush the system

 

[durhamplumber]

There is fook all wrong with a properly installed microbore system. ( In copper with no twin entry valves )
We fitted hundreds of systems in the 70 / 80s which are still working properly.

Yeah rite....and 1000s that are a complete bag of useless s..te..Original poster, if you already have crud in your system, flush is waste of time,,,and chances of you not having circulation problems soon,is zero.

 

[Mottie]

Before I had my boiler replaced last year I removed all the rads, drained and physically flushed them out on my lawn using a hose pipe, half filled them again, shook them up, repeated that until water was running completely clear from them. I got what I thought was an excess of black silt out of them considering the system had a powerflush just a year previous to that when I had the system converted to sealed with an unvented hot water cylinder - I watched it being done and the water came out like ink. I then refitted the rads, added some chemical flush, filled the system and ran it for about a week. I then drained and filled the system several times just before I had the boiler fitted. Perhaps that might be a halfway solution for the OP?

 

[Terrywookfit]

Yeah rite....and 1000s that are a complete bag of useless s..te..Original poster, if you already have crud in your system, flush is waste of time,,,and chances of you not having circulation problems soon,is zero.

There are also tens of thousands of small bore systems that are a bag of $ hite for exactly the same reasons ……

ie, fookin useless plumbers who are clueless!!

The problems with micro bore are caused by undersized excessively long pipes and cock up F/E sucking air.

I agree that powerflushing is a waste of time on 8mm.

 

[ScottishGasMan]

Kept treated and clean 8mm is fine, I preffer 10mm mind you, 8mm doesn't allow much flow through it at the best of times but if it was enough before it would be enough after.
Powerflushing 8mm however would be a complete waste of money. You physically cant get the flow rate up high enough to move significant dirt from the system.

Short of a repipe the only way to really ensure that its clean enough for a new boiler, is to treat the system with a strong cleansing agent which would help clear the microbore, then individually remove the radiators take them out side and flush/hammer with with mains. Refit and then fill and flush system a few more times to ensure all cleanser is out of the pipework as well. Fit new boiler and inhibit system

 

[Mottie]

Sort of like I said two posts earlier.....