Flushing a new system before combi install ?

[mikej2005]

Hi guys,
I'm currently replacing all the radiators and all the pipework in my house, ready for a new boiler (Worcester 37CDi combi).

The house is fairly large, so effectively has two circuits - the upstairs pipe runs will be in copper with soldered fittings (mainly Yorkshire) and the downstairs circuit will be copper with mainly pushfit fittings (for convenience).

Do anyone have any recommendations as to whether there is a need to flush all the new pipework and radiators out prior to the boiler installation and if so, what's the best way to do it ?

Cheers.

 

[Agile]

Of course its necessary!

By a bottle of sentinel X300 and follow the instructione exactly!

Also existing pipework should be treated and power flushing is best!

Tony

 

[corgiman]

what he said



lots of sh1t in new rads and think about the amount of flux/sodder that will be in there

defo needs flushing

stop being as lazy as I am and get it done

 

[Dan Robinson]

If all the pipes/rads are to be new then you'll still need a flush to get the manufacturing crud and flakes out.

Probably a hot flush with Sentinel and a good few dumps of the system water will be fine (fill up run hot with chmical in for required period). On scratch installations we use a capped off full-bore lever vavle instead of a drain off cock making this more feasable. Using a powerflush machine is a bit OTT.


I would strongly recommend a Magnaclean on the return by the boiler. They make future maintencance sooo mcuh easier.

 

[mikej2005]

If all the pipes/rads are to be new then you'll still need a flush to get the manufacturing crud and flakes out.

Probably a hot flush with Sentinel and a good few dumps of the system water will be fine (fill up run hot with chmical in for required period). On scratch installations we use a capped off full-bore lever vavle instead of a drain off cock making this more feasable. Using a powerflush machine is a bit OTT.

I would strongly recommend a Magnaclean on the return by the boiler. They make future maintencance sooo mcuh easier.

Thanks for your comments guys. I was hoping that replacing ALL of the pipework and rads would remove the need for a powerflush, but appreciate that the stuff you mention still needs flushing out.

Are you suggesting that a lesser flush with suitable chemical agent can be done with the new boiler in place ? Is this OK provided the water is dumped promptly, or would simply passing through the boiler do it any harm ?

The old boiler is long gone, so it's either that or a hosepipe !

That Magnaclean looks interesting - I'll have a think about that.

 

[Dan Robinson]

Powerflushing won't be needed but:

Flush

Dump water

Hot Flush With Sentinel

Dump water

One more for luck


Magnaclean is a no brainer.

 

[mikej2005]

Powerflushing won't be needed but:
Flush
Dump water
Hot Flush With Sentinel
Dump water
One more for luck

Sorry Dan - just to confirm - do this with the new boiler in place, ie. use the new boiler to flush the system through ?

Cheers.

 

[Agile]

Its best to do it with the old boiler if its still working.

If not then flush the system with mains pressure until its clear and then add the X300 and heat with new boiler to about 70°C and run for about an hour.

Tony

 

[mikej2005]

Thanks Tony - much appreciated.

 

[Bambergaspipe]

quote="Agile"]Its best to do it with the old boiler if its still working.

Pretty pointless if renewing all pipework & rads (sigh)

 

[DP]

If system is not cleaned, copper swarf will inevitably end up in the radiators to start chemical reaction that will eventually lead to pinholes. (Bit of copper on the metal surface will cause local errosion of sheet metal).

 

[namsag]

Why go to hassle of connecting a brand new system to an old boiler that may not be in the same position as new one... Flushing as Dan says and with the new boiler in place will not cause any problems.. Power flushing is not required.... If you want the to flush it without the boiler in place ,the CDi is fitted onto a jig that gets pre plumbed so do all pipework and rads and leave boiler off and rig up a something to attach a hose to flow and return valves at the jig and flush with mains water.

 

[mikej2005]

Why go to hassle of connecting a brand new system to an old boiler that may not be in the same position as new one... Flushing as Dan says and with the new boiler in place will not cause any problems.. Power flushing is not required.... If you want the to flush it without the boiler in place ,the CDi is fitted onto a jig that gets pre plumbed so do all pipework and rads and leave boiler off and rig up a something to attach a hose to flow and return valves at the jig and flush with mains water.

I maybe should have made it absolutely clear that the old boiler is currently rusting in the garden !

The choice I was referring to was between flushing with or without new boiler in place, but not with the old one.

I'd also spotted that it's possible to fill the system via the jig so that sounds like a good bet.

Cheers.

 

[namsag]

Mike in mentioning flushing after connecting to old boiler i was replying to the stupid comment made by Agile.

 

[gas4you]

If the old system is really sludged up bad I would flush with Sentinel X800 or Fernox DS 40 without the new boiler in place, then when new boiler is on and working I would flush again with X400 hot.

This is only if old rads and pipes are being reused though.