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Air in System - Bubbling Noise on Boiler

Postby beadie » Tue Mar 10, 2009 8:31 am

Am having an issue when the boiler is set to HW. There is a bubbling noise heard from the boiler. Does not seem to do it when boiler is on CH. Had British Gas in as I have homecare. They advised that there was a lot of air in the system and this was due to the sludge in the pipework.

I agree that there is a lot of air in the system as I have to bleed the radiators every 3 weeks and yes the water in the system is very dirty.

They advised a Powerflush (Quote £592). Is this the only option or could it be something else. Would be loathed to have the flush done and it not be the problem. Any advice gratefully received.

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Simply Build It

Postby stoneyboy » Tue Mar 10, 2009 10:40 pm

Powerflushing is the current "must have" service for curing all ills.
Try flushing the system yourself then add a system cleaner and follow the instructions.
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Postby Steve the gas » Wed Mar 11, 2009 5:50 am

And found out where the air is getting in.
All this new oxygenated water will make the system worse - corrosion wise
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Postby rosebery » Wed Mar 11, 2009 7:06 am

Black water or reddy brown water?

Black water = sludge.

Reddy brown water = system probably pumping over.

LoL BG love to sell a powerflush as a cure all - even when they don't really know what the problem is they are trying to solve!! Ask yourself this if the CH system is full of sludge why doesn't it do it when CH is working?

Although you probably have some sludge its more likely that your boiler is scaled up and is kettling. Power flush on its own won't remove that.

Get an independent RGI in to look at your boiler who isn't on some fancy commission scheme. He'll tell you exactly what you problem is and how to solve it in the most economical fashion.

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Postby beadie » Wed Mar 11, 2009 8:07 am

Can someone tell a novice like me how a powerflush is done.
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Postby plumbbob » Wed Mar 11, 2009 10:06 pm

I agree with all the above posts, but would add the point, if the system is filled with sludge, the pressure in the system will rise, and if it is poorly designed, the result will be an increased possibility of over pumping or air being drawn in.

If air is being drawn in at all, this points to a design error and should be dealt with to prevent long term damage to the system.

The usual problem is the feed and expansion pipes to and from the header tank are placed too far apart. For a good design, they should join the circuit within inches of each other.

Power flushing is where a high velocity pump is fitted in the circuit to pump water and cleaning chemicals around. The speed of flow causes the sediment to become suspended, which is then flushed from the system.
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