Knocking from inside boiler

[DiyGas1701]

Since restarting my central heating I have have noticed a sound, which sounds like knocking, also a kettling noise, these noises only appear as the boiler warms up , and will disappear when the correct temp is maintained.

The make is a Worcester Bosch 24i sealed system combi, and is is about 2 years old, and was serviced early this year.

I did add a couple of rads a year ago, but no problems occurred then, and I did try to flush through the new ones at the time.

All rads have been bled, and all heat up fine and quickly, even the farthest one, so I know the pump works, this also has been bled.

Does anyone have any suggestions please, as I don't want the boiler to incur damage, I am thinking of draining and flushing with cleanser, is it worth doing this a new so shouldn't be caked up with any lime/sludge , thanks in advance for any suggestions.

 

[captain_pugwash]

Hi,
I had the same thing last Autumn depsite my own system boiler being less than 2 years old. Turns out it was totally full of crap - don't think the entire system was ever flushed after the commissioning of the system.

I had my first hint when I took out the drain plug and filter and loads of jet black water and soot came into the bucket - try this and see what you get.

If it is all black then you could do what I did which was to pump in Fernox flusher (it uses the sealant guns and an adaptor for the filling loop) and run the system then flush it all out. I did this twice until the new fill up of water ran clear and now the boiler runs silently.

Good luck

 

[richie2305]

Nice one, I didn't know you could get some flusher/adapter to connect to the filling loop, makes life easier, I would have poured it down the towel rad.

I will give this a try, did you mean drain through the drain taps at the lowest point, I'm not aware of any filter in the system, if there is it has passed me by, also would it be possible to drain some by releasing the pressure valve or is that asking for trouble.

Thanks for your help.

 

[DiyGas1701]

In case you are confused by the reply from a different sender, I replied from another computer, hence another log in name.

 

[captain_pugwash]

not sure about your boiler but I think they pretty much all have the same thing - a drain plug somewhere under the boiler where the flow/return pipes are - usually to drain the boiler without draining the entire system. Mine also has a filter that can be removed and cleaned - mine is right next to the internal pump.

I stick a hosepipe on this drain tap and empty the boiler into a bucket - this is how I could see how ****ty the original water was.

The Fernox cartridges then go into the simple guns used for sealants etc and Fernox supply the right size fitting for the filling loop connector.

I ran my system for an hour with the Fernox, then drained it, re-did the Fernox again, re-drained it and then when the water ran clear the second time I put in the Fernox inhibitor for the normal running and it's been fine ever since (touch wood, lucky rabbit's foot etc).

 

[DiyGas1701]

I couldn't see anything obvious to drain the boiler, apart from a couple of spring circlip type things near the pressure relief valve, it looks these allow quick removal of the valve, I will have a closer look when I have got the fernox restorer and protector, I might drain the whole system anyway and clean everything.

I will let you know what I find, and how it went, thanks for your help.

 

[2face]

power flush it m8 the restorers are ****e .. they are only for removing flux etc on a new install.
power flush takes 4 hrs then all metalica are removed and add a decent inhibitor and you will have no more problems .

http://www.pflush.com/ have a read here for your symptons

 

[DiyGas1701]

I had already ordered some Fernox restorer and protector before your reply, so I will try this first especially as its a lot cheaper, it hopefully should be ok as system a couple of years old, will try power flushing as a last resort.

I will probably have a go on the weekend, the noise has been reduced to just kettling now, the knocking has calmed down for some reason, perhaps any debris is now floating round the system.

I will let you know when I have finished, thanks.