OV system banging noise at boiler. Happened a few times, likely cause?

[armyash]

Hi guys as above really, been to a couple of jobs where there has been a banging noise at the boiler on an OV system. everything is circulating ok and getting hot but occasionally there's a banging noise coming from the boiler.

What can cause this? muck in the system? Struggling pump?

Thanks

 

[julesverne]

Without thinking of the obvious it could be no bypass on system so if both 2 ports shut down it can cause a clunking noise or sludged heat exchanger

 

[bigads28]

Are they old cast iron heat exchangers? Gravity hot water?

It's mostly sludge on old stuff, can be pumps. If it's running ok then leave well alone you'll create problems.

If it ain't broke don't fix it!

 

[armyash]

Are they old cast iron heat exchangers? Gravity hot water?

It's mostly sludge on old stuff, can be pumps. If it's running ok then leave well alone you'll create problems.

If it ain't broke don't fix it!

The latest was a Worcester RI.

Leave it well alone I did, i advised that as it's currently working and i haven't heard the banging myself it's not worth messing with as i could cause an issue.

Just asking out of interest more than anything as it's annoying going to jobs where it's all working but the customer says there's something wrong. I tell them if it's all working, there is nothing for me to fix and the noise they hear could be a number of things but not worth messing with as could create a bigger problem than just noise.

 

[Nostrum]

New boilers?

somethings overheating but the cause could be numerous things, faulty stat, poor circulation etc

 

[Nostrum]

I've seen numerous Worcester Ri with crossed flow and return that do this. Partly because of the stupid arrows they put on the chassis that don't match up if you take the pipes up the back!

boiler seems to work fine but the thermistor is measuring the return temp so can boil if flow temp is excessive.

 

[gasmanrob]

Someone forgot to wire the pump from the boiler to provide overrun had that a few times.

Blocked/restricted h plan

zone valve upside down

zone valve too close to the pump

no system bypass

lack of water in the system

 

[armyash]

cheers for the excellent replies, plenty for me to keep an eye out for.

 

[Nostrum]

Yes the pump over run wiring is another very common issue!