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radiator banging

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Joe Shmoe

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hi

Have an entire closed central heating radiators with combi-boiler installed 5yrs ago, had no problems yet, and had boiler serviced last year. All of a sudden one radiator is making a single massive clang a few mins after the heating comes on. It's happening everytime the heating turns on.

Once or twice I've also heard it do a sort of knock-knock-knock for 30secs, which never happened before either.

Never had any issue before and its just this one rad.

Any ideas?

Cheers Joe.
 

sparkymarky

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gas combi or oil combi, you mentioned it was a closed system what is the system pressure reading?
it sounds like water hammer due to the water not circulating efficiently, so it is boiling the water in the boiler and turning it to steam (hence the bang). this may be due to low pressure, a faulty pump, burner set up too hot, dirt in the system or a incorrectly operating divertor valve.
hope some of this helps, mark.
 

Joe Shmoe

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cheers mark, it's gas. But the bang seems to be the rad, not the boiler?
 

misterfish

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May be its nearby pipework or the radiator itself expanding with the heat and catching against something (like a joist or bracket) and then moving suddenly and noisily. Apparently pipes should be wrapped in felt when going through joists to allow smooth and silent expansion.

Misterfish
 

nev

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sparkymarky":32mdsqlk said:
gas combi or oil combi, you mentioned it was a closed system what is the system pressure reading?
it sounds like water hammer due to the water not circulating efficiently, so it is boiling the water in the boiler and turning it to steam (hence the bang). this may be due to low pressure, a faulty pump, burner set up too hot, dirt in the system or a incorrectly operating divertor valve.
hope some of this helps, mark.
+1
generally the only things you can do yourself would be bleeding the rads and checking the pressure.

Check the pressure gauge, make sure you're in the green. Increase if needed by opening feeder valve, probably a flexi pipe going from one pipe to another. if pressure is too high reduce by bleeding a radiator.
If the pressures ok, you can try bleeding the offending rad (with heating off) and when done top up the pressure if need be by opening the feeder valve momentarily.
see about halfway down this page...http://www.miketheboilerman.com/openorsealed.htm
 
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