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Over the last few days we have noticed a loud knock/bang and then a series of ticking noises for about 30 seconds at the point our hot water loop closes.
This doesn't happen first time after the CH comes on but once we have called off some water from the tank and it reheats it.
The initial knock/ bang if enough to set the baby monitor off.
Stuck TRV?
The radiator in the little mans room (the first fed radiator) seems to be the most afflicted.
Any suggestions/thoughts/help.
Has your wife been touching the thermostat?
No. 😆
Only one thermostat ( other than TRVs ) and that's on the boiler.
Very basic ( read old ) system.
No. 😆
Only one thermostat ( other than TRVs ) and that's on the boiler.
Very basic ( read old ) system.
Phew! Have you tried bleeding the rads?
air.. its ironically called 'knock'
Haven't touch the radiators yet.
Wouldn't know why air had gotten in.
No issues during the rest of the time it's on, just for the 30 seconds or so.
The air is often hydrogen and is a result of a chemical reaction in the system (so I've been told).
Try bleeding all the radiators which shouldn't take long, see if that helps.
From your description I'm unclear if it's the CH heating making the noise or the HW system?
Air doesn't get in, hydrogen builds up when your steel radiators oxidise inside. You can test for it by holding a match to the vent when you bleed the rad. Keep your eyebrows well away though. If it is hydrogen, you need to add more of an antioxidant like Fernox.
The loud bang reverberating through the pipes could be the hard rubber ball inside the Y plan valve if you have one. If only simple motorised valves, I'm not sure whether they also have a rubber ball on an arm for blocking the water. Whatever, it's wearing out.
The ticking noise, if it's not thermal expansion, could be a blob of solder jumping around in the inlet pipework to the rad. Try closing the valve a little while it's ticking to see if that affects it.