Direct cold water feed tank overfull and bubbling noise

[JohnP2712]

Hi

Thanks for any help in advance

I have a 10 year old central heating system with traditional cold water feed tanks in the roof. The indirect tank sits on the same plinth as the larger heating water tank. copperwork is the larger microbore mostly. Around 5 years ago a new 15mm feed for radiators to the system was added along with a new Worcester Oil fired boiler (bigger to match the new capacity needs). Since then TRV's have been added to all (bar one) radiators and several new raditors installed to replace the older looking ones. Around six months ago a new radiator was fitted along with a drain point (this being on the microbore side). All was well and 3 bottles of inhibiter added into that radiator. After a couple of months however I noticed a bubbling noise at 7:00AM every time the heating came on which has got progressivly louder. There was no air present in any of the radiators, pump or hot water bleed point noticed ever. In desperation I went into the loft two days ago and discovered that the in-direct feed tank water was over the ballcock and pressure relief pipe mouth (the pipe that connects to the indirect system for safety release I guess?). This pointed to a new issue. The overflow seems to be fitted too high, so I understand that is a problem which need fixing. However another issue was some weird fungal slime growth on the ballcock of about a fist size which I removed.

As a quick fix to the overflow I syphoned off water until the ballcock started to allow clean water into the tank. The water I took off was a bit black. However the pressure relief pipe end was now open and not lying in the water.

The bubbling noise didnt occur this AM. So apart from fixing the overflow point is there anything else I should be concerned about?

Thanks all

John

 

[Softus]

The bubbling noise didnt occur this AM. So apart from fixing the overflow point is there anything else I should be concerned about?

The water level is clearly too high, so either it always was or water is entering the primary circuit.

If your system is conventionally indirect, then the water will be coming either through a faulty/worn float valve, or through a hole/split in the coil in the cylinder. The former is cheap and quick and fix, so do that first. The latter is expensive to fix and a large job for a novice.

 

[JohnP2712]

Thanks for your reply.

I have done some more investigations. The ballcock was definitely set too high. I have adjusted it and removed more water. After one day the water had not increased and everything (bar the overflow outlet being higher than the pressure relief outlet and the ballcock) looks OK. The ballcock is shutting off OK it seems.

I think that maybe the fungal ball of gunk stopped the ballcock from working correctly and it increased the level, which was too high to start with. Also I suspect that when the pump starts up the level in the pressure relief pipe rises slightly. So if the level in the tank is too high you can get an overflow each time. That would explain the black water in the tank.

Why it bubbled I don't quite understand but I'd bet is was something to do with the pressure relief outlet being under water?

I am also hoping that the above is correct. I don't want to have to replace the cylinder in this weather!

Thanks again