Any way of telling if vented central system is leaking?

[Mmcgar]

Hi all, I don't know much about plumbing or central heating so apologies if I use the completely wrong terminology here.
I have a reasonably oldish style of central heating. It's not a combi boiler, rather it's a standard boiler and separate hot water tank. When I had a service done ingot chatting to the engineer who explained it was a vented system, so whereas with a combi boiler a leak could be detected by loss of pressure, with this system any loss of water would simply be "topped up" by the header tank (I think it was the header tank he said but I can't be sure).
So onto my issue, I have quite bad banging pipes at the moment which seems to be getting worse by the day. I really notice it in my downstairs wc (the mains water entry to my house) I hear a sound of running water (even tho I'm not running any) and then a bang, I guess this is likely to be water hammer and probably a separate issue but I'm wondering if the running water is actually my header tank being topped up from replenishing my central heating system? I am the middle house in a 5 row of terraces so it could also be my neighbours running water that I'm hearing through my mains inlet but I'm not sure how feasible this is?
Either way I'm wondering if there's any way of testing if my central heating system has a leak, it is run in microbore pipe which I already suspect is clogged up but I'd like to know if there's an actual leak, I'm guessing if there is one then it'll be downstairs as I have no staining etc on any ceilings.
Thanks in advance

 

[Agile]

Very simple.

Turn off the supply to the header tank and monitor the level over a few days whilst you don't use the heating or boiler.

Tony

 

[dilalio]

Can you put this down to a particular time of day/night or does the banging continue throughout?
If you have noticed it at a particular time (ie whilst sitting on loo in the morning) then I would turn off your main stopcock before that time and listen to see if it occurs! I have a feeling that it is your neighbour drawing mains water and bad clipping of pipework in either their/yours/both properties is causing the bang as the flow is opened/closed! Washing machines are particularly likely to cause violent stop/starts of mains flow which can reverberate throughout mains pipework!
See if you can ask your neighbour to operate their mains whilst you monitor from the wc in your house.

 

[Mmcgar]

Thanks both for the advice. In addition to what I mentioned last night. When I was lying in bed thus morning I could hear a steady trickle of water for ages, after wandering around my house with my ears to the walls I noticed that the noise was coming from my loft. I guess this is the header tank, I suppose it will likely be refilling the hit water cylinder? The only hot water that was ran this morning tho was my wife doing some dishes so I'd be suprised if it took that long too refill that small amount of water, I suppose my question is, do these tanks only refill when it falls below a certain level (in which case taking longer to fill up would make sense) or does it continually top up any small amount of water that is used (in which case I'd have expected it to only take a minute or 2 to retop uo)?

Agile, can I just clarify 2 points, normally where is the valve to shutoff the header tank located? And when you say monitor the level do you mean monitor the level of the header tank? Would the header tank not simply retop itself up even if there was a leak?

Diallo, yes it does tend to be worse at night, which might make sense if the neighbours were at work all day but it's actually pensioners that live round about me so at least 3 of the other houses are occupied most of the day. The noise has got a fair bit worse since a cold tap in my bathroom stopped working so I'm going to replace this just in case but I suspect it's more a longer term problem than this. I have only recently bought the house, I noticed that the cisterns take ages to fill up, I checked the valves and I noticed that the guy who stayed here before me (who was engineer) had turned the valve slightly to limit the flow (see picture ) so my guess is this problem has being going on for ages and he had tried to limit the flow to limit the noise

 

[dilalio]

If this occurs at night, it is worth noting that mains pressure usually increases at night, due to lower demands on the supply! This means that your ball valve fills the tank quicker and shuts of more violently which can cause the water hammer! I think you'll need to get up there and observe it if you are able... Don't go through the ceiling tho

 

[AGAS]

edit

 

[Agile]

You turn of the supply TO the header tank so it cannot refill.

If no valve then just tie up the ball valve!