System regularly vents into header tank...help please!

[bongodrum]

My overflow regularly drips water from the header tank, in the short term I often empty some of the water with a jug but there's clearly a problem here!.

I've witnessed the vent pipe spilling water into the tank - the water in the tank is usually warm/hot and it is rusty in colour - the ball cock in the tank seems to be faultless.

I've tried turning the pump setting to "1" but all this did was make the radiators cold! (so I turned it back to "2".

I've just turned the thermostat on the cylinder down from 60c to 50c....is this likely to stop the venting in the system? or is the problem deeper than that?

Many thanks in advance to anyone who can help, Matt.

 

[electronicsuk]

My overflow regularly drips water from the header tank, in the short term I often empty some of the water with a jug but there's clearly a problem here!.

I've witnessed the vent pipe spilling water into the tank - the water in the tank is usually warm/hot and it is rusty in colour - the ball cock in the tank seems to be faultless.

The two problems aren't necessarily related. The water level in the central heating feed + expansion tank will change as the system heats/cools due to the expansion of water as it's heated, but obviously it shouldn't fill to the point of overflowing.

So, a few questions. You say the ball cock seems faultless - how did you come to that conclusion? If it fails to close properly and leaks even slowly, this will eventually lead to the header tank overflowing and hence a dripping overflow pipe.

To categorically rule out the ball cock, I would suggest isolating the water supply to the filler valve on the tank (assuming there is an isolator valve somewhere nearby) and then see how it goes for a few days. If the tank no longer overflows, you know where the problem lies. If the problem persists, it could be due to a leaking coil in your HW cylinder, assuming you have one.

The vent pipe spilling may not be related - how often and when does it happen? If it's only for a very short duration when the system is turned on/off (i.e. pump starting/stopping) then it may not be worth worrying about. The rusty coloured water is an indication that the system may need cleaning and inhibiting, but as the water from the vent pipe is ultimately fed from the CH header tank anyway, it wont be the cause of your overflowing.

 

[75pete]

The fact that your tank is over flowing [ are you talking about the small tank and if so ] :could inturn make the vent, vent as the difference in head has been reduced.
Start by getting the level correct in the tank and as said, double check that the ball valve is not letting by.
The water level needs only be a couple of inches above the outlet/down feed. You should have a min of 450mm from the top of the water to the top of the vent.

 

[bongodrum]

[/quote]To categorically rule out the ball cock, I would suggest isolating the water supply to the filler valve on the tank (assuming there is an isolator valve somewhere nearby) and then see how it goes for a few days. If the tank no longer overflows, you know where the problem lies.

• Going to give the above a go. Just been into the loft to get the level right and isolate the filler valve....the water in the tank was practically boiling! IS IT SUPPOSED TO BE? The central heating is on at the moment! Anyway thought i'd best empty as much as possible and let cold back into the tank....filler valve isolated, have made a note of the level.
  
  Unsure about how often the pipe vents but I've seen it do it a few hours after the pump initially starts - with the water in the tank being that hot though I'd have thought quite a lot.
  
  Thanks for the advise folks...i'll hopefully be able to give a clearer picture in a day or so!
  Cheers, Matt.

 

[tincup]

Could be a partialy/blocked feed pipe.
Tie ball cock up and drain a couple of litres off does the level in the small F/E tank drop? If not, run a magnet over the point where the feed pipe joins the system, most likely place for blockage.

 

[bongodrum]

Could be a partialy/blocked feed pipe.
Tie ball cock up and drain a couple of litres off does the level in the small F/E tank drop? If not, run a magnet over the point where the feed pipe joins the system, most likely place for blockage.

Sorry Tincup, I don't quite get what you're saying! I can isolate the ball cock by turning off the ball valve (or tying it up), no probs there. Just the rest of it I don't get.....can you explain it as though my 5 year daughter daughter would understand (i'm a bit of a novice I don't mind saying).

Many thanks
Matt

 

[electronicsuk]

Magnetite, iron oxide and the like can build up in the feed pipe and cause it to become blocked. If you follow the feed pipe down from the tank until it tees in (usually near the pump and vent pipe, too) and then run a magnet over the pipes in the area, it shouldn't stick, as copper is non-ferrous. However, any blockages made of ferrous metal will cause the magnet to stick.

 

[twgas]

Ask your 5 year old daughter to explain it (she probably undstands it)
Firstly tie up the ball valve.
Next, find a drain point - connect a hose to it and open it.
Thirdly, go and look to see if the water level in f&e tank has dropped.
Whether it has or not you've either got a (partial) blockage where the cold feed joins the system or it's piped wrongly.

 

[bongodrum]

Magnetite, iron oxide and the like can build up in the feed pipe and cause it to become blocked. If you follow the feed pipe down from the tank until it tees in (usually near the pump and vent pipe, too) and then run a magnet over the pipes in the area, it shouldn't stick, as copper is non-ferrous. However, any blockages made of ferrous metal will cause the magnet to stick.

Between you all I think you may have cracked it. The magnet sticks to the horizontal pipe inbetween the vent pipe and the pump. I assume this pipe will need to be cut out and replaced and the system flushed! Am I right in saying this or is there an easier way?

Thanks again all
Matt

 

[twgas]

sounds right to me.