Water running from overflow pipe in eaves

[FarleyRow]

Hello, can anyone offer any insights into this?

My loft overflow pipe has started overflowing - running at a steady dribble which stops for a while if the hot water tap is turned on.

I have a condensing boiler / gravity fed system. Water was dripping this morning despite central heating and hot water not being on.

I have an engineer coming out to look at it on Tues (as part of home care cover), but trying to figure out what is happening before then. I know that it could be as simple as an issue with the ball valve, but I am concerned that is might be an issue with the hot water cylinder. I'll give you the full history in case there are any clues there for you...

I had the boiler serviced at the start of this month (4th). System all working fine, but I let the engineer know that I still have extremely hot water in my taps and that the system never seems to cut out when hot water has been on for long enough to fill the tank (this has been the case for 2 years and he was the 3rd engineer I mentioned this to). He checked the cylinder, said the valve coming from it was working fine, but turned the thermostat on the cylinder down from 65 to 55 degrees - not sure that this made any difference tbh.

10 days later (15th) I had a FL fault on the boiler, engineer came out and (after working on the boiler to try to clean the ignition) discovered this was caused by the gas meter turning itself off and closing the valve (caused by faulty smart meter - which I have a separate thread about). For the whole week meter kept shutting off and I had to keep pressing buttons on meter to reopen - after a week, air temperatures increased and the gas meter hasn't shut off again.

The day after the engineer came, when the hot water was running there was a huge, rushing sound of water throughout the whole house. This settled and I thought it was just air in the system and I thought nothing more of it.

On Friday (26th) I noticed the overflow dripping/dribbling. Heat and hot water was on. Dripping continued after running cold tap, but stopped after running hot tap. As mentioned earlier, overflow was dripping this morning despite heat and hot water not having been on since the evening before.

I'd be really grateful for any comments on this. Thanks.

 

[Exedon]

Chances are it is just a ball valve only way to check is go in loft and have a look.
If you have 2 tanks one small one larger see which ball valve is dribbling.

 

[FarleyRow]

British Gas engineer has been out this evening and can't see anything wrong with ball valves, other than the main water tank being a bit fuller than it should be. Overflow pipe has been dripping/dribbling almost continuously since Friday, except for stopping for a while when the hot water tap has been turned on - but of course did not drip at all while he was here!

He says the wrong type of appointment was booked by British Gas Homecare and I need to go back to them for an appointment with a plumber.

 

[old duffer]

so logic says that if water is coming from an overflow pipe then its dong its job so now the question is why.
What stops the water from continually feeding into the tank? a simple ball valve. What can go wrong with a ball valve? well if the arm is allowed to move freely to close the apature then it must be the apature that is not being sealed. What seals the apature? rubber...has it perished?

 

[Hugh Jaleak]

From the above information, the first thing I'd be looking at is the Cold Water Storage cistern. Had anyone been drawing off hot water prior to the BG Man's arrival?

If the Cylinder coil is pinholed, it's usually the smaller Feed and Expansion cistern that will overflow, provided its lower than the level of the Cold Storage, as the pinhole allows the Primary and Secondary systems to mix. However, that would cause a constant overflow, so my money is on Ballvalve in Cold Storage Cistern letting by.

 

[HERTS P&D]

First thing to do is lower the water level and fit a new ball valve to the cold water storage tank. You may have a home care policy but you are not getting a decent plumber.

Andy

 

[ChrisJP]

The fact that drawing off some hot water stops the overflow temporarily does indicate that it is the cold water storage tank in the loft that is overflowing. As you draw off hot water the cold water tank tops up the cylinder so the cold water level briefly drops until it is replenished by the cold water feed. Almost certainly the problem is with the cold water feed float valve in the cold water tank and is nothing to do with the central heating or boiler.

 

[plumblddy]

Replace the ball valve in the main cold water tank.

 

[creamola]

Hold on - you say you have a "gravity feed system" so does this mean you have a hot water tank - where the water is heated in the tank via the heating circuit heat exchanger (basically a curly copper pipe running from top to bottom inside the H/W tank)?

If you do have this, then check that the overflow that is dribbling: is the overflow from the loft cold water tank and not the separate hot water tank vent/overflow?

I don't want to worry you, but I was having exactly your symptoms. Turned out, that the heat exchanger in the H/W tank had furred up and sprung a leak, so some of the hot water from the heat exchanger was being forced into the standing h/w in the tank - thereby increasing the pressure in the tank, which was blowing out of the roof mounted (well it poked out under the tiles) overflow pipe.

That it stops/lessens when you draw off hot water, kind of fits.

The only solution for me, was to replace the H/W tank in the airing cupboard. [Once I had disconnected it from the pipework, it wouldn't budge - so I thought it was bolted to the floor. Turned out, it wasn't bolted down, just contained so much limescale, it was like trying to manoeuvre Nelson's Column out of the cupboard. Took two of us to get it downstairs - one stair at a time..]