Header Tank Overflowing - Not the Ball Valve

[sbarrick]

Hi All

This is my first post on the forum, and know little about plumbing. But here is my problem.

My header tanks keeps overflowing. I have replaced the ball valve and checked this several times for leaks to which there is none. So I can confirm that it is not the Ball valve. The tank in the loft continues to fill up over a number of days and overflows via the overflow pipe outside. We have not had our central heating on or the emersion heater and still it is filling up. HOW????

I tested this today, no heating or emersion heater and did not use the hot water for several hours and the tank water depth rose by about an inch.

Our system is an indirect vented system with tank in loft. The Tank is a Showmax Supercal Cylinder.

Can someone please help with advice.

 

[kevplumb]

coil is leaking in the cylinder

 

[TicklyT]

Juist to be clear here - is it the larger cold water storage tank, or the smaller heating feed and expansion tank that's overflowing?

 

[sbarrick]

It is the larger tank that is leaking. Ball value is defiantly not leaking.

 

[danhiltonplumbingservices]

this could be your coil .

I have just fixed a problem like this and i found it to be ( now i found this hard to understand and im a plumber for 4 1/2 years) the main cold water to a mixer valve ie shower or bath tap etc was passing somehow and back filling the hot water.

This was slowly filling the tank up from the feed pipe to the cold water tank.

This in turn will slowly fill the header tank up and then overflow. the tap or shower etc. dont have to be turned on and no hot water or heading has to be on .

if you have a gate valve on the feed pipe from your cylinder ( 22mm pipe from top of cylinder) i would turn it off and see if in a hour or so it rises if not you have found your problem

 

[sbarrick]

I am just going to try this method, have posted on other forums and they have advised the same could be a problem.

"If you run the hot starting at the kitchen sink, then with a hand on the hot pipe, open the cold tap, does the hot pipe go cold. You'll need to check every one with a mains cold separately"

 

[sbarrick]

Okay just tried this method in the ensuite. Ran the hot water and felt the hot water pipe heat up, then turned on the cold water and the hot water pipe when cold.

But how do I fix this?

 

[danhiltonplumbingservices]

hope i helped to fix the problem

 

[twgas]

if you have a gate valve on the feed pipe from your cylinder ( 22mm pipe from top of cylinder) i would turn it off and see if in a hour or so it rises if not you have found your problem

this will not prove it to be anything in particular as, because the cold will be coming in at mains pressure it will just make its way up the vent pipe and into the tank that way. Isolating individual taps would, in my opinion, be a better test.

 

[danhiltonplumbingservices]

i turned the gate valve off then looked at the taps and found my problem so it worked for me but i understand what you are saying as a plumber if i did see it do that i would know it was back filling i forgot to say about the vent lol

 

[mikeyd]

But how do I fix this?

With a check valve in the hot supply to the offending tap. http://www.google.co.uk/#q=check+valve+15mm&hl=en&sa=2&fp=d7bf5ffd599cb934

 

[sbarrick]

Just check screwfix and found some,

Pegler Single Check Valve 15mm @ £3.99
Check Valve Single 15mm @ £1.14

Whats the difference.

I take it they work by only letting water pass one way?

Just found this post which is the £1.14 version.

//www.diynot.com/shop/SINGLE_CHECK_VALVE_15MM/6419

 

[mylocalgasman]

First thing to test is the washing machine feeds turn the valves off, check if this cures problem. If not check your taps, most new mixers have separate supply pipes into mixer body, some older mixers have feeds that are joined up their length except the last couple of inches.

 

[sbarrick]

First thing to test is the washing machine feeds turn the valves off, check if this cures problem. If not check your taps, most new mixers have separate supply pipes into mixer body, some older mixers have feeds that are joined up their length except the last couple of inches.

Checked the one in the en-suite and the hot water pipes turn cold when I put the cold water on. So presume this is not helping matters.

 

[mikeyd]

I have seen some check valves say they are suitable for hot and cold which makes me think some are not suitable for hot. I'm not a plumber though and could well be wrong but I'd go for one marked suitable for hot.