Header Tank Keeps Draining

[pghstochaj]

Hello everybody,

Long time reader of the website, and now in need of some help, so thanks very much in advance for anybody that can help! I finally thought I was on top of my DIY, but my central heating system is playing up. And I have very limited knowledge of central heating systems.

I have a standard (?) indirect gas fired central heating system with hot water cylinder, a gas boiler feeding the hot water cylinder indirectly through a coil, or heating the radiators (controlled via a valve), a cold water storage tank and a hot water header tank. I think.

This morning my shower was quite cold, and my radiators wouldn't get hot. Turned out that the boiler was turning on for short periods and then switching off - I am guessing because of a lack of water in the system and nothing was flowing.

I tried to bleed the radiators, but no water or air came out. I went into the loft and the smaller of my two tanks (the header tank, right?) was empty. The isolation valve to fill it via a ball valve was closed, so I opened it and let it fill. The ball valve isn't working properly so this must have been shut off in the past (I got the house a year ago). Now firstly, am I right in thinking that this tank is just for expansion of the hot water circuit, and therefore it is not unreasonable for the valve to have been shut and it not have been a problem until now?

After the tank was filled, I went through all of the radiators and a bleed point on the pipework (above the valve) in my laundry cupboard and they all filled. The boiler started up and after continually bleeding the system radiator by radiator, it stayed on and everything was fine.

This was around 2pm, and then at 10 pm I tried to turn the radiators on and had the same problem, boiler wouldn't stay on and no air/water to bleed from the radiators and I found the header tank empty.

Now I know I need to replace the ball valve in the header tank as it is not working, but I also shouldn't be losing all of the water in this circuit, should I?

I have no visible signs of water leaks internally, and I haven't spotted anything outside of the house (but I am in Manchester so I am used to seeing wet ground!). Does anybody have any suggestions as to where my header tank water is going in such a short space of time, please!?

The only thing I could think of is that the hot water cylinder coil is leaking so all of my header tank water is going into the radiator circuit and then leaking into the cylinder and then taps? BUT, since 2 pm all I have done is washed my hands a few times, so if my theory falls down as I don't think I have used that much water.

I hate plumbing

All the best guys and girls and thanks very much in advance for any advice you may have.

Paul

 

[seco services]

If you've been in a yr and the ball valves been isolated all this time
and you say since refilling it's drained within a day the problem has only just occured in the last day or so.

 

[pghstochaj]

Thanks - I agree, but other than that I am stuck on what causes it

 

[seco services]

Did you leave the isolation valve to the ball valve open after refilling ?

Is the cws tank higher than the f/e tank (small one) ?

 

[pghstochaj]

No, I have left the isolation valve closed, because I assumed I had filled the system, bled the air and therefore I could close until I replaced the ball valve. It would currently go to the overflow - as the ball valve doesn't shut off most of the time.

Yes, the big cold water tank is higher than the small tank.

Thanks

 

[seco services]

Not knowing how much you filled the tank and then shut the valve off you could of had an airlock in the system then after bleeding and any airlocked removed the tank had emptyed.

Can you not refill the system bleed etc top tank up after bleeding but keep a closer eye on the tank level ie every hour if still draining then i would suspect a problem.

Are the downstairs rads pipework exposed or under floorboards/screed floor ?

I wouldn't be suspecting the cylinder coil.

 

[JohnD]

when you bled the radiators, extra water was needed to displace the air, and it will have run down from the highest point, so you will have got air in the pipes at the top of the system. You need to leave the ball cock able to keep filling the system until it is running properly and you have got all the air out.

this might be a good time to think about a simple chemical clean with X400.

 

[pghstochaj]

That's a fair comment, I will do it more scientifically tomorrow.

All the radiator pipes are in the walls.

 

[seco services]

All the radiator pipes are in the walls.

So all rads are on drop downs from upstairs ?

 

[pghstochaj]

when you bled the radiators, extra water was needed to displace the air, and it will have run down from the highest point, so you will have got air in the pipes at the top of the system. You need to leave the ball cock able to keep filling the system until it is running properly and you have got all the air out.

this might be a good time to think about a simple chemical clean with X400.

I hope it is as simple as that and I will try again tomorrow, I am pretty sure that there was plenty of water in the expansion tank by the time I had completed by bleeding - I kept topping up during the bleeding and only stopped topping it up once I was nearly finished bleeding - i.e. only a small amount then displaced.

I will look up X400.

Thanks

 

[pghstochaj]

All the radiator pipes are in the walls.

So all rads are on drop downs from upstairs ?

I am not sure of the runs, I have the main radiator feed leaving my laundry cupboard approximately in the centre of the house, then all of the radiators just have microbore pipe sticking out of the wall - I haven't ever chased any pipework in between.

 

[seco services]

I would make sure if your loosing water first before using x400 or you'll be chucking that down the drain.

 

[Nige F]

Hello everybody,

Long time reader of the website, Now firstly, am I right in thinking that this tank is *just for expansion of the hot water circuit,* and therefore it is not unreasonable for the valve to have been shut and it not have been a problem until now?

Now I know I need to replace the ball valve in the header tank as it is not working, I hate plumbing
Paul

Seeing as you`re a long time reader , I won`t take the **** I`ll just say - It`s a Feed and expansion tank - It isn`t not unreasonable to leave the valve shut - get a new one and leave it turned on

 

[pghstochaj]

Hi,

Thanks for the pointers last night. Tank is full, all radiators bled, hot water has been running and pipework vent point bled, now heating is on.

Will monitor tank level and keep it topped up today, and continually check radiators are bled. If it is still losing level, it must be a leak, right?

I guess it can't be the coil as my cold water tank is higher than my hot water header tank, i.e. the flow would fill up my header tank. So, does that leave me with only two options?

Leak inside boiler - what would the signs to that, is it possible?
Leak from my pipework somewhere, but slow enough not to yet be obvious?

Anything else I haven't considered? I have just finished redocorating and put down laminate flooring in most places

 

[pghstochaj]

I will do, but surely it should only need occasional top up? I will replace the ball valve, but only once I know where the header tank water is going, if anywhere. Otherwise I will just keep feeding the leak.

Hello everybody,

Long time reader of the website, Now firstly, am I right in thinking that this tank is *just for expansion of the hot water circuit,* and therefore it is not unreasonable for the valve to have been shut and it not have been a problem until now?

Now I know I need to replace the ball valve in the header tank as it is not working, I hate plumbing
Paul

Seeing as you`re a long time reader , I won`t take the **** I`ll just say - It`s a Feed and expansion tank - It isn`t not unreasonable to leave the valve shut - get a new one and leave it turned on