Hot water feed problem - conventional system

[gideononline]

Hi there, first post to the forum, and I was hoping for some help before calling in a plumber.

I have a convential system where I have a main cold tank in the loft which feeds :

The electric shower in bathroom (which is working fine)
The cold water supply in upstairs bathroom,
The hot water cyclinder/boiler in upstairs bedroom which then supplies:
The hot supply in the bath & sink in upstairs bathroom
The hot water supply in downstairs kitchen

Now I was abroad for 3 months and when I returned, I had no running water from the hot taps at all and I could hear the main tank in loft constantly filling itself. I though there may be problem with the ball cock, but this did not seem to be the case. I turned the mains supply into the tank off to stop the loud noise that was vibrating down the pipes. Later when I turned this back on and moved the ball cock slightly, it seemed to stop filling itself as before. The tank hadn't been overflowing when I had been away so where was this water going?!l No sign of any water anywhere in the house so I thought it may have been some sort of air blockage. I connected the hot and cold washing machine supplies together downstairs and tried to back flush the main supply up through the hot water system.
I done this both with the hot water valve turned on & also off (which flushed it through the clylinder/boiler overflow pipe) This appeared to have done the trick as I now have running water through the hot taps both upstairs & downstairs.
Now as soon as I turn the hot water valve on, it is draining out the main supply tank, just seems to be running straight through the hot water system and I can't figure out why or where it is going (some draining pipe hidden I presume?)

Any advice would be very much appreciated
Pete

 

[kirkgas]

if the loft tank is constantly running then the water must indeed be running out of the bottom of the tank, follow the 22mm cold feed after is connects into the bottom of the cylinder to where it goes outside, there must be a drain valve on it somewhere (hopefully outside) which will prob be running, it may be under the floor which happens but obviuosly isnt right, whatever is happening needs to be rectified as it is wasting a massive amount of water

 

[gideononline]

Thanks Kirk, I've kept the supply into the cyclinder off as not to just waste the water, the cylinder appears full and while I keep the supply into it off, it will function ok and Ill have running hot water shortly after turning the booster on. But as soon as I turn the feed back on, it just starts draining from the main tank again, with no apparent outlets on. I'm just cratching my head as to why suddenly it just seems to be running straight throught the hot water circulation, and where exactly it is going!

 

[kirkgas]

right, start again, when the cold feed to the cylinder is shut you have water at the hot taps, that cant be right, (perhaps the valve you THINK is the cold feed valve is a drain valve, therefore when shut it is keeping the water in the cylider as it should) then when open it is draining the water out of the cylinder and running through the loft tank, as it should, have a good look at the positioning of the valve you are closing in relation to the tee piece which enters the bottom of the cylinder, IF it is a cold feed valve it must be before the tee enters the cylinder, IF it is a drain valve it must be after the tee

 

[gideononline]

Yeah realised I didn't explain that very well, sorry!
In order to have any running hot water, I have to turn the feed to the cylinder OFF.
This then gives the water in the cyclinder a chance to heat up.
Now after a while, I turn the feed to the cylinder back ON,
and will have running hot water if i run the hot taps.
But then the problem again arises with the main header tank constantly filling up while the feed to the cylinder is on.

There is a small valve/ not sure exactly what it's called but it's not like a stopcock red tap, just a little valve thing which is just underneath the feed into the bottom of the cylider, but it's rock solid and that pipe then goes down under the ceiling i guess, not sure where it continues too as its out of sight. I take it this is used to drain the cylinder, but where does it drain to?
Bit confused, sorry! bit of a novice!

Was wondering if it had anything to do with the electric shower, but dont know how, never quite understood how they work, how cold water can pass through at the speed it does and come out burning hot instantly!

 

[Reg Man]

Have you got suspended wood floor down stairs? If so, could have a burst hot water pipe under the floor downstairs.

 

[plumbitp]

Do you have an expansion tank for the Central heating? Is this fed from the mains or has it been plumbed to be fed from the header tank? If it has been fed from the header then maybe theres a leak in the central heating somewhere and is contantly trying to refill itself? Freeze burst while away? Disclaimer: Im not qualified plumber yet so I could of course be talkin utter tosh but just my under(possibly misunder)standing of what could be happening??

 

[tamz]

Or maybe if the expansion pipe goes outside below the water level it may be burst.

Best to bite the bullet and get a plumber in to have a look.
We are not all rouge traders or as expensive as you think.
Get a local guy on recommendation if you can and try to steer away from the big ads.

 

[gideononline]

All heating is electric, so only have the one main header tank in loft feeding the hot water cylinder in room below. When I'm up in the loft and turn the stopcock off that feeds the cylinder, leave it for a bit.. then turn it on, it definitley shoots through that outlet pretty fast at first , then slows but keeps running throught the system, even though no taps, outlets etc are on. Does the definitley mean a leak somewhere although unable to isolate it, don't know where its going or if the leak must be underneath the house.

Thanks for all the replies, it's helping me just speaking it over with someone!

 

[tamz]

This is the best photo i can find quickly on the web. Bit small but it will do


As you can see from the drawing if the tank in the loft is running it must be running to some where. If all the taps are closed everything will stop.
It is either running from a burst pipe in an unseen place, from a drain valve or from a burst vent if it exits the roof below the water level. You need to get this attended to. If you don't it will damage your building and will cost a lot more to put right.
Leave it much longer and you will probably smell it.
Phone a local plumber.

 

[Bartdude]

Try and find the pipe connected to the drain valve,if that goes outside it could well have frozen and burst in the recent cold weather,that would be my bet. It's obviously not easy to find or you would have by now so I'd also advise calling a plumber in. Sooner rather than later too.