Water tank filling with feed isolated

king2

I got a call from my sister at 1230 last night, water was leaking through her ceiling.I went into the attic and saw that it was coming from the water tank.

The central heating expansion tank directly over the water tank was replaced about a year ago but was left resting on an edge of the water tank causing it to bend under the weight and allowing the water to flow out.I turned on taps to decrease the level in the water tank and tied up the ballcock to stop the tank filling and left thinking this would stop the tank overflowing again.

It overflowed again this morning however, worse because water wasnt seen coming through the ceiling for a few hours probably.The Wooden floor in the room below is wrecked, buckled.The water tank is filling up even though the ballcock on the inlet pipe is isolated.

The only other way I can see that water can get into the tank is through the central heating expansion tank overflow, but its not because the expansion tank ballcock is cutting off water well before it reaches the overflow pipe. The central heating expansion tank appears to be continuously filling however for some reason.

I have the central heating tank properly supported now so if/when the water tank does fill too high water will exit through the overflow pipe, but why is the water tank filling?

zxcvbnm12

are there mixer taps in the house

king2

Yes, two mixers, Kitchen Sink and Bath

zxcvbnm12

if u shine a light into the tank check is there any disturbance of water?shine the light at the 350s on the bottom of the tank and check can u see water swirling out of one of them

Billy Bunting

Bit confused. You say "The central heating expansion tank directly over the water tank " is it over the tank, higher than the tank ????

heinbloed

As doubted by Billy Bunting already:

The CH tank directly above the drinking water tank calls for problems, think about cross contamination.

This couldn't have been a professional job from the beginning.

I have the central heating tank properly supported now so if/when the water tank does fill too high water will exit through the overflow pipe, but why is the water tank filling?

Because there is nothing to stop it.
A faulty installation.

Maybe- and we can only guess without having seen it- there is an automatic filling valve installed (at the boiler?) which is open?
Maybe there is a connection (because of an internal leak) in the cylinder between the two systems?

Get a plumber in.

king2

zxcvbnm12 wrote: »

if u shine a light into the tank check is there any disturbance of water?shine the light at the 350s on the bottom of the tank and check can u see water swirling out of one of them

Can't see any disturbance of water,what is the 350s?

king2

Billy Bunting wrote: »

Bit confused. You say "The central heating expansion tank directly over the water tank " is it over the tank, higher than the tank ????

Yes it is over and higher than the water tank, always was AFAIK

king2

heinbloed wrote: »

As doubted by Billy Bunting already:

The CH tank directly above the drinking water tank calls for problems, think about cross contamination.

This couldn't have been a professional job from the beginning.



Because there is nothing to stop it.
A faulty installation.

Maybe- and we can only guess without having seen it- there is an automatic filling valve installed (at the boiler?) which is open?
Maybe there is a connection (because of an internal leak) in the cylinder between the two systems?

Get a plumber in.

The water tank only supplies the hot water cylinder and the cold water tap on the Bath. Everything else appears to be connected to mains.The house did undergo some extensions during the 80s by a builder. I dont think plumbing was his strong point.

The CH expansion tank is above the Water tank but the only connection between them is that they are on a common feed and the overflow from the expansion tank will route into the water tank. If the only inlet to the water tank is cut off and the CH tank is not overflowing how can the water tank level increase? Can water come back up through the outlets at the bottom of the tank? I would have thought that would be impossible against the weight of the water in the tank.

heinbloed

King2 wrote:

...the overflow from the expansion tank will route into the water tank.

This is an illegal installation. The water from the heating circuit should never be consumed by humans or animals.

Pete67

Probably a pinhole leak in the heating coil inside the hot water cylinder.

king2

Pete67 wrote: »

Probably a pinhole leak in the heating coil inside the hot water cylinder.

would it be possible to prove for certain that this is the problem before having a new cylinder installed? What is the going rate for a new cylinder plus installation? thanks

Carlow52

king2 wrote: »

would it be possible to prove for certain that this is the problem before having a new cylinder installed? What is the going rate for a new cylinder plus installation? thanks

u will need to isolate the coil in the cylinder or else cut off the outlet from CH tank and block the CH expansion pipe so as u stop the water flowing through the pine hole. Cutting off the CH tank outlet only will not work until the water in the CH system gets to the same level as the pin hole.

What is not at all clear is why the over flow from cold tank is not working?

ps if u do block the CH expansion pipe pls remember to open it when repairs are done

Pete67

king2 wrote: »

would it be possible to prove for certain that this is the problem before having a new cylinder installed? What is the going rate for a new cylinder plus installation? thanks

Lots of ways to do this, I'd suggest close the valve on the cold feed to the cylinder, drain cylinder using a hosepipe (should be a drain fitting where the cold feed enters the cylinder), remove the immersion element (or the blank cap in it's place if you don't have one) and take a look inside the cylinder with a torch. You should be able to see/hear if there is a leak from the coil.

A new insulated cylinder costs between 250 to 400 depending on size, plus a couple of hours labour for a plumber.

Oh, and the old cylinder is worth a nice few quid at the scrappies (pure copper)

Don't run the heating with the CH vent and expansion pipe blocked, at best the safety valve will lift, and worst something will burst possibly violently spraying hot water and steam everywhere.

king2

Carlow52 wrote: »

u will need to isolate the coil in the cylinder or else cut off the outlet from CH tank and block the CH expansion pipe so as u stop the water flowing through the pine hole. Cutting off the CH tank outlet only will not work until the water in the CH system gets to the same level as the pin hole.

What is not at all clear is why the over flow from cold tank is not working?

ps if u do block the CH expansion pipe pls remember to open it when repairs are done

The overflow from the tank is working ok. The leak occured because the CH tank was not properly supported over the water tank and caused a side of the water tank to bend and let the water out over the side before it reached the overflow.

Im not too sure how to block the CH tank outlet and expansion pipes.Could I shut off the water feed to the CH expansion tank by just tying up the ballcock valve supplying it? Would the water in the CH system then drain through any hole in the cylinder coil into the water system and then stop when it got to the same level as the hole in the cylinder? would the level in the water tank then stop increasing proving that a hole in the cylinder coil was causing the problem? Thanks

danjo-xx

king2 wrote: »

Im not too sure how to block the CH tank outlet and expansion pipes.

There are rubber bungs you can get for blocking outlets.



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