Overflow issue combination cylinder

[Illuminate]

I instanly assumed I had a problem with the ballcock valve as overflow pouring out but on inspection I noticed that the ballcock is working efficiently but water seemed to be coming into the top of the tank from what I think is the internal vent making me think the hot water is overheating and drawing up? Immerssion issues or??

The water is coming out of the hole to the left above the ball cock as shown in photo?

Any help welcome?

 

[Timmy D]

What do you mean by pouring? Like a kitchen tap kinda flow rate?

If so, you may have a crossover from the mains water to the hot system.

Without knowing/seeing your outlets (taps/showers) it’s hard to be 100% accurate but to want to check all outlets which have mains cold water and hot from this tank. Typically the kitchen sink.

Go under the kitchen sink and listen for water moving through the tap supply pipes when the tap is off.

If you hear water, turn off the cold supply to the tap and you should hear the water stop.

Then check the tank, it should have stopped overflowing.

If so, new tap required.

This type of cross over can also happen at shower valves which have a mains supply but less common.

If you get a new tap, get one that is designed for low pressure systems and mixes the hot/cold at the end of the spout; rather than at the cartridge.

5 hours ago I came across and fixed this issue which 4 other people had missed and kept changing the ball cock. One even suggested a new hot water cylinder as he suspected the old one was scaled up and causing the issue.

 

[snowhead]

Given it says Toilets only on the cylinder I'd guess this is Commercial.

As above, it's Cold to Hot crossover, probably in a thermostatic mixer supplying the basins taps or mixer tap.
Find the TMV(s) and the Hot feed to it will be Cold, run a Hot or mixer tap and the pipe will go hot for a while.

 

[SJB060685]

As above. If a constant flow then you have a back feed from cold main to gravity hot water somewhere. If only a little when cylinder is heating its another issue.

 

[Illuminate]

What do you mean by pouring? Like a kitchen tap kinda flow rate?

If so, you may have a crossover from the mains water to the hot system.

Without knowing/seeing your outlets (taps/showers) it’s hard to be 100% accurate but to want to check all outlets which have mains cold water and hot from this tank. Typically the kitchen sink.

Go under the kitchen sink and listen for water moving through the tap supply pipes when the tap is off.

If you hear water, turn off the cold supply to the tap and you should hear the water stop.

Then check the tank, it should have stopped overflowing.

If so, new tap required.

This type of cross over can also happen at shower valves which have a mains supply but less common.

If you get a new tap, get one that is designed for low pressure systems and mixes the hot/cold at the end of the spout; rather than at the cartridge.

5 hours ago I came across and fixed this issue which 4 other people had missed and kept changing the ball cock. One even suggested a new hot water cylinder as he suspected the old one was scaled up and causing the issue.

That's great advice mate, really appreciate it. Yeah the flow is much like a tap. This morning i isoltated the hot feed leading to faucets and it stopped (the back flow) and obviously the overflow issue and so you must be right. Thanks. I will try tomorrow

 

[Illuminate]

Given it says Toilets only on the cylinder I'd guess this is Commercial.

As above, it's Cold to Hot crossover, probably in a thermostatic mixer supplying the basins taps or mixer tap.
Find the TMV(s) and the Hot feed to it will be Cold, run a Hot or mixer tap and the pipe will go hot for a while.

Wpuld this be a replacement tmv needed?

 

[Timmy D]

Wpuld this be a replacement tmv needed?

Whatever is passing, will need renewing but ensure it’s rates for uneven (high/low) pressures.

Go around and isolate one supply (hot or cold) at each outlet, one at a time until you find the problem one. Take some pics of it and we can likely add some more advise.

 

[snowhead]

Would this be a replacement tmv needed?

The easy fix is just to put Check valve / NRV in the Hot to stop the cold flow into it.
Most TMV have check valves built in, but do fail.

 

[Illuminate]

Thank you all for your help. Job complete. On inspection I noticed the sound of water from a row of the female toilet basin taps which stopped when all isolated and that in the gents toilets all the hot feed on the mixer taps had been connected to non return valves but none in the female basin mixer taps. Instead of just attaching a non return to the main feed to all the taps I installed each hot tap with one for extra reassurance. Working fine now

 

[Illuminate]

Also the main feed to all the taps was quite concealed where it branched out and so I would of had to install two 22mm non return valves which I did not have on me and so I just installed four no return valves to each hot feed on the tap

 

[Ric2013]

Instead of just attaching a non return to the main feed to all the taps I installed each hot tap with one for extra reassurance.

What you did was the right thing to do, and compliant with UK legislation.