Stop hot water from hot water tank

[aaad1]

Hi all,

I was planning on changing the kitchen tap (no isolation valves) but couldn't stop the hot water from the hot water tank (Megaflo heatrae stadia).
I have changed bathrooms taps before and have stop hot water to the taps by shutting off the cold inlet to the cylinder (Last year).

Unfortunately, when I tried to turn off the cold inlet to the tank, hot water is still running to the taps even after waiting a good 20 seconds. Feels like pressure wasn't dropping in the pipe. I have even turned off the red value that is connect to the outlet at the top of the cylinder (apparently hot water from out from top - this didn't work either).

When I open back up the cold inlet value, I can hear cold water rushing into the system filling it up.

I have attached some pictures for references.

Any ideas or help would be greatly appreciated.

Many thanks

 

[Stuckinarut]

It’s an unvented cylinder, so I would have thought turning the cold main off would suffice.

 

[aaad1]

It’s an unvented cylinder, so I would have thought turning the cold main off would suffice.

I thought that too. In the past, I would turn the black cold water inlet valve and that would work. Am I missing something?

 

[Mottie]

Turn off the stop cock to your house.

 

[aaad1]

Turn off the stop cock to your house.

I tried that. Turned the main cold water valve under the kitchen sink. Turned the upstairs black cold water inlet to the cylinder as well as the red valve from top of the cylinder.

Still getting a lot of water out from hot taps, can't be that much hot water pressure buildup in the pipes?

 

[Stuckinarut]

I thought that too. In the past, I would turn the black cold water inlet valve and that would work. Am I missing something?

I don’t think you’re missing anything. If turning the mains off, does the cold water stop?

 

[aaad1]

I don’t think your email missing anything. If turning the mains off, does the cold water stop?

I just tried this again. Turning off the mains under kitchen sink turned off the cold tap for kitchen (no water out immediately).
I also turned the black cold water inlet to the cylinder (shown on picture).
Tried a cold water tap upstairs but still getting a lot of water out? Where is this coming from?

 

[Stuckinarut]

Tried a cold water tap upstairs but still getting a lot of water out? Where is this coming from?

I wonder if there’s a passing mixer, or maybe if converted the old storage cistern is still connected?

 

[aaad1]

I wonder if there’s a passing mixer, or maybe if converted the old storage cistern is still connected?

It shouldn't be old storage cistern (like a cold water tank in loft?), house is from 2007 and there's no tank in the loft.
The only mixer tap is the kitchen tap.

There is a pressurised red cylinder (1.2 bars) above the hot water cylinder, I'm guessing that's for building up the pressure? Can water bypass that at all? Or any other pipes that it's bypassing somehow?

 

[Stuckinarut]

There is a pressurised red cylinder (1.2 bars) above the hot water cylinder, I'm guessing that's for building up the pressure? Can water bypass that at all? Or any other pipes that it's bypassing somehow?

That should be for the expansion used in central heating. You should have another for potable water, although you could have what’s known as a bubble top cylinder.

 

[terryplumb]

Show us a pic of your mains cold water stopcock where the mains water enters the property.

 

[aaad1]

That should be for the expansion used in central heating. You should have another for potable water, although you could have what’s known as a bubble top cylinder.

As far as I'm aware, there isn't any other water containers anywhere? Guessing it is a bubble top cylinder then?

 

[aaad1]

Show us a pic of your mains cold water stopcock where the mains water enters the property.

Here's the mains stopcock

 

[terryplumb]

With that stopcock closed ,open all hot and cold taps upstairs and downstairs ,leave them open ,for two minutes then go around and see which taps ( hot and cold) are still giving water.

 

[aaad1]

With that stopcock closed ,open all hot and cold taps upstairs and downstairs ,leave them open ,for two minutes then go around and see which taps ( hot and cold) are still giving water.

Do I turn the black cold water inlet valve to off position next to the hot water cylinder (1st original picture) as well?