If ball valve is so great ...

[DiyNutJob]

Yes its a problem. No valves are allowed on the safety vent. If you want to add a valve to the hot distribution pipe, it must go after the Tee on the downwards section of the vertical pipe.

Your answer completely makes sense to me. We could have an explosion!

I don't fancy messing with the shortish vertical pipe. So, I will substitute the gate valve in the loft instead, and take a gamble with degrading rubber in the ball valve.

 

[Elkato531]

We could have an explosion!

If the valve was closed and numerous safety devices failed then that is a possibility. The regulations, however, have to take the worst case scenario into account even if very unlikely.

 

[DiyNutJob]

DNJ only sources parts made of the very finest Chinesium, note

What is a man to do when screwfixium isn't working? I have a better idea, I have decided to cancel isolation valves. A master shut off valve or a redundant pair of it is all I need. I rarely need to change stuff.

 

[DiyNutJob]

I have loosened the gate valve for extraction. But there appears no way to get the valve out. How can I do this? The tank side is flexi and can be pushed in a little. The the tank connector looks a bit fragile and I might end up ripping up something. Also the tank connector is unfamiliar to me. What is giving it a water seal and do I need a new seal if I were to disconnect the tank?

 

[DiyNutJob]

Turned out the pipe is seized on the tank connector end, and I will have to either cut the pipe or disassemble the tank connector.

 

[Burnerman]

The valve will just be stuck with calcium deposits and won't be too severe.......can you rock the valve to and fro a little, supporting the length that goes into the plastic tank?
The water seal is courtesy of the polythene washers, probably one either side.
Have you any movement outwards on the right hand length of pipe?
John

 

[DiyNutJob]

The only way to get the pipe out is from inside tank. Theoretically, I could force everything and it might work. But I really don't want the risk of additional breakages.

Reason for the gate valve failure is a large lump of calcium and copper "galvanic" reaction. It doesn't look like there is much hope for gate valves.

 

[opps]

gate valves are full bore and they can be set partly open, also they cant be knocked open or shut, unlike the 90 handle ones (I know some have metal locking plates)

bear in mind the one youve linked is a budget valve, I tend to prefer Pegler brand for these

Years ago I used a cheap toolstation one in a customer's home. Two years later, the fitting snapped. Fortunately it was not on the supply side. Still resulted in about £5k of damage. Looking at the snap you could see the granular texture, implying a cheap casting. I now only buy Pegler lever valves.

 

[DiyNutJob]

While sitting comfortably at my table manipulating the removed gate valve, I have to retract my earlier assessment. There is hope for gate valves after all. The correct way to fix partial gate closing is to repeat the closing action 200 times. There's a good probability the calcium will be chopped up. Increasing that to 500 times increases the probability of success and less work than replacing the valve. The action needed is to close to max, back off enough for the gate to unstick, repeat at a high pace. This involves rapid back and forth mini turns by the hand. The turns would be no more than 90 degrees.

 

[DiyNutJob]

What a fork up! I thought I was dealing with 22mm pipes and fittings. Turns out they are 28mm. I have neither the tools nor supplies to deal with that. Everything will have to go back as they were.

 

[pcaouolte]

The correct way to fix partial gate closing is to repeat the closing action 200 times. There's a good probability the calcium will be chopped up. Increasing that to 500 times increases the probability of success and less work than replacing the valve. The action needed is to close to max, back off enough for the gate to unstick, repeat at a high pace. This involves rapid back and forth mini turns by the hand. The turns would be no more than 90 degrees.

And all that broken up calcium stays in the system and blocks filters on showers and aerators on taps

 

[DiyNutJob]

And all that broken up calcium stays in the system and blocks filters on showers and aerators on taps

There is no guarantee where it will go. There's just as good a chance it will go to somewhere that does no harm. For the pressure feed to the hot water tank, it will go to the bottom of the tank, and not much of it. The photo shows 30 years worth.

 

[robinbanks]

One of my tasks every Christmas holiday is to go and operate every shutoff valve and isolator in the house, to avoid just this

Like getting old, if you keep working you keep working. It's when you stop you stop

Motion is lotion

 

[DiyNutJob]

One of my tasks every Christmas holiday is to go and operate every shutoff valve and isolator in the house, to avoid just this

Like getting old, if you keep working you keep working. It's when you stop you stop

Motion is lotion

You can if you wanna. I am a no maintenance kinda guy and prefer a solution that works when needed. I believe I have that solution. Anyway, I restored everything back to how it was, and completed everything I needed to do under the kitchen sink. I need a couple days more of leak tests and done for the current job. Now that I can shut off the water, this opens up other jobs up stairs.

The removed valve was mechanically sound after descaling and I don't foresee having to change it. If I have to, I know exactly all the tools, supplies, and steps needed. I also got a closer look at a pegler 22mm ball valve. It came with teflon seals and the ball was largely protected by the seals when the valve was open. It won't suffer from rubber problems and looked like a good solution if needed.

Gate valve is OK in my book. I didn't need a strip down. But, here's for future reference.