Replacing gate valve from CW storage tank to HW cylinder

[ian_uk1975]

Need to replace this as the existing one appears to have broken inside (open, but possibly not all the way). This is causing my shower pump to pull some air when the bath filler is on full tilt since the HW cylinder isn't filling fast enough to keep-up (that's the theory, anyway). I intend replacing the faulty gate valve with a full bore level ball valve (which I've already done on the gravity cold supply to the pump).

I've stood staring at valve and pipework and can't figure-out how I'm going to do this, for the following reason... if I drain-down the CW storage tank and run the hot taps (with pump off) until they run dry, isn't there still going to be a load of static water left in the pipe from the CW storage tank to the HW cylinder?

 

[avonmouth]

About a towel full depending on distance from tank.......just do it.

 

[Madrab]

Not got a drain tap at the bottom of the cylinder if you're worried about the amount of water in the pipe?

As avon mentions though, get a few towels down and fire away

 

[ian_uk1975]

Not got a drain tap at the bottom of the cylinder if you're worried about the amount of water in the pipe?

As avon mentions though, get a few towels down and fire away

I have and it doesn't work! Mind you, that would also drain the cylinder I'd assume.

 

[JimCrow]

is the gate valve you are replacing above the height of the cylinder?.

 

[ian_uk1975]

is the gate valve you are replacing above the height of the cylinder?.

Yes, by about a couple of inches, so should be OK on the bottom half.

 

[avonmouth]

If the gate valve is above the cylinder then the cylinder will not empty when you replace it.Just turn off mains,drain down the tank and do it.

 

[45yearsagasman]

Or simply bung the outlet of the cold water tank and open your hot taps. That way you won't waste a tankful of water.

 

[scoobydo123]

Or bung it

Doh 45years beat me to it

 

[Agile]

If you need air to enter the pipe after bunging the feed then either opening a compression nut a fraction of a turn or sometimes the spindle gland nut on the gate valve.

But as suggested a bath towel should adequately soak up all the water in the pipe.

Tony