Seized gate valve from header to immersion

[bmouthboyo]

I would like to replace my ancient heater element on my immersion tank but the only valve from the header to the cylinder is seized.

I managed to get maybe 5 degrees turn on it but reluctant to get tools on it encase I break it.

Any suggestions? Heat? Bung the hole leaving the header tank?

I guess as a last resort I could stop the rising mains stop cock and drain the tank via taps but wanted to check first.

Thanks

 

[stem]

There should be a drain off valve at the bottom of the hot water cylinder where the feed pipe enters it. If you turn off the mains water supply, or tie up the ball cock to stop the feed tank filling, you can then drain off the cold water below the level of the immersion heater and replace it.

As a word of caution, if you only drain the hot water using the hot taps, once the feed tank is empty, water will stop flowing to the taps, but the cylinder will still be full of water (the hot water comes out from the top) and when you remove the immersion heater you will likely still get a considerable quantity of water coming out, so should use the drain off to get it below the level of the immersion heater regardless.

Gate valves tend to seize up if not used, particularly if they have been left in the fully open position, so when you replace it, fully open it and then close it slightly ie one quarter of a turn.

 

[bmouthboyo]

There should be a drain off valve at the bottom of the hot water cylinder where the feed pipe enters it. If you turn off the mains water supply, or tie up the ball cock to stop the feed tank filling, you can then drain off the cold water below the level of the immersion heater and replace it.

As a word of caution, if you only drain the hot water using the hot taps, once the feed tank is empty, water will stop flowing to the taps, but the cylinder will still be full of water (the hot water comes out from the top) and when you remove the immersion heater you will likely still get a considerable quantity of water coming out, so should use the drain off to get it below the level of the immersion heater regardless.

Gate valves tend to seize up if not used, particularly if they have been left in the fully open position, so when you replace it, fully open it and then close it slightly ie one quarter of a turn.

Unfortunately my cylinder does not have a drain off valve

I am curreently draining the tank via the hot taps. Is there no way I can prevent water leaking out? How much are we talking once the header tank is drained?

 

[stem]

The amount of water contained in the area shown by the arrow below.

 

[stem]

Having looked at your previous thread, I see that your pipe layout is slightly different, so I have modified the drawing, but the amount of water is the same.



I would add a drain off too, for next time.

 

[terryplumb]

Replace the gate valve with a full bore lever operated valve ,not another gate valve.they are rubbish ,and dont work when you really need them to.

 

[terryplumb]

Are you sure you don't have a drain cock ? Located on the pipe that feeds into the bottom of the cylinder ?

 

[75pete]

If needs must, and you can only drain down as far as the tee on top of your cylinder, it looks like you need to either if you are lucky and the tee is a compression fitting, undo the top compression, lift the pipe up and out or cut the pipe above the tee. Once lifted, drop in a hose and drain out.

 

[bmouthboyo]

OK so I drained via the hot water taps and had a load of towels ready...

Luckily only about 50 ml worth came out. Replaced the immersion and swapped on/off switch for timed / boost one. Weeped a little at first as I was worried about over tightening but nipped it up and seems good. Just heating water now to test.

Thanks for help all.