Draining hot water tank

[RolandK]

Hi, I have a hot water cylinder heated by twin immersions. I need to drain this down. Can I do this by turning off the mains so that the cold water tank in the loft does not refill and simply darin the whole lot through the hot taps. That is emtying the cold water tank then the cylinder?

Thanks,
Rolande

 

[WaterTight]

Firstly if you don't how to do it, you shouldn't be trying to fix/replace the cylinder yourself. You won't manage it.
You want to isolate the water feeding the cylinder as close to the cylinder as is practicable. So you might turn off the cylinder cold feed valve or you might tie up the arm in the cold tank or you might turn off it's own feed pipe valve. The further back you isolate the more there is to drain. But if you don't want to go turning rusty gate valves or going in the loft your method will still work.
Opening the hot taps will only drain past the draw off point on the top of the cylinder. Few ways to empty it but best is probably to syphon it out with a hose through the vent connection.
Is your cylinder only heated by twin immerstions? Presumably so, I'm not experienced enough to know whether two immersions means that'll be the only heat source. But just incase you can have a coil passing through the cylinder as well (from your heating circuit) you want to be sure that's not the case too as this will also be full of water that has to be drained separately.

 

[Plamber]

With 2 immersion, i'd imgine bottom one is on a timer that cant be changed, as in it come on for 2 hours evening and morning. the top one is for your boost. this is usually the setup when a cylinder is heated by 2 immersions, unless its a new house which has a massive cylinder, heated by CH coil and immersions.

put off water and attach a hose to the draincock.

What are you planning do to out of interest?

 

[RolandK]

Thanks guys,

what I planning is to replace the hot water outlet pipe as I've rerouted the new pipework to be a lot les tortuous than it is now! At the moment it is taken off very high up on the outlet/expansion pipe in the loft and I want it to be taken off lower down in the airing cupboard so it can link up to the new pipework.
It's correct that the bottom immersion is economy 7 and top one is the boost/standby, no other hot water heating as we are all elec. If I do fully drain the tank is it worth replacing the immersions at the same time as they are a few years old now and we are in a hard water area? I'm a bit nervous about getting them out without damaging the cylinder, what you reckon?

Thanks,
Roland

 

[Plamber]

Nah, if the immersions are working fine i'd leave them well alone. no need to touch them. if the HW tank isn't getting moved, and all your doing it moving the HW draw off pipe you wont need to drain the cylinder.​

 

[RolandK]

Ok thanks, will do. So if i just empty thru the hot taps and empty the cold tank that will be enough to clear the take off right down to the tank connection?

 

[Plamber]

well emptying just the cold water tank or shutting the supply to the cylinder makes it ok to cut into the pipework AFTER the cylinder. if you are cutting into the cold feed AT the cylinder or changing an immersion heater you should drain the cylinder.