Hot water tank

[RonE]

I have an indirect hot water tank connected to the central heating boiler which has been there for around 30 years. Went to replace the jacket yesterday and noticed severe rust around the boiler inlet pipe. How difficult is it to replace the boiler and how do I drain it down? I cannot see any drain point at the bottom of the tank unless it is around the back and I cannot get to it.
All help appreciated

 

[nickso]

its not particularly difficult but it can be time consuming, especially for your first go.

you will have to drain down the cylinder and the boiler heating side for a start (or bung it).

if there is no drain cock on the cylinder open a hot tap till it drains the pipework remove the drawoff connection on the top and use it to syphon the water out, a suitable length of copper to the bottom of the tank and a hose to outside will do.

 

[RonE]

thanks for the info I neve thought about syphoning it. My only concern now is the boiler? this is beginning to sound like a job for a plumber. I thought I would be able to disconect at the tank. Sorry for the ignorance but does that main that when I disconnect the boiler pipes at the tank there will be a gravity push from the heating side?

 

[nickso]

whatever is in the pipework on the boiler side will have to be drained/bunged before you start or you will get very wet.

two pipes into the cyl, probably be roughly parallel to each other, are from the boiler side.

 

[RonE]

How do I drain these pipes. Can be done from the boiler or can I do it by loosening the connections at the tank and draining gradually into a bucket. I am presuming that it is just the water in the pipes that are affected and the central heating is unaffected.

 

[seco services]

find a drain cock on a radiator that will drain the primary circuit.

 

[RonE]

Excuse my ignorance but am I reading this correct that I would have to drain down the whole of the central heating system to change the hot water tank. I always thought the hot water was on a seperate run to the central heating?

 

[seco services]

the water that gos round your rads is the same water that runs round the coil in the cylinder to heat it
the water you use from your hot tap is what fills the cylinder.
the two pipes into the side of the cylinder is only connected to a coil

http://www.diydoctor.org.uk/project_images/boilers/Conven_s.gif

 

[powell30]

no offence intended ron but if you are not familiar with indirect systems and from your answers your not, get a professional in.....it will save you in the long run......plus, refilling old gravity fed systems can be a nightmare......dirt, airlocks etc etc

 

[RonE]

Thanks Guys, it looks like I will have to fork out. Dosnt sound cheap either

 

[seco services]

afraid not.