Cast iron radiator questions

[jamespetts]

May I ask - if one is thinking of having cast iron radiators installed in place of ordinary flat panel radiators, is there any great advantage (for example, in terms of installation cost) to having them all done at once, or might it equally well be done room by room on different occasions?

Also, is there any difficulty with cast iron radiators if there is a domestic water softener installed?

 

[Justin Passing]

All together will be
cheaper - think of need to drain the system
better - one lot of new water, less corrosion.

Water softeners can introduce chlorides etc which are bad in CH systems.
Use mains water.
Your kitchen cold tap etc should be mains water, unsoftened.

 

[jamespetts]

All together will be
cheaper - think of need to drain the system
better - one lot of new water, less corrosion.

Water softeners can introduce chlorides etc which are bad in CH systems.
Use mains water.
Your kitchen cold tap etc should be mains water, unsoftened.

Splendid, thank you, that's very helpful. I suppose that the central heating inlet can bypass the water softener? (Although, would this not have the central heating furring up with lime? Or do the inhibitors in the radiator circuit prevent that?)

Out of interest, why the cold tap in the kitchen?

 

[Justin Passing]

You probably wouldn't water the garden with softened water either
Water regs require an unadulterated outlet. I can't remember if it's actually specified which one, but it's always the kitchen sink, for drinking.

Lime isn't normally a problem in the radiator system because it doesn't get changed frequently enough. Some inhibitors claim to stop deposits of limescale on boiler parts.

 

[jamespetts]

Splendid, thank you for your help. One further question - should one redecorate before or after changing the radiators?

 

[Justin Passing]

Afterwards, but it depends...
Holes in the wall and the old wall covering will show when you take the old rads off and be visible through the vertical slots in the new CI ones, if they are that type.
You can't deal with them before you take the old rads off, but it would also be tricky after the new rads are in, so you'll probably have to move the new radiators anyway while deco is done.
Bear in mind that the pipe spacing will probably be different; further from the wall, if not the lengths. You may need to paint new pipes.
If the new rads only fix to the floor, it should be possible to get behind them to decorate. If not, you'll have new rad valves which will help.

To replumb pipes to fit new rads you'd probably drain the whole system. To remove/refit a rad onto the valves, you wouldn't.