What are the MUST DOs when replacing a radiator?

[Scud14]

Hello guys... I'm asking this on behalf of my friend.

She wants to replace a leaking old radiator with new one.
She got the new rad. and is going to buy wither Drayton or Honeywell thermostatic valve and lock shield.

She was looking for installer to do the job and she got some quotes.
Some of them said something about adding "inhibitor" but others did not.

Could you please advise what are the correct and professional steps should be done when doing that job?

So she knows which one to hire.

 

[Madrab]

The ones that are saying they'll add inhibitor are correct IMO. Replacing a radiator will require the system to be refilled with plain water to bring it back up to the correct pressure, lowering the concentration of inhibitor within the system. Ideally the concentration would be tested first to see how much is required. Inhibitor reduces corrosion of the system internals, maximising their life and helping to avoiding the dreaded black sludge. All CH systems should have it.
An easy test is taking some water out of the system, place it in a sealed jar with a shiny steal nail and waiting a few days, if it starts to rust then not enough inhibitor.

 

[Charnwood]

An easy test is taking some water out of the system, place it in a sealed jar with a shiny steal nail and waiting a few days, if it starts to rust then not enough inhibitor.

I had one of those in my office 40 years ago, one bottle with and one without inhibitor.

 

[Terry lambert]

There're are a few variables that mean you may not need to drain the system to change a rad

Open vented, you could create a vacuum to change the valves and just drain the rad

Some guys I know have freeze machines so that they don't have to drain the system if it's sealed ( combi etc)

If it's imperial rad size to metric and your replacing to the nearest size, then a couple of rad extensions would mean no major alterations to pipe work and so above would still apply

If they are planning on draining the system, then yes, inhibitor should be added.

If your system hasn't been regularly topped up, you may decide that you want inhibitor added anyway

 

[namsag]

Well if she is buying everything herself why are you asking ? would she not just buy this too .
But terry has given the correct answer