Worcester Bosch 30cdi CHW heat exchange question

[Metalworker]

Love this site, have never had to post before as usually find the answer hidden somewhere. My question is this.

When replacing the DHW heat exchanger in my WB greenstar 30cdi combi boiler. Should I drain down the system first?

I've had a good read of the instructions in the WB Installation manual (about 10 lines of text) and I doesn't mention doing this and only refers to undoing two screws.

Surely I can't be this lucky.

Let me down gently please.

 

[petit_pablo]

If you want to remain dry then yes drain the system.

And turn your mains water off to the boiler.

 

[Agile]

PP is clearly short of work and needs to spin it out to occupy all day long.

You only need to isolate the boiler on the valves underneath. That saves airlocks and a lot of bleeding air when refilling.

Tony

 

[nickso]

Or leave the valves completely alone and just drain the boiler

 

[Metalworker]

Okay so a couple of options open to me (reminds me of Harry Hill...but which one is best FIGHT!!!) anyway, if drained will I need to add anything when I fill it back up again? I can't see why but then I'm master of asking the stupid question.