CWS float valve: part1/2 compatibility

Tonight the arm of the ballcock feeding the cold water storage cistern in my attic broke (quite puzzling: maybe due to strong wind causing some turbulence??).

Anyway, I need to replace it. I know it's faster to replace only the part inside the tank, undoing the very last compression nut.

But can I do that when passing from a "part 1" to a "part 2" valve?

Otherwise, I might choose to stick with part 1 to cut the hassle.

PS: I'm talking about an open vented pumped S-plan system, common here in UK, aka "hydronic heating system" in USA.

 

Either just replace the internal parts of the part 1 or replace the whole thing with a part 2. It shouldn't be difficult to swap the whole thing.

This is a UK site.

 

Ok, thanks, I'm deciding now what to buy.
Partially related: do you know why the valves I'm looking to buy all specify "Side Entry" in their description?
Should I care about that when choosing?
I googled to no avail.

I know, but now I have the habit of attaching this clarification just in case, after getting some bewildered questions on other forums. Should remember not to do that when in UK

 

Side entry is common for storage cisterns, bottom entry is more for wc cisterns, with the cistern entry at the bottom.

 

If you stick with part 1, you risk backflow, as they’re only permitted now with adequate backflow prevention measures. (All to do with water regulations). Part 2 and 3 are fine.

 

Thanks for your useful replies. Still choosing what to buy: now the choice is between plastic seat and brass seat (more expensive).
I am again clueless, as couldn't find much on google about why that matters.
Any idea?

 

https://www.screwfix.com/p/fluidmas...VBLDtCh3EiQNuEAQYBCABEgJ5J_D_BwE&gclsrc=aw.ds

 

Plastic is fine .

 

Thank you, that's cheap.
Link has some problem for me, I edited it a bit and hope this works: Fluidmaster Brass Part 2 Float Valve ½" (978FY)

 

I think some links aren’t working due to the Coronavirus.

 

You're right: mine doesn't work, too. Totally baffling (I see no connection with covid). Copy/paste should work: https://www.screwfix.com/p/fluidmaster-brass-part-2-float-valve-/978FY

 

https://www.diynot.com/diy/threads/links-to-screwfix.544514/

 

So I ordered a part 2 to replace my broken part 1, but now I have a silly question: can I keep the old rubber ball? Or do I need to buy a new one?

 

If it’s rubber it may fail, if it’s plastic, clean it and reuse, providing it’s not damaged.

 

It's plastic, sorry, and it looks ok. My question was more about the compatibility: i.e., will it fit on the new valve?

(sorry, the valve hasn't arrived yet, so I cannot try myself; just thought to save some time and ask)