Adding radiator support to partition wall

[TryAgain1]

A small airing cupboard has 3 standard partition walls and each partition wall has several verticals. I found out that the airing cupboard radiator's brackets were coming loose because of inadequate rawl plugs. So I removed sections of plaster, added four 7"x3" CLS timber horizontal wood (blockers)between the 3 (1 left, 1 centre 1 to right) verticals (verticals are 4" x 3" timber) then put the plasterboard back then put a bigger radiator in the airing cupboard. I uses hex screws to remount the brackets to the blockers behind the plaster. Due to lack of access to the left and right verticals I could only attach the blockers using two 6x80 wood screws drilled diagonally per edge and I did reinforce with flat bar brackets on each edge. The new radiator is about 25kg plus 15kg water weight so about 40kg. So 40/4 about 10kg per bracket so about 5kg per pair of 6x80 wood screws so about 2.5kg per 6x80 screw. Hopefully I have sized the mechanical fixing right? Here are some pics for context: Pic 1 showing the blockers added

 

[Wayners]

Id just use a polymer grab and 6mm MDF stuck to wall. Emulsion.
Fit radiator to that.

You can use corefix maybe

 

[TryAgain1]

Id just use a polymer grab and 6mm MDF stuck to wall. Emulsion.
Fit radiator to that.

You can use corfix maybe

The airing cupboard is tiny so I didn't want to add timber in front of the plasterboard. Said timber would have to be 3" x2" minimum to allow the hex screw to go through. So is my solution using the blockers in the post above safe and good enough?

 

[Wayners]

Ok. I get it now.

Remove all the plasterboard so that only one piece is fitted.
Marked red.
You will only have one joint to worry about.

Put timber in just under so top edge is screwed through both the old board and new board.
Screw joints will stop movement.

You don't need those surface plates. They will cause issue when new plasterboard is fitted over.
One screw either side and sunk in.
If wood is snug add wood glue before you add a screw. Will be solid.
Remove all this plasterboard

Fit wood just under old board and the green is new screws

That's how I'd do it.
Keep it simple with minimum filling.
You made that much harder than it needed to be.
Just want one new piece of plasterboard in there.

 

[denso13]

Hopefully I have sized the mechanical fixing right? Here are some pics for context: Pic 1 showing the blockers added

Looks good, more than enough for the radiator.

 

[endecotp]

A small airing cupboard …. The new radiator is about 25kg

That sounds like a very large radiator for a small airing cupboard

Hopefully I have sized the mechanical fixing right?

It sounds more than adequate to me.