Why is the Trv leaking after removing radiator

[Pisces67]

It's valliant trv from the 90s

 

[Stigster]

A 3/4 blanking cap should fit that thread but I cannot absolutely guarantee that. Like Shaun says, I too have never seen a 3/4" TRV outlet in a house before but there it is, looks like that's what you've got.

 

[Pisces67]

A 3/4 blanking cap should fit that thread but I cannot absolutely guarantee that. Like Shaun says, I too have never seen a 3/4" TRV outlet in a house before but there it is, looks like that's what you've got.

Yes these are from 1996, valliant.
This is the current modification I have made follwing the purchase of the 1/2 inch blanking nut,

 

[Stigster]

That's a good way to overcome the problem. Well done!

 

[Pisces67]

That's a good way to overcome the problem. Well done!

Before I redose with sentinel X100, is there any point in putting in a cleaner, emptying and then dosing. Clean water came out of the rad and only dark black fine debris water came out of the holes in rad.

 

[ShaunCorbs]

I wouldn’t just dose with x100

 

[Pisces67]

I wouldn’t just dose with x100

What do you recommend?

X400, run for a couple of weeks, drain and then add x100

 

[ShaunCorbs]

Just add x100 when your finished