Radiator help (please )

So now you know that the rad works - it just wasn't getting the hot water pushed to it. How open is the lock shield valve on the radiator that you've teed off? Sounds like just a balancing issue.

 

There are lots of posts on here about balancing. If we take the rad at the top of the stairs as an example, when the flow from the boiler gets there it can either go through the radiator and back to the boiler via the return pipe or it can branch off and go to your new radiator and then back to the boiler. Water is lazy and will take the easiest route so by closing down the lock shield valve you are making the route through your new radiator at least as easy as the old one. The trick is to turn down all the lock shields so only some water flows through with enough left to go to all radiators equally.

As a rough guide, start with all the lock shield valves half a turn open and adjust more or less as required. Before you start, record all the current lock shield positions (how many turns each is open) in case it all goes wrong and you need to return them to how they were.

 

I’m not a plumber.

I’ve had this issue.
I would go round the house and turn all the rads off just leaving the problem rad open. it should heat up, then go round turning others back on but just a quarter of a turn.

Do a couple at a time giving them time to warm up completely and checking problem rad.

keep doing until all rads back on. if you have any rads which are too hot and others not quite hot enough, turn the too hot ones down just a touch and open up the cooler ones. It does take time and some trial and error.

I’m sure a plumber will tell you the right way to do it, but this is what I’ve done with success.

Note
If you turn all rads off (except problem rad) and it doesn’t heat up, it is t a balancing problem I think.

 

Excellent
Glad it’s sorted and thanks for reporting back.