Replacement Radiator

Cheillie2020

I'm looking for some advice, it might be that I need a plumber but I'm usually pretty good and DIY so just looking to see if I'm on the right lines. 

I live in a 2-year new build so the heating pipes are plastic to the rads. 

I'm wanting to replace a standard double rad to a tall rad. This one: http://www.victorianplumbing.co.uk/urban-vertical-radiator-anthracite-double-panel-1600mm-high

Here is either side of my existing rad. 
 

Am I correct in thinking that I 'could' simply uncouple the bolt that is going into the radiator either side, and then attach them to either side of the new radiator?

I could buy these to match: https://www.victorianplumbing.co.uk/monza-modern-anthracite-angled-thermostatic-radiator-valves
But I would need to drain the system right in order to attach them?

Thanks in advance. 

Ebe_Scrooge

In theory, if you want to leave the valves and just replace the rad, it is just a case of closing the valves and unscrewing them - as long as the valves are working properly and do close fully, which hopefully they will if they're fairly new.  Close the TRV fully.  Also close the lockshield fully, but count how many turns it takes to fully close it.  Open the bleed valve, then unscrew the valves from the radiator - have a bowl or two and some old towels handy to catch the water that will drain out of the rad.

Once it's drained, lift it off and fit your new rad - if the width is the same as your existing one it should just connect up easily.  Obviously if the tails are a different spacing then you'll need to adjust the pipework (check/measure the dimensions before you start the job!)

Once it's fitted, open up both valves - open up the lockshield by the same number of turns as it took to close it, so that you don't upset the balancing of the system.  Open the bleed valve to let the new rad fill up, top up the system as necessary, and you should be good to go.

It's probably worth giving all the other rads a quick bleed as well.  In theory, no air should have got into the rest of the system assuming the valves closed securely, but for the sake of a quick 10-minute whizz-round there's no harm in double-checking.

To answer your second question - if you're wanting to replace the valves then yes, you'll need to drain the system.  If the radiator is upstairs then you'll probably get away with just draining the top half of the system, i.e. the upstairs radiators, as long as you've remembered to switch off the water supply into the header tank (if you have one).  You can get a pipe-freezing kit, which is sometimes used by plumbers so they don't have to drain the system.  Very convenient, but highly unlikely to be worth the expense for a DIY situation where you'd only every use it once in a blue moon.