Changing radiators in lounge

FataVerde

Renovating a Victorian flat and want to change the position of the current type 21 radiator (600Hx1500). It's now on an internal wall where I plan to have a sofa and want to move it under the windows. I can't use the same rad because the windows are low and would only accommodate a 400H rad. The lounge is 3.5x4.5m, glazed windows in a mid-terrace so only one external wall and first floor so above heated room. I want a type 21 for decent output but not as thick as a 22.

1. I'm trying to decide whether to install two small 400x1000 type 21 rads, one under each window, or a larger 400x2000 running from one window to the next or even a smaller 400x1600. Online calculators determined I need 3744BTU and 1097watts. All of my above scenarios are way above these figures so it seems like overkill. At the same time, I don't want to lift the boards again after reclaiming them.  I also have a large hallway leading out from the lounge to the kitchen without a rad. I've rented a larger flat with a larger ground floor lounge and a 600x1400 had no problems heating it.

2. Brands: Not all brands produce the 400H (Stelrad doesn't) so I found the following brands within this range: Kudox at Screwfix, Revive at Columnrads, Kartell KRad and Milano at roughly comparable prices. Any recommendations on which brand might be better, more reliable, more solid white finish?

3. Are the discounted Kudox TRV that Screwfix offers any good or should I shell more money for Kartell TRV valve and lockshield?

ComicGeek

I would install 2 slightly smaller rads under the windows assuming that the windows are the same size/height etc - I would do low level column rads personally rather than panel rads. 

Or I would install a single vertical rad on the internal wall to minimise pipework changes, positioned away from the sofa.