Heating for open plan kitchen

[IE00]

Hello,

We've got a rear extension which we are just about to install the radiators for, but the plumber thinks we don't have enough heat for the open plan kitchen dining. I've attached a diagram. Using the DIY.com BTU calculator we need 13,000 for a dining room of 9 x 4m with 2.7m ceilings.
The BTUs are the following:
Plinth heater - 1800
Hall radiator (600x1824) - 8000
Dining room (300x1824) - 5200

By my calculation we have enough BTUs but he seems to think the hall radiator will not be effective in heating the big room properly. Do you think we need a bigger dining room heater?

 

[RandomGrinch]

Just a DIY'er, so feel free to ignore!
I'm sure someone with infinitely more knowledge will be along soon!

Personally, I would consider getting a vertical rad for the hall, and place it as near to the kitchen as possible.

A decent sized vertical with multiple columns can easily get the extra BTU you require, and they are very good at setting up convection currents that should help spread the heat through the space. A dark coloured one may also help!

 

[Loofah]

Just make the dining room one higher, as you've already suggested. Also run the details through a few other calculators, there's lots online