The Building Regs are not keeping up with research (1), hence they still think zoning is a good thing. Have a look at the video linked below concerning turning off individual rooms, it shows turning off the radiator in one room could actually cost you more, rather than less:

www.heatgeek.com/.../

(1) I'm currently in an argument with a Building Inspector from the Council. New build, MVHR system. He says he wants an extractor fan fitted in a walk in wardrobe room (approx 3m x 4m). the MVHR system has been designed for the property, and has got an extract from that room. He still says it needs additional ventilation!

alanblaby said:

www.heatgeek.com/.../

Not too well explained (for me at least) - "Turning off individual radiators is like applying the breaks. The heat source will have to work hotter to put the required energy into the property!" - but why? I'm guessing that the theory is that with one room cold, the adjacent rooms will have slightly higher heat loss, so their radiators will have to work somewhat harder....?
I don't entirely see that that directly results in higher flow temperatures though - normally the flow temp is set by a thermostat on the boiler -  it seems plausible that flow temperatures would remain the same but the "on" duration for the adjacent rooms would be a little longer. Some empirical data might have been useful.

   - Andy.

alanblaby said:

He still says it needs additional ventilation!

point him to the https://www.labc.co.uk/sites/default/files/content/domestic_ventilation_compliance_guide_2010.pdf

   - Andy.

My interpretation was that there is a floor to the boiler's output, so if you turn off sufficient radiators, the boiler will start to cycle on and off, which reduces its efficiency.

BTW, we all know that they are convectors rather than radiators. 

we all know that they are convectors rather than radiators.

Indeed - heating/plumbing system components are some of the best mis-named .... boilers don't (otherwise they'd explode), radiators are mostly convectors, as you correctly say, header tanks are really cisterns not tanks (by definitions tanks are closed not open - so the hot water cylinder is a tank (but they usually call it a cylinder instead), but the header tank isn't) and modern pipework consists of tube, not pipe (a pipe has a socket at one end and a spigot at the other).

   - Andy.

The building regulation F1 (1) says:

" F1. (1) There shall be adequate means of ventilation provided for people in the building.

Requirement F1 does not apply to a building or space within a building:

a. into which people do not normally go;

b. which is used solely for storage; or

c. which is a garage used solely in connection with a single dwelling."

A walk in wardrobe might be deemed to be a space used solely for storage. There might be some actual dressing going on in there, but the same could happen in the garage, thinking dungarees 

Also ADF1 says;

"Extract ventilation

1.17 Extract ventilation to the outside should be provided in all of the following spaces.

a. Kitchens.

b. Utility rooms. 

c. Bathrooms.

d. Sanitary accommodation."

WIWs don't fit in those categories.

Edit; seem to have replied to the wrong post, meant to reply to the ventilation post by Andy.

The building regulation F1 (1) says:

I'm not disagreeing (although I can see a point of view that people would be expected to enter a walk-in wardrobe (given the walk-in bit), and unlike a garage (which typically has a large door direct to the outside) wouldn't be expected to have incidental ventilation. My point was that even if ventilation was considered necessary, then the existing whole-house system should do the job perfectly well (as the compliance guide says) - indeed sticking a simple extract fan into a home that's presumably designed to be reasonably air-tight, and when it's running reducing the pressure in that room, will likely undermine the whole-house something rotten.

   - Andy. 

Yes it’s a two storey 3000 sq ft house. I believe as others have said that it is a building control decision to have each room zoned which does make a lot more work for us. The design was done by a reputable heating company so have no problems with it, they are designing around what building control demand. As regards the original question of using flex to the stats, I think I will go with the flex to cut down on space aswell as this is what the design specifies!

Comfortable, but not huge!

14 stats still seems over the top, but I understand the reason why. The S-plan box must be a bit full!

I still have no problem with the flex - it seems an obvious solution.