Thanks Alan, interesting ideas. Once set up, It sounds like there would be no user input. Normally on radiators, there is a lockshield valve and a manual valve (or TRV), for users to adjust. If, in this example, a user was able to turn off one or two radiators, this would surely have an effect on the balance of the system, so that possibly the reference room radiator, in the room with the thermostat, would experience a different flow from that which it was commissioned for, and an effect on any temperature difference, between eg bedrooms and lounge, which were designed for.

The OP, Peter, mentioned manifolds in their second post, so I assume they are wet UFH manifolds, one on each floor. 

As Andy said Approved Document L book 1 

"5.20 For heating systems in new dwellings, or when a heat generator such as a boiler is replaced in an existing dwelling, each room should be provided with thermostatic room controls. These should be capable of being used to separately adapt the heating output in each room served by the heating appliance. Where justified in accordance with paragraph 5.21, heating may be controlled for each heating zone rather than individual rooms."

But that doesn't preclude anyone from designing something different, as long as it is no worse than full compliance.

Edit; the building regs have hummed and ahhd about TRVs. They were once required, then when Boiler Plus came along they dropped the requirement, then last year they are back in, along with (one of the four) boiler Plus measures. 

I have UFH in my flat, I tend to leave the  thermostat at room temp all year round, but then I have cats who don't go out much ;)

OlympusMons said:

The OP, Peter, mentioned manifolds in their second post, so I assume they are wet UFH manifolds, one on each floor.

This is a big house, so possibly >1/floor.

IIRC, step-daughter's house has 8: 3 on the ground and first floors, and 2 on the top. The house is circa 200 m².

I can see the point in not heating the guest bedrooms, but if they are going to warm up due to heat below and to the side, the economy may be trivial.

BTW: IIRC, we used 4 core flex for the stats. (Hubby's choice, not mine.)

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.

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.