Thanks for the replies.
Maybe i should have gone into more detail in the opening post.
We are having an extension built at the rear and side of the property. The whole interior has been removed, including electrics and plumbing, and it will be brought up to at least modern building regs.
There are only a few hours a day that no-one is home. Most of the house will be in use and tbh with the size of the property/ rooms and our inability to keep bedroom doors closed, it seemed inefficient and expensive to have separate zones.
I have done several heat loss calculations and taken an average. The only rooms that im unsure ufh will be enough in, are the 2 spare bedrooms and the bathroom. The 2 spare bedrooms are just over 8m2 and require 85w/m2 at a room temp of 20c and outside temp -3c. Do you think there is enough floor spare to give adequate heating with only ufh?
I have spoken to a few local ufh companies but they all seem to want to sell me way too many things with thermostats for every room, which i cant see the sense in. The next ufh company i speak to is also a veissmann trained installer. Thats why im asking here so that i can get a better idea of what i want/need before speaking to him.
Bathrooms are generally supplemented with a towel rail., with the rails straight of the floor loop, OK so they're only 30-50C, but they're covered in towels!! I've close banded pipes around rooms before to get the watts/M2 jagged up a bit.
Who told you a Bedroom should be 20C, bloody el!! With radiant heat from UFH & little air flow/drafts 17 is equal to 20C.
UFH companies make no money from pipe or fittings, the only way they make money is from selling you controls. Golden Rule KISS.
The index floor loop would need to be sized to establish if one circulator would be addiquid for the whole system. In my experience, no.
Most companies selling UFH kits would do you a design.
For that size of house I wouldn't spend a fortune on an expensive Gerry boiler, complete waste of money, more knobs, bells & whistles to go wrong!!
Oh you can get 100watt/M2 outta screed concrete floor - with tiles, as Danny boy has stated. But it's verging on the uncomfortable & more difficult to control on our 'four seasons in one day' British climate!!
Spend loads of money on insulation, get the best U values you can. It'll save on heating installation costs & more importantly, long term running cost.
HTH