Adding a single room wet UHF to a tado-controlled radiator home

BruceUK

Hi,

We're renovating our small kitchen and want to use a wet UFH system as there isn't space for an effective radiator. The rest of the house is all radiators in a single zone, powered by a combination boiler. We use the original Tado thermostat to control the temperature in the main living area, and smart radiator valves on the bedroom radiators, each able to call for heat independently if needed, to control the bedrooms.

Our builder has suggested two options for the underfloor heating in the kitchen:

• Plumbing 22mm pipes all the way back from the kitchen to the boiler (i.e. a second zone). As the boiler is literally the opposite corner of the house and in the attic this isn't an appealing prospect.
• Running piping from the existing downstairs radiator circuit the UHF pump. He noted that in this case the kitchen could only get heated if other areas are calling for heat from the boiler; which the UFH thermostat wouldn't be able to do. He's also suggested this setup would avoid the need for a manifold.

I have two question:

• Using the system without a manifold implies (to me) there's no cold water being mixed in in the UFH circuit, so the flow temperature in the UFH would be the flow temperature in the radiators (which could surely be too high, even for wet UFH in screed with a tile floor). Is my understanding correct, and if so is this wise?
• He proposes to use the UFH system's thermostat (attached to the kitchen wall) to control the pump (so whether there is hot water being pumped around the kitchen UFH). I would then add a Tado temperature sensor, and configure that to be able to call for heat. This would allow the kitchen to call for heat if needed. We'll add SRV to the living room radiators so the living room doesn't overheat if the kitchen needs more heating. Has anyone done something similar? Do you set both thermostats to the same temperature?

All thoughts and suggestions welcome!

-Bruce