Underfloor Heating - Best Connection?

[adaze]

After a bit of advice on the best/ most appropriate connection for UFH. Currently building a small extension (4.5mx 2.5m) which will be bathroom and kitchen, have screeded the floor and installed 15mm plastic pipe for underfloor heating. Now im not sure of the best method to connection to the existing central heating (Bosch Worcester Greenstar 25CDi). Is it easy enough to install a room thermostat and connect this to a mixer valve and just connect this to the existing rad system? Or do I need to wire back to the boiler and connect up there, bit confused I everything I find seems to be conflicting

 

[Agile]

There is nothing conflicting if you understand what you are doing!

You ned a UFH circulating pump and a blending valve so the temperature does not exceed 50°C on the UFH circuit!

Tony

 

[simond]

It depends how well you want it to work.

Best practice suggests you will put a zone valve and thermostat on the UFH section feeding the manufacturers UFH manifold and pump set.

The existing heating should also be be zoned with a stat.

This way, either circuit can be timed separately. You will find the UFH works better if left on for longer periods than you might time rads.

 

[bengasman]

Underfloor heating has usually a lag of one to two hours. It will work a lot better if you have it on a separate timer, especially if you do not have radiators in the extension.

 

[chrishutt]

There is a low cost control system for small UFH installations based on a thermostatic control valve on the return connection of the UFH circuit. When the hot flow water reaches the return valve the valve will close and halt the circulation, so limiting the temperature rise of the floor. After a while the valve opens a little until the UFH circuit is refilled with hotter water from the main flow, and so forth. Danfoss make the control valve.

 

[adaze]

Thanks for your suggestions. Is a pump necessary or is this dependent on the floor area being supplied?

I had a look at the Danfoss control valve that seems like a simple option, but I think its drawback would be the lack of direct control over the room temperature.

Where would be the best place to find info on wiring in an extra thermostat (with or without timer), I think this sounds like quite a big job. The boiler we have has a wireless timer/ stat (MT10RF - W7716192037) is this likely to be compatible with an additional timer/stat? I haven't been able to find any info on the Bosch site. I figure that a stat could be wired independently controlling the inlet outlet (like the Danfoss valve), but obviously a timer would need to link back to the boiler...