control heating in new extension

[Nick Holmes]

Hi, a rather basic question.

We are building a new extension (single room).

The intention is to have one trench radiator in the floor and to connect this to the outflow and return pipes under the floor of the adjacent existing room (which is itself at the endo of the ground floor circuit (all floors in the house are independent zones). Currently most rooms have TRVs. The boiler is a combi.

The new extension is fully insulated and compliant with Part L U values.

How is it best to control the radiator in the new extension? Given the trench rad, a conventional TRV seems not sensible (sensor inside rad trench).

Two possibilities have occured to me.

1. I believe it is possible to but a TRV with a 'remote' temp sensor

- connected by a plastic pipe. Not sure how far this can run or how effective it is.

1. A more elaborate and expensive solution would be to use a motorised 2-way valve with a conventional wall mounted room thermostat; this would also allow a simple on-off switch (effectively creating a sub-zone). Problems with this include pipe sizes/composition. valves seem to be at least 22mm, our existing pipes are smallbore copper (can they be 10mm?) and we were contemplating using plastic pipes (15mm??).

Any help or advice would be much appreciated.

Best wishes

Nick

[Owain]

I think microbore could be as small as 8mm. In which case they will probably be sized to supply only one radiator, and you would need to run new pipes back to the manifold or main flow/return pipes on that zone.

You will also need to run new call for heat wires back to the main wiring centre, if you want truly independent control of the new zone.

You can get adapters from almost anything to copper pipe, and from copper pipe to almost anything.

Owain

[auctions]

are great. Use a VAL-12 in the 15mm pipework linked to one of their thermostats.

A

[Ed Sirett]

And for all the sizes so if you ned to add a zone valve to 8mm pipe it's not that difficult.