Adding a zone - 2 port valves - control

[stu550]

In an effort to make our heating system more efficient I'd like to try adding a zone for the bedrooms. Fortunately the pipe work should make this quite simple as the zone would be the last 4 radiators - there would be no requirement for only the bedrooms to be heated and not the house.

I thought the simplest way to do this would be to add a 2 port valve after the supply to the last radiator in zone 1, before it goes on to the 3 bedrooms.

Firstly, is this okay to do? Do I need a bypass or can the pipe just stop - rememeber it will be circulating closely as I was planning on adding this valve next to the radiator.

Because of the location of the new valve and current boiler/ programmer (opposite sides of the house) i'd like to have it switched totally independent to the heating programmer to open morning and evening.

The plan would be to go for a normally closed valve. So... how do I control/ power this?

I was thinking of a having a fused spur that would supply the valve via a new programmable thermostat. This would also give this zone frost protection and keep the bedrooms at a minmum temperature (assuming the heating is on).

Questions:

1 - how much power does a valve require to keep it open?
2 - can I just turn on/ turn off the supply to this valve to open/ close it? I am not sure how I would power it if this was needed in order for it to close? Is the spring inside enough to close against the water pressure?
3 - would a supply from a fused spur be okay?
4 - what recommended programmable thermostat would you recommend - ideally one that is mains fed and does not require batteries changing.

Anything else I should be thinking of?

Thanks

Stuart

 

[andytw]

I don't see a problem if you turn off all the radiators individually, or with a manual gate valve in the common feed pipe so using a zone valve would seem to be a good idea.

Honeywell 2 port valve V4043 is available in 15 or 22mm and is normally closed. Apply power to open it. Remove power and it closes under spring power.
Power consumption I think is about 10 watts.
Have a look at the web page http://www.honeywelluk.com/products/Valves/Motorised-Valves/V4043-Motorised-Valves/

Wiring from a spur would be fine.
One tip, I would install it where you can get at it in case the actuator fails in the future. It can be replaced without draing but you need access.

Can't comment on a programmer.

andytw