Control of second heating zone.

[Cdbe]

Hi, I want to create a heating zone for my 4 bedrooms upstairs. I'm a bit unsure about where to put the second stat - other than the bedrooms there's just a landing at the top of the open plan stairwell - if I put it there it will be affected by the heat rising from below. Does this matter and do I actually need the second stat or can I just rely on the trvs in the bedrooms? All I want to achieve is to have the heating in the bedrooms on/off at different times to the rest of the house.

 

[Chalked]

Is he pipework suitable or ar you altering It?

 

[Cdbe]

Hi, it will be, the whole 40 year old system is being replaced/repiped in stages in conjunction with renovating and extending the house. The upstairs rooms will be fed by individual 15mm branches off a 22mm manifold in the cupboard where the valves, cylinder etc will live so it's just an extra 2 port valve and the new programmer has 2 htg channels.

I just don't really know the best place for the stat - current experience tells me that the upstairs landing is as warm as the downstairs of the house so if we've had the downstairs heated all day a stat on the upstairs landing won't call for heat for the bedrooms?

 

[Chuck]

I'd put the zone thermostat in the coldest bedroom, typically north-facing. (I don't like of having some rooms in a house significantly colder than others in order to avoid condensation issues.)

A disadvantage of configuring the bedrooms as an independently-controlled zone is the small amount of power that is typically needed results in short-cycling of the boiler. This makes the pipework creak with constant expansion and contraction every cycle. This can be avoided by not having a separate thermostat for the bedrooms zone but letting the downstairs thermostat control the boiler and just have a timer that switches off the bedrooms zone during the day.

If it's your own home and you use a wireless programmer-thermostat you can try various arrangements before finalising. A room with a thermostat must have at least one always on radiator, i.e. a lock-shield instead of a TRV. While experimenting you can just leave the top off a TRV and once you're happy replace it with building-regs compliant lock-shield.

 

[Gasmk1]

look at the evohome as this controls each room individually, never fitted one so cant comment as to it being good or bad

 

[Cdbe]

Thanks, the idea of just a timer controlling the bedrooms sounds low tech enough for me (I'm not that keen on all the wireless stuff to be honest). Could I use a 2port valve (which I have) without the switching circuit and control this from channel 2 of the programmer? I know the bedrooms could only be on when the main heating is in but what we want is say 5pm till 10 for downstairs and 9pm-10 for the bedrooms, we only have it on for half an hour in the morning so that doesn't really matter.

 

[Gasmk1]

yes you dont need to use the switching side of the valve

 

[Chuck]

Could I use a 2port valve (which I have) without the switching circuit and control this from channel 2 of the programmer? I know the bedrooms could only be on when the main heating is in but what we want is say 5pm till 10 for downstairs and 9pm-10 for the bedrooms, we only have it on for half an hour in the morning so that doesn't really matter.

Yes. I think you will find that arrangement and use pattern will work well. To avoid potential future confusion make sure you write a clear explanation of how the system is configured and intended to work and keep it with the documentation for your boiler, etc.

 

[Cdbe]

Thanks, that's great.