Central Heating - Multiple Zones?

[RogerM]

I think you mean the optimiser - a complex 'sliding' time clock?

Basically its called a compensated flow system. Most systems are designed to operate at (cope with) say -5degs c. At that temp the boiler pumps out a system flow temp of 70degs c (ish). Ones rads are then sized to put sufficient heat into the building to bring to its set point. As teh outside temp warms up (gets closer to the set point) heat is still needed but not quite as much. So, the system calculates what the flow temp should be in order to reach set point and not over shoot (which is where all the wasted energy goes).

Bosch do a great control for about £100 that has an outside air sensor with it. It links directly into the boiler via its networking ability. I have to say its a bit of a sod to get to know but once set correctly its superb. It has an ability to put in offset for the room sensor (that means if your sensor is in the hall and reads 18c when you're toasty in the sitting room at 21c you can put in an 'offset' of 3c effectively fooling the sensor that you've reached set point. It also has night set back so when its really cold the system doesn't switch off just lowers the space temp to say 14c during the night so nowt freezes. It also has an inhibit temp so that if the outside temp is at a point the heating won't come on for no one (thereby stopping the significant other putting the htg on when its a tad chilly in but not out ;-)

All in all a FAB piece of kit that will save a fortune over the years.

D

That's really interesting Dave - thanks for posting. Is there any way the system can differentiate between the zoned radiator circuits and UFH? We are nearly up to roof plate on a large kitchen extension and want to put UFH into it whilst the rest of the house remains on rads. We have concrete floors so retrofit of UFH throughout isn't practical, but is the preferred option for the extension.

Unless I'm mistaken, we will need to keep the kitchen UFH on a separate zone to the already zoned upstairs and downstairs so that lower temp water can go through the UFH when compared to the rads. Introducing a compensated flow system as you describe appeals - but is it practical in the system I've just described?

 

[YorkshireDave]

UFH can still operate on a compensated system but it would requirre an addional controll valve and controller. TBA with the effeciency of UFH the additional expense is not really worth it. From a simplistic cost benefit point of view its best to keep it to one type of system. If you have two zones the flow temp should be determined by the highest temp requirement.
David

 

[RogerM]

UFH can still operate on a compensated system but it would requirre an addional controll valve and controller. TBA with the effeciency of UFH the additional expense is not really worth it. From a simplistic cost benefit point of view its best to keep it to one type of system. If you have two zones the flow temp should be determined by the highest temp requirement.
David

So are you saying that as the rest of the house is on rads (about 1700 sq ft), the extension (about 400 sq ft) should also be on rads? As the extension is a kitchen/diner/living area we expect to virtually live in it!

Or that it's fine for the extension to have UFH on a separate zone to the rads, but don't bother with weather compensation?

 

[Dibs-h]

I think you mean the optimiser - a complex 'sliding' time clock?

Basically its called a compensated flow system. Most systems are designed to operate at (cope with) say -5degs c. At that temp the boiler pumps out a system flow temp of 70degs c (ish). Ones rads are then sized to put sufficient heat into the building to bring to its set point. As teh outside temp warms up (gets closer to the set point) heat is still needed but not quite as much. So, the system calculates what the flow temp should be in order to reach set point and not over shoot (which is where all the wasted energy goes).

Bosch do a great control for about £100 that has an outside air sensor with it. It links directly into the boiler via its networking ability. I have to say its a bit of a sod to get to know but once set correctly its superb. It has an ability to put in offset for the room sensor (that means if your sensor is in the hall and reads 18c when you're toasty in the sitting room at 21c you can put in an 'offset' of 3c effectively fooling the sensor that you've reached set point. It also has night set back so when its really cold the system doesn't switch off just lowers the space temp to say 14c during the night so nowt freezes. It also has an inhibit temp so that if the outside temp is at a point the heating won't come on for no one (thereby stopping the significant other putting the htg on when its a tad chilly in but not out ;-)

All in all a FAB piece of kit that will save a fortune over the years.

D

Dave - have you got any links you can post for the Bosch thingy and compensated flow systems in general?

Cheers

Dibs

 

[YorkshireDave]

Read this
http://www.greenbuildingforum.co.uk/new ... sionID=189
and this
http://www.worcester-bosch.co.uk/homeow ... controller