On Monday, February 17, 2014 8:31:37 AM UTC, harry wrote:
"Onetap" wrote in message

Quick answer there would typically be a pair of flow and return pipes,

usually in a services duct in a central stairwell. From that there would be

flow and return branches to each flat. Each radiator would connect between

the F&R, a TRv would restrict the water flow as the room temperature reached

the setpoint.



You should be able to turn all your rads off, or just have one or two on

without affecting the rest of the block.



Here's the thing though. As TRVs close down, the volumetric flow rate

decreases and the pump differential pressure increases; look at a pump

curve. Hopefully the new boilers had intelligent pumps that throttle back to

maintain a constant differential across F&R. If not, it can cause much TRV

whistling since they can only cope with a limited pressure differential

across them.





There are various designs.

Different ideas from different times and different fuels.

Normally in large systems there is a pump in the boilerhouse that circulates

constant temperature water round a single pipe loop/system that is in a

central position

The individual flats probably each have their own pump abstracting water

from this loop and individual control sytems.

No.
PHXs have become quite common, a simple way of hydraulically separating landlord's and tenant's systems.


Not popular these days, inefficient and expensive to install.

It's more usual for each flate to have it's own boiler with a gas supply

running round the building.

(This can bring it's own dangers though.)

Only where mains gas is available.