"Derek G." wrote in message
...
On Mon, 30 May 2011 21:58:12 +0100, David J
wrote:


I bought a new house in 1970 that had a warm air CH system, originally
oil-fired, from a central distibution storage tank. There was no gas
in the small town at the time. The downstairs ducts were all under the
suspended floor. When town gas was supplied about 10 years later,
most of my neighbours changed over to gas-fired boilers, and many also
changed to radiators. I eventually bought a new gas-fired warm air
boiler and retained the ducts. I found that they were perfectly
effective - although I realised later that the original design was
technically flawed.

If you study a/c systems in hotel rooms, you will see both inlet and
outlet ducts for good circulation. Our builder had installed only
inlet ducts - assuming that the return air would find a way back via
gaps around the doors. Bad design that, just to keep the costs down.


Our 1972 Wimpey house (so presumably centrally specified) had flow and
return vents (The *big* return vent) in the through lounge, but all
the rooms upstairs had a couple of inches removed from the lights over
the upstairs doors to create an unimpeded path back to the big vent in
the lounge. It had no adverse aspects.

Derek G
Cheers everyone that answered. Have offered on a different flat for a number
of unrelated reasons, however grateful for the advice all the same. And
sorry for releasing the resident looney