DoN. Nichols wrote:

snip

Hot air central heating is uncommon in English homes. There was a
fashion for using it in cheaply built 1960s and '70s homes, but it was
generally poorly implemented and noisy, so it fell out of favour and the
standard is now water central heating. We had a house with hot air
central heating while I was at school. The boiler was like a coffin on
end which stood in our kitchen. It had hardly any controls: on/off and a
temperature control which you had to turn with a coin, if I remember
correctly. Some large buildings here use hot air central heating, or
water central heating with a blower behind the radiator. Those that I've
seen either use a PSC motor or more commonly a three phase motor, but in
both cases they've been single speed. Modern factory heating systems
might use variable speed motors, but most of the stuff I work on dates
back a few years. It looks like the domestic technology developed in the
US, but died in England.


One reason for the technology living on in the US is that here
we tend to need air conditioning in the summer as well, and a combined
hot-air furnace and air conditioner is a quite reasonable way to go
about it.

Enjoy,
DoN.

That makes good sense, Don. No one has air conditioning here. Also, if
it's a combined AC/heating system, the inefficiency of the motor won't
be an issue for half the year. Do you know the exact arrangement of
windings employed in these motors? I'm curious to know.

Best wishes,

Chris