It used to be we had open fires. But then hot water radiators came in -
much cleaner, and easier to manage.
Nowadays we seem to be moving towards underfloor heating - where
effectively the entire floor is a radiator. Efficient, but slow to respond.
But there was a time when hot air systems were popular, and I think
still are in the USA.
Does anyone know why they went out of fashion? It can't just be because
they made a great place for spiders to hide!
Wummin prefer radiators. Or brainwashed into thinking they 'need'
radiators by various house-flipping tv programs.
Warm air systems had one major defect, you still needed to use
electricity to heat the hot tank, even if you had a gas-powered
Also, I'm not sure how you would meet modern fire regs if you had
ducting in the void between ground floor and upper floor with its
potential to assist the spread of fire and smoke.
I think they tended to use a lot of space with ducting and the only ones I remember were electric powered which involved having a large heater unit somewhere taking up most of a cupboard. Electric heating probably made sense when we were being told nuclear energy would be too cheap to meter but that soon changed. I would imagine there was quite a lot of heat loss in the ducting and insulating the lot was probably time consuming and expensive compared to lagging a couple of pipes. I do not think they were an easy install for retro fitting compared to installation in a new build. At the same time gas was getting comparably cheaper with North Sea gas coming on tap and at the same time gas boilers getting more compact
It's partly to do with comfort, warm air circulating can feel like a
draught. We used to set ours at 25c but also needed a radiant heater in
addition to feel comfortable.
Stub duct systems can be economical to instal but if long duct runs are
needed that can get expensive to install.
I guess its mostly that in the UK most peoples idea of central heating
is a boiler and rads.(up to now at any rate)
Underfloor is mainly for new builds or major refurbs where it can be
In the end it is just changing trends.
On Mon, 26 Oct 2020 10:51:53 +0000, Vir Campestris
The brand-new bungalow I had in the early 1970's had oil-fired hot air
CH. Basically a large oil-drum type cylinder with some baffles and
perforations in the lower part, with a chunk of fiberglass insulation
to act as a wick, and with a flue emerging from the top. A side arm
did have a water jacket in the pretence of heating the DHW. It was
situated in a broom-cupboard-sized room in the centre of the bungalow
with vents in and out of the three adjacent rooms - kitchen, sitting
room and hall. Very primitive, antediluvian even, with the only
control being a knob to regulate the flow of oil and hence the degree
I improved it by fitting a solenoid with a bypass needle valve to the
regulator to allow low and high oil flows, a thermostat in the sitting
room, a timer, and fans in the upper exit ducts to circulate the air.
It then all worked very well for twenty years until we sold the
property. I assume the new owners ripped it all out and put in
something a bit more modern and less Heath-Robinson!
In message <rn6a0h$1mu9$ email@example.com>, Andrew
Mother in law had it in a mid 60's flat. Central storage bank, asbestos
insulation! off peak electric. Immersion for hot water.
Not noticeably noisy and the ducting tucked away in the ceiling void.
Downsides, cost cf gas, inlet and exhaust well away from windows leading
to cold exterior walls/condensation and black mould:-(
Leasehold property so insulating cavity not really doable.
Gas boiler plus double glazing a big improvement but subsequent tenants
failed to ventilate to save gas plus airing washing indoors continued
the mould problem.
I used the ducting to feed room air to a heat recovery/vent system which
helped but the flat was sold on so I don't know the current situation.
Tricky Dicky submitted this idea :
There were gas heated versions of hot air systems. Those I came across
had been Those I came across had been condemned, because the burned
compartments eventually leaked into the air sections.
We had that only gas powered (but with an electric fan[sol if either
fuel supply failed])and we were in a flat not a bungalow, so we didn't
have that at all (just something similar) ;O).
Three short ducts to Living room, hall, kitchen. No heating upstairs.
Called the heating unit "the Dalek"
Cat LOVED the vent she/he (various cats, all seemed the same), not so
daft on it when it was actually blowing but the area around it must have
Not sure they were ever that popular - although there was a time some
places were built with central columns to allow installation of the
heater and easy ducting.
I would guess that the fact much of our building stock is quite old and
predates CH of any sort, a wet system is a much easier retro fit. Is
also generally more space efficient, and runs quieter with no fans etc.
Still popular in the US though - probably partly helped by many places
seeming to have basement space to install them, and larger properties in
general, so loss of space to ducting is probably of an issue.
There is still at least one major provider of the kit for UK installs
Yep. The house I bought in 1984 had a Johnson-Starley unit in the
kitchen. This had a gas-fired water heater which worked by convection
(no pumps). The hot water rose to the hot tank in the bathroom airing
cupboard directly above the heater. The gas also heated a heat exchanger
to warm the air which was driven by a centrifugal fan round the ducting.
I absolutely loved the system. It had *one* moving part - the fan.
Nothing went wrong or needed replacing in the 14 years I was there. The
"maintenance" consisted of vacuuming the fan and wire filter once a year.
What I liked was that within a couple of minutes of getting in to a cold
house the room air was already getting warm, and I don't remember it
being at all draughty. I don't see why installing ducting should be
expensive, and it doesn't take up much space - a 25 x 10 cm gap low-down
on a wall is all that is needed.
In contrast, heating through radiators is a system seemingly designed to
make money for installers and maintainers. It has a long thermal lag,
which may or may not be a good thing, and it "circulates" heat only by
convection. Its radiators take up a large amount of space on a wall,
which cannot be used by anything else.
I would happily rip out the radiators we have here and replace it by a
warm-air heating system (using, of course, the same ducting for cold-air
cooling in summer). It helps that we are in a bungalow which makes using
the loft for ducting pretty simple). Sadly, The Management doesn't have
the same view on warm-air heating as I do!
No idea, but it would it be any different from heating/cooling through
ducting in commercial buildings?
Two weeks before Chernobyl and not related, we had a serious house fire.
The house was gutted by a fire storm caused by our recently serviced Creda
ducted warm air heater and circulated through under floor ducts. The
property was a 4 bedroom dormer-bungalow. The ducts made it so easy to
propagate the fire to every room within minutes. The family was very lucky
to escape any injury and special thanks go to our Dobermann who alerted
everyone to the pending disaster.
On 26 Oct 2020, Vir Campestris wrote
I grew up in Canada in the 1950s and 1960s with oil-fired, forced hot
air heating, with a furnace and large oil tank in the basement, and a
fan forcing the hot air through ductwork running to each room.
It worked fine, but I can think of a couple of disadvantages for a
lot of the UK housing stock: it would be a bugger to retrofit in
solid-wall house (rather than building it in too a stick-built/balloon-
framed house), and the furnace, tank, and ductwork took up a lot of
room. That's not much of a problem if you have a full-size basement,
but otherwise it needs a lot more space than a boiler in a cupboard
feeding CH pipes and radiators.
 Our cat certainly liked it: she'd lie on top of the hot-air
Very difficult to retro-fit, so only really used in new builds. With
those, if you are going to go to all the trouble of fitting the ducting,
air conditioning makes more sense. It is much more energy efficient and
can cool in the summer as well as heat in the winter.