The weather has suddenly turned hot so we have turned the central heating
All fine and dandy - however we spend the winter with these large panel
radiators heated by a boiler chucking out heat to keep the place warm.
Why don't we have a chiller alongside the boiler so that in the summer we
can pump ice cold water around the system and cool the whole place down?
Could it be the temperature differential?
Water at 50C to raise the temperature from 1C to 20C?
Water at 1C to lower the temperature from 30C to 20C?
We don't blow hot air round for heating (well, some do) so why do we blow
cold air round for cooling?
With anti-freeze in the system the temperature of the radiators could go
below 0C (just don't lick them).
Presumably there isn't a good design for a water based chiller which
compares with air con systems.
AS I said, dumb idea.
Radiator at 1oC in a room at 20oC...
o Problem #1 - condensed water running off the radiator onto the floor
o Problem #2 - rather limited ability to cool the room
If a room is too hot...
o Good - Blinds with curtains are good, particularly if blackout/foil
o Best - Stick an old dust sheet over the window outside
Obviously CWI & Loft I will help keep a house cooler.
Takes a 1-ton HVAC compressor a long time to cool a semi,
and at considerable cost with current/future electricity prices.
So treating the cause rather than the effect is a lot cheaper.
I was thinking about this last year, the year before that and last
night as a matter of fact.
One thing which might cause problems is the condensate. Chill the
radiators below the room temperature and condensation will form on
pipes and the radiators.
It has been done, there are heat pump boilers about that do just that.
Its a good way to top up ground heat sources too.
Its not done more because of cost and complexity, the average "engineer"
struggles with the combi systems.
Several reasons, that being one of them. You'd get some cooling from
the rads but the temperature differential means it would be
You'd need a huge radiator/heat exchanger radiator to get some useful
cooling. It has been done with UFH (big heat exchanger area) but you
need to ensure the water temperature remains above the room dew point
or you get condensation forming on, or within, the floor. I think the
dew point is about 11 degC at average indoor conditions of about
21degC & 50% Rh.
The heat exchanger area is also why you usually blow air around; the
area necessary is achieved in a small package volume by using a coil
of finned tubes, similar to a car radiator; or more like 4 car
radiators in a row. Heating coils are usually 1 row with water at
70/50 flow/return. Cooling coils are typically 3 or 4 row with chilled
water at 6/12.
If you were to just cool the room, without causing any condensation,
this has the effect of increasing the Rh, i.e., same moisture content
in gms water per kg of air, but lower temperature. In a UK summer,
this makes it horribly humid & clammy, more uncomfortable than being
just hot. Your personal evaporative cooling system, sweating, is less
effective. It's also why those nasty swamp evaporative coolers are
pants. It will work in a dry environment.
Condensation is another reason; You'd not only get puddles under
radiators, but you'd get moisture migrating into the building from
outside, adding greatly to the cooling load. Condensation tips out of
air handling units' drains in summer like there's a tap running
inside it. It an absolute bitch if the chilled water pipework and
fittings are inadequately insulated and the vapour barrier is
ineffective. I know of plantrooms that will be 2" deep in water in
The common strategy now is to supply the fresh air required for
ventilation from central air handling plant; that is, air cooled to
condense out the excess moisture and then reheated to the supply
temperature. The cooling loads are dealt with locally by circulating
chilled water, above the dew point temperature, to chilled beams. Any
high heat loads (typically computer rooms) are handled with a fan coil
unit (mini air handling unit).
This link will take you to a website which actually makes something
similar, these panels can be used for cooling too, just make sure you
read it properly.
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