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 lined 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 insignificant.
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 summer.
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).
Possibly because aircon is (afaik) an American invention? In most parts of the country they tend to heat with air rather than water, so natural to do the same with cooling?
They would be fine, if it was designed to work in the first place. I can't imagine someone just replacing a boiler with a heat pump unit without a redesign to use the cooling effect.
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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