The weather has suddenly turned hot so we have turned the central heating
off.

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.

But why?

Cheers

Dave R

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.
--
Dorothy Bradbury

David WE Roberts submitted this idea :

Presumably there isn't a good design for a water based chiller which
compares with air con systems.

AS I said, dumb idea.

But why?

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.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

"David WE Roberts" wrote in message
news
The weather has suddenly turned hot so we have turned the central heating
off.

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.

But why?

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.

In message , David WE Roberts
writes
The weather has suddenly turned hot so we have turned the central heating
off.

Presumably there isn't a good design for a water based chiller which
compares with air con systems.

AS I said, dumb idea.

But why?

'kin expensive and inefficient

--
geoff

On 9 May, 20:17, David WE Roberts wrote:

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?

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).

In article ,
David WE Roberts wrote:
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?

The temperature differential wouldn't be great enough.
When heating, the rads run at something like 3 to 4 times the room temp.

--
*A plateau is a high form of flattery*

Dave Plowman London SW
To e-mail, change noise into sound.

David WE Roberts wrote:

We don't blow hot air round for heating (well, some do) so why do we blow
cold air round for cooling?

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?

Pete

"Onetap" wrote in message
...
On 9 May, 20:17, David WE Roberts wrote:

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?

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).

A very sensible and accurate analysis if I may say so, there is your answer
David.

Regards
Don

In article ,
dennis@home wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
David WE Roberts wrote:
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?

The temperature differential wouldn't be great enough. When heating,
the rads run at something like 3 to 4 times the room temp.

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.

It could be made to 'work' if you used a fluid that allowed rather less
than 0C - but there are lots of other problems as have been stated.

--
*Does fuzzy logic tickle? *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
David WE Roberts wrote:
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?

The temperature differential wouldn't be great enough.
When heating, the rads run at something like 3 to 4 times the room temp.

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.

On May 9, 8:17 pm, David WE Roberts wrote:

.... Nothing like what I thought he was going to write

The thread appeared immediately below the "Grand Designs Live" thread,
and I thought it was going to be another one along the same lines :-)

On 9 May, 20:17, David WE Roberts wrote:
The weather has suddenly turned hot so we have turned the central heating
off.

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.

But why?

Cheers

Dave R

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.
http://www.spcoils.co.uk/Products/Ra...anelsMain.html