RE: Air Con vs. Heat Exchangers

["Kenneth Watt" <kennethwatt@xxxxxxx>]

Mark,

There are systems that allow this sort of use of air-con/heating through
"blown-air" systems and they are readily available from a number
of places.
Most are designed for commercial appliacations though and, as such, cost
packets! This is due to the technicalities of the electronics and cooling
power, put it this way, a compressor for a domestic fridge freezer US size
is ?200-250 that cools, approx, 8cu ft to -18C and 15cu ft to 3C now
imagine
on the same scale the cost to cool a home! It doesn't quite work out that
way but you'll see what I'm driving at, it all comes down to scale and
efficiency of the actual components. BTW, that US fridge/freezer retails at
1.5K!

K.

-----Original Message-----
From: Mark Harrison [mailto:Mark.Harrison@xxxxxxx]
Sent: 18 May 2001 15:17
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] Air Con vs. Heat Exchangers


OK - here's the complex one!

This allows three separate modes:

1: Basic heat exchanging only, to warm incoming air, for ventilation in a
fuel-efficient manner.

2: Heat exchanger bypassed, heat pump cools the incoming air, for summer
cooling.

3: Heat exchanger warming incoming air, then heat pump heating it, for
winter heating.

For clarity, I've included the "airflow" paths with other paths
greyed out
for all three modes. As Ian says, it may be possible to consolidate the
"exchanged" and "bypass" paths for the _outgoing_
airflow in a domestic
system.

In principle, there's a fourth mode, which is bypassing the heat exchanger,
but not turning on the heat pump. It would basically be ventilation only,
with no heating/cooling. Not sure whether you'd ever end up using it except
in situations where the heat pump was thermostatically controlled and you
didn't want it to get any colder indoors!

Mark Harrison
Head of Systems, eKingfisher

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-----Original Message-----
From: Mark Harrison [mailto:Mark.Harrison@xxxxxxx]
Sent: 18 May 2001 11:42
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] Air Con vs. Heat Exchangers


OK, here's the next phase.

This has a "heat pump" in series with the "bypass" air
routes. This is on
the basis that you switch the unit into "exchanger bypass" mode
when you
want to cool down the incoming air rather than let it be pre-warmed, and
you
don't bother cooling pre-warmed air.

Furthermore, this assumes that you only bypass the exchanger when you want
to cool the air! A bit naive, perhaps, but wait until the next stage...

In principle, you can acheive this with a domestic air-con unit with a
separate fan unit (that would normally hang outside the window) as follows:

- The Incoming air vent "outside" gets connected to the
"suck in air from
the room" input on the A/C
- The Incoming air vent "room side" gets connected to the
"blow cold air"
output on the A/C
- The Outgoing air vent "room side" gets connected to the
"input on the
separate fan unit" on the A/C
- The Outgoing air vent "outside" gets connected to the
"output on the
separate fan unit" on the A/C

In the case of a "single unit with warm air trunk"-type A/C, then
realistically you just "t-piece" the trunk in with the Outgoing
air vent as
near as possible to the pump, and rely on the pump to suck through all the
air. What you may find, therefore, is that you need a twin-speed pump on
the
going in this case, which runs faster when the air-con's on!

The final piece (coming soon), is the bit that I always have to think hard
about. It combines the use of this system, with the ability to "run
the
air-con backwards" and use the "hot air out" on the aircon
to _heat_ the
rooms...

Mark Harrison
Head of Systems, eKingfisher

****************************************************************************
Kingfisher plc
Registered Office: North West House, 119 Marylebone Road, London NW1 5PX
Registered in England, Number 1664812

This e-mail is only intended for the person(s) to whom it is addressed and
may contain confidential information.  Unless stated to the contrary, any
opinions or comments are personal to the writer and do not represent the
official view of the company.  If you have received this e-mail in error,
please notify us immediately by reply e-mail and then delete this message
from your system.  Please do not copy it or use it for any purposes, or
disclose its contents to any other person.  Thank you for your
co-operation.
****************************************************************************



-----Original Message-----
From: Mark Harrison [mailto:Mark.Harrison@xxxxxxx]
Sent: 18 May 2001 11:09
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] Air Con vs. Heat Exchangers


> But the Baxi system sadly doesn't allow this, which is why I haven't
> done anything to date.

Seems mad that it doesn't! I've got various brochures at home from other
companies who provide similar stuff... let me know if you want me to dig
out
some other names...

Alternatively, for the price of a four valves and a couple of meters of
ducting, you could probably rig up something yourself (see attached.) I
would guess that the four valves could be wired in parallel, and run of a
single (X-10?) relay...

Mark Harrison




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