Airgen – the Air Source Heat Pump from
Keston
The Keston Airgen is a sophisticated Air Source
Heat Pump (ASHP), designed and built specifically
for the UK climate.
Some ASHP’s on the market are
adaptations of air conditioning units built for the
Far East, where humidity is high and temperatures
are tropical. The British Isles is also humid, however
the more temperate climate means that flow temperatures
need to be high to satisfy radiator circuits and hot
water requirements. The Airgen has been designed with
these conditions in mind, bringing domestic hot water
up to 65C, with no need for the support of
an immersion heater or direct resistance heater.
At the same time Keston’s air
source heat pump provides space heating for radiators
and under floor heating systems at variable temperatures
from 35C to 55C.
During its operation the unit is so
effective at extracting heat that it becomes very
cold and may occasionally need to run a defrost cycle,
up to once an hour. This feature ensures efficient
and reliable operation in the UK’s unique maritime
climate. A low speed axial fan means super quiet operation.
The units are independently tested
to the highest standards of EN14511.
Domestic applications
The Airgen comes in three models, giving
a complete spectrum of choice for the domestic market:
- 4.5 kW system - for small
flats
- 9kW
- 12kW - for larger properties
Light commercial
The 9kW and 12kW versions can be banked together,
with bespoke designs, utilising Keston’s multi-boiler
rig expertise, available for light commercial applications.
Rigs can be built to interact with a number of Airgen
units, up to an output of 40kW, to deliver a highly
efficient system.
Installation and maintenance
Installed externally to the building, with no flue
or chimney requirement, each unit has simple plumbing
and electrical connections with only a single-phase
electricity supply required. Keston’s air source
heat pumps low starting current ensures that all models
are well within domestic limits and avoid the need
for costly three-phase electrical supply.
Airgen is virtually maintenance free, only the 12kW
model requires a yearly refrigerant check to meet
current regulations.
Keston Airgen bivalent heating packs
Despite the fact that the Airgen operates from as
low as -15C, with functionality including
a heated drip tray and four minute frost cycle enhancing
its capabilities, as with all air source heat pumps,
efficiency is compromised when the temperature drops.
At temperatures below freezing a high-efficiency condensing
boiler is a cheaper option.
All Airgen models are available as part of a bivalent
heating pack. The Airgen then provides heating for
85% of the time, with the boiler making up the balance
on colder days.
Also in the pack is a 210litre qSpa un-vented cylinder,
which stores the piping hot water without the need
for tanks in the loft space. The qSpa is mains fed
so the hot water pressure is balanced with the cold,
providing the perfect combination for mixer taps and
showers. The hot water delivery is such that power
showers and pumps are surplus to requirements.
An optional extra is a buffer tank which smoothes
out the operation of the Airgen unit by preventing
short cycling, further ensuring that radiators do
not cool when the system is going through its four
minute defrost cycle. The size of the buffer tank
varies to suit the size of air source heat pump unit
supplied. |
