Section 15: Operation
Page 62
15.1 General
The Grant VortexAir Hybrid consists of a Grant Aerona³ 16kW air
source heat pump and a Grant high efficiency condensing oil boiler
(fitted with a low NOx blue flame burner).
The principal objective of the hybrid is to use the heat pump as
much as possible to provide space heating, either with or without
any assistance from the oil boiler, throughout the major part of the
year. The oil boiler is intended only to support the heat pump when
it cannot provide sufficient heat output to meet the demand and/
or where the heat emitters (eg: radiators) cannot meet the heat
demand at the lower flow temperature under the coldest conditions.
In warmer periods, the heat loss from the building will be
substantially less than that under ‘design conditions’, i.e. the lowest
temperature at which the heat loss of the building was calculated.
Under these warmer conditions the heat pump will be able to
produce the heat output required to meet this reduced heat loss at
a flow temperature sufficient to achieve the necessary heat output
from the heat emitters (radiators).
As conditions get colder the heat loss from the building will increase,
requiring a greater output from the heat pump and a greater flow
temperature to ensure the necessary heat output from the heating
system radiators.
Under the coldest conditions, the heat pump will not be able to
meet the heat loss of the building and, even if it could, the lower
flow temperature will be insufficient to ensure that the radiators
can produce the required heat output. It is under these coldest
conditions that the oil boiler will be required as a back-up. If correctly
sized, the boiler output will meet the heat losses and maintain the
indoor design temperature when the outside (ambient) temperature
is at its lowest, i.e. at the outdoor design temperature used for the
heat loss calculation.
15.2 External heating system controls
The Grant VortexAir will operate in response to a 230V switched
live demand from the heating and hot water control system, e.g. an
S-plan type system. Refer to Section 12 for electrical control wiring
details.
This switched live will be connected to one of three terminals on
the Heating System Controls terminal block, located in the hybrid
control panel, as follows:
•
Terminal 7 – Hot water demand (low temperature when using
the Grant Digital two-stage Cylinder thermostat)
•
Terminal 8 – Hot water demand (high temperature when using
a standard cylinder thermostat or the Grant Digital two-stage
Cylinder thermostat)
•
Terminal 9 – Central heating demand
There must only be ONE switched live on terminals 7, 8 or
9 at any one time. Thus, hot water demands must be set (on
the programmer) to occur at a different time to the central
heating demand.
NOTE
!
15 Operation
15.3 Oil/Hybrid Switch
The Grant VortexAir Hybrid has two basic operating modes:
•
Hybrid – where both the heat pump and oil boiler can operate
together, depending on the prevailing ambient conditions. See
Section 15.4.
•
Oil – where only the oil boiler can operate. The heat pump (if
installed and connected) is effectively switched off when the
VortexAir Hybrid is in this operating mode. See Section 15.5.
The operating mode is selected by the setting of the Oil/Hybrid
switch to either ‘Oil’ or ‘Hybrid’ as required. This switch is located
on the hybrid control panel fascia (inside the boiler casing). See
Section 14.
15.4 Hybrid Operation
As each application of the VortexAir Hybrid will be different, in order
to achieve the most efficient operation of the Grant VortexAir Hybrid,
using the Heat Pump to the maximum, it is essential that the Boiler
Control and Air Control Thermostats (located on the hybrid control
panel) are correctly set during commissioning. Refer to Section 16.6
for details on how to set these two thermostats.
The temperature settings for these two thermostats must be
determined for the building in question using the Grant VortexAir
Hybrid calculator. This is available as a download from the Grant UK
website www.grantuk.com. Refer to Section 16.5 for further details.
In the hybrid operating mode (i.e. with the Oil/Hybrid switch set
to ‘Hybrid’) the Grant VortexAir hybrid can operate in one of three
ways:
•
Heat pump only – under warm/mild conditions
•
Heat pump with a small input from the oil boiler – under colder
conditions
•
Oil boiler with a small input from the heat pump – under the
coldest conditions
This operation is basically controlled by the ambient air temperature.
The first and second stage air temperatures, set on the Air Control
Thermostat, will govern when the hybrid switches between these
three forms of operation or where the heat pump automatically
request assistance from the oil boiler.
The first and second stage temperatures, set on the boiler control
thermostat, will govern the flow temperatures when the boiler is in
operation.
Содержание Aerona3 Series
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