Section 15: Operation
Page 63
15.4.1 Heat pump only
When the ambient air temperature is warmer, the heat loss from the
property will be significantly lower than that at the design conditions,
i.e. when the ambient air is at its coldest for the area concerned.
Thus the heat demand will be significantly less than the maximum
and will be within the capacity of the heat pump.
Also, with this lower heat demand the heating system emitters (e.g.
radiators) will be able to deliver the required heat output at the lower
flow temperature from the heat pump, e.g. 45°C.
This will be the situation when the ambient air temperature is above
the first stage (Relay R1) temperature setting of the Air Control
thermostat. Refer to Section 16.6.2.
Thus, at temperatures above this value only the heat pump will be
operating to meet the heat demand of the system.
The default value of this first stage (Relay R1) setting for the Air
Control thermostat
=A1 (parameter SP) default 9°C + A2 (parameter C1) default 3°C =
12°C
The actual values for A1 (parameter SP) and A2 (parameter C1)
must be determined using the Grant Hybrid calculator.
15.4.2 Heat pump with boiler back up
When the ambient air temperature is a little colder, the heat loss
(and thus the heat demand) will increase, although it will still be less
than the maximum heat demand at the design conditions.
Under these conditions the increased heat demand can either
no longer be met by the heat pump alone, or the heating system
emitters (e.g. radiators) will be unable to deliver the required heat
output at the lower flow temperature from the heat pump, or both.
This will be the situation when the ambient air temperature falls
below the first stage (Relay R1) temperature setting, but is still above
the second stage (Relay R2) temperature setting, of the Air Control
thermostat. Refer to Section 16.6.2.
The default value of the second stage (Relay R2) setting for the Air
Control thermostat
= A3 (parameter SP2) default 1°C + A4 (parameter C51) default 3°C
= 4°C
Actual values for A3 (parameter SP2) and A4 (parameter C51) must
be determined using the Grant Hybrid calculator.
In this situation, the heat pump will still be operating but is backed
up by the boiler, operating at a restricted output, to provide a greater
combined heat output and a higher flow temperature (e.g. 55°C) to
allow the heat emitters to deliver the required heat output.
This flow temperature is controlled by the first stage (Relay R1)
setting of the Boiler Control thermostat. Refer to Section 16.6.1.
The default value of this first stage (Relay R1) setting for the Boiler
Control thermostat
=B1 (parameter SP) default 52°C + B2 (parameter C1) default 3°C
= 55°C
Actual values for B1 (parameter SP) and B2 (parameter C1) must be
determined using the Grant Hybrid calculator.
In all conditions, the Boiler Control Thermostat will almost
always show an R1 and R2 demand as the water stored in
the boiler will be below the desired flow temperature of the
heat pump. The burner will only fire when there is a demand
from either the Air Control Thermostat or the heat pump is
switched.
NOTE
!
15.4.3 Boiler with heat pump
When the ambient air temperature is at or near the design
conditions, the heat loss (and heat demand) will be at or near
maximum.
Under these conditions the heat demand can only be met by the
boiler, with some contribution from the heat pump.
Also, the heating system emitters (e.g. radiators) must operate at a
higher flow temperature in order to deliver the required heat output.
This will be the situation when the ambient air temperature falls
below the second stage (Relay R2) temperature setting of the Air
Control thermostat.
In this situation, the boiler will be operating at maximum output
(either 21kW or 26kW or as set on commissioning) to meet the heat
demand with a higher flow temperature (e.g. 70°C) to allow the heat
emitters to deliver the required heat output.
This flow temperature is controlled by the second stage (Relay R2)
setting of the Boiler Control thermostat. Refer to Section 16.6.1.
The default value of this second stage (Relay R2) setting for the
Boiler Control thermostat
=B3 (parameter SP2) default 67°C + B4 (parameter C51) default
3°C = 70°C
Actual values for B3 (parameter SP2) and B4 (parameter C51) must
be determined using the Grant Hybrid calculator.
The heat pump is operational and can also operate with the boiler
when the return temperature is low enough, e.g. during initial start-
up when the system is cold. After that the boiler will be providing the
majority of the heat output to meet the system demand.
15.5 Boiler Only Operation
When the Oil/Hybrid switch is set to ‘Oil’, only the boiler will operate
to meet any heating (or hot water) demand.
The heat pump is effectively switched off and will not respond to
any heating (or hot water) demand.
If only the boiler is installed and it is to operate as a ‘stand-alone’
unit (until the heat pump is installed and connected), the Oil/Hybrid
switch MUST be set to ‘Oil’.
Содержание Aerona3 Series
Страница 57: ...Section 13 Flue System and Air Supply Page 57 Figure 13 8 Flue clearances...
Страница 77: ...Section 19 Spare Parts Page 77 Figure 19 4 15 21kW baffles Figure 19 5 21 26kW baffles...
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