Grant Products HPAW155 - Manual (Page 20)

16
Sealed Systems
The following components are required
to use the Grant Aerona heat pump as
part of a sealed heating system. Due to
the lack of space these components
are not located within the heat pump,
but have to be fitted external to the
unit.
a) expansion vessel (of the correct size
to suit the volume of the system)
b) Pressure relief valve – 3 bar
c) Pressure gauge
d) Filling loop
e) Tundish
These items may already be installed on
the existing system. If so, they should
be checked to ensure the integrity and
suitability of the components before
proceeding to re-use them.
Refer to Section 14 for details of the
Grant sealed system kits designed for
use with the Grant Aerona heat pump
range.
The expansion vessel can be fitted to
either the flow or return pipes but
ensure that there is no automatic or
manual valve in line that may prevent
the heat pump utilising the expansion
vessel.
The filling loop can be sited anywhere in
the system, but it must always be sited
within visual distance of the pressure
gauge. The nominal filling pressure for
the system when cold is 1 bar.
Before filling the system check the
expansion vessel charge pressure. This
should be 0.2 – 0.3 bar higher than the
cold fill pressure for the system.
It is good practice to have automatic air
vents at all high points of the system,
particularly where pipes fall vertically –
e.g. drop feed systems. The immersion
unit within the heat pump has a factory
fitted manual air vent.
7 Sealed Systems
Cylinder
Stat
Room
Stat
Internal wiring
centre
Heating Load
Programmer
Expansion
vessel
Pressure
Gauge
Filling
Loop
Raising
Main
Figure 7-1: Sealed system layout
Outside
wall
Auto
Bypass
Flow
Flexible
pipe
Isolating
valve
Isolating
valve
Return
Grant Aerona
Heat Pump
Primary
Pump
Condenser
Heat Pump
ATC
CH Flow
DHW Flow
CH Retur
n
DHW Retur
n