gledhill Torrent GreenHeat OV TGH140 Design, Installation & Servicing Instructions page 19

INSTALLATION
Typical schematic wiring diagram and system con guration for the Torrent GreenHeat HP-solar.
WIRING DIAGRAM
Page 36
Boost Immersion Heater
All Torrent GreenHeat HP models are tted with a 3kW immersion heater so that the
store can be heated to a temperature above the heat pump delivery temperature to
increase the hot water performance of the unit if necessary. Because the TorrentHP is
a primary thermal store it is not necessary to heat the store above 60°C for hygienic
protection against growth of 'legionella' . This is because the domestic hot water is
heated instantaneously via a heat exchanger and so there are no legionella problems
associated with stored water.
This is of great signi cance for the heat pump application where the heat pump will
not normally be able to raise stored water to above 60°C which is necessary to sterilise
a cylinder.
By using the immersion element to boost the water temperature (not needed for
legionella protection as described above), this will provide a greater volume of hot
water from a given size of cylinder (see gures 3-5, page 5). However, the overall
COP of the system will reduce and so to maximise the bene t of tting a heat pump,
minimal use should be made of the immersion heater.
The immersion heater should not be left permanently switched on as this will drastically
reduce the contribution of heat pump to hot water heating and hence increase the
running costs.
If the use of the immersion heater is necessary to meet the hot water requirements of a
dwelling, then the preferred method of controlling it is described below.
5 COMMISSIONING
5.1 Open the incoming stop valve and fill the domestic hot water system. Fill the whole of the primary
heating system and the thermal store with potable water through the feed and expansion cistern.
5.2 Check the water level in the feed and expansion cistern and adjust the ball valve if necessary.
Check the whole of the primary heating an domestic hot and cold distribution system, including the
HP
heat pump and the Torrent for leaks.
5.3 It is essential that all systems function properly for optimum performance and to achieve this:
(a) The primary system should be commissioned in accordance with good practice and generally
in accordance with the requirements of BS 6798, BS 5449 and BS 7593. Full details of the
requirements are given in PAS 33:1999 under section 10 Commissioning.
Typical schematic wiring diagram for the boost immersion heater
(b) The heat pump manufacturers instructions should be followed during the commissioning
using programmable immersion heater timer.
phase.
(c) If solar thermal system is fitted it should be commissioned as per manufacturers instructions.
(d) When using either cleansing or corrosion inhibitor chemical, the manufactures instructions
must be followed.
5.4 When determining the quantities for cleanser required, the volume of the Torren
to the water content of the primary system. Although the Torrent
requirements, the radiators and other parts of the circuit will require the application of a scale and
corrosion inhibitor. The heat pump and the external connecting pipework will also require protection
against freezing. For this reason, a combined antifreeze and inhibitor product such as Fernox Alphi
11 must be used.
5.5 If it is proposed to 'powerflush' the heating system we would recommend that the TorrentHP is
isolated from the heating system being cleaned. Failure to do so could seriously damage the unit. If
in doubt please contact our 'Technical Helpline'.
6 SERVICING
INSTALLATION
Control By Programmer
The operation of the boost immersion heater
can be controlled by means of an independent
time switch as shown schematically. The on time
settings on the immersion heater should be
between 30 – 60 minutes later than the on times
set for the hot water programmer channel.
For example if the hot water is programmed to
come on between say 0600 – 0900 and 1700 –
2200 then the immersion heater timer setting
should be 0640 – 0900 and 1740 – 2200. This will
make maximum use of the heat pump allowing
it to charge the store to the maximum potential
temperature before any use of the immersion
element.
Additional top and bottom thermostat pockets
can be provided in case a more sophisticated
control system is required to be tted.
Control By Heat Pump Control System
Where more sophisticated control systems
are used to control the immersion heater, the
immersion heater may be programmed to only
achieve 60°C. Please consult the heat pump
manufacturer's instructions/help desk for
further information on their control systems to
ensure that the required operation is achieved.
tHP
should be added
HP
has no special water treatment
WIRING DIAGRAM
Page 37