Installation & Maintenance Instructions for an unvented
hot water cylinder with internal thermal expansion
Hot Water
Energy
Storage
Unvented Cylinder
SEPT 2018
11
INDIRECT TWIN COIL CYLINDER
UPPER COIL
The upper coil is connected to the fossil fuel boiler as per the
instructions for the Indirect single coil model with the dual
stat control and high limit thermostat inserted into pocket
G1 (lower diagram page 12). The wiring requirements are as
depicted on page 12-14.
LOWER COIL: SOLAR INSTALLATION
The flow and return from the solar heat source are to be
connected to the indirect coil. Either primary coil connection
may be utilised as the flow or return. The solar primary circuit
must have its own dedicated circulating pump, thermal
and safety controls which must be installed as per the solar
manufacturers instructions. The solar control system used
must be of the solar differential control type and should be
connected to the solar sensor.
The solar sensor, supplied as part of the solar controls should
be inserted into Pocket G1 and is held in-situ with the black
sensor pocket retaining bung provided.
It is necessary to connect the solar pump via the over-
temperature high limit cut-out (provided) into dry stat
pocket G2 to ensure the heat input to the solar coil is
interrupted if the cylinder overheats. Solar hydraulic staion
including pump and non return valves should be used. If solar
controls do not offer appropriate isolation a 2 port zone valve
(not supplied) can be used with the pump and high limit stat
as shown on page 12.
G2
D2
F
B
G1
D1
E
C
D2
A
D1
Boss centre from floor
Capacity
(Ltrs)
Height
(mm)
Diameter
(mm)
A
(mm)
B
(mm)
C
†
(mm)
D1
(mm)
D2
(mm)
E
(mm)
F
*
(mm)
G1
(mm)
G2
(mm)
175
1371
580
535
1025
914
349
859
993
NF
404
1025
201
1561
580
535
1091
964
379
909
1059
1026
434
1091
243
1806
580
535
1316
1034
379
979
1304
1271
434
1316
285
2076
580
535
1588
1064
414
1009
1556
1523
469
1588
* Not always fitted refer to table above
† Not to be used as the primary heat source