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1.
To obtain the best performance from your OSO unvented system it is advisable to feed the unit
with an uninterrupted supply.
2.
Locate the water heater in a suitable position to facilitate the installation of the cold water supply,
discharge fittings and pipework. Also take into account access to the immersion heaters and the
commissioning valve.
3.
Fit the combined male elbow drain cock to cold supply point (13), so that the compression fitting
is vertical.
4.
Fit the commissioning valve (12) to the commissioning fitting.
5.
Fit both 1/2'' male solar sensor pockets to the Solar Sensor bosses (19).
6.
Fit the female outlet of the tee piece to the temperature and pressure relief valve (5) with the
horizontal connection facing right at approx. 45°.
7.
Fit the tundish (6) to the tee piece using a short length of 15mm copper tube.
8.
Fit the length of copper tube 22mm specified in Table 2 to the cold feed elbow (see 3 above).
9.
Fit the pressure reducing valve (3) to the top of the copper tube (see 7 above), so that the black
knob is facing right.
10.
Connect the flexible hose to the 1/2’’ outlet of the expansion valve (4) and the horizontal outlet
of the tee piece (see 5 above). Discard compression nut & ring.
11.
If a balanced mains pressure cold water supply is required to
a shower or bidet (over rim type
only),
remove the blanking cap from the pressure reducing valve (3) and connect to the shower
or bidet cold supply.
Using the balanced cold connection to feed bath taps can reduce the flow
available to the unvented cylinder. (Major shower manufacturers advise fitting a mini expansion
vessel in the pipework to accommodate thermal expansion and prevent tightening of shower
controls)
12.
Before connecting the multibloc, flush the cold supply pipework of all flux and debris.
13.
Connect the multibloc to the pressure reduction valve (Multibloc) (3).
Hot water supply
14.
Connect the hot water supply pipe to the outlet (9). Ensure connection is water tight.
Secondary return
15.
A secondary return facility is provided on all units. Fit a 1/2’’F x 1/2’’M x 15mm Tee piece between
the commissioning valve (12) and the commissioning fitting. See also figure 4 on page 16.
Discharge pipe
16.
Connect the discharge pipe
from
the tundish (6). This must have a continuous fall and be fitted
in accordance with The Building Regulations (see page 6 and 16).
Boiler Primaries
Primary flow & return and motorised valve
17.
The boiler primary flow and return connections should be made to the upper coil connections
unit. The motorised valve must be fitted into the primary flow. The primary flow and return fittings
are 3/4’’ BSP female. The valve has 22mm x copper connections.
18.
For electrical connection of the motorised valve and immersion heater, please read Electrical
Installation Instructions. (Pages 7 - 11)
Solar Primaries
19.
The Solar flow and return connections should be made to the lower coil connections.
Temperature control from the Solar circuit is achieved using a differential solar controller. This
controller must be wired in series through the thermal cut-out on the OSO thermostat (see figure
4 pages 9 & 11).
If Solar Panels are to be installed at a later date then connect the boiler primaries to the lower
coil.
COLD WATER SUPPLY