Community Heating Fl Ow And Return Connections; Cold Water Supply Connection; Domestic Hot Water Fl Ow Connection - Heatrae Sadia HI-MAX INSTANT ID 5-60 Installation, Operation And Maintenance Manual

6.6 Community heating fl ow and return
connections
The community heating (district heating) fl ow and
return connections are located at the top of the HIU,
unless stand-off bracket B is used, in which case they
will be found at the bottom of the unit. Please see
Figure 23 on page 26 for more details.
Figure 25: Community heating fl ushing bypass
FBP
HM1
HM2
HM
S2
P
P1
S1
Flushing Bypass during
maintenance and
commissioning
FBP
HM1
HM2
HM
S2
P
P1
S1
Flushing Bypass during
forward fl ushing
Legend
Valve open
Valve closed
Water fl ow
28
FBP
HM1
HM2
HM
S3
S2
P
P1
S1
Flushing Bypass during
normal HIU operation
FBP
HM1
HM2
HM
S3 S2
P
P1
S1
Flushing Bypass during
back fl ushing
6.6.1 Community heating fl ushing bypass
It is recommended that a fl ushing bypass arrangement is
installed in the community heating fl ow and return pipes
to the unit. The fl ushing bypass (FBP) is a pipe between
the district fl ow and return pipes fi tted with an isolation
valve to allow the distribution network to be fl ushed free of
debris during the installation and commissioning process
(as detailed in Figure 25).

Note there is a drain valve fi tted in the HIU
which can be used for forward and back fl ushing
purposes during maintenance. Do not forward or back
fl ush debris through the unit during the commissioning
phase of the installation.

6.7 Cold water supply connection

Refer to the installation schematic (Figures 17 and 18,
pages 15 and 16) for details of the pipework layout.

A servicing valve is incorporated into the cold water
S3
supply pipe on the fi rst fi x rail to enable the HIU to be
isolated and serviced. Access to this valve is gained
from the underside of the unit.

A stop cock should be fi tted in the cold feed pipework
as close as is practicable to where the cold mains
enters the apartment.

Generally the cold mains to the unit and the hot water
distribution pipework should be minimum 22mm pipe
with short runs of 15mm pipe to terminal fi ttings such
as sinks and basins. However, pipe sizes may vary due
to system design.

Consideration should be given to system pressure,
thermal expansion and potential water hammer
during normal operation.

Where the water pressure coming into the apartment
is high, it is recommended that a PRV is fi tted to
regulate this down to 3 bar g.

If a non return valve is fi tted in the cold supply line
to the unit, it is recommended that a 1 litre potable
water expansion vessel is installed to accommodate
expansion.

When fi tting an expansion vessel, it is good practice
S3
to protect the other system components from
excessive pressures against either the expansion
vessel diaphragm failing or the gas charge naturally
depleting by fi tting an expansion relief valve.
Expansion vessels should be regularly inspected and
serviced, this should be written into the installation's
service regime.
6.8 Domestic hot water fl ow connection

The domestic hot water fl ow pipe is fi tted with a
safety tempering valve (Stv) which acts as an excess
temperature safety device. This is factory set to 60
and must not be adjusted.

Note there is a drain valve fi tted in the cold
feed pipe in HIU, this can be used for fl ushing the cold
water supply pipework prior to fi lling the hot water
system.
O C