Mira COMBIFLOW User Manual page 11

2. Unvented mains pressure showers
The shower can be installed with an unvented, stored hot water cylinder. Only a
"competent person" as defined by the Building Regulations may fit this type of
system.
For packages with no cold water take off after the appliance reducing valve, it
will be necessary to fit an additional drop tight pressure reducing valve when the
mains pressure is over 5 bar. The drop tight pressure reducing valve must be set
at the same value as the unvented package pressure reducing valve.
Note! An expansion vessel MUST be fitted (and regularly maintained) if any
form of backflow prevention device is fitted, e.g. non-return valve, PRV. This will
ensure that excess expansion or pulse pressures do not damage the product or
the plumbing system.
Safety devices not shown for
clarity
Expansion Vessel
High Inlet Pressure
Combined outlet PRV
with internal non-return valves
- Expansion vessel required.
For latest prices and delivery to your door visit MyTub Ltd 0845 303 8383 www.mytub.co.uk
COLD
Reduced pressure to cold inlet of shower
Reduced pressure
to unvented cylinder
HOT
Reduced pressure to cold inlet of shower
High Inlet Pressure
Cold takeoff after PRV
- Expansion pressure taken up by
unvented cylinder expansion vessel.
11
Reduced pressure
to unvented cylinder