HAMWORTHY HEATING LTD
47
Wessex ModuMax
mk3
Boilers
500001308/C
E1.2 Minimum System Water Pressure
To comply with guidance note
INDG436 (Health and Safety Executive)
, the minimum pressure requirements at the
boiler are given below :
-
Individual boiler
@ 82°C
.........................................................................................................
0.5 bar
Multiple boilers
With flow isolation (pump or valve) @ 82°C
............................................................................
0.5 bar
Without flow isolation @ 11°C rise across the system @ 82°C
............................................
0.5 bar
Without flow isolation @ 20°C rise across the system @ 82°C
............................................
1.0 bar
Without flow isolation @ 30°C rise across the system @ 82°C
............................................
1.7 bar
Without flow isolation @ 40°C rise across the system @ 82°C
............................................
2.6 bar
Please note that the maximum flow temperature available from the controls is 85°C
E1.3 Pressure Relief Valve (Safety Valve)
The most important single safety device fitted to a boiler is its safety valve. Each boiler module is provided with a
capped R¾” stub pipe for the fitting of a safety valve (not supplied). BS 6644 provides comprehensive information
for the selection and location of safety valves and attention is drawn to the higher capacity requirements of safety
valves for pressurised hot water systems.
Figure E1.1.1
-
Typical Piping Layouts
UNVENTED SYSTEM: Primary loop, Hamworthy recommended system.
VENTED SYSTEM: Primary loop, Hamworthy recommended system.
Circulation pump
valve
Drain
Expansion pipe
Feed
pipe
Mains water
Hamworthy Modular Boilers
Module
Safety
T
Feed &
expansion
tank
valve
Module
1
2
valve
Float
Drain
Valve
Module
3
P
gauges
Pressure &
Temperature
T
Circulation pump
Valve
(System)
Heating load
Automatic
Air Vent
Valve
Air Vent
Automatic
Valve
valve
Drain
Valve
Module
Hamworthy Modular Boilers
Safety
T
valve
Module
1
2
Drain
3
Module
P
gauges
Pressure &
Temperature
T
Automatic
Air Vent
Heating load
Lockshield
valve
fill line
Temporary Double
check
valve
vessel
Expansion
valve
Lockshield
Mains water
valve
Drain
valve
Lockshield
(Primary loop)
(System)
Circulation pump
(Primary loop)
Circulation pump
