Supplied By www.heating spares.co Tel. 0161 620 6677
8
221504A
2 Water System
3 LITRES (0.66 gals)
MAKE-UP BOTTLE
(if required)
NON-RETURN
VALVE
AUTO
AIR
VENT
FLOW
DRAIN
COCK
BOILER
SAFETY
VALVE
(Make-up
alternatives)
EXPANSION
VESSEL
PRESSURE
GAUGE
CIRCULATING
PUMP
FILLING POINT
AIR
RELEASE
POINT
HEATING
CIRCUIT
22mm (min)
BY-PASS WITH
LOCKSHIELD
VALVE
RETURN
5814
Diagram 2.3SEALED WATER SYSTEM DIAGRAMMATIC LAYOUT
2.7 Domestic Hot Water Cylinder
The hot water cylinder must be of the double feed fully indirect
type. Not the single feed self priming type.
2.8 Sealed Water Systems
The installation must comply with the appropriate requirements
of the current issue of BS5449, BS6759, BS6798, BS4814 and
BS7074 Part 1 and 2.
See diagram 2.3 for a suggested layout.
2.9 Safety Valve
A safety valve must be fitted to a sealed water system.
It shall be preset, nonadjustable with a lift pressure of 3bar,
incorporating seating of a resilient material, a test device and a
connection for drain.
The drain from the safety valve must be routed clear of any
electrical fittings and positioned so that any discharge can be
seen.
2.10 Expansion Vessel
A diaphragm type expansion vessel, conforming to the current
issue of BS4814 (see also BS7074 Part 1 and 2) must be
connected at a point close to the inlet side of the circulating
pump, see the diagrammatic layout, diagram 2.3, unless laid
down differently by the manufacturer.
The expansion vessel volume depends on the total water
system volume and the initial system design pressure. For any
system an accurate calculation of vessel size is given in the
current issue of BS7074 Part 1.
Example: For an initial system design pressure of 0.7bar, the
minimum total vessel volume required is 0.063xTotal System
volume.
Note: A higher initial design pressure requires a larger volume
expansion vessel.
Guidance on vessel sizing is also given in the current issue of
BS5449 and BS7074 Part 1.
The charge pressure must not be less than the static head of the
system, that is, the height of the highest point of the system
above the expansion vessel.
The water content of the boiler is given in the Data Table 1.
To Next Page
Loading...
