Glowworm Lighting 40 manual Expansion Vessel, Flow Boiler MAX

2 Water System

2.10 Safety Valve

A safety valve must be fitted to a sealed 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.

2.11 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 2.4 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.

3 LITRES (0.66 gals)

MAKE-UP BOTTLE (if required)

	Open (vented) system.				4357A
	Recommended
	relationship between
450mm	pump, cold feed and
	vent.
MIN.
	22mm (MIN) VENT
HEIGHT
	FEED AND
	EXPANSION
	CISTERN
	15mm (MINIMUM)
	COLD FEED
	15mm (MINIMUM)
	BY-PASS WITH
	LOCKSHIELD VALVE
1150mm	RET.	CYLINDER		FLOW
MIN.
			RET.
	PUMP		HEATING
	150 mm		FLOW
BOILER
	MAX	Diagram 2.3
	AIR				5609
	RELEASE
	POINT

NON-RETURN VALVE

HEATING CIRCUIT

AUTO

AIR

VENT

FLOW

RETURN

DRAIN

COCK

FILLING POINT

15mm (min)

BY-PASS WITH

LOCKSHIELD

VALVE

CIRCULATING

SAFETYPUMP VALVE

PRESSURE

GAUGE

(Make-up alternatives)

BOILER	EXPANSION
	VESSEL

Diagram 2.4

9 221834B