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SITING THE UNIT
This unit can supply outlets above it or at some distance from it but any outlets above the unit will reduce the available outlet
pressure by 0.1 bar for every 1m of height difference. The maximum length of the "dead leg" should be as stated in the Water
Supply (Water Fittings) Regulations 1999 G18.7, in particular to the area of most frequent use.
Particular attention is needed if sitting in a garage or outbuilding as the unit should be protected from frost. All exposed
pipework must be insulated. The unit must be installed UPRIGHT on a flat base capable of supporting its weight when full
(please see the technical specification section for weights). The minimum recommended cupboard size is 650mm square.
Sufficient access to allow maintenance of the valves should be considered. In addition the immersion heaters are 400mm in
length and this distance should be considered to allow withdrawal for servicing if required. The discharge pipework from the
safety valves should fall continuously and terminate safely.
SCHEMATIC DIAGRAM
SECONDARY
FLOW
SECONDARY RETURN CIRCUIT
(200, 250 & 300 LITER SIZES)
1
2
3
PRIMARY
FLOW
DUAL
STAT
PRIMARY
RETURN
9
WATER SUPPLY
The performance of any unvented system is only as good as the mains water supply available. To this effect the maximum
possible water demand should be assessed, with the knowledge that the mains supplies both hot and cold services
simultaneously.
The water heater itself operates at a pressure of 3 bar, controlled by the inlet control set, and is capable of delivering over 50
litres per minute. The high quality inlet control set has been designed to make the most of the flow rates available.
The water supply should be checked to ensure it can meet these requirements. If necessary, consult the local water authority
regarding the likely pressure and flow rate availability.
Consideration should be given to upgrading existing ½" (15mm) cold mains pipework to a larger size if the recommended
minimum pressure/flow rate is not being achieved.
Note: A high static (no flow) mains pressure is no guarantee of good flow availability. In a domestic installation 1.5 bar and 25
l/min. should be regarded as the minimum. The maximum mains pressure that the inlet control set can cope with is 10 bar.
4
5
COLD FEED
unvented hot water cylinders
installation and maintenance instructions
6
FLEXIBLE HOSE
COLD
MAIN
2
7
8
BALANCED COLD
CONNECTION
Legend:
1. Bronze Pump
2. Non Return Valve
3. Two Port Valve
4. Temperature & Pressure Relief Valve
5. Expansion Relief Valve
6. Expansion Vessel with wall bracket
7. Pressure Reducing Valve
8. Isolating Valve
9. Drain Valve (not supplied)
Note:
The pressure reducing valve, non‐return
valve and expansion relief valve are
combined together in the inlet control et.
On 125‐170L sizes there is no dedicated
secondary return boss and the secondary
return circuit should be tee'd into the
cool feed pipe just above the drain elbow.
Page 3 / 20
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