It can accept up to 7l
It can accept up to 7l (1.5 gal) of expansion water. If the heating circuit has an unusually high water content, calculate the total expansion and add an additional sealed expansion vessel with adequate capacity. Domestic Water: The domestic water must be in accordance with the relevant recommendation of BS 5546:1990. Copper tubing to BS EN 1057:1996 is recommended for water carrying pipe work and must be used for pipe work carrying drinking water. The domestic hot water temperature should be be adjusted to trip at 60˚C. This temperature will prevent the formation of limescale in hard water areas. Note: This appliance is capable of producing domestic hot water of up to 70˚C. For extra security against scalding a thermostatic blending valve may be installed on the domestic hot water outlet. Secondary Return: The secondary return connection can be used as an option. A Non Return Valve (not supplied) must be fitted to prevent back flow and a Bronze Pump will be needed in conjunction with a Pipe Thermostat to circulate the hot water (neither of which are supplied). Table 1. Sizing of copper discharge pipe “D2” for common temperature valve outlet sizes. Valve outlet size Minimum size of discharge pipe D1* Minimum size of discharge pipe D2* from tundish G 1/2 15 mm 22 mm 28 mm 35 mm G 3/4 22 mm 28 mm 35 mm 42 mm G 1 28 mm 35 mm 42 mm 54 mm Maximum resistance allowed, expressed as a length of pipe (i.e. no elbow or bends) Up to 9 m Up to 18 m Up to 27 m Up to 9 m Up to 18 m Up to 27 m Up to 9 m Up to 18 m Up to 27 m Resistance created by each elbow or bend 0.8 m 1.0 m 1.4 m 1.0 m 1.4 m 1.7 m 1.4 m 1.7 m 2.3 m Worked Example: The example below is for a G 1/2 Temperature & Pressure Relief valve with a discharge pipe (D2) having 4 no. elbows and length of 7 m from the Tundish to the point of discharge.From Table 1 Maximum resistance allowed for a straight length of 22 mm copper discharge pipe (D2) from G 1/2 T & P valve is 9m. Subtract the resistance for 4 no. 22 mm elbows at 0.8m each = 3.2 m. Therefore the maximum permitted length equates to: 5.8 m. As 5.8m is less than the actual length of 7 m therefore calculate the next largest size. Maximum resistance allowed for a straight length of 28 mm pipe (D2) from G 1/2 T & P valve equates to: 18 m. Subtract the resistance for 4 no. 28 mm elbow at 1.0m each = 4 m. Therefore the maximum permitted length equates to: 14 m As the actual length is 7 m, a 28 mm (D2) copper pipe will be satisfactory. 20
Residual Head of the Boiler ΔT = 20 o C Operating Pressure mCE m/H 2 O Minimum flow (thermostatic valves closed) 6 5 4 GV 3 2 PV 1 0 100 300 500 700 900 1100 l/h 200 400 600 800 1000 1200 Fig. 10.5 16 7 12 13 A BC D E F V Pressure Reducing Valve 1 3 4 5 6 Cold Water Inlet Other Users 2 9 8 8 10 11 Drain Tap (at lowest point) Fig. 10.6 A - Gas Inlet B - C.H. Return C - C.H. Flow D - D.H.W. Secondary Return E - D.H.W. Flow F - C.W. Inlet 1 - Gas Meter Inlet Cock 2 - Gas Meter 3 - Gas Meter Outlet Cock 4 - Internal Gas Cock 5 - Appliance Gas Inlet Cock 6 - Cold Water Inlet Cock 7 - D.H.W. Expansion Vessel 8 - Cock 9 - Secondary Return Pump 10 - Thermostat 11 - Time Control Clock 12 - T&P Valve 13 - Tundish 21
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