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Worked example of discharge pipe sizing
The example on page 18 is for a G
the point of discharge.
From Table 5:
Maximum resistance allowed for a straight length of 22mm copper discharge pipe (D2) from a G
Subtract the resistance for 4 No. 22mm elbows at 0.8m each = 3.2m
Therefore the permitted length equates to: 5.8m
5.8m is less than the actual length of 7m therefore calculate the next largest size.
Maximum resistance allowed for a straight length of 28mm pipe (D2) from a G
Subtract the resistance of 4 No. 28mm elbows at 1m each = 4m
Therefore the maximum permitted length equates to: 14m
As the actual length is 7m, a 28mm (D2) copper pipe will be satisfactory.
INDIRECT MODEL
Boiler Selection
The MEGAFLO Eco Solar Indirect models are supplied with an auxiliary heating coil and is suitable for use with most gas or oil fired boilers
compatible with unvented systems i.e. fitted with a temperature control thermostat and thermal cut-out. If in doubt consult the boiler
manufacturer. Solid fuel boilers or any other boiler in which the energy input is not under effective thermostatic control, unless additional and
appropriate safety measures are installed, SHOULD NOT be used. The boiler used can either be a sealed system or open vented type, maximum
primary circuit pressure 0.3Mpa (3 bar). The primary flow from the boiler MUST be pumped. Gravity circulation will not work due to the special
design of the primary heat exchanger. It is recommended that an air bleed point or automatic air vent is incorporated in the primary return
pipework close to the MEGAFLO Eco Solar unit. The boiler flow temperature should usually be set to 82ºC (maximum flow temperature to primary
heat exchanger 88ºC). The boiler cannot be vented through the MEGAFLO Eco Solar unit.
Indirect Thermal Cut-Out And 2-Port Motorised Valve
To comply with Building Regulations, and to prevent the MEGAFLO Eco Solar from overheating the 2-port motorised valve supplied MUST be fitted
to the primary flow to the indirect coil (see Figure 11 below).
Figure 11 - Primary connections to indirect units
TO HOT OUTLETS
AIR VENT
(MUST BE AT THE HIGHEST
POINT OF THE SYSTEM)
PRIMARY RETURN
TWO PORT MOTORISED VALVE (SUPPLIED)
PRIMARY FLOW
PRIMARY FLOW
SOLAR PRIMARY RETURN
SOLAR PRIMARY FLOW
/
temperature relief valve with a discharge pipe (D2) having 4 No. elbows and length of 7m from the tundish to
1
2
/
temperature relief valve is 9m.
1
2
/
temperature relief valve equates to 18m.
1
2
Unvented Hot Water Cylinder
COLD WATER INLET
19
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