Heatrae Sadia ELECTROMAX SOLAR Installation & Servicing Instructions Manual page 20

• 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 G1/2
temperature relief valve equates to 18m
• Subtract the resistance of 4 No. 28mm elbows at 1.0m each = 4.0m
• Therefore the maximum permitted length equates to 14.0m
• As the actual length is 7m, a 28mm (D2) copper pipe will be satisfactory.
TABLE 02:
Valve outlet Minimum size of
size discharge pipe
D1
G1/2 15mm
G3/4 22mm
G1 28mm
FIGURE 09: DISCHARGE PIPE ARRANGEMENT
Safety device
(e.g. Temperature
relief valve)
20
Minimum size of
discharge pipe
D2 from tundish
22mm
28mm
35mm
28mm
35mm
42mm
35mm
42mm
54mm
Metal discharge pipe (D1) from
Temperature relief valve to tundish
500mm maximum
300mm
minimum
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Regulation G3 section 3.9d i-iv,
Table 4 and worked example
Maximum resistance
allowed, expressed as
a length of straight pipe
(i.e. number of elbows
or bends)
up to 9m
up to 18m
up to 27m
up to 9m
up to 18m
up to 27m
up to 9m
up to 18m
up to 27m
Tundish
Resistance created
by each bend.
0.8m
1.0m
1.4m
1.0m
1.4m
1.7m
1.4m
1.7m
2.3m
Discharge below
fixed grating
(Building Regulation
G3 section 3.9d gives
alternative points
of discharge)
Fixed grating
Trapped
gully