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3.11. Long pipe runs and excessive use of 90° elbows will significantly reduce the
head available to supply the Mira Extreme. If the effective head is less than
80 mm:
3.11.1. The expected flow rate may not be achieved.
3.11.2. Air may be drawn into the hot supply from the vent pipe, causing
spluttering and temperature fluctuations at the handset.
Use the table below to calculate the actual head of water (x) needed in your
installation.
Size
Pipe Run/Quantity of
15 mm
A x 120
Pipe
22 mm
B x 20
Pipe
15 mm
No. of
Elbow
Elbows
22 mm
No. of
Elbows
Elbow
effective head required.
A = Total length of 15 mm pipe in hot water supply pipe run*
B = Total length of 22 mm pipe in hot water supply pipe run*
C = Total length of 15 mm pipe in cold water supply pipe run*
D = Total length of 22 mm pipe in cold water supply pipe run*
*Measure from the base of the cold water cistern to the relevant inlet port on the Mira Extreme.
Example: With A = 1.5 m, B = 2.5 m, C = 2.2 m, D = 0 m.
Size
Pipe Run/Quantity of
15 mm
A x 120
Pipe
22 mm
B x 20
Pipe
No. of
15 mm
Elbows
Elbow
No. of
22 mm
Elbows
Elbow
Add the minimum
effective head required.
12
Hot Water Supply
Elbows
x 120
x 20
x 55
x 15
Add the minimum
Required head
of water – x mm
Hot Water Supply
Elbows
1.5 m
x 120
2.5 m
x 20
3
x 55
2
x 15
Required head
of water – x mm
Cold Water Supply
Head
Pipe Run/Quantity of
Loss
Elbows
( m m )
C x 120
D x 20
No. of
Elbows
No. of
Elbows
Add the minimum
+80
effective head required.
Required head
of water – x mm
Cold Water Supply
Head
Pipe Run/Quantity of
Loss
Elbows
( m m )
180
C x 120
50
D x 20
No. of
165
Elbows
No. of
30
Elbows
Add the minimum
+80
effective head required.
Required head
505
of water – x mm
Head
Loss
( m m )
x 120
x 20
x 55
x 15
+80
Head
Loss
( m m )
2.2 m
x 120
264
0 m
x 20
3
165
x 55
0
x 15
+80
509
0
0
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