26
10.3.1
EXPANSION VESSEL SIZING
The following information is based on an inlet pressure of 3.5 bar. If a different inlet pressure is to be used, please
consult
BS6700.
V V = S V * e
0.45
Where:
V V
=
Vessel Volume
S V
=
System Volume
e
=
Coefficient of Expansion
(See
Table 10.1
)
Stored Temp.
C
30
35
40
45
50
55
60
e
0.005
0.006
0.008
0.010
0.012
0.015
0.017
Stored Temp.
C
65
70
75
80
82
85
90
e
0.020
0.023
0.026
0.030
0.031
0.033
0.037
TABLE 10.1
COEFFICIENT OF EXPANSION OF WATER AT 3.5 BAR INLET PRESSURE
10.4
DE-STRATIFICATION
If the hot water system does not include a constantly circulated building return, it is recommended that a de-
stratification pump is fitted, between the building flow connection and the drain connection of the storage vessel, to
ensure an even temperature distribution throughout the stored water. De-stratification pump kits are available as
ancillary items; please contact Lochinvar Limited for details.
10.5
CIRCULATING PUMPS
In order to ensure the correct flow rates through the water heater, the unit requires a bronze glanded pump sized to
overcome the resistance of the heat exchanger and a primary pipework loop. The primary loop should be no longer
than 14 metres plus the following fittings:
6 x 90
Elbows
2 x Unions
2 x Full bore lever ball valves
2 x Tee fittings (cold feed & building return)
For longer distances or a greater number of fittings, the pump may have to be resized.
The specification of this type of pump ensures that the bronze body and associated parts in contact with water are
suitable for potable use. A "glanded" construction is required to ensure that any scale in the system does not build up
within the pump and cause a resistance that can lead to a loss of water flow. Glandless (canned rotor) pumps are not
recommended by Lochinvar Limited due to the fact that in hard water areas, scale can build up within the rotor and
failure can occur, not only of the pump but also the heater itself. The warranty will be void if a failure of the heat
exchanger occurs due to a "glandless" pump.
Model
Differential (K)
FLOW
(Litre/sec)
Total System Pressure
Loss (Meter- H
2
0)
EKW45CE
10.0
0.98
7.32
EKW60CE
10.0
1.17
6.71
EKW85CE
10.0
1.80
6.07
EKW115CE
10.0
2.82
8.51
EKW145CE
10.0
3.19
7.93
EKW175CE
12.2
3.30
7.90
EKW205CE
12.2
4.00
9.80
EKW235CE
13.3
4.20
9.40
TABLE 10.2
SYSTEM HEAD LOSS
Primary circulating pumps are available as ancillary items; please contact Lochinvar Limited for details.
