11
6.3.6
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 5.1)
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
6.3.7
COEFFICIENT OF EXPANSION OF WATER AT 3.5 BAR INLET PRESSURE
6.4
DE-STRATIFICATION
6.4.1
GENERAL
The De-stratification Pump Kit works by using a pump to circulate water from the top of the vessel to
the bottom of the vessel. This action ensures that the water held in the unit is maintained at a
consistent temperature throughout. By achieving a uniformed stored water temperature of at least
60°C, the risk of any bacterial contamination is virtually eliminated.
If the SST is to be installed alongside a circulating water heater then a De-stratification pump may not
be required due to the high turbulent flow created by the matched primary shunt pump supplied.
Systems that have a building loop incorporated onto the vessel may not require a De-stratification kit,
as the circulation around the building from the top of the vessel back to the bottom should provide
sufficient mixing.
6.4.2
REQUIREMENTS
Lochinvar has developed this kit to meet the stringent recommendations of both the HSE Approved
Code of Practice L8 and Department of Health Memorandum HTM 04-01 relating to the control of
legionella. For full compliance, a timer should be used to operate the pump for a period of at least 1
hour each day.