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12.0 WATER CONNECTIONS
12.1
GENERAL
TTW water heaters require a minimum flow rate and must also be installed with separate storage vessels. Suitably
sized pumps and separate storage vessels are available from Lochinvar Limited as ancillary options.
To preserve the warranty on the appliance Lochinvar Limited insists on the use of glanded
pumps.
Recommended pipework layouts are available for different water heater and storage vessel combinations. Please
refer to
www.lochinvar.ltd.uk
The requirements of minimum water flow are given in Table 10.3. Recommendations for the water circulation
system are given in BS6644 and CP 342. The following notes are of particular importance.
1.
When the unit is being utilised as a direct-fired water heater it is designed for use with a direct type
storage vessel. Contact Lochinvar Ltd for help in sizing the storage vessel
2.
Circulating pipework not forming part of the useful heating surface should be insulated. Cisterns,
expansion vessels and pipework situated in areas exposed to freezing conditions should also be insulated.
3.
Drain valves must be located in accessible positions that will permit draining of the entire system including
the unit and the storage vessel.
4.
Tapping sizes for connection to the water system are detailed in Table 2.1.
5.
Ideally, individual valves should be fitted to each unit to enable isolation from the system. The
arrangement must comply with the requirements of BS6644.
12.2
UNVENTED SYSTEM ARRANGEMENT
It is strongly recommended that unvented hot water systems be installed by an approved
installer.
If the Lochinvar TTW water heater is to be used in an unvented arrangement, the system should follow the guidance
given in BS6700 and must comply with Building Regulations 1992: Part G3,in England and Wales,P5 in Northern
Ireland and P3 in Scotland.. A kit of components that have been suitably sized for the unvented operation of the
appliance is available from Lochinvar Limited. For further information, please see our unvented/boosted systems
guide, available on our website.
The maximum working pressure of the water heater is 8.0 bar.
12.2.1
EXPANSION VESSEL SIZING
The following information is based on:
Working pressure of 3bar
Pressure relief valve setting of 6 bar
V V = S V * e
Expansion vessel efficiency =0.45
Where:
V V
=
Vessel Volume
S V
=
System Volume
e
=
Coefficient of Expansion
FLOW
TEMP.
C
e
12.2.2
COEFFICIENT OF EXPANSION OF WATER AT 3.5 BAR INLET PRESSURE
for details.
(See Table 10.1)
35
40
45
0.006
0.008
0.010
50
55
60
0.012
0.015
0.017
0.020
65
70
0.023
34
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