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4
SYSTEM REQUIREMENTS - Central Heating
Notes
a. The method of filling, refilling, topping up or flushing sealed
primary hot water circuits from the mains via a temporary
hose connection is only allowed if acceptable to the local
water authority.
b. Antifreeze fluid, corrosion and scale inhibitor fluids suitable
for use with boilers having aluminium heat exchangers may
be used in the central heating system.
Advice should be sought from a local water treatment
company.
General
1. The installation must comply with all relevant national and
local regulations.
2. The installation should be designed to work with flow
temperatures of up to 82
3. All components of the system must be suitable for a working
pressure of 3 bar and temperature of 110
should be taken in making all connections so that the risk of
leakage is minimised.
The following components are incorporated within the
appliance for the central heating:
a.
Circulating pump.
b.
Safety valve, with a non-adjustable preset lift pressure
of 3 bar.
c.
Pressure gauge, covering a range of 0 to 6 bar.
d.
A 8-litre expansion vessel, with an initial charge pressure
of 1.0 bar.
e.
Diverter valve.
f.
Filling loop.
4. 'Make-up' Water. Provision is made for replacing water loss
from the system, via a filling loop supplied and fitted to the
appliance.
Note.
The maximum cold water capacity of the system should
not exceed 143 litres, if not pressurized. However, if the
system is to be pressurized, the efficiency of the
expansion vessel will be reduced and a larger vessel (or
smaller system volume) may be necessary. If the capacity
of the vessel is not considered sufficient for this, or for any
other reason, an additional vessel MUST be installed on
the return to the boiler.
Guidance on vessel sizing is given above.
5. Filling. The system should be filled by the following
method:
a.
Through the filling loop fitted to the appliance.
Connecting the inlet manifold to the CH return.
i.
Thoroughly flush out the whole system with
cold water.
ii.
Fill and vent the system until the pressure
gauge registers 1.5 bar, and examine for leaks.
iii. Check the operation of the safety valve by
raising the water pressure until the valve lifts.
This should occur within 0.3 bar of the preset lift
pressure.
iv. Release water from the system until the
minimum system design pressure is reached;
1.0 bar if the system is to be pre-pressurised.
12
o
C.
o
C. Extra care
GENERAL
Safety valve setting
Vessel charge pressure
System pre-charge pressure bar
System volume
(litres)
25
50
75
100
125
150
175
190
200
250
300
For other system volumes
multiply by the factor across
Water Flow Rate and Pressure Loss
Max CH Output
Water flow rate
Temperature Differential
Head available for
system pump.
istor system store -
bar
3.0
bar
0.5 to 0.75
None
Expansion vessel
volume (litres)
1.6
3.1
4.7
6.3
7.8
9.4
11.0
10.9
12.9
11.9
14.0
12.5
14.7
15.6
18.4
18.8
22.1
0.063
0.074
kW
23.4
(Btu/h)
(80 000)
l/sec
0.37
(gal/min)
4.8
o
C
15
o
(
F)
(27)
m.w.g.
2.3
(ft.w.g.)
7.5
Installation and Servicing
1.0
1.8
3.7
5.5
7.4
9.2
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