8
combination boiler -
Installation and Servicing
GENERAL
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 copper heat
exchangers may be used in the central heating system.
Advice should be sought from a local water treatment
company.
THERMOSTATIC RADIATOR VALVES (TRV)
It is recommend that heating systems utilising full thermostatic
radiator valve control of temperature in individual rooms should
also be fitted with a room thermostat controlling the
temperature in a space served by radiators not fitted with such
a valve as stated in BS. 5449.
When thermostatic radiator valves are used, the space heating
temperature control over a living area having a heating
requirement of at least 0.9kW (3000Btu/h) of the boiler heat
output should be achieved using a room thermostat whilst
other rooms are individually controlled by thermostatic radiator
valves. A higher proportion of TRVs may be used, provided that
a bypass between the boiler flow and return is fitted, to ensure
adequate flow when all TRVs are closed.
For further information refer to the 'Good Practice Guide 143', a
publication of the Energy Efficiency Office, available from the
Building Research Establishment, Garston, Watford WD2 7JR.
Tel: 01923 664258.
ELECTRICAL SUPPLY
Wiring external to the appliance MUST be in accordance with
the current I.E.E. (BS.7671) Wiring Regulations and any local
regulations which apply.
The point of connection to the mains should be readily
accessible and adjacent to the boiler.
3
SYSTEM REQUIREMENTS - Central Heating
Safety valve setting
bar
3.0
Vessel charge pressure
bar
0.75 to 1
System pre-charge pressure
bar
1.0
System volume
Expansion vessel
(litres)
volume (litres)
25
1.8
50
3.7
75
5.5
100
7.4
125
9.2
150
11.0
175
11.9
190
14.0
200
14.7
250
18.4
300
22.1
For other system volumes
multiply by the factor across
0.074
WATER CIRCULATION SYSTEM
The boilers are designed for connection to pressurised, fully
pumped, sealed water central heating systems ONLY. The
domestic hot water (DHW) calorifier is incorporated within the
heat exchanger and only requires connection to the mains
water supply.
IMPORTANT
A minimum length of 1m of copper pipe MUST be fitted to both
flow and return connections from the boiler before connection to
any plastic piping -
This applies to ALL types of installation
Ensure that the mains water supply pressure is
adequate to provide the required DHW flow rate. Refer to
Table 2 on page 2.
The central heating system should be installed and
commissioned in accordance with BS. 6798 and, in addition,
for smallbore and microbore systems BS. 5449.
The domestic hot water system should be in accordance with
BS. 5546 and BS. 6700.
Copper tubing to BS 2871:1 is recommended for water
carrying pipework and MUST be used for pipework carrying
potable water.
Any soldered joints on potable water pipework MUST NOT be
made with solder containing lead.
Ancillary pipework not forming part of the useful heating
surface should be lagged to prevent heat loss and any
possible freezing - particularly where pipes run through roof
spaces or ventilated underfloor spaces.
Draining taps MUST be located in accessable positions, which
permit the draining of the whole system.
They should be at least 1/2" BSP nominal size and be
in accordance with BS 2879.
Maximum recommended system hydraulic losses are given in
the Table within Frame 4.
WATER TREATMENT - See frame 6
