Heating and hot water systems
The heating system should be installed in accordance
with current HVCA Codes of Practice and BS 5449
Part 1 (Forced Circulation Hot Water Central Heating
Systems).
The water flow connection can be made to one of the
two tappings on the left or right side of the boiler. The
return connection can be made to one of the tappings
on the secondary heat exchanger. See
fig 3
for details.
A drain-off cock should be fitted at the lowest part of the
system. Where the boiler is also used for providing
domestic hot water, an indirect cylinder to BS 1556
Part 1 must be used.
Flush the system to remove any residue before
installing the circulating pump. Ensure all unused
tappings are plugged before filling the system.
To achieve maximum system efficiency, the heating
system should be designed to ensure a boiler flow
temperature of between 55°C and 70°C, and a flow
differential temperature of between 20°C and 30°C.
Electrical supply
All electrical wiring must be carried out by a qualified
electrician in accordance with current IEE Regulations
and any local regulations that apply.
The boiler must be earthed and the supply cables must
be longer than the current-carrying conductor cables
(i.e. live and neutral supply cables). The minimum
requirement for the power supply is PVC sheathed
flexible cord, 0.75mm² (24x0.2mm, code designation
H05 VV-F or H05 VVH2-F), as specified in table 16 of
BS 6500.
The 230V, 50Hz electrical supply must be fused via a
double-pole switch
—with contact separation of at least
3mm in both sides, and via a shuttered socket adjacent
to the boiler (both devices must meet the requirements
of BS 1363).
All external cables entering the control box must be
secured in position through use of the strain-relief
bushes (supplied, see
fig 7
).
In certain areas, there may be a known risk of high and
low voltage fluctuations; though use of a voltage-
sensitive device, the burner should be prevented from
starting if the voltage drops or rises to a level sufficient
to endanger the installation.
FIG. 7