Supplied By www.heating spares.co Tel. 0161 620 6677
British Gas RD1
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Installation & Servicing
25
INSTALLATION
38 FROST PROTECTION
Central heating systems fitted wholly inside the house do not
normally require frost protection as the house acts as a
'storage heater' and can normally be left at least 24 hrs.
without frost damage. However, if parts of the pipework run
outside the house or if the boiler will be left off for more than
a day or so, then a frost thermostat should be wired into the
system.
This is usually done at the programmer, in which case the
programme selector switches are set to OFF and all other
controls MUST be left in the running position.
The frost thermostat should be sited in a cold place but
where it can sense heat from the system.
Wiring should be as shown, with minimal disturbance to other
wiring of the programmer.
Designation of the terminals will vary but the programmer and
thermostat manufacturer's leaflets will give full details.
If a boiler is installed in a garage it may be necessary to fit a
pipe thermostat.
Diagram A
shows a double pole frost thermostat, which
should suffice for all systems which do not use the OFF
terminals of the programmer.
Diagram B
shows a 'change-over' frost 'stat, which will cover
most systems which do use CH OFF. If, however, on such a
system the HW pipework is in an isolated part of the house, a
second frost 'stat may be used to protect it. If in doubt, ask
your installer for advice.
Clock with volt free contacts should be used.
39 COMMISSIONING AND TESTING
(a) Electrical Installation
1.
Checks to ensure electrical safety should be carried out
by a competent person.
2.
ALWAYS carry out preliminary electrical system checks,
i.e. earth continuity, polarity, resistance to earth and
short circuit using a suitable test meter.
WARNING.
Whilst effecting the required gas soundness test and purging air from the gas installation open all windows and
doors, extinguish naked lights and
DO NOT SMOKE.
(b)
Gas Installation
1.
The whole of the gas installation, including the meter,
MUST be inspected and tested for soundness, and purged
in accordance with the recommendations of BS. 6891.
2.
Purging air from the gas installation may be expedited by
loosening the union on the gas service cock on the boiler
and purging until gas is detected.
3.
Retighten the union and check for gas soundness.
INST
ALLA
TION
