INSTALLATION
18
Mexico Slimline CF440 -
Installation & Servicing
21 HONEYWELL 'C' PLAN
Gravity HW & Pumped CH
Notes.
1.
Some earth wires are omitted for clarity.
Ensure proper earth continuity when wiring
2.
Numbering of terminals on thermostats is
specific to the manufacturer.
20 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 'stat 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 'stat 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.
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 thermostat, 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 thermostat may
be used to protect it.
If in doubt, ask your installer for advice.
Boiler supply connector
Pump
Terminal strip
suitably
enclosed
T
y
pical programmer CH may
be selected independently
M
A
INS
MEX 2134
E
N
L
LEGEND
b
blue
bk
black
br
brown
r
red
or
orange
w
white
gy
grey
y/g
yellow/green
INST
ALLA
TION
200946-1.p65
3/9/2004, 3:30 PM
18
