HRT4-A, HFT4 and HTT4
User and Installation Instructions
Mains Operated Electronic Room Thermostat with
Load Compensation temperature control software
The HRT4-A is a 230 volt electronic room thermostat
designed to provide optimum comfort with close control of
the energy used to heat the home. These instructions also
apply to the HFT4 frost thermostat and the HTT4 tamper
proof thermostat.
INSTALLATION AND CONNECTION OF THE HRT4-A,
HFT4 AND HTT4 MUST BE CARRIED OUT BY A
SUITABLY QUALIFIED PERSON.
WARNING: ISOLATE MAINS SUPPLY BEFORE
COMMENCING INSTALLATION.
The HRT4-A will only operate on a 230 Volt mains
electricity supply and until power is connected the
thermostat will be inoperative.
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What is a room thermostat? ... an explanation for
householders
A room thermostat simply switches the heating system on
and off as necessary. It works by sensing the air
temperature, switching on the heating when the air
temperature falls below the thermostat setting, and
switching it off once this set temperature has been
reached.
Turning a room thermostat to a higher setting will not make
the room heat up any faster. How quickly the room heats up
depends on the design of the heating system, for example,
the size of boiler and radiators.
Neither does the setting affect how quickly the room cools
down. Turning a room thermostat to a lower setting will
result in the room being controlled at a lower temperature,
and saves energy.
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The heating system will not work if a time switch or
programmer has switched it off.
The way to set and use your room thermostat is to find the
lowest temperature setting that you are comfortable with,
and then leave it alone to do its job. The best way to do this
is to set the room thermostat to a low temperature - say
18°C - and then turn it up by one degree each day until you
are comfortable with the temperature. You won't have to
adjust the thermostat further. Any adjustment above this
setting will waste energy and cost you more money.
If your heating system is a boiler with radiators, there will
usually be only one room thermostat to control the whole
house. But you can have different temperatures in
individual rooms by installing thermostatic radiator valves
(TRVs) on individual radiators.
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If you don't have TRVs, you should choose a temperature
that is reasonable for the whole house. If you do have
TRVs, you can choose a slightly higher setting to make
sure that even the coldest room is comfortable, then
prevent any overheating in other rooms by adjusting them.
Room thermostats need a free flow of air to sense the
temperature, so they must not be covered by curtains or
blocked by furniture. Nearby electric fires, televisions, wall
or table lamps may prevent the thermostat from working
properly.
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Additional User information
Set the dial to the required room temperature by lining up
the temperature marked on the dial in degrees C against
the setting mark to the left of the dial.
The indicator light will be On when the thermostat is 'calling'
for heat. (In other words the thermostat has detected that
the room is not warm enough compared to its set
temperature).
If the indicator light is Off then either the room thermostat is
sensing that it is warm enough and has switched Off or that
the timeswitch / programmer has switched Off.
N.B. If the timeswitch or programmer has switched Off the
thermostat will not operate.
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Installation Instructions
Positioning the Room
Thermostat
The HRT4-A should be
mounted on an internal wall
approximately 1.5 metres
from floor level and should
be in a position away from
draughts, direct heat and
sunlight. Ensure that there
will be enough space to
allow easy access to the
two retaini ng screw s
located at the base of the
wall plate.
N.B. For the HFT4 Frost
Thermostat, locate in the
coldest part of the house to
be protected.
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Fitting the wall plate
To remove the wall plate from the HRT4-A undo the two
retaining screws located on the underside, the wall plate
should now be easily removed. Once the wall plate has
been removed from the packaging please ensure the
HRT4-A is re-sealed to prevent damage from dust, debris
etc.
The wall plate should be fitted with the wiring terminals
located at the top and in a position which allows a total
clearance of at least 50mm around the HRT4-A thermostat.
Direct Wall Mouting
Offer the plate to the wall in the position the HRT4-A is to be
mounted and mark the fixing positions through the slots in
the wall plate. Drill and plug the wall, then secure the plate
in position.
The slots in the wall plate will compensate for any
misalignment of the fixings.
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Wiring Box Mounting
The HRT4-A wall plate may be fitted directly on to a single
gang steel flush wiring box complying with BS4662, using
two M3.5 screws. The HRT4-A is suitable for mounting on a
flat surface only, it must not be positioned on an unearthed
metal surface.
Electrical Connections
All necessary electrical connections should now be made.
Flush wiring can enter from the rear through the aperture in
the wall plate.
The mains supply terminals are intended to be connected
to the supply by means of fixed wiring. The HRT4-A is
mains powered and requires a 3 Amp fused spur. The
recommended cable size is 1.0mm .
2
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The HRT4-A is double insulated and does not require an
earth connection, an earth connection block is provided on
the backplate for terminating any cable earth conductors.
Earth continuity must be maintained and all bare earth
conductors must be sleeved. Ensure that no conductors
are left protruding outside the central space enclosed by
the backplate.
THESE INSTRUCTIONS ALSO APPLY TO THE HFT4
AND HTT4
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Wiring Diagram and Electrical Connections for the
HRT4-A, HFT4 and HTT4
Maximum load 3 Amps @ 230V AC
3
N
1 2
L
4
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Internal wiring diagram
These thermostats have an internal connection which
makes them only suitable for mains voltage applications.
No additional linking between terminals is required.
This diagram is schematic and should be used for
guidance only. Please ensure that all electrical wiring
complies with the current IET regulations.
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Fitting the thermostat to the wall plate
Complete the installation by swinging the room
thermostat into position by engaging with the lugs at the
top of the wall plate before pushing it firmly home into its
plug-in terminal block.
Tighten the 2 captive
screws on the underside of
the unit.
Now ensure that the
heating system is
responding to the On/Off
commands from the room
thermostat and explain its
operation to the
householder before
handing over these
instructions highlighting the
'explanation for householders' on page 3.
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HFT4 frost thermostat and HTT4 tamper proof
thermostat
Follow the same instructions as for the HRT4-A but set the
temperature using internal setting dial. Frost thermostats
would normally be sited in the most vulnerable part of the
building for maximum protection
Internal
setting dial
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Wiring conversion charts
Replacing existing thermostats
HRT4-A HRT 3 HRT 2 HRT 1
LIVE 1 1 1 1
NEUTRAL 2 4 4 4
EARTH E - - 3
SWITCHED LIVE 4 3 3 2
Replacing other thermostats
HRT4-A Drayton RTs Honeywell
1 & 2 T6360B
LIVE 1 L 1
NEUTRAL 2 N 2
EARTH E E E
SWITCHED LIVE 4 3 3
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DIL switch settings - LC (Load Compensation)
temperature control software
Thermostats using LC control
algorithms will reduce the
temperature swing that normally
occurs when using traditional
CYCLE
bellows or thermally operated
thermostats. As a consequence,
an LC regulating thermostat will
maintain the comfort level far
mo re efficiently than any
traditional thermostat.
Switch positions for
different LC settings
When used with a condensing
boiler, the LC thermostat will help
to save energy as the control algorithm allows the boiler to
operate in condensing mode more consistently compared
to older types of thermostat.
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Ÿ DIL switch numbers 7 and 8 should be set as diagram
opposite.
Ÿ For Gas boilers set the LC setting to 6 cycles per hour.
(Default setting)
Ÿ For Oil boilers set the LC setting to 3 cycles per hour.
Ÿ For Electric heating set the LC setting to 12 cycles per
hour.
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Thermostat specifications HRT4-A/HTT4/HFT4
Power Supply 230v 50Hz
Contact rating 3 (1)amp at 230v AC
Temperature accuracy +/- 0.5°C
Contact type Micro disconnection
Dimensions 86mm x 86mm x 36.25mm
Pollution control Degree2
Design standard EN 60730-2-9
BS EN 60730-2-9
Temperature range HRT4-A 5-30°C
HTT4 10-30°C
HFT4 0-20°C
Rated Impulse voltage Cat II - 2500v
Enclosure protection IP30
Case material Thermoplastic flame
retardant
Ball pressure test temperature 75°c
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NP0 08 38 46 00 0
Secure Meters (UK) Ltd
Secure House, Lulworth Close,
Chandler's Ford,
Eastleigh, SO53 3TL, UK
t: +44 1962 840048 f: +44 1962 841046
www.securemeters.com
Part Number P83846 Issue 8
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