1
Installation & Commissioning Guide
Control Features
The TP75 Series of programmable room thermostats incorporate two
special features that can be enabled at the time of installation -
Optimum Start Control and Chrono-proportional Control
Optimum Start Control (OSC)
With this enabled the event 1 control temperature, (which would
normally be an increase from an overnight set-back temperature),
may be programmed to be achieved by a desired time. The heating
plant will be switched on earlier than the programmed time by a period
related to the start-up curve selected and the space temperature
sensed at the beginning of the selected start-up period. The diagram
below indicates the switch on periods for the available start-up curves.
If OSC is disabled then the unit will operate as a conventional room
thermostat, switching on the heating plant at the event 1 time with the
event 1 temperature being achieved in a time related to the prevailing
conditions.
Battery Compartment Flap lowered
This product complies with the following EC Directives:
Electro-Magnetic Compatibility Directive.
(EMC)
(89\336\EEC), (92\31\EEC)
Low Voltage Directive.
(LVD)
(73\23\EEC), (93\68\EEC)
Chrono-proportional Control
Traditional ON/OFF room thermostats control room temperature by
switching the circulating pump, and usually the boiler, on and off.
Because of the thermal inertia of the heating equipment and the
relatively large switching differentiials of on/off devices large space
temperature variations often occur, resulting in poor comfort conditions.
Chrono-proportional Control as implemented in the TP75 overcomes
the problem by ensuring that the boiler fires regularly for periods
calculated to maintain radiator temperature without overheating and
to prevent the radiator temperature falling to a level which can allow
down draughts from cold surfaces, e.g. windows, to cause discomfort.
The control logic works on a proportional band of 2°C which assumes
that the boiler will operate at full load when the sensed space
temperature is 2°C or more lower than the programmed set point.
The following graph shows the relative on/off periods per cycle against
variances in deviation from the set point.
OFF Time
S
y
stem Load
0% 25% 50% 75% 100%
0%
25%
50%
75%
100%
100% 75% 50% 25% 0%
Set Temp
-0·5°C
-1·0°C
-1·5°C
-2·0°C
P
roporti
onal B
a
nd
ON Time
OFF
TIME
20 15 10 5 0
min.
ON
TIME
0 5 10 15 20
min.
OFF
TIME
10 7·5 5 2·5 0
min.
ON
TIME
0
2·5
5
7·5
10
min.
3 Cycles / hour
HC75--3
6 Cycles / hour
HC75-C3
Lo
ad
cu
rve
Ï
Desired Event 1
temperature.
Selecting 0
effectively
disables the
OSC function.
Available
Start-up
Periods
With a -2°C deviation and the 30 min. curve selected the
heating plant will switch on 15 min. before the Event 1 time.
De
gr
e
e
s
be
lo
w
t
h
e
de
si
re
d
te
m
p
e
rat
ur
e a
t t
h
e b
e
g
inn
in
g
o
f t
h
e O
p
ti
m
u
m
St
ar
t
P
e
ri
od
120
90
60
30
Event 1
min.
min.
min.
min. time (0)
-1°C
-2°C
-3°C
-4°C
Electronic Programmable Room Thermostats
TP75 with integral sensor
TP75A with remote sensor
TP75B with remote teleswitch
TP75AB with remote sensor & teleswitch
Specification
Control temp. range
: 5°C to 30°C (41°F to 85°F)
Power Supply
: 2 x AA size high quality
alkaline batteries
Switching Action
: 1 x SPDT, type 1B
Switch Rating
: 10 - 250Vac, 50/60 Hz, 2(1)A
Temperature Accuracy
: ± 0.5°C
Time Keeping Accuracy
: ± 1 minute/month
Low Battery Warning
: 15 days duration
Memory Retention with Batteries Removed : one minute
Enclosure Rating
: IP30
Maximum Ambient Temp
: 45°C
Designed to Standard
: BS EN60730-2-9
Overall Dimensions
Unit
: Width: 135mm
Height:
88mm
Depth:
32mm
Remote Sensor
: Width:
61mm
Height:
45mm
Depth:
22mm
Pollution Situation
: Degree 2
Software Classification
: Class A
Rated Impulse Voltage
: 2.5 KV
Ball Pressure Test
: 75°C
TP75
TP75
