Instruction Manual

STEP 3 - (continued)
Summary of Temperature Control
1- Electr
ic ON / OFF thermostats are a
v
ailable up to three stages f
or room or duct control and up to four
stages for duct control only. Three and four stage thermostats are not recommended for FINE or
MEDIUM temperature control because of their large diff
erentials
. Ho
wever, they are suitable for
CO
ARSE control.
2- P.E.
Switches with a pneumatic ther
mostat are recommended for up to four stages only and can be
used for FINE as well as MEDIUM or COARSE control.
3- FULL SCRs are compatible with electronic or pneumatic signal.
The
y are recommended where FINE
temperature control and energy conservation is required. As a general guideline, it is economical to
use Full SCR on heaters up to 70 Amps total load. Between 70 and 120 Amps, the cost is slightly
more expensive and beyond 120 Amps Hybrid controllers are the best choice.
4- Hybrid controllers are compatib
le with electronic or pneumatic signal. They are recommended where
FINE temper
ature control is required and where the heater capacity is too large to be controlled
economically b
y a FULL SCR (over 120 Amps).
5-
Thermolec is engaged in a countinuous effor
t of product development, hence
, the following inf
ormation
is presented as a gener
al overvie
w of existing products and can be modified without further notice
.
Notes:
a- Although ON/OFF stages can off
er some economy, in most multi-stage (2 stages and o
ver)
applications up to 40 KW
, SCR proportional control can be obtained at almost the same price.
Please see selection of most economical KW / v
oltage combination on page 7.
b- In order to manage the energy resources properly and provide the best comfort,
Thermolec recommends specifying a proportional control at all times.
ON/OFF Room Thermostats
24 volts wall thermostat, ON-OFF type with built-in thermometer and adjustable heat anticipator.
1 stage 2 stages
1 and 2 stages
T874 Honeywell
1F30W-301 (1 stage) and 1F37-408 (2 stages) - White-Rodgers
THREE EASY
STEPS
T86 Honeywell