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TWO-STAGE THERMOSTAT

The control card of the furnace auto-detects the two

stages of the thermostat.

W1 The thermostat closes the R-W1 circuit, which acti-

vates the rst stage of the heating sequence (±50% hea-

ting). The blower starts up at low speed and the furnace

elements are activated one by one to reach the adjustable

temperature limit set by the potentiometer on the furnace

control card.

If there is still a W1 heating demand after 30 minutes, the

heating sequence continues as per the W2 sequence.

AND/OR

W2 If the thermostat closes the R-W2 circuit, the

sequence continues as follows: the blower switches to the

medium speed and all the furnace elements are activated

one by one (100% heating). The plenum temperature is still

limited by the potentiometer of the control card.

The SFECM series allows to adjust the continuous ventilation airows independently from the ventilation airow in

heating mode. Note that it also allows airows as low as 300 cfm in continuous ventilation.

CONTINUOUS VENTILATION

Two ventilation speeds can be selected on the furnace control panel: LOW SPEED CONTINUOUS VENTILATION or

HIGH SPEED CONTINUOUS VENTILATION. The user can select the ventilation speed by pressing the CONTINUOUS

VENTILATION button.

CONTINUOUS HEATING

The continuous heating option allows one or two heating elements to operate continuously. The user can select min (one

element) or max (two elements) continuous heating by pressing the CONTINUOUS HEATING button.* The continuous

heating mode is useful from the beginning to the end of the heating season since it reduces temperature variations into

the house. If the minimum or maximum continuous heating option is activated by the user, the furnace will deactivate it

when the heating season ends (more than two hours without any heating demand). Moreover, it will reactivate it when a

new heating season begins.

HEATING DEMAND, STANDARD MODE

(WITH T-STAT INTELLIGENCE)

Note that the pilot light indicating the heating option will blink if the furnace deactivates this option because the hea-

ting season is over. This indicates that the continuous heating will be activated again at the start of the next heating

season.

*Please note that for model #1021, the minimum and maximum continuous heating are the same (one element).

100% HEAT,

MED SPEED

ADJUST. LIMIT

50% HEAT,

LOW SPEED

ADJUST. LIMIT

1 STAGE W1 2 STAGES W1 W2 W1 > 30 MIN

ACTIVATION OF RELAYS, 3-SEC. INTERVAL

AIR CONDITIONING

The furnace supplies the necessary 24V power for the thermostat relay (R-Y terminals) to control the air-conditioner compres-

sor relay. When the R-Y terminals are activated, the blower starts-up at high speed. See the connection diagram page 6.