1718
10
GB
ECONOMIZER
This economizer can be wired to 2
nd
stage thermostat or
to an external probe.
The economizer, connected to the 2
nd
stage thermo-
stat, performs two functions:
1. Delay of 5 - 6 seconds in the intervention of the 2
nd
stage valve against 1
st
stage valve.
2. In relation of the position of the plug B, it determines
the type of required operation:
NOTE
In this case the setting screw A is not necessary.
Should the economizer be connected to an external probe, the operation at 1
st
or 2
nd
stage
will be related to the external temperature.
When the external temperature is higher than the fixed value the economizer permits the burner
operation only at 1
st
stage; on the contrary when the external temperature decreases in relation
with the fixed value, the economizer permits the burner operation only at 2
nd
stage.
The external temperature causing the economizer intervention might be chosen between –5
°
C
and + 10
°
C, turning the setting screw A using the screw-driver.
For this type of operation the plug B has to placed in the position
I - II
.
When the plug B is in the position
II
or
I
, the burner operates as previously indicated.
S7341
II - I
II
I
II - I
II
I
II - I
II
I
Position
I - II
= Burner operation in 1
st
or 2
nd
stage on request
of the 2
nd
stage thermostat.
Position
II
= Burner operation only in 2
nd
stage - compulsorily.
Position
I
= Burner operation only in 1
st
stage - compulsorily.
B