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Post-purge of the oil burner is controlled through the electronic circuitry supplied. Post-purge tim-
ing is variable. The factory set post-purge timing is at approximately one minute. It is recom-
mended that it be left at this setting. In no case should the post purge timing be reduced to less
than 1 minute.
Length of Vent Kit
Minimum Post Purge Time
0 - 10 Feet
1 Minute
10.1 - 15 Feet
1 Minute
15.1 - 20 Feet
2 Minutes
Times are approximate and should be considered minimum settings for the length of intake pipe
installed.
The length of post-purge may be increased on those units using the Beckett AFII or Riello BF-5
oil burners to any value up to its maximum setting if field conditions require a longer purge cycle.
The length of post-purge on the Carlin burner is not adjustable. The post purge timing on the
Carlin burner is 90 seconds.
4. Aquastat Relay
This control is installed in the 3/4" fitting next to the domestic coil. These immersion type con-
trols are used with forced hydronic heating systems which include domestic water service. This
model provides high and low limits for maintaining minimum boiler water temperature and cir-
culator controls. This control can also be used for multi-zone control by using a separate circula-
tor and an R845 relay for each zone. The primary control is factory wired to the aquastat relay.
These controls, working as a system, will prevent the circulator operation if the water tempera-
ture is below a predetermined low level. Likewise, if the water level reaches a predetermined high
limit, the burner will automatically shut off.