LP-428 Rev. 6.6.16
33
Figure 20 - Cascade Master and Follower Wiring
K. Optional High Gas Pressure Switch
1. If an optional high gas pressure switch is used, it should be
installed on the outlet side of the gas valve of both boilers.
This is normally closed and will open if the pressure goes
above 1.5” w.c. on the outlet side.
2. Locate the two pigtails hanging from the electrical box inside
of the boiler cabinet. Remove and discard the jumper plug from
one of the unused pigtails.
3. Connect the high gas pressure switch to the pigtail that you
removed the jumper plug from.
L. Optional Low Gas Pressure Switch
1. If an optional low gas pressure switch is used, it should be
installed on the inlet side of the gas valve of both boilers. This is
normally closed and will open if the pressure goes below 1” w.c.
control signal to the terminals marked 16, 0-10 VOLT + and
17, 0-10 VOLT – in the electrical junction box (shown in Figure
20). Caution should be used to ensure that the 0-10 VOLT +
connection does not become connected to ground.
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