B12 - checking the high gas pressure switch, Checking the high gas pressure switch, Section b12 - high gas pressure switch – LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual User Manual
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Service Manual - NeoTherm 500
Checking the High Gas Pressure Switch
B12
The high gas pressure switch is a 24V manual reset switch that acts to
cut power to the gas valve if the gas pressure is too high for proper op-
eration. The type of switch used is integrally vent limited, and does not
require venting to the atmosphere.
24V AC present?
(switch open)
Yes
Check gas supply.
Call gas company.
Gas pressure should be
lower than 13” w.c.
Check for 24V AC across
the switch.
Reset the switch manually
by pressing the button.
WARNING -
Never jump this
switch!
Switch resets?
No
Yes
Temporary drop in
gas pressure.
Switch is OK.
Gas supply OK?
No
Call the gas company
and correct the problem.
(If the switch was tripped, you will feel a resistance.
The voltage should return at the switch terminals.)
Yes