B13 - checking the low gas pressure switch, Checking the low gas pressure switch, Section b13 - low 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 Low Gas Pressure Switch
The low gas pressure switch is a 24V manual reset switch that acts to cut
power to the gas valve if the gas pressure is too low for proper operation.
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
greater than 3” 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
Test the switch. See Section B14
Replace if necessary.
B13