High-Efficiency Commercial Gas Series - Service Manual
Technical Literature Department
24
Ashland City, Tennessee © 2008
Servicing should only be performed by a Qualified Service Agent
CONTROLS – PRESSURE SWITCHES (cont)
Top View of Pressure Switches
BLOCKED INTAKE AIR
PRESSURE SWITCH
M ODEL PRESSURE
M ode ls 120 - 199
Natural -0.65”WC
LP -0.85”WC
M ode l 250
Natural -0.85”WC
LP -0.85”WC
Norm ally Clos e d /
Ope ns on a Fall in
Pre s s ure
Tole rance +/-.05”WC
LOW GAS PRESSURE
SWITCH
M ODEL PRESSURE
Natural +4.0”WC
LP +8.0”WC
Norm ally Ope n / Clos e
on a Ris e in Pre s s ure
Tole rance +/-.05”WC
BLOCKED EXHAUST
PRESSURE SWITCH
M ODEL SWITCH
120N +1.2”WC
150N +0.98”WC
199N +1.06”WC
250N +4.0”WC
120LP +1.3”WC
150LP +1.3”WC
199LP +4.0”WC
250LP +2.0”WC
Norm ally Clos e d /
Ope n on a Ris e in
Pre s s ure
Tole rance +/-.05”WC
BLOWER PROVER
PRESSURE SWITCH
M ODEL PRESSURE
All +0.75”WC
Norm ally Ope n / Clos e
on a Ris e in Pre s s ure
Tole rance +/-.05”WC
