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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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hOW DO YOU LIGHT THE PILOT OF A RUUD FURNANCE

Customer Question

hOW DO YOU LIGHT THE PILOT OF A RUUD FURNANCE?
Submitted: 6 years ago.
Category: HVAC
Expert:  Douglas replied 6 years ago.
Hi, I'm Douglas and I am here to help you resolve problems with your heating and cooling equipment.

We may need the serial number so we get the right control instruction but let me see real quick.
Customer: replied 6 years ago.
sER #bn3d207f41857188
Expert:  Douglas replied 6 years ago.
That furnace has an automatic ignition system. When a call for heat comes, the inducer motor (the one that blows the combustion gasses out the plastic pipe) starts, the vacuum produced closes a pressure switch and sends voltage to the Honeywell ignition module which should start a sparking at the pilot and energize the gas valve.

Does the inducer motor start with a fresh call for heat? (Cycle the power off and then back on, and turn the thermostat up so it calls for heat).
Customer: replied 6 years ago.
how high should we turn the thermostat?
Expert:  Douglas replied 6 years ago.
just above the room temperature.

Make sure the breaker to the furnace (in the breaker panel) is turned on and the blower door is firmly in place.
Customer: replied 6 years ago.

the blower is running but it has not kicked in.

Expert:  Douglas replied 6 years ago.
Ok which blower, the main circulating blower or the inducer one?
Customer: replied 6 years ago.
the inducer fan and it's getting hot.
Expert:  Douglas replied 6 years ago.
Ok..it may get warm, but shouldnt get hot unless it's been on for quite some time. Do you see a rubber tube leading to a pressure switch from that inducer?
Customer: replied 6 years ago.
yes
Expert:  Douglas replied 6 years ago.
ok... before doing anything there, go out to where the furnace flue pipe sticks out the wall and see if there are any obstructions in the pipe (ice, nests, toys etc). If there is anything clear it out. Leave the furnce inducer on, it should be blowing out that pipe
Customer: replied 6 years ago.
nothing is blocking this...there is air coming out.
Expert:  Douglas replied 6 years ago.
Ok... back to the pressure switch. Remove the hose and blow the hose out to make sure it doesnt have any water in it. Probe the port where the hose connects to the inducer to make sure it's not blocked. Inspect the hose to make sure it's not torn, or has any pin holes in it and reconnect it just to the pressure switch.

Cycle the furnace off and back on. When the inducer starts gently suck in on the hose to see if you hear the switch click. Hold it and see if it goes through the ignition cycle.
Customer: replied 6 years ago.
what do you mean hold it? plug it with my finger?
Expert:  Douglas replied 6 years ago.
Or pinch it off, just make sure it doesnt lose the vacuum and click again.
Customer: replied 6 years ago.
I plugged it and did not hear any click.
Expert:  Douglas replied 6 years ago.
not even when you sucked in on it? You didnt hear the pressure switch click?
Customer: replied 6 years ago.
no. however, when I suck on it and turn it on, it does not turn on until I let air into the hose.
Expert:  Douglas replied 6 years ago.
yes, you have to let the inducer start before sucking in on it.

Customer: replied 6 years ago.
no it does not click.
Expert:  Douglas replied 6 years ago.
Ok...

Put the hose back on.

Turn the power to the furnace off. remove the two wires from the pressure switch. Hold them apart and turn the power back on. After the inducer starts, hold the two wire ends together and see what happens.
Customer: replied 6 years ago.
what is a pressure switch...the inducer?
Expert:  Douglas replied 6 years ago.
the inducer is the small blower. The pressure switch is at the other end of the small rubber hose leading from the inducer. Its a small round disk about 2-3" in diameter with a rubber hose connecting to it.
Customer: replied 6 years ago.
the furnace does not turn on with the two wires unplugged,
Expert:  Douglas replied 6 years ago.
I am going to opt out here. Be sure to put them back on how you found them. I think we've tested what we can but maybe one of the other guys can help further. It may be ideal at this point to call a service tech.
Customer: replied 6 years ago.
Thank you,