How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Bill Your Own Question
Bill, HVAC Technician
Category: HVAC
Satisfied Customers: 318
Experience:  15+ years service tech.
Type Your HVAC Question Here...
Bill is online now
A new question is answered every 9 seconds

My Ruud gas furnace model UGPH-10EAMER was cycling but not

Customer Question

My Ruud gas furnace model UGPH-10EAMER was cycling but not igniting. I replaced the igniter and now it isn't cycling at all.
Submitted: 7 years ago.
Category: HVAC
Expert:  Bill replied 7 years ago.
will the blower fan come on if you put the thermostat "fan" switch to the on position?
Customer: replied 7 years ago.
No. Before replacing the igniter, the draft blower motor was coming on for the purge, the igniter was not lighting and it was shutting off. After replacing the igniter, nothing is happening.
Expert:  Bill replied 7 years ago.
make sure the lower door of the furnace is properly in place, if it is not the safety switch will not be engaged and the furnace will not work.
Customer: replied 7 years ago.
That switch seems to be engaged with the cover closed and when it is engaged, there is a definite humming sound which seems to be coming from the lower box.
Expert:  Bill replied 7 years ago.

sounds normal, the only thing replaced was the ignitor?

have your double checked all the other wires to make sure they were not accidentally moved or disconnected?

you can try to connect the red (R) and the white (W) at the back of the thermostat and see if the furnace starts.

is this a battery operated stat?

Edited by Bill on 2/7/2010 at 8:45 PM EST
Customer: replied 7 years ago.
All the wires are tight. The thermostat is battery operated but I replaced the batteries. I have volt meter. Is there somewhere I can apply the voltmeter to see if its getting power? I'm pretty sure it is. Is there something upstream from the ignitor that might be failing? The fan has to go on first, right?
Expert:  Bill replied 7 years ago.

try to remove the batteries for at least 6 min. than reinstall, this will rest the stat.

the first thing to stat will be the inducer fan motor than after apox 45 sec. the ignitor should start to glow.graphic

Customer: replied 7 years ago.
I tried taking the batteries out. Thermostat has 4 wires. Is it on house power with a battery back up? I tried putting the red and white wires together. Nothing. Put it back to normal. Nothing.
Expert:  Bill replied 7 years ago.

this does not make sense.

you can try to go to the furnace, remove the lower door, than try connecting the R and the W , where the stat wires connect, than hold the door safety switch in and see if it starts any thing.

Bill and other HVAC Specialists are ready to help you
Customer: replied 7 years ago.
They seem to go through the safety switch and then run to a pretty complicated circuit board. I don't see any way to hot wire that and not sure I want to. It looks expensive. I guess I'm going to have to get a repairman.
Expert:  Bill replied 7 years ago.
sorry we could not go further.