DIY Home Improvement Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
First, it's a Whirlpool model NUGE105KG01. We've replaced many parts on it over the years, so much of it is new.

The heater will come on, the blower motor runs, and then after a little time, the igniter lights and the flames start. Between 30-90 seconds later though, the flames go off. This cycle will repeat.

We've removed the flame sensor and used steel wool to clean it, as many videos and answers seem to suggest, but it didn't make a difference. I'm not sure what the model number on the flame sensor is, or I'd just buy a new one and replace it since it seems like an easy try(and not that expensive).

This is a video of the sequence in case it may shed light. Any help is appreciated. (it won't let me post it until I've posted a message, so it will follow)
 

·
Hvac Pro
Joined
·
23,688 Posts
The flame sensor is actually part of the pilot burner and you would have to replace the whole burner. That is not the problem or it would not light and run more than a few seconds if dirty.

There should be a combo fan and limit control above the burners with a rotary dial. Post a video of it.

It may be that it is cycling on the high limit control. You can check from the limit side of it to ground to see if it is cutting out and watch the dial rotate.

If it is going up to the 180-200 deg point you may have poor airflow. If it has been cycled hundreds of times it may be weak or inaccurate.

Point is something is shutting off the power to the ignition control and you need to find out what.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #4 ·
Here's a video and pic of the fan limit control. We replaced it about 5 years ago. Far as I can see it's not really rotating much if at all. I'm not sure what the life of those things is.

 

Attachments

·
Registered
Joined
·
5 Posts
Discussion Starter · #5 ·
My thermostat is about 10 years old...what do you think the chances are that it could be that gone bad? (I ask because it's a cheap and easy fix that I could try, and if it doesn't work, no big deal--at least I have a new thermostat)
 

·
Njuneer
Joined
·
1,069 Posts
That limit would take less time to test that you posting your question. Get the meter out and test it. If the high limit is still engaged when it kicks out, make sure you are actually still getting signal from the Tstat. Outside of that, the controller may be at issue. Since I realized my mistake of discussing resoldering the board, just realize that what can happen over time is that board experiences rapid heating from the burner and current to the MV, then cools. That can cause cracks in the solder joints so it would work until it heats up a bit, then loose connection.
 

·
Hvac Pro
Joined
·
23,688 Posts
It does not look like it has warmed up enough to rotate past the limit setting.

You could have a variety of problems.

Your pressure switch may be tripping if it is not getting enough draft or it is weak. Remove the hose from it and poke the hole thru on the furnace where it attaches in case it is plugged.

It may be brittle and break and you may need a new hose so beware. It is high temp silicone hose not rubber or vinyl.

The proper way is to use a manometer and see how much draft you have and compare it to the switch rating if it has it written on it.

You can remove the thermostat wires after labelling them and then jumper R to W. If it keeps running it may be a faulty thermostat.

The ignition control may be failing.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #8 ·
Thanks! We're going to do some of the tests you suggested tomorrow to see if we can figure it out, and if not, guess we're going to have to call someone. (we've always been able to fix it in the past, but this time it's being tricky...)
 

·
Registered
Joined
·
11,139 Posts
It does not look like it has warmed up enough to rotate past the limit setting.
.
It's been a long time since I've seen that particular style of mechanical high limit, so it's a bit fuzzy, and it's hard to tell in the video, but I was thinking it might just be getting up there. I do see the stop pin just past the switch.

The OP should probably test across it for power after it shuts down.

Cheers!
 

·
Hvac Pro
Joined
·
23,688 Posts
It is a White Rodgers and yeah that is a really old furnace and getting past it's prime.

Burners look OK and lots of them rot out at the sides and spew flames sideways.
 

·
Registered
Joined
·
19 Posts
First, check the pressure switch voltage, it should be 0 v if works correct, you also need to check the vent pipe connected with the inducer motor. it may have some obstruction inside.
 
1 - 11 of 11 Posts
Top