Gas furnace question - don't know where to ask?

[theanimala]

So I recently moved and I have been having an issue where my furnace will turn on and start heating but after a minute or two you can hear the fire turns off (blower is still working) for another minute or so and then the flame kicks back on for another minute before turning off again.

I called my local utility company (I have it covered under their warranty) and they said it's because the temperature sensor is turning off the flame due to heat. I don't believe the previous owner cleaned the filters often and even though they are clean now they said the AC coils in the ductwork behind the furnace are most likely clogged. Because of this the machine has to keep cycling the heat. They said it is not dangerous but it is not very energy efficient. They made it sound like I would have to replace the furnace in order to clean the coils. Does this sound right?

Not sure who I would call to try to clean it and what a reasonable charge would be. Any of you smart people have any advice?

 

[SpatiallyAware]

You definitely don't have to replace it to clean the coils, but it could be a mega PITA. You could replace it with a really cheap (but CLEAN) blue filter just to see if it runs correctly.

It's under warranty...? I would make them come out and show you the problem.


For what it's worth it sounds like a flame sensor to me. You might try googling the furnace make/model and 'clean flame sensor' to see how to clean it.

 

[jagec]

If it's covered under warranty, there should be NO charge. If they decide to replace the whole unit when a simple cleaning would have sufficed, that's on them, not you.

 

[SpatiallyAware]

If it's covered under warranty, there should be NO charge. If they decide to replace the whole unit when a simple cleaning would have sufficed, that's on them, not you.

I have a feeling that they're claiming the unit isn't broken, just that it wasn't maintained properly thus isn't as efficient as it could be.

 

[TWG1572]

Our water heater did the same thing and it was the flame sensor. Is there a blinking code light going? It should help you narrow down the issue.

When our water heater did it, we simply had to rub the sensor down with a scotchbrite pad to get the oxidation off and it would be good for another 1-2 years. Less cheap people than I would probably replace it, but there was no guarantee the new one wasn't going out in 2 years again anyway...

Edit: be careful because they could try to go down the no preventative maintenance = no warranty route.

 

[notty22]

I have Guardian Care insurance on my Gas/AC furnace also. I was getting cycling , and it would start to fire but not. It was a vacumn/solenoid that checks for exhaust venting. It could have been electrical or the rubber gasket dried out in it. Theres a few safety checks/ solenoids that have to trigger.
Sounds like I would ask for a different tech. If he did not change anything, it will probably progressively get worse.

 

[HardcoreRobot]

i was gonna say flame sensor too. on my unit, all I needed to do waspull off the panel, unscrew on screw holding the sensor in place, pull out the rod, run some sandpaper over it and no problems ever since (couple years ago).

 

[BurnItDwn]

Had similar issue, and it was indeed a dirty flame sensor. Sanded it a little bit, and worked like new... On Dec 25 2012, had an issue where the ignitor wouldn't even light. That was an expensive service call (can't buy ignitor from 7-11 which was pretty much the only open store).

 

[SpatiallyAware]

I have managed a number of home hvac units, and in my experience they're very easy to maintain yourself.

Find the manual and take it apart to clean the coils. At that point you'll have seen pretty much everything on the inside of the unit. If it's ~10 years old then it's overdue for a cleaning anyway.

Nowadays with the internet they're not hard to repair yourself, other than discharging/refilling the system.

 

[dullard]

In my experience it is probably the flame sensor or something is wrong with the exhaust.

If the flame sensor is bad, then the fix is easy to do yourself and cheap. Might as well just try that. If you are lucky and have a common furnace, then any home improvement store will have a flame sensor for your model for ~$15. Or you can order one online pretty easilly.

If that doesn't work, then I'd call a professional HVAC repair company. The exhaust could be blocked (dead bird/squirrel or leaves). The exhaust pressure sensor could be bad. The exhaust fan could be going out. The exhaust seals could be bad. Or possibly the circuit boards have gone bad. Since there are so many things to check, hire someone who has a single fixed price for diagnosing the problem (probably ~$100 give or take depending on your area) rather than someone who charges by the hour (this may take 3 hours at ~$100/hour).

Also, if the exhaust system is bad, that could potentially be life-threatening. Don't delay.

I don't see what the coils being clean/dirty has to do with your complaint.

 

[theanimala]

Thanks everyone for the great advice. The unit is about 15 years old and I highly doubt it's been cleaned out. I will try to find some service manuals online to see what I can do myself, if not I agree it's time to call someone to clean/service the unit.

 

[edro]

I have had the exact same issue at 2 different houses.
1. It was a blocked exhaust on a natural gas furnace. The exhaust was fed into the unused chimney. The chimney didn't have a cap on it, so it filled up with debris and leaves. Once I took the exhaust pipe off and cleared the blockage, it worked fine.

2. Second issue was with my current propane furnace. The propane line regulator went bad and wasn't supplying a solid flow of propane. It took a ton of service calls before they pinpointed it. It was the regulator right next to the house, not the one on the tank.