Hi everyone,

I have a Heil forced natural gas furnace that was put in in 2005. This is my first year in this house and I have had a great winter with this furnace. Suddenly yesterday I ran into a problem.
The furnace is making wierd clicking noises I never heard before when trying to light the pilot light when the furnace is kicked on by the thermostat. I will list the other symptoms below.

1. Pilot light always lights intermittently after 1-2 attempts.
2. Once lit it will intermittently light the burners but the burners seem to blow the pilot light out and then it tries to relight
3. If it lights again it will run for 1-4 minutes but then shuts down before reaching set thermostat temp.
4. After shutting down it restarts this whole process 5 minutes later or less.

Things I have noticed:

1. The fan blades are clean and the overall condition of the furnace looks good.
2. Filter changed regularly this year since I have been here.
3. Previous heater was installed by owner (he was a HVAC tech)
4. Condensation line was ran too parallel by me so there was condesation not properly draining. ( The line had been cut so repaired by me). No condensation backed up into pump but it was pooling 1 foot downline fully.

Things I have tried:

1. Pulled filter to see if it was an airflow issue.
2. Cut condensation line and ran it straight to a bucket
3. Pulled my hair out

What could be the cause of this???? Winters up here are harsh and I am a mechanically inclined DIYer who doesnt like paying for potentially easy fixes.

Make: HEIL
Model h9mpd100j14b1
Thermostat: Programmable Hunter

 

Dirty pilot orifice, dirty flame sensor, or bad ignition control based on the symptoms.

How does the pilot look before the burners come on? It should look like a small jet and have a strong blue colour.

I think your furnace may have a honeywell smart valve (valve with the ignition control built in); according to others on this board, they're problematic. Wait for more replies to confirm this.

 

If you'd like to rule out the t-stat, remove it from the wall and jumper terminals R and W together.

 

I really doubt its the thermostat. I can unplug the thermostat from the wall and the heater will continue to to run until I return it to the wall. As far as the pilot is concerned.....the flame doesnt look as strong as you speak of but it is blue and fairly large. 1.5 inches long. The thing that is confusing me is how the furnace will run for a short period but then its almost as if there is a back draft of some sort and then the burner flames get shut off/blown out. It tries to relight then shuts off for 5 min before trying again.

In my exaust tube that vents out the side of the house I hear water on start up sometimes gurgling around in there. My heat vent comes out of the furnace makes a 90 degree bend and heads straight out of the house via PVC.

I feel like this still could be related to condensation. I have heard condensation can be a big issue with 90% efficent furnaces. Sometimes it kicks no condensation out until a minute or two into the run cycle. Combine that with the improperly draining tube mentioned in orignal post I think it could be linked.

 

Make sure that the drain on your vent tube is not plugged or partial plugged

Double check your gas pressure.....