[Bassjoshua]

I have a Tappan Furnace/ Air Conditioning unit that is giving me trouble. Before I call in a specialist I wondered if it was something I could handle on my own.

The furnace engages, the glow plug heats and then ther 3rd and 4th burners come on. The flames go out immediately, the furnace reengages the 3rd and forth burner come back on.. and this continues 2 to 3 times until the first two burners finally light. I imagine because the thermocouple is on burner 1, and 1 and two don't fire each time.. this is probably why it shuts back down and tries again.

Burner 1 and 2 are the first off the gas main and 3 and 4 are further down so I assume its not a pressure issue.

I'm worried because it's not everytime that this happens.. but when it does I can smell gas in my utility room like it's seeping out and not burning off.

I generally give the flame stick a light cleaning annually so it's not causing the problem.

Any thoughts? Thank You!

 

[how]

The burners have a thin slot (usually) facing the heat exchanger which allows the flame to ignite all the burners together. Yours sounds like its dirty and needs to be cleaned.
If you really have a thermocouple in that furnace then that slot might be facing upwards instead.

 

[Bassjoshua]

Additional questions

I have blown out the pin holes where the gas comes out, as well as the chutes. At this time there is not chance of something being clogged. It continues to happen. and in looking through the chutes and heat exchange "when" all 4 do light I see no build up.

Two things I noticed are:
when all for light simultaneously the hot surface igniter stays on a little longer then when 2 light,

as well as the round thing above the chutes, appeals a little rusty. Could either of theses me a problem?

And is the igniter cleanable by a light sanding as I do my flame stick (Thermocouple)?

 

[Doc Holliday]

thermocouple or flame sensor? a flame sensor is one single metal rod with one wire going to it from the control board (do you have a control board?) that sits in the flame.

either way, the orifice where the gas is distributed is indeed still clogged. Needs to be pulled out and thoroughly cleaned. You can do this yourself but you need to disassemble the entire gas assembly.

There is no other explanation for those first two burners not lighting. I'd also have the a/c tech check gas pressure across the gas valve.

 

[how]

Send picture of the burners and igniter. If one burner lights, they all should light.
The most common causes are , dirty cross over, missalighned cross over, debris obstructed burner diffuser or a dead spider in the burner manifold that is rolling up against inside of a burner orifice.