Orange flame on FMS-117t/118t stove

[J C]

OK so in another thread I detailed how I merged a Fire Maple 118. Anyway long story short I fired it up and the flame starts blue but quickly turns a deep orange. It's still blue at the holes but the rest of the flame is very much orange. I swapped the parts back over and same thing, so it's not a result of the mod I don't think. The 117 (no pre-heat tube) does not do this.

The section that seems to be making the difference is the fuel-line/pre-heat tube/base piece. Also the fact that it happens after about 20-30 seconds leads me to think something about the pre-heating is going awry, but I don't know enough about stoves to figure it out.

I'm assuming that something is wrong and I should ask for a replacement, but wanted to check here first. What do other 118 users report?

EDIT: Sorry been getting confused with numbers. The 118 is the stove with the issue, the one with the pre-heat tube. The 117t doesn't have a preheat tube and works fine.

EDIT 2: After some digging I found a post by Stuart R stating "The cause is not the temperature of the pre-heat tube (it only needs to be warm for the fuel to vapourise) or the length which is in the flame (it does not even need to be IN the flame to get warm). Indeed, if the pre-hea tube gets too hot you will see o different effect which gives an orange flame." My new question is: should I be worried about the orange flame?

[Roger Caffin]

I don't THINK so.

I did measure the CO emission for orange flames and there did not seem to be much effect.

What you could do is bend the preheat tube away from the flames a bit. I THINK what you are seeing is free carbon atoms in the fuel due to the preheat tube being too hot and breaking the butane/propane down before it reaches the jet.

I THINK. Inspired guessing.

Cheers

[J C]

Thanks Roger!

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