I've read that it may have nat gas orifice making it burn rich.
If new to location, verify lable is for LP and gas pressure. If NAT, contact a service agency for install and conversion.
Yellow flame indicates improper fuel air mix. A lack of oxygen. This can be a gas problem, a carburetor/burner problem, or a venting problem.
Gas Problem; Use a Manometer to measure the pressure. 11 inches water.
I forgot to mention a not fully opened gas supply valve. Sorry bot that.
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