Flame on main hob of range master 110 is yellow and smelly also black sooty deposit left on jets

have this done by a gas fitter as it is not just a matter of different jets but also an adjustment of the air shroud around those jets to obtain a clear flame at the flame rings (hobs)

I presume you're talking about a gas furnace, even tho the title says Rheem gas water heater. Either way, it works the same for both.

Any black coloring on the heat exchanger is *not* from overheating. Black is from a sooty flame caused by a mis-adjusted burner. (In fact, a sooty flame is less hot). There is an adjustable "air intake plate" for air to enter the burner where the gas enters the burner. A proper flame is made by adjusting this air opening so the proper gas/air mixture feeds into the burner. If the air vent is closed too much it produces a sooty flame.
The age of the furnace is the most important aspect, and that helpful to determine a likely condition of the heat exchanger and burners. Other than a badly adjusted flame, the main thing to watch for is a badly rusted out heat exchanger. But black does not mean rust.

This is probably the result of inefficient burning of gas resulting in sooty deposits being left on the base of saucepans etc. It may be that the gas jets are blocked with spilt material and need cleaning. Try removing the gas hub with the gas jet holes in and sliding a paperclip sized rod into each hole to dislodge any material. Blow in the holes afterwards to force any loose material out. If this fails you may need a gas fitter to adjust the gas mixture regulators.

I would call a gas installation engineer as to me the pressure sound incorrect.
Safety is paramount with gas.

Bad gas pressure will cause sooty deposits

Lack of air to burn will cause this . air mix on burner needs adjusting . crack or leak on burner would upset flame . burner could need cleaning .

Sounds like a regulator issue. A very uncommon issue with bad propane could do that as well, but not likely. It won't hurt to pull out the burners and clean them. clean and inspect all fittings, try once more, then look at replacing the regulator. Farmerbear at FixYa.com

Have to adjust the piolot lights for the amount of gas coming out. U have too much gas coming out(yellow flame). On older gas ranges, there was a small screw between the piolot light & burners that had to be adjusted. (if this is a older model) have to turn the screw just a little at a time, till ur flame returns to blue on ur burners. Hope this helps.

the flame safety device need replacing (FFD)... this lets the full gas through when flame is sensed... safety 1st as a gas engineer will be required..

you can phone rangemaster helpline on 08707 895 107 spare parts or tech team.