Ed P
TVWBB Platinum Member
I bought a replacement burner for my Q 120 and was disappointed in the operation...it was hard to light and, at the lowest heat setting, was too easy for parts of the flame to be extinguished. I compared it with the Weber burner it was replacing and noticed several significant differences, so I thought that I would compare the larger Genesis 1xxx-5xxx burners with aftermarket. Keep in mind that Weber parts are engineered...aftermarket parts are reverse engineered from Weber parts with enough changes to avoid copyright infringement.
The first difference is the venturi area. The aftermarket, a $15 Stanbroil set, is at the top, Weber at the bottom. Notice the Weber venturi is longer and smoother.
The Stanbroil venturi Is not formed well and is a good bit shorter. What does the venturi do? The gas, as it exits the orifice, passes through the venturi and creates a pressure drop, which sucks in oxygen through the air intake behind it. Inadequate mixing with oxygen can lead to weather-related ignition problems (see flammability limits below) and incomplete combustion. Longer and smoother is better. Here is an illustration:
picture taken from https://www.semanticscholar.org/
LPG will only ignite at a specific concentration (flammability limit)... the lower flammability limit is 1.81% and the upper flammability limit is 8.86%. Anything outside of those limits won't burn, and that's why complete mixing with oxygen is important, especially when trying to light a burner when the air is cold, damp and heavy.
Ok, 2nd area of difference is in the burner jets (holes). Here are the differences (again, Stanbroil at the top, Weber at the bottom). Notice the aftermarket manufacturers favor larger jets but fewer of them, possibly to avoid infringement. I'm not going to take the time to do the math here, but my experience with the Q 120 burner is that, if you count up the open area that the burner jets present to the gas mixture, larger/fewer jets have more open area. (And it does add up! With the Q 120 I counted 178 burner jets at about 0.045" diameter for a total opening of 25 square inches, and that's not counting the 2 slot jets). What does that mean? Well, as I've said before, pressure and flow run counter to each other...that is, where you have pressure you have no flow, and where you have flow you have no pressure. So the pressure within the burner is limited by how much gas can squeeze through the orifice. The gas mixes with oxygen, expanding at the same time, and tries to exit through the gas jets. If you have more open area for the gas mix to escape, the gas pressure within the burner will drop. A drop in burner pressure means the flames won't "stand" away from the burner as much, and will be more easily extinguished by a gust of wind at the low end of things, and could lead to the burner getting hotter at the high end.
Lastly, there is a big difference in crossover tubes. Here is the comparison (again, Stanbroil at the top):
The Stanbroil is punched, again larger holes and fewer of them. The Weber's, and this is interesting to me, are actually louvers! There is no material removed, only deformed to the inside where they act like air scoops. Now why would they do that? Probably because it works better.
(I tried to get a good picture of the inside of the tube but my phone kept auto-focusing on another area).
I can understand rehabbers changing out burners as part of the rehabbing processs for the sake of appearance, but for the guys who are building the keepers, the original Weber parts are superior to the aftermarket, and I wouldn't be so hasty to put an inferior product in its place. It costs more for a quality product. Just my $.02.
The first difference is the venturi area. The aftermarket, a $15 Stanbroil set, is at the top, Weber at the bottom. Notice the Weber venturi is longer and smoother.
The Stanbroil venturi Is not formed well and is a good bit shorter. What does the venturi do? The gas, as it exits the orifice, passes through the venturi and creates a pressure drop, which sucks in oxygen through the air intake behind it. Inadequate mixing with oxygen can lead to weather-related ignition problems (see flammability limits below) and incomplete combustion. Longer and smoother is better. Here is an illustration:
picture taken from https://www.semanticscholar.org/
LPG will only ignite at a specific concentration (flammability limit)... the lower flammability limit is 1.81% and the upper flammability limit is 8.86%. Anything outside of those limits won't burn, and that's why complete mixing with oxygen is important, especially when trying to light a burner when the air is cold, damp and heavy.
Ok, 2nd area of difference is in the burner jets (holes). Here are the differences (again, Stanbroil at the top, Weber at the bottom). Notice the aftermarket manufacturers favor larger jets but fewer of them, possibly to avoid infringement. I'm not going to take the time to do the math here, but my experience with the Q 120 burner is that, if you count up the open area that the burner jets present to the gas mixture, larger/fewer jets have more open area. (And it does add up! With the Q 120 I counted 178 burner jets at about 0.045" diameter for a total opening of 25 square inches, and that's not counting the 2 slot jets). What does that mean? Well, as I've said before, pressure and flow run counter to each other...that is, where you have pressure you have no flow, and where you have flow you have no pressure. So the pressure within the burner is limited by how much gas can squeeze through the orifice. The gas mixes with oxygen, expanding at the same time, and tries to exit through the gas jets. If you have more open area for the gas mix to escape, the gas pressure within the burner will drop. A drop in burner pressure means the flames won't "stand" away from the burner as much, and will be more easily extinguished by a gust of wind at the low end of things, and could lead to the burner getting hotter at the high end.
Lastly, there is a big difference in crossover tubes. Here is the comparison (again, Stanbroil at the top):
The Stanbroil is punched, again larger holes and fewer of them. The Weber's, and this is interesting to me, are actually louvers! There is no material removed, only deformed to the inside where they act like air scoops. Now why would they do that? Probably because it works better.
(I tried to get a good picture of the inside of the tube but my phone kept auto-focusing on another area).
I can understand rehabbers changing out burners as part of the rehabbing processs for the sake of appearance, but for the guys who are building the keepers, the original Weber parts are superior to the aftermarket, and I wouldn't be so hasty to put an inferior product in its place. It costs more for a quality product. Just my $.02.