Conversion from propane to natural gas


 

Tommy M

New member
I got a brand new Weber Genesis II S-310 Stainless propane grill for half price.

I bought it thinking it should not be hard to convert to natural gas.

I looked up the size of the drill bit required for making the orifices the correct size for around 12,000 btu on each burner using natural gas. Used number 53 drill bit. The grill is rated around 38,000 btu.

Just hooked up the grill to test and it seems that the fire is too small.

Are the valves different on propane grills versus natural gas grills?
 
This is not a job to be taken lightly. In some cases YES the valves are SLIGHTLY different and in others no they're not. Part of being successful is knowing which you have and how to do the mods PROPERLY. You cannot just go blindly on this. You can cause poor performance or worse HUGE safety issues plus know you have now voided the warranty so it is DOUBLY important you just don't go willy nilly doing something like this
 
I don't just do anything "willy nilly".
I explained how I got here.

I asked one simple question.

Are the valves different on propane grills versus natural gas grills?

Specifically on my Weber Genesis II.

I would appreciate it if anyone who is knowledgeable about my question can answer it.
 
Tommy, this thread might help you...

https://tvwbb.com/showthread.php?77007-E-320-Genesis-conversion-Natural-Gas-over-to-Propane-!!!

AFAIK the orifices on the NG are larger than the propane ones...I could be wrong though. LMichaels has a wealth of knowledge on gas conversions and he is the go to guy for this kind of stuff (and other stuff as well). I believe by modifying your manifold you have voided the warranty but I'm guessing that was a risk you were willing to take...? I do hope that thread helps you out though. Good luck!
 
Hey Tommy... could you please post your model number from the sticker on your Weber and post it here. I'll try and help you if you like, thanks
 
Picture of Label

Apparently I cannot post pictures.

Info on label:

Part number 61000001
Serial number GN50883XX
XX is for privacy reasons
37500 BTU
Gas pressure 11" WC
 
Thank you for the chart link.

That is the same chart which I used.
#53 drill bit at pressure of 7 should yield ~12000 btu per burner. There are 3 burners, so 36000 btu is just under the rated 37,500 btu of the grill.

How do you even know you have a pressure of 7" WC? Do you have a manometer? Know how to use one?. Like I said just hogging out orifices without KNOWING what you have to begin with is not the best way to do things. If you don't know how to use one or don't have access, score yourself a regulator. They typically come set for 4" WC but are clearly marked. This way no matter what you KNOW your pressure and it helps even out pressure variations due to varying loads on the gas line and especially if the outlet is at the far end after all appliances have had their fill of gas
This is all homework you HAVE to do to make sure it's done correctly and SAFELY and had you read any of the posts I have done to help guide people through this you would see I always start with "know the pressure FIRST" than make the changes
 
Hey Tommy, I have a post 2010 S-310 NG that i am looking to convert to LP, would you be interested in trading orifices? That should take care of the main burners for both of us. They should be interchangeable if i'm not mistaken, but maybe LMichaels could chime in on that.

Ooops, just realized you already drilled yours, my bad.
 
Last edited:
E-330 LP to NG conversion

Hi. I just picked up a Genesis E-330 3-Burner Propane Gas Grill (Model #: 6537001), originally purchased from HD in 2015. I’d prefer to use the NG line installed at our house (previous owners had a Napoleon connected).

Between this and other forums, and YouTube, the conversion is as simple as drilling out orifices to swapping out the entire manifold, adding a regulator, and making an adjustment to the knobs.

I believe LMichaels above referenced a guide for performing the conversion (I understand this is not sanctioned by Weber, and will void any warranty) - I’m just interested in getting my grill working, and doing it safely and properly.

Any guidance or advice is much appreciated.
 
Too bad yours is a three burner. I have a NG manifold I would give you, but it has the 4th sear burner. Actually, I think your firebox has the opening. It is just covered with a plate. It would take a new front panel and other parts, though.
 
Jon If he has a 330 it has the 4th burner. Plus a side burner. So if you have a NG manifold for use by a sear burner type Genesis unless he's got his models wrong it will work. As for the original question if he has the easier to work with variable valves then simply swapping in NG orifices is just the ticket. The OP need only to decide and determine A what is current gas pressure at his outlet and B does he want to use a regulator on the grill. Both decisions will effect the final size of orifice to use. IIRC the Genesis has a built in regulator on the NG models so your manifold would only require he buys a NG regulator and he's golden
 
A question for Larry..... Our house has NG. It feeds 2 HVAC furnaces, kitchen stove, a fireplace, and My Genesis. I've noticed a slight dip when the stove or grill first lights, but recovers the pressure in one to two seconds. Should I have the gas company come out again to check the meter & pressure reducer or is that normal? Both I believe to be about 24 years old. The stove and Weber are at the far end of the house (about 60 ft) from the meter. Everything runs fine, but it is noticeable especially with the stove burners.
 
Some dip is normal. Though here at my own home, my grill outlet(s) are at the far end of the line. At the head of the line is my 75k btu furnace and tapped off that line is my 200kbtu tankless water heater. Prior to the 75k furnace I had a single stage 125k btu furnace. So when it turned on it was a full 125k. The water heater is staged based on flow but I don't know how low it goes only that it can draw up to 199,900 BTU. Though even with every tap on in the house I have never been able to outrun it. The new furnace is only 75k but even during the coldest blast we had last winter it never ran above 63% output and only for a short time typically only running at 40% output for the most part.
Further down the main line is my kitchen range. At the far end is the final connections one to my fireplace (40k btu max but I only run it on low) and my grill taps. One for the Genesis and one for the Wolf. If I turn on both grills full blast I will see a slight dip in output but not much. My main gas feed is 1" pipe so perhaps I have more than enough volume. Also odds of having everything go full bore all at once are slim.
If the slight fluctuation bothers you, you could add a regulator to the grill (if it doesn't have one) to reduce running pressure to 4.3" WC and even out the flow but then you'd need to rejet the grill to compensate
 

 

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