LP to Natural Gas Conversion- Fail - BBQ Central

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Old 06-03-2013, 11:46 AM   #1
Join Date: Jun 2013
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Unhappy LP to Natural Gas Conversion- Fail

First off, what a great site. Incredible resources here. Thanks for that!!

So I have a Kenmore grill that's about 6 years old. Sears told me that even though it's not officially listed as capable of being changed from LP to NG, that it would work. So I bought the kit. I replaced all the burners and the heat diffusers (mine were cracked and rusted out), and I switched out the orifices. What my grill seems to lack in regard to the Kenmore instructions is the ability to turn the valve stem counter clockwise twice. I tried this on the side burner and the brass valve stem broke. So I’m guessing that part can’t be done. And I think that is the root of my problem.

When I turn the grill on to light it I can tell that there is a HUGE amount of gas coming into the grill. It’s significantly louder than when it was on propane. And with the air shutters open 1/8th of an inch per Kenmore instructions they won’t even light. When I close the shutter all the way they do light up instantly, but the flame is bright yellow and about 2.5-3 inches in length. Not good. Even turned down to low they are still bright and still longer than 1 inch.

So I used the T-Valve coming from the house to lower the flow of gas thinking that would help. And it did. A bit. But while the grill heats up to 600 degrees, it’s behaving more like an oven than a grill. The grates just don’t heat up well. It took nearly 30 minutes cook a very small salmon filet that usually takes about 13 minutes.

I’m guessing that I’m just getting way to much gas coming into the grill. Some research suggests that a NG regulator may be necessary? Before I dump any more money into this old grill I'd like to know if that could work. I'm already into this thing for about $300 in the kit and the replacement burners and heat diffusers.

Any suggestions would be appreciated.


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Old 06-03-2013, 01:38 PM   #2
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Your getting more gas coming in and it's not cooking as fast? Something doesn't seem right.

I hope this isn't negative!
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Old 06-03-2013, 02:27 PM   #3
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obviously. the Kenmore instructions say to close the air shutter down to 1/8th of an inch for NG. But it won't light at all with that much airflow. It will light only if I close the shutter off entirely.

And the more I think about this the more confused I get. I know i have a ton of gas coming in, but the flame is yellow.

With the shutter still closed I lowered the amount of gas that I had coming in and the flames got more blue. but the temp at the grates went down.

Crap. I think I may have figured this out. I have plenty of gas, and not enough air. I need to open the shutter to let more air in to accommodate for the large amount of gas.

But that does not explain why it wouldn't light at all at 1/8th but will light when the shutter is completely closed.

I have 4 burners. When I get home tonight i'm going to leave one closed, one open 1/4 of the way, one open half way, and one open all the way and see what happens.
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Old 06-04-2013, 06:33 AM   #4
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Can you call the service man from the gas company? The orifice for natural gas should have a larger hole in it than the orifice for the LP. (I used to do this stuff for a living in a former life...) Can you post pictures of the orifices and the heat diffusers, shutters, etc?

These problems are why I use wood and charcoal, plus, I can't blow up the neighborhood using wood and charcoal (and food tastes mo-betta, too).
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Old 06-04-2013, 10:26 AM   #5
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The orifices are the 1.37 ones that Kenmore sold me. They are larger than the LP ones I removed.

When I tried to open the air shutter to full, half, or quarter it wouldn't light. So I turned the gas down at the t-valve from the house.

I got the burner that has the air shutter open fully to light when I barely had the gas on. But as soon as I turned up the gas at the t-valve you could see it blow out the flames. Same with the half open and quarter open shutters

I'm convinced now more than ever that the gas flow coming from the house is WAY too high for that grill.

I'm back to thinking that a NG regulator will do it. ????

I'll try to get some pics when I get home.
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Old 06-07-2013, 10:26 AM   #6
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Okay, so I think it's working!!!

The 3/8 inch hose that I had from the house with no regulator was replaced with a 1/2 inch hose and a regulator. With the air shutters opened 1/4 of an inch I get tight blue fame about an inch long. The grill easily reaches 600 degrees now and the grates are actually hot!!
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Old 06-07-2013, 06:26 PM   #7
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Nice! Good job finding the solution, now it's time to cook!
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Old 06-10-2013, 02:40 PM   #8
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