New finding on LP to NG conversion

So I was experimenting today with my Genesis 2000. I have been meaning to put it on NG from LP and get it moved to my deck. Many things got in the way and it was more convenient for a long time to leave it on LP. Today I finally did it. So I did a quicky clean up on it and against everything I have told people about this I simply slapped a set of orifices in it. I did it knowing full well low/medium settings will be off a little bit but I figured since I KNOW this it's not an issue as I can figure out how to compensate for it safely. But I also did one other thing. I used orifices I had set up for a "regulated" supply IOW about 4" WC, but I instead put it on full line pressure since I did not want to be bothered with it. Knowing full well once my garage is cleaned out and winter hits in full I may decide to bring it back to the garage on LP and I didn't want to be bothered with a lot of extra work.
So here is what I discovered. By running it on size 53 (.0595") orifice it is just a hair hotter on full blast but not unmanageably so. Just made it up to full temp a hair faster and a hair over running it one size down and regulated. So now I get to trying low/med settings and it works fine. So again this is PURELY EXPERIMENTAL so I am NOT fully endorsing this, but, it seems to be working just fine and I intend to do a slab of ribs this evening on it and I will report back here what happens.
If anyone close by hears a loud boom and a mushroom cloud........................................well send help and maybe some dinner too as it means my ribs are ruined
Again this will ONLY work if you're running unregulated AT THE GRILL and you have solid flow at a full 7" WC at your connection. Both of which I have verified
What I can tell you is doing this in reverse NG grill to LP is definitely not as "easy". I know I have done it and the low setting is definitely too hot along with medium. Again if you KNOW it going in it's NOT dangerous simply something you need to "compensate" for by juggling burners off and on where you normally might not have to.

You mention that you've messed with NG to LP. Did you try adjusting the LP pressure? It seems to me that the whole NG unit would be setup with the same ratios as far as settings and orifices go. Seems like 2, 3 or 4 psi on LP might not work too bad. Any insight on that?

LMichaels said:

I used orifices I had set up for a "regulated" supply IOW about 4" WC, but I instead put it on full line pressure since I did not want to be bothered with it. Knowing full well once my garage is cleaned out and winter hits in full I may decide to bring it back to the garage on LP and I didn't want to be bothered with a lot of extra work.
So here is what I discovered. By running it on size 53 (.0595") orifice it is just a hair hotter on full blast but not unmanageably so.

Click to expand...

So for 4” WC, what is the orifice size you should be using? According to this table, it is 51 for 4” WC and 53 for 7” WC with 12000 BTU burners which I think is what is on the Genesis.

What do you use to measure your gas pressure? Have you ever noticed that it fluctuates when you are using other devices in the house (e.g, boiler, dryer, stove, etc)?

I use a simple Manometer. As for fluctuations I have not noticed much if any. However I don't have that much in series with the outdoor connection. I don't have a gas dryer any more, My water heater, while it is a demand style and can draw up to 199900 BTU all my outlets are low flow, I have a HE washing machine that does a whole load of clothes with something like 7 gal water total, my dishwasher uses something like 4 gal total for a load and my gas range never sees more than a fraction of it's full gas draw. Even my furnace has gone down from a 125k BTU draw down to a max 80k and even that modulates so would never draw full amount unless it was so cold out there I would never bother with my grill(s) anyway. The ONLY thing I have not tried is running it with the Wolf going wide open as the Wolf draws from the same "tap". So there may still be an issue where it calls for me to modify the valves to operate in it's full range. That's why I am "hedging" on my report. Also I apologize I got cross eyed looking at the chart. I meant a 51 size which full open at 7" is ~13k BTU
So it runs just a hair hotter and faster to temp BUT it will throttle down safely. But again the caution here is it needs full 7" WC not the 4" if it has the regulator. Bottom line it's trading a little higher top end so the bottom end keeps gas going.
Again beware I have NOT fully "vetted" this setup under all conditions yet. This is all preliminary as I was fully expecting this to NOT work and I did it only because I wanted to be able to just pop out the orifices and reinstall the LP hose if I want to put the grill in the garage this winter. So truly I am being VERY cautious here as I don't want anyone to start being angry with me and doing the "you said it would work now I have no eyebrows" thing.
Again I stressing that I KNOW there may be a safety issue and I am operating on that knowledge. Unlike some of the clowns on the internet who say "oh just do this or put these parts in and magically it works" I am being VERY VERY cautious. The reason being is if you run down to low and you have a flame out or partial flame out you could have a SERIOUS issue. A partial flame out could cause a large buildup of unburned gas. You open the lid to check what you're cooking and because of the change in air flow that unburned gas hits a part of the burner(s) still burning and BOOM. I had this happen to me on an old gas stove. Let me tell you when you open that oven door and there is a sudden ignition it is quite the adventure!

My Genesis Silver C NG came with 50 jets and specified 7". I would think that 51 jets at 7" should run pretty well. My LPG genesis hasn't been able to run on low for 5+years. Really not a big deal. Once you figure out how low you can actually go without a flame out, just keep it above that setting. I just cleaned the gunk out of the valve bypasses this morning, and low runs real steady now.