Summit 650 Rebuild and Conversion from LP to NG, including spool valves.

[SteveRichards]

I bought a well used Summit 650 LP for cheap. It won't arrive for a couple days. It's an older model with 6 burners + wood box + infrared but no sear section. No pop up rotisserie either, just a mount for the conventional one.

I have 2 Weber Genesis (SIII?) 3XXs, one LP, one NG.

The first 300 Genesis is a side control LP with a side burner. This is a parts BBQ. The cabinet is rusted out and it is missing the flavor bars and grill. It got it for free. I was/am going to use the top part to make a slide out BBQ for my RV. I don't need the base.

The second is a Genesis 310 front control NG without a side burner. It is in good shape, needs no work. I'll sell it when my 650 is done.

I want the 650 because I used my divorced friend's 470 for the last 2 years. He recently found a new place that allows BBQs, so he wants his 470 back. I like 2 things about the Summits over the Genesis - the smoke box and the infrared heater. I live in Canada and it gets cold here and the infrared heater is a great addition at times.

I don't really need all the cooking area that the Summit has. I'd prefer a 470 but beggars can't be choosers.

I know about the cook box rot on the Summits. I'm hoping mine isn't too bad. If it is bad, I have a collection of SS sheet metal as well as a welder that I'll use to rebuild it. I think the grill is in good shape, not sure about the flavor bars, I'll see when it gets here.

I want to convert it from LP to NG. I know that the orifices and the valve spools are different (larger)on the NG models compared to the LP models. The NG needs larger holes in both the orifices and the valve spools. I intend to take apart my Genesis BBQs (one LP , one NG) and measure the orifice and spool valve holes and then drill them out to the same size in my 650. Or calculate what size they should be on the 650 and drill them to that.

Question: are the burners, controls and flavor bars the same on a Summit as they are on a Genesis, just more of them ? I know the smoke box burner and the smoke box and infrared heater valves are different.

Question: has anyone else drilled the orifices and spool valves to convert a Summit from LP to NG ?

Question: what NG pressure does a 650 Summit use ? Same as a Genesis ?

Question: what if, instead of drilling the orifices and spool valves, one ran the NG at a higher pressure ? I believe my NG supply pressure is 11 WG.

If anyone wants to swap a NG valve assembly for an LP valve assembly and regulator, let me know.

 

[LMichaels]

The Summit used a NG regulator and IIRC operated at right around 4"WC (I have no idea how that is measured in metrics though). However if you FULLY understand the dynamics of gas, most of your questions would be "self answered". All I can tell you is proceed at your own peril. You may or may not be successful.
But, quite honestly, I'd be looking over some gas flow charts and such.
I have a tendency to be "blunt" but just about anyone here can tell you the bluntness comes with honesty.
Good luck.

 

[SteveRichards]

The Summit used a NG regulator and IIRC operated at right around 4"WC (I have no idea how that is measured in metrics though). However if you FULLY understand the dynamics of gas, most of your questions would be "self answered". All I can tell you is proceed at your own peril. You may or may not be successful.
But, quite honestly, I'd be looking over some gas flow charts and such.
I have a tendency to be "blunt" but just about anyone here can tell you the bluntness comes with honesty.
Good luck.

I'm an engineer. I have a decent understanding of gas flow.

The NG spool valve and metering orifices are much smaller than the propane orifices.

The propane regulator on my LP Genesis is a 698, which operates at 11" WC. The orifice size for 10,000 BTU LP @ 11"WC is #62, 38 thou.

My NG Genesis 310 doesn't have a regulator, so it operates at my house NG pressure, which is 7" WC in Canada.

I'm going to take apart my BBQs and measure and compare the spools and orifices.

Question: does a NG Summit 650 have a regulator on it or does it operate on the house pressure ?

According to this document https://weber.mizecx.com/retrieve/s3/knowledge/WEBER_LG/90921/90921.pdf, part #44 on page 6 appears to be a bulkhead with a regulator. Page 12 and 13 also show a bulkhead with a regulator. Yet my Genesis doesn't have a regulator.

When I do my conversion, should I do like my Genesis and not use a regulator or use a regulator ?

Natural gas is 1030 BTU per cubic foot.
Propane is 2516 BTU per cubic foot.

Here is a really good document on orifices for gas.

Learning Task 3 – Block E: Fuel Gas Systems

opentextbc.ca

 

[SteveRichards]

So why do the NG Summits (470, 650 and 670) use a NG regulator (set at 4" WC) and the Genesis 310 doesn't ?

Is it because the Summits have more burners and draw more gas and thus the house gas pressure might fall when all the burners are operating ? Thus if a Summit is regulated to 4" WC even if the pressure falls down from the house supply (7" WC) they will always have the same gas pressure, provided it stays above 4" WC ?

FWIW, I found the heat output of my buddy's 470NG to be pretty poor, especially in winter. I was running the controls at full output and it took forever to get the heat up to 400F.

 

[SteveRichards]

LP: 10,000 BTU/burner / 2516 BTU/CFM = 4 CFM. 4 CFM @ 11" WC = #64 or #65 drill (35-36 thou) with an orifice factor of 0.90.

NG: 10,000 BTU/burner/1000 BTU/CFM = 10 CFM. 10 CFM @ 7" WC = #55 drill (52 thou) with an orifice factor of 0.90.

NG: 10,000 BTU/burner/1000 BTU/CFM = 10CFM. 10 CFM @ 4" WC = #53 drill (59.5 thou) with an orifice factor of 0.90.

Source: https://opentextbc.ca/plumbing3e/back-matter/imperial-orifice-capacity-table-flow-values-in-cfh/

The valve spool orifices will need to be enlarged as well.

Should I purchase a 4" WC regulator for my Summit 650 or run at house pressure ?

 

[LMichaels]

The NG spool valve and metering orifices are much smaller than the propane orifices.
Actually they are not. It's the opposite.
My NG Genesis 310 doesn't have a regulator, so it operates at my house NG pressure. I think that is 11" WC as well.
I am unsure what Canada operates at but if it's like the US it's 7"WC not 11. (11 is LP)
Question: does a NG Summit 650 have a regulator on it or does it operate on the house pressure ?
IDK the answer to this. You would need to consult a parts catalogue on that model. I believe it does have one, however I've never owned or worked on one of them so IDK the answer there.
Also if you found the heat output on the 470 poor one of 2 things. Either it really was not a NG grill but one somebody messed with thinking I'll just slap on a NG hose, or 2 you have a flow issue at your location.
Best recommendation I can give you is do it correctly. Get a true NG manifold and regulator setup. Because from your questions and comments you have me concerned. Sorry. It's the best recommendation I can give you.

 

[SteveRichards]

The NG spool valve and metering orifices are much smaller than the propane orifices.
Actually they are not. It's the opposite.

Yes, I got that backwards.

My NG Genesis 310 doesn't have a regulator, so it operates at my house NG pressure. I think that is 11" WC as well.
I am unsure what Canada operates at but if it's like the US it's 7"WC not 11. (11 is LP)

I have since found out that Canadian residential pressure is 7" WC, not 11" WC.

Question: does a NG Summit 650 have a regulator on it or does it operate on the house pressure ?
IDK the answer to this. You would need to consult a parts catalogue on that model. I believe it does have one, however I've never owned or worked on one of them so IDK the answer there.

If you read the next post, I looked in the manual and it has a regulator.

Also if you found the heat output on the 470 poor one of 2 things. Either it really was not a NG grill but one somebody messed with thinking I'll just slap on a NG hose, or 2 you have a flow issue at your location.

It's not a flow problem, it is a pressure problem. But yes.

Best recommendation I can give you is do it correctly. Get a true NG manifold and regulator setup. Because from your questions and comments you have me concerned. Sorry. It's the best recommendation I can give you.

I am not going to spend that kind of money. I am going to drill out my spools and orifices. Stay tuned.

 

[LMichaels]

Yes, I got that backwards.




I have since found out that Canadian residential pressure is 7" WC, not 11" WC.




If you read the next post, I looked in the manual and it has a regulator.



It's not a flow problem, it is a pressure problem. But yes.




I am not going to spend that kind of money. I am going to drill out my spools and orifices. Stay tuned.

Guess I will watch for the mushroom cloud

 

[SteveRichards]

It's not rocket science. Just a bit of math.

 

[SteveRichards]

My CAD$100 650 Summit

Seller said they were selling it because the burners weren't working. They are covered with a 1/4" of crud !

It's absolutely filthy. The grill is like new. The flavor bars are in good (excellent?) condition. The cook box is in very good shape. The smoke box has never been used. The side burner pot ring still has the paint on it.

I'll probably convert it to natgas. Yes, I know about the controls needing to be changed.

I wish it was a 470 instead of a 650. I'm usually just grilling for myself but sometimes I'm doing a brisket or a batch of ribs. Maybe I should clean it up and flip it ?

 

[LMichaels]

Likely the crud may have "saved" the firebox. Never ceases to amaze me how people can spend A LOT of $$$ on a nice thing and let it go to waste. Being a 670 you have a lot more to worry about if attempting a conversion. You have the side burner to contend with, (which BTW you only need to be concerned with the orifice on it), and then IR burner. I've never been inside one of these with an IR burner so IDK what type of challenges await you there. And then IDK how the "snap jet" things work on these and what's involved in changing fuel type on it. Because here too, I've never even seen a snap jet valve up close. You MIGHT turn out VERY lucky though and the valve spools may be the continuous type. In which case it's simple matter of calculating BTU/Flow/pressure desired (and IIWU) I would buy orifice "blanks" then size them carefully. Buy more than you need (just in case). Also if it becomes a long term keeper and you ever have it at a place without NG hookup you can easily "put it back".

 

[SteveRichards]

Likely the crud may have "saved" the firebox.

Yes, though I am not sure how much they actually used it.

Never ceases to amaze me how people can spend A LOT of $$$ on a nice thing and let it go to waste.

I know, right ? These things are thousands of dollars when new. This is my 5th Weber. It never ceases to amaze me when people say they are going to get a better BBQ. What would be better than a Weber ?

Being a 670 you have a lot more to worry about if attempting a conversion.

It's actually a 650, not a 670. The 670s have a searing burner in the middle, mine does not.

You have the side burner to contend with, (which BTW you only need to be concerned with the orifice on it), and then IR burner.

I've got a NS Genesis 300 here. I assume that the valve spools and orifices would be the same on a 650 as on a 300, except the Genesis runs at house pressure (7" WC) whereas the Summits have a 4"WC regulator. The burners are all the same BTUs. I intend to take my 300 apart and do some measurements. I'll post the results here.

I've never been inside one of these with an IR burner so IDK what type of challenges await you there.

It's just a control valve and orifice. No different than any other burner.

And then IDK how the "snap jet" things work on these and what's involved in changing fuel type on it. Because here too, I've never even seen a snap jet valve up close. You MIGHT turn out VERY lucky though and the valve spools may be the continuous type. In which case it's simple matter of calculating BTU/Flow/pressure desired (and IIWU) I would buy orifice "blanks" then size them carefully. Buy more than you need (just in case). Also if it becomes a long term keeper and you ever have it at a place without NG hookup you can easily "put it back".

I plan to drill out the valve spools if I convert it to NG. Once I do that there will be no going back.

 

[LMichaels]

Yes, though I am not sure how much they actually used it.



I know, right ? These things are thousands of dollars when new. This is my 5th Weber. It never ceases to amaze me when people say they are going to get a better BBQ. What would be better than a Weber ?




It's actually a 650, not a 670. The 670s have a searing burner in the middle, mine does not.




I've got a NS Genesis 300 here. I assume that the valve spools and orifices would be the same on a 650 as on a 300, except the Genesis runs at house pressure (7" WC) whereas the Summits have a 4"WC regulator. The burners are all the same BTUs. I intend to take my 300 apart and do some measurements. I'll post the results here.



It's just a control valve and orifice. No different than any other burner.



I plan to drill out the valve spools if I convert it to NG. Once I do that there will be no going back.

Don't go messing with the spools. IIRC the Summit uses a different style valve (at least they did on the 2nd gens and I'm sure it's followed through on the 3rd gen and on). Last 2 Summits I did for people did not need any spool mods. If you go messing with them you will likely end up in deep trouble with a grill you cannot regulate properly. Always TEST and VERIFY. I was taught a lot of stuff by my friend who's licensed in doing gas. Also get yourself a manometer, and make sure you have adequate pressure at your outlet. Don't go diving in headlong because you cannot "reverse" it if you get it wrong

 

[SteveRichards]

Don't go messing with the spools. IIRC the Summit uses a different style valve (at least they did on the 2nd gens and I'm sure it's followed through on the 3rd gen and on). Last 2 Summits I did for people did not need any spool mods. If you go messing with them you will likely end up in deep trouble with a grill you cannot regulate properly. Always TEST and VERIFY. I was taught a lot of stuff by my friend who's licensed in doing gas. Also get yourself a manometer, and make sure you have adequate pressure at your outlet. Don't go diving in headlong because you cannot "reverse" it if you get it wrong

The NG and LP Summits use a different valve manifold. There is more difference between the manifolds than just the burner orifices.

Here is what happens when you try to use propane orifices with a natgas spools:

The orifices in the natural gas spools are very large compared to the natural gas spools and thus they don't control the flow of propane properly. Propane spool orifices won't flow enough natgas to heat properly.