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Eric D

Better Regulation Means Better Heat

17 posts in this topic

My 2004 Jenn Air model 720 -0061 three burner is one of the first of the all stainless steel grills by Nexgrill built for Lowes. This model had a bad rap for low heat output. There have been a number of modifications developed by members here on the BBQ Source Forums that correct this issue very elegantly. Doing some testing of my own grill I notice the 11 inches of water that should be on the main manifold was about 9". Not knowing a lot about propane regulators and propane properties, I decided to do a deep-dive into the mysterious world of propane. No, I didn't stick my head into the propane tank, but kind of felt like I did after reading all the material I could find. So, to save everyone the pain, I put together the information that I found the most useful. I'll try and keep it short; yeah, right.

 

Regulator, why do we need them?

The regulator that comes with most of our grills is a single stage unit. The regulator takes the pressure from the tank, about 100 PSIG and reduces it down to about ½ a psi. They work fairly well most of the time. The down side of this type of regulator, it doesn't compensate for differences in tank pressure due to changes in outside temperature. They actually set them for 11 inches WC (water column) at 60º F and atmospheric pressure of 14.48 psia. If the outside temperature is higher then 60º F then the pressure at the grill could be more then 11 inches WC. If the temperature is less then 60º F then the pressure could be less then 11 inches WC. The normal allowable range is 9 to 13 inches WC pressure to feed the grill.

I wanted to improve the gas flow to my grill and correct the low pressure. I decided that I would upgrade to a better pressure regulator that I could also adjust if I found a need to.

 

After much research of many different pressure regulators I ended up purchasing a Marshall Model 290 two-stage regulator. Instead of one regulator like the stock unit that comes on most of our grills, this unit has two regulators. There's a high-pressure regulator that reduces the propane tank 100 + psig down to 10 psig. This is fed into the second regulator that reduces the 10 psig down to 11 inches WC. By having the first high pressure regulator in the system, temperature changes of the propane tank have little to no influence on the final output to the grill, holding the 11 inches WC.

 

Installation

 

I had first planed to mount the new regulator to the grill cabinet inside area. After looking for a long time trying to figure out a good location, I took a different route. I removed the tank connecter from the old regulator and installed it onto the new with Teflon tape, being careful not to over torque the fitting. Next I installed a 90º fitting into the outlet side of the regulator, and into it a hose barb fitting. I cut the original low-pressure hose off the old regulator and installed it onto the barb fitting and securing with a screw type hose clamp. I then attached the low-pressure hose and the regulator to the tank. Using dish soap in some water I brushed down all the connections and then slowly opened the tank valve. Great! No Leaks! I turned everything back off and installed my tee fitting at the end of the low-pressure valve and reconnected the fitting. Slowly turned everything back on. Checked one more time for leaks. Then turned on all the main burners. The new two-stage regulator came adjusted right at 11 inches WC. I wanted more btu's out of my grill so I adjusted it up to 13 inches WC. We have had some 97º F days here and the regulator holds perfect at the new set point. I have since removed my tee for the gauge and have leaked checked everything.

 

The regulator is a tight fit under the grill, but with the 90º fitting on the outlet it works just fine.

 

There are a number of places on the web that sell this regulator. If you do a search for Marshall 290 two-stage regulator you find may places, prices in the range of $14.95 to $20. With fittings, my total cost was about $25.

 

Eric D

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Thanks for the research and excellent write up, I guess that's my next mod :P

 

Takeahike66

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Thanks for the research and excellent write up, I guess that's my next mod
TakeAhike,

 

Thanks for the kind words. I understand that this regulator comes standard on some of the much higher end grills.

 

I also wanted to mention that there is one down side of increasing the grill feed pressure as I did from 11" to 13" WC. It could affect the low temp of the grill where you might not be able to get the temp low enough for roasting. It's been to hot around here (upper 90's) for me to check the low end temp, but I will soon.

 

Regards,

 

Eric D

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Actually with the adjustable, We can set it to 13" wc when we need the high heat, and reduce it back down to 11" when we are doing indirect cookin. So this shouldn't be a problem.

 

Takeahike66

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Actually with the adjustable, We can set it to 13" wc when we need the high heat, and reduce it back down to 11" when we are doing indirect cookin. So this shouldn't be a problem.
Good point. I have an all stainless steel inches of water pressure gauge that I thought I might install permanently. This way I would always know what the pressure is.

 

Eric D

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Good point. I have an all stainless steel inches of water pressure gauge that I thought I might install permanently. This way I would always know what the pressure is.

 

Eric D

 

Here is my experience in installing the two Stage regulator and results:

 

Following Eric D guidelines, here is how I installed and tested the Marshall 2-stage regulator.

 

After attempting some Boston Butts on the JennAir with the OEM Nexgrill regulator, I could not get the smoking temp down low to 225 degrees. The lowest I could get was around 325 degrees at the hood, which was probably 300 degrees at the warming rack.

 

I had the Marshall model 290 regulator on hand, but never had a chance to install it. Knowing I better get the temp down in order to do low heat smoking, I gather the parts to reassemble the hose with the new regulator.

 

The regulator I purchase was off of EBay for about $14.00. The other parts cost about $5.00

 

 

 

The regulator does not come with any fitting. The left size connects to the hose. The right size goes to the tank. Note: Marshall regulator has a 1/4 FIP fitting to connect to the POL connector, and a 3/8" FIP for the hose connector. The Nexgrill regulator has 1/4 " FIP on both ends.

 

 

 

 

This is the vent that is discussed in different vendor catalogs. The opening must be facing down if the regulator is exposed. This end is attached to the hose that connects to the grill

 

Normally the regulator is in the cart under the grill so it is protected from rain. f you did a built-in with the grill and the tank is exposed, you have to get the right regulator in such that the position of the regulator whether vertical or horizontal has the vent opening facing down or buy the cover ($3.00) for the regulator. Those are the different model numbers that I could not understand the differences. Now I know a little bit about what they are talking about. If the tank is in the cart and not exposed, the vent can face any direction. If exposed, the vent must be pointed down to prevent water from entering through the vent hole.

 

The different models are designed for either a vertical or horizontal mounting,

 

 

 

This end is attached the POL that connects to the tank.

 

 

 

Picture of the layout of the parts needed to make a new hose with the regulator. You do not necessary need to use a right angle connector at each end. I thought I would give it a try. (See later pictures how it hooked up.). The left side is a 1/4 “MIP and FIP 90 degree elbow. The right size is a 3/8 " elbow. The 3/8 MIP with 3/8 " barb has already been inserted into the hose and secure with a hose clamp. The fitting next to

it is the old compression connector that was cut off. Above is the old regulator. The original barb was 5/16", but I could not find one. I used a 3/8" barb. I heated the barb first with a touch and quickly pressed it onto the end of the hose and secure with a screw clamp. All threads were coated with pipe compound to complete the seal. All connections test with a water/soap solution for leaks prior to lighting.

 

 

 

Picture of the old regulator after disassembly.

 

 

 

 

The new regulator hooked to the tank for testing.

 

 

 

 

Another picture of the regulator hooked up. The black hex knob is where the adjustment knob is hidden under. Just unscrew the black knob. Underneath is another knob with a hex hole in it. Use a hex wrench to adjust the pressure. Turn in (CW) to increase pressure and raise the heat output. Turn out (CCW) to lower the pressure and reduce the heat output

 

Results of my tests are below:

 

Ok - I hook up the Marshall two-stage regulator to the JennAir and it does adjust the gas flow significantly.

 

The adjustment is a plastic knob under the cover of the dark hex nut in the center of the large diameter regulator. It is adjusted via hex wrench. I marked its original position and turn inner knob in two complete turns. You could hear the gas increase at the burners. It had a very minor roar and the flames were longer. I did not measure the increase in pressure being delivered to the burners. I DO NOT plan to run it at this high level, I was just testing to see if there was an increase in gas delivered to the burners.

 

 

 

In between each test - I open the hood until the hood temp went down to 200 degrees

 

To get quick results I started with three burners on low:

 

1) Regulator at factory setting:

Hood temp 350 degrees

Oven temp at griddle 325 degrees

 

 

2) Regulator adjusted by two turns out (CCW) - lower pressure:

Hood temp 310 degrees

Oven temp at griddle 275 degrees

 

3) Regulator adjusted by two turns out (CCW) - 1 burner only:

Hood temp 225 degrees

Oven temp at griddle 175 degrees

 

4) Regulator adjusted by one turns out (CCW) - 1 burner only:

Hood temp 225 degrees

Oven temp at griddle 200 degrees

 

5) Regulator set at factory position - 1 burner only:

Hood temp 240 degrees

Oven temp at griddle 210 degrees

 

6) Regulator set at factory position - 1 burner only: burner to mid-position

Hood temp 260 degrees

Oven temp at griddle 225 degrees

 

So this test shows that the adjustable regulator can increase the heat output, and lower the heat to allow good slow bbqing

 

 

Note the griddle was not directly over the burner- griddle was on far left over two burners not used in the test. The three burners and 1 burners were on the right side of the grill. When only 1 burner, it was the far right burner. The oven thermometer was on the right edge of the griddle. I wanted to be able to observe the flames, so no grates and tamers were over the burners.

 

Hopes this help.

Edited by takeahike66

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TakeAHike,

 

I like your use of the two 90° fittings on the regulator. It looks like this makes for a more compact installation.

 

Since I've converted my grill, we have had different temperature days from upper 90's to the low 50's. With the new regulator I see less of a performance hit as compared to the original Nexgrill regulator. Higher end grills (higher dollar) have this regulator as their stock unit. For the money, I think Nexgrill should consider this type of regulator for all their grills.

 

Very nice write up! ;) Thanks,

 

Eric D

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Takeahike,

 

Did you test the temp with a oven guage on the warming rack?

 

Thanks for the writeup....

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Takeahike,

 

Did you test the temp with a oven guage on the warming rack?

 

Thanks for the writeup....

 

I wanted to get the new regulator installed, and didn't know that the outlet holes were different than the original regulator, so spend time going back for the right parts. So I was in a hurry to rebuild the regulator hose and check and see what affect it had on heat. The warming rack was being cleaned after doing the Boston Butt as you suggest (up on the rack) and was not available. Since I wanted to do a lot of different test run, I just set the oven thermometer on the griddle off to the side. The hose was just run throgh the drawer opening with the tank outside. Now that I know it can work, I will install the tank back in the cabinet and rerun the test at the warming rack to establish the setting I need to maintain 225 degress at that level. Will keep everyone updated.

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TakeAhike,

 

Thanks for the kind words. I understand that this regulator comes standard on some of the much higher end grills.

 

I also wanted to mention that there is one down side of increasing the grill feed pressure as I did from 11" to 13" WC. It could effect the low temp of the grill where you might not be able to get the temp low enough for roasting. It's been to hot around here (upper 90's) for me to check the low end temp, but I will soon.

 

Regards,

 

Eric D

Well Eric...based on the big sq. root drop in vapor pressure at 27 degrees minus the cooling effect of vaporizing the gas...my suggestion is control the source...wrap the tank in a electric blanket...lol

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I wanted to get the new regulator installed, and didn't know that the outlet holes were different than the original regulator, so spend time going back for the right parts. So I was in a hurry to rebuild the regulator hose and check and see what affect it had on heat. The warming rack was being cleaned after doing the Boston Butt as you suggest (up on the rack) and was not available. Since I wanted to do a lot of different test run, I just set the oven thermometer on the griddle off to the side. The hose was just run throgh the drawer opening with the tank outside. Now that I know it can work, I will install the tank back in the cabinet and rerun the test at the warming rack to establish the setting I need to maintain 225 degress at that level. Will keep everyone updated.

 

Finished putting my grill back together, and ran a quick test.

 

Two stage regulator at the original setting.

I use two burners on high to get the hood temp up to 250 (5 minutes), then shut off one burner, and left the far right burner on low. Let the temp settle down and remain constant. (5 minutes).

 

Reading were as follow:

220 degree - Oven thermometer on warming rack

225 degree - Hood thermometer

240 degree - Thermometer hanging from top edge of hood

 

 

 

In my orginal post a couple of post earlier in this forum when I did the initial test with the Marshall two-stage, the oven thermometer was set on the right edge of the griddle you see in the picture above. The three burners were on the right side where the grates are now.

 

I believe the adjustable is set at a lower pressure setting than the NexGrill regulator.

 

The bottom line. You can adjust the pressure to maintain an even 225 degree at any level of the grill, from the grate to above the warming rack. When needed, it can be turned up to provide greater heat output. :rolleyes:

 

Here is how the regulator now fits in the 5-burner using two 90 degrees elbow on each end of the regulator.

 

 

 

The photo above shows the regulator attached to the tank in a horizontal position with the first elbow permitting the regulator to be position next to the tank verses coming straight out. Helps to save space.

The second elbow aligns the hose toward the top of the cart. This provides a straight line without any bend in the hose.

 

 

 

This is a closer view of the hose from the tank. It has a nice smooth bend from the regulator through the top toward the gas manifold. I believe just removing the U shape bend has increased the gas flow by at least 10%. IMOH

 

 

Now I ready to try my Boston Butt again!!!!!! :lol:

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Added more details on how the elbows on the regulator eliminates the sharp bend in the hose for propane models. You might try this before installing a two-stage regulator!!!!

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Added more details on how the elbows on the regulator eliminates the sharp bend in the hose for propane models. You might try this before installing a two-stage regulator!!!!
TakeaHike,

 

The added photos with the two 90° fittings looks like the ticket. Nice photos.

 

The two-stage regulator will improve cold weather cooking compared to the single stage that comes with most grills. I always had trouble with getting hood temps greater then 400° F at 50 and below outside temps. With mine set a 13" wc I can get 550° F without any of the other grill mods.

 

I'm still planning on adding a gap seal. I have the stainless steel for the job, but I am in the middle of putting my all-in-one sheet metal shear, bender, and roller tool on a new stand. Once this is done I'll get started on the mods.

 

Happy grilling,

 

Eric D ;)

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Had a little surprise walking through Lowes today. Looking through the grill accessory area, I found right there on the shelf the same two stage regulator I installed on my grill. It is Lowes item number 14572. It comes with the type of tank fitting that requires a wrench though. An the price is higher then what you can find it on the web for. At my local Lowes they had it priced at $39.95.

 

Eric D

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Had a little surprise walking through Lowes today. Looking through the grill accessory area, I found right there on the shelf the same two stage regulator I installed on my grill. It is Lowes item number 14572. It comes with the type of tank fitting that requires a wrench though. An the price is higher then what you can find it on the web for. At my local Lowes they had it priced at $39.95.

 

Eric D

 

Eric:

 

Thanks for the part # on the two-stage regulator. I stopped at my local Lowe's, and they didn't have it in stock ... talked to the Store manager, and he said he'd start stocking them.

 

BG in WV

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