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Increasing heat for a gas grill

bill1

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1. Thanx for the flow info.
2. Yes 7"wc pressure.
3. Bought the grill new.
4. I have an enormous set of drills. My earlier confirmation on this got lost in the sauce.
5. I will now measure the orifices and match the btu/hr in the chart.
6. BTW the manufacturer recently gave me numbers on their orifices designating ng. They match on mine. Nevertheless, I'll measure them.
7. QUESTION: if the orifices already match the advertised btu/hr ... whats the sense in opening them up, which would be dangerous, correct? I mean I'd have no bearing or basis for selecting the new hole sizes. Unless maybe if I open them up incrementally and test them on low.
If the manufacturer specifies a 7 inch water column head at your grill, and
If you have accurately measured 7" wc pressure at your grill, and
If you know the total btu/h of your grill as it was designed, and
If you have accurately measured the diameters of your orifices and they match the btu/h for your grill per the chart for 7"wc, and
If you have verified no debris, spider webs etc in your line and your control valves appear to work normally,
Then you have the optimal setup as the manufacturer intended.
But if the piping out to the grill is new, it may take a while to purge out the air in it so you can deliver your gas company's ng. This is of course, dependent on the length of the line. Note also that CH4 is lighter than N2 or O2 so if you have some low spots in your line where air is trapped, it can take particularly long to start running pure ng.
 

pmarc

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Joined Aug 25, 2021
If the manufacturer specifies a 7 inch water column head at your grill, and
If you have accurately measured 7" wc pressure at your grill, and
If you know the total btu/h of your grill as it was designed, and
If you have accurately measured the diameters of your orifices and they match the btu/h for your grill per the chart for 7"wc, and
If you have verified no debris, spider webs etc in your line and your control valves appear to work normally,
Then you have the optimal setup as the manufacturer intended.
But if the piping out to the grill is new, it may take a while to purge out the air in it so you can deliver your gas company's ng. This is of course, dependent on the length of the line. Note also that CH4 is lighter than N2 or O2 so if you have some low spots in your line where air is trapped, it can take particularly long to start running pure ng.
About to buy a manometer any brand you suggest? They range from $11 - $50.
 

bill1

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Joined Apr 25, 2015
Unless you plan to use it a lot, I'd go cheap. It's easy to calibrate/verify with a few feet of clear poly tubing full of water and bent into a U. So if you read 7"wc from your gas line, verify it reads the same with 7" of water on the other side of U tube. (Ask me if you don't know how to do this.)
I would tend to prefer an analog over digital gauge, but this may be an area where the cost differential might not be worth it to me.
 

pmarc

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Joined Aug 25, 2021
Unless you plan to use it a lot, I'd go cheap. It's easy to calibrate/verify with a few feet of clear poly tubing full of water and bent into a U. So if you read 7"wc from your gas line, verify it reads the same with 7" of water on the other side of U tube. (Ask me if you don't know how to do this.)
I would tend to prefer an analog over digital gauge, but this may be an area where the cost differential might not be worth it to me.
Unless you plan to use it a lot, I'd go cheap. It's easy to calibrate/verify with a few feet of clear poly tubing full of water and bent into a U. So if you read 7"wc from your gas line, verify it reads the same with 7" of water on the other side of U tube. (Ask me if you don't know how to do this.)
I would tend to prefer an analog over digital gauge, but this may be an area where the cost differential might not be worth it to me.

Will this do the job? I dont know how to convert psi, though. They all seem the same.
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bill1

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Will this do the job? ...
NO! Not at all. This reads to 60psi. This is for pressurizing a recently plumbed line with an air compressor, BEFORE THE NG IS TURNED ON, to verify there's no leaks. It's for use with air, typically from a bicycle pump, at high pressure but no flow. You come back a day later and make sure the pressure (of air) reads the same to verify no leaks. Then you're safe to start natural gas which is at much lower pressure.
Newton said "If I can count it I can understand it". You simply must understand the basic unit conversions to understand a field of study and work in that field safely. God stuck us in a basic atmospheric pressure of 14.7psi. That equals 1.00 absolute atmospheres of pressure. 1 atmosphere supports a 760millimeter column of mercury or a 407 inch column of water. Everything we measure is relative to absolute and is called gauge pressure. 60 psi gauge pressure (also referred to precisely as 60psig) is 4 atmospheres over atmospheric so would be more than 1600 inches of water column. You want to measure the difference between 6 & 7 inches-wc. It would be impossible to read that small a number on a gauge like you posted. You need something like this. Note that it reads a max gauge pressure (absolute atmospheric pressure reads as 0) of 25 inWC. So 7 inchWC (what you're trying to verify) will put the dial at about "9 o'clock" on this analog gauge--easily read. That lines up with 4 ounces per square inch gauge. Since there's 16 ounces of force per pound of force (just as there is 16 ounces of water in a pound of water) that's telling you 7"wc equals 1/4 psi. But again, you can't read .25psi on a scale that goes to 60. (But if you find something cheaper than $40 that reads to 1psi max, you'd be in the right ball park.)
 

pmarc

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NO! Not at all. This reads to 60psi. This is for pressurizing a recently plumbed line with an air compressor, BEFORE THE NG IS TURNED ON, to verify there's no leaks. It's for use with air, typically from a bicycle pump, at high pressure but no flow. You come back a day later and make sure the pressure (of air) reads the same to verify no leaks. Then you're safe to start natural gas which is at much lower pressure.
Newton said "If I can count it I can understand it". You simply must understand the basic unit conversions to understand a field of study and work in that field safely. God stuck us in a basic atmospheric pressure of 14.7psi. That equals 1.00 absolute atmospheres of pressure. 1 atmosphere supports a 760millimeter column of mercury or a 407 inch column of water. Everything we measure is relative to absolute and is called gauge pressure. 60 psi gauge pressure (also referred to precisely as 60psig) is 4 atmospheres over atmospheric so would be more than 1600 inches of water column. You want to measure the difference between 6 & 7 inches-wc. It would be impossible to read that small a number on a gauge like you posted. You need something like this. Note that it reads a max gauge pressure (absolute atmospheric pressure reads as 0) of 25 inWC. So 7 inchWC (what you're trying to verify) will put the dial at about "9 o'clock" on this analog gauge--easily read. That lines up with 4 ounces per square inch gauge. Since there's 16 ounces of force per pound of force (just as there is 16 ounces of water in a pound of water) that's telling you 7"wc equals 1/4 psi. But again, you can't read .25psi on a scale that goes to 60. (But if you find something cheaper than $40 that reads to 1psi max, you'd be in the right ball park.)
I ordered yours. Thanx. This is gonna be an easy fix. If the pressure at grill is below spec, I'll re-locate the grill to within 10 feet of the beginning of the line, after measuring pressure again. No way I'm gonna replace 100 ft of pipe. BTW the orifices hole sizes match for the advertised btu. And no cobwebs, etc. There are no elevation drops in line. It's flat all the way. Been used about 10 times so not sure air has to be forced out, at this point.
 
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bill1

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I ordered yours. Thanx. This is gonna be an easy fix. If the pressure at grill is below spec, I'll re-locate the grill to within 10 feet...
I wouldn't assume you have a pressure drop problem with your line. You need to take two pressure measurements, both at your current grill location. One with no flow. So just attach your new gauge and see what you read direct at the spigot. Then hook up the line to your grill, with a tee to your gauge, and measure the pressure with the grill at full heat, drawing gas. If it's a significantly lower number, then yeah, you're losing too much pressure in the line and we can discuss options.

But you may find your problem is you have greater than 7"WC. In which case your simplest fix is to add 7"wc regulator at the grill. Good for safety too.

But a 100' line takes a while to purge at these flows. So try not to vent your line (much) when you do these minor plumging changes at your grill location.
 

Fueling Around

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I wouldn't assume you have a pressure drop problem with your line. You need to take two pressure measurements, both at your current grill location. One with no flow. So just attach your new gauge and see what you read direct at the spigot. Then hook up the line to your grill, with a tee to your gauge, and measure the pressure with the grill at full heat, drawing gas. If it's a significantly lower number, then yeah, you're losing too much pressure in the line and we can discuss options.

But you may find your problem is you have greater than 7"WC. In which case your simplest fix is to add 7"wc regulator at the grill. Good for safety too.

But a 100' line takes a while to purge at these flows. So try not to vent your line (much) when you do these minor plumbing changes at your grill location.
There should be a shut off valve at the end of a 100' line before you feed the appliance.
Flow is significantly reduced at 100' straight line plus much more for every elbow. Not familiar with pipe fitter code on up sizing diameter.
 

pmarc

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Joined Aug 25, 2021
I wouldn't assume you have a pressure drop problem with your line. You need to take two pressure measurements, both at your current grill location. One with no flow. So just attach your new gauge and see what you read direct at the spigot. Then hook up the line to your grill, with a tee to your gauge, and measure the pressure with the grill at full heat, drawing gas. If it's a significantly lower number, then yeah, you're losing too much pressure in the line and we can discuss options.

But you may find your problem is you have greater than 7"WC. In which case your simplest fix is to add 7"wc regulator at the grill. Good for safety too.

But a 100' line takes a while to purge at these flows. So try not to vent your line (much) when you do these minor plumging changes at your grill location.

The gauge at the spigot reads 6 oz / in sq or 10 in H2O (I have to exchange the T tonight - wrong size)
 
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bill1

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Can you give me an interim reply on these numbers, thanx.
I believe you said the vendor told you your grill NG mod was sized for 7 inchWC. If you have 10 instead, you need a regulator set for 7.

CORRECTION: you might need a regulator. Repeat the measurement with a tee and gas flowing through your lit grill. Fueling Around thinks you may have more drop than I. Let's see.
 
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pmarc

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Joined Aug 25, 2021
I believe you said the vendor told you your grill NG mod was sized for 7 inchWC. If you have 10 instead, you need a regulator set for 7.

CORRECTION: you might need a regulator. Repeat the measurement with a tee and gas flowing through your lit grill. Fueling Around thinks you may have more drop than I. Let's see.
I'm not sure exactly where to hook up, inside the grill. For example, I can access where the gas enters behind the gas knob (then the gas leaves this device and runs a foot in two thin coiled tubes, to the burners. Actually there's no where else to hook up the T.
 
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bill1

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Where your hard line ends MUST be a csa-certified valve that is normally closed. Off this you install a tee, then you plumb your flex-line to the bbq. Plumb your new gauge to the remaining arm of the tee. When everything is tight, open the main valve. Your manometer should read the same 10inWC. Now light your bbq as always. What does the gauge read now? The difference is the total pressure drop for the entire plumbing system for the flow your grill draws. If it's right at 7inWC, you're good to go. If more, you need a regulator. (You SHOULD have a regulator anyways, but I've said that before.)
 

pmarc

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Joined Aug 25, 2021
Where your hard line ends MUST be a csa-certified valve that is normally closed. Off this you install a tee, then you plumb your flex-line to the bbq. Plumb your new gauge to the remaining arm of the tee. When everything is tight, open the main valve. Your manometer should read the same 10inWC. Now light your bbq as always. What does the gauge read now? The difference is the total pressure drop for the entire plumbing system for the flow your grill draws. If it's right at 7inWC, you're good to go. If more, you need a regulator. (You SHOULD have a regulator anyways, but I've said that before.)
 

pmarc

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With unit on, at high, the pressure is 6 in H2O. Which is 14% low. I don't think adding 14% would do anything. Between you and me.

Some Details: the two pressure exercises (grill on, grill off) were done using the 10 ft hose the unit came with. One end attached at the unit, the other end at the on / off valve. (The hard line on/off valve has a funky opening which already fit the hose end perfectly).
 
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bill1

Master of the Pit
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Joined Apr 25, 2015
With unit on, at high, the pressure is 6 in H2O. Which is 14% low. I don't think adding 14% would do anything. Between you and me.

Some Details: the two pressure exercises (grill on, grill off) were done using the 10 ft hose the unit came with. One end attached at the unit, the other end at the on / off valve. (The hard line on/off valve has a funky opening which already fit the hose end perfectly).
It appears from the table that you'd increase your orifices by...wait for it...less than a drill size to be optimal now. Therefore yes, you're close enough.
So, are you still feeling your grill still isn't getting hot enough? If that's the case, you could share a picture of the blue flame from the burners.

But I'm most concerned by your statement the hard line valve has a funky opening. This stuff all needs to fit exactly and precisely. You need to know the difference between tapered and straight pipe threads, etc. And I think you said the hard line is half-inch pipe, so the valve would have 1/2 NPT females on it. Your flex hose I'd guess would end in an AN flare fitting but it would come with an adapter to 3/8 NPT male. But that wouldn't fit 1/2 NPT female at all. Do you understand all these fitting names? If not post some pics with a ruler for a scale and we can walk you this.
 

pmarc

Fire Starter
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Joined Aug 25, 2021
It appears from the table that you'd increase your orifices by...wait for it...less than a drill size to be optimal now. Therefore yes, you're close enough.
So, are you still feeling your grill still isn't getting hot enough? If that's the case, you could share a picture of the blue flame from the burners.

But I'm most concerned by your statement the hard line valve has a funky opening. This stuff all needs to fit exactly and precisely. You need to know the difference between tapered and straight pipe threads, etc. And I think you said the hard line is half-inch pipe, so the valve would have 1/2 NPT females on it. Your flex hose I'd guess would end in an AN flare fitting but it would come with an adapter to 3/8 NPT male. But that wouldn't fit 1/2 NPT female at all. Do you understand all these fitting names? If not post some pics with a ruler for a scale and we can walk you this.
Ignore my “funky” remark. I just didn't want to deal with an opening which uses a quick-attach mechanism. In the end all was attached perfectly, as I used flared ends where needed - I know that gas leaks if you attach threads to threads, etc. There was zero gas leak during any of the tests.

I'll wait til sun down, or close, or you won't see the flame in a photo. Guessing the 100 ft run caused the 14% drop. Partly due to the length of the run, and partly due to reduced pipe size. Regardless of how you guys end up interpreting the flames, I'll be buying a new grill. While looking at total btu/hr divided by grate surface size. Because that ratio for this grill, is particularly bad.
 
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pmarc

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Joined Aug 25, 2021
Ignore my “funky” remark. I just didn't want to deal with an opening which uses a quick-attach mechanism. In the end all was attached perfectly, as I used flared ends where needed - I know that gas leaks if you attach threads to threads, etc. There was zero gas leak during any of the tests.

I'll wait til sun down, or close, or you won't see the flame in a photo. Guessing the 100 ft run caused the 14% drop. Partly due to the length of the run, and partly due to reduced pipe size. Regardless of how you guys end up interpreting the flames, I'll be buying a new grill. While looking at total btu/hr divided by grate surface size. Because that ratio for this grill, is particularly bad.
 
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