Supercharging a natural gas BG14 burner

[JonW]

Whether you need to bore your valves or not depends on if they were originally setup for propane. The orifice on propane is smaller, so you definitely need to bore those out if you are moving to NG. I have installed two of the blower fans on my rig. The original was for my boil kettle, but I have since added one to my HLT. Because it is so much more efficient than without the blower, I now heat my MLT strike water in my HLT and them move it over once it hits a set temp. I then use the MLT burner (low output) to get/keep the strike water at temp for mashing in. I'm doing 15 to 22 gallons of liquid in my kettles and there is no way I could get there without the air assist.

Do a test on your own system like my original tests I showed - e.g. use an air gun at very low pressure. You will see the difference immediately. I'm actually toying with the idea of drilling out one of my valves to do a new test with an even higher NG flow rate. Normally, you wouldn't be able to do this as the NG flames would be yellow and sooting and no real heat, but with the blower fans on there, I think I can even increase the NG flow rate over the normal valves.

Just play with it and you'll see what you can do.

 

[dahlseid]

I have installed two of the blower fans on my rig. The original was for my boil krettle, but I have since added one to my HLT. Because it is so much more efficient than without the blower, I now heat my MLT strike water in my HLT and them move it over once it hits a set temp. I then use the MLT burner (low output) to get/keep the strike water at temp for mashing in. I'm doing 15 to 22 gallons of liquid in my kettles and there is no way I could get there without the air assist.

Do a test on your own system like my original tests I showed - e.g. use an air gun at very low pressure. You will see the difference immediately. I'm actually toying with the idea of drilling out one of my valves to do a new test with an even higher NG flow rate. Normally, you wouldn't be able to do this as the NG flames would be yellow and sooting and no real heat, but with the blower fans on there, I think I can even increase the NG flow rate over the normal valves.

Just play with it and you'll see what you can do.

Thanks JonW! I am looking to set up my boil kettle and my HLT as well, so it is great to learn that your experience led you to the same conclusion. I am even thinking of setting up my mash tun too, to speed heating the water for dough in, after which I keep temp via a HERMs set up. Thoughts? The speed is attractive, but so is eliminating uncombusted methane, which is an even more potent greenhouse gas than carbon dioxide.

I expect to have to play around a little. I am still interested in hearing what you and others have found works. For example, it would be good information for me to have a starting point, such as I run my blowers full at 12V, use a 1" ID tubing of about 2 feet overall length, and have my valves set standard for NG. Even so, I have to limit air flow some, and I do that by..... I like my eyebrows the way they are!

Any other input is welcome, especially anything specific.

 

[Hockeyman]

As a gas fitter by trade it scares me immensely when atmospheric burners are tried to become power burners with air injection. 99% of burner issues is upstream pipe sizing. With both natural gas and propane, you cannot just look at the pressure at your burner, you need to ensure your pipe capacity is correct for the load connected.

First off, one definitely needs to ensure that your gas supply piping is correctly sized for what output you would like at your burners... Determine your longest run and total load on your piping system. The longest run is from your gas meter to the furthest connected appliance, any connection made with in 2 feet of the gas meter (manifold connection) is typically considered its own run. Then total up all connected appliances by their input rating on the rating plates of the appliances.

Once you know what your longest run and total load are, now you can see if your pipe size can support the load.

For example, if your longest run is 50 feet and you have a furnace say 60kbtu, hot water heater 40kbtu, and you want your burners to be say 100k x 2. Your total load would be 300k. Based on piping charts @ 7"wc you would require a 1.25" black iron line off your meter to feed the connected load. Off the 1.25" main, the take offs to your furnace and hot water tank can be 1/2" if individually piped or 3/4" if combined, then 1/2" to the gas valves. For 2 x 100k burners you would need a minimum of 1" pipe to the stand.

If you are running tubing, or using flex connectors (look at the tag attached to the flex connector, capacity will be listed on it) there are different charts for capacity, as black iron is NPS and tubing is measured by the OD... Now if you plan on running 1/2" tubing on your stand, you'll choking off your capacity as 1/2" tubing @ 10 feet is only good for 50kbtu. So no matter what modifications you make to the burner and orifice, you will only get 50kbtu output. Now if you sized your tubing on the stand with 5/8" to each burner and the each run is under 10 feet, you know your max capacity you can get out of your burner is 101kbtu.

So now that your pipe is appropriately sized for capacity, keep in mind that anything inline that the gas flows through will cause pressure drop. Ie solenoids, gas valves, ball valves, fittings. Typically you need not worry about fittings as they are added into the piping sizing charts and 0.5"wc pressure drop is factored into the chart.

So before any modifications are made to professionally engineered and designed burners please ensure you're not unintentionally under sizing your gas piping giving you capacity issues.

edit: added capacity chart.

 

[day_trippr]

Was there anything indicating fuel starvation is the issue here?

 

[Hockeyman]

Burners are professionally designed to work with no modifications provided they have the correct orifice installed to operate at a specific pressure. If you can provide the burner rating and manifold pressure, I can advise on the correct orifice size. If your burner is to run at 100kbtu @ 7"wc you need a 22 (99k) or 21 (102k) orifice.

 

[Hockeyman]

After reading up on the BG14 burner... please take note.

The BG14 burner is a high pressure burner and is not designed to run on low pressure natural gas @ 7"wc. I would strongly advise on not continuing any forced air modifications. With the risk of burner blockage or any other chance of air regulator malfunction, air can over come the 7"wc gas pressure at the orifice and back feed into the gas line, which in turn can create the correct air gas ratio inside your gas piping. The potential to have a catastrophic event to all attached gas piping including the piping inside your home if your burner ever flashes back on you is not a risk anyone should take.

But if you do continue against better judgement, please consider adding check valves on the gas line at your burners due to the risk of over pressurizing the burner > 7"wc with compressed air being introduced at the venturi.

 

[dahlseid]

Burners are professionally designed to work with no modifications provided they have the correct orifice installed to operate at a specific pressure. If you can provide the burner rating and manifold pressure, I can advise on the correct orifice size. If your burner is to run at 100kbtu @ 7"wc you need a 22 (99k) or 21 (102k) orifice.

Thank you Hockeyman for drawing attention to the issues of adequate gas supply and safety concerns that accompany "supercharging" a burner. I have these burners with these valves. They are reported to be designed for low pressure. They are 10" diameter and supposed to deliver 60,0000 BTUs at 11" WC. Presumably, the valve orifice is sized correctly for this.

I have my NG plumbed to a regulator on my brew stand; until the regulator the gas is at the pressure that comes out of the meter to the house. It then goes through 26 to 34 inches of 3/4 black pipe manifold (44 inches total), through a Honeywell valve, to the first through the last of three burners. From the valves, gas goes through a 1/2" appliance line of 18", 24", or 36" to the orifice/valve on the burner.

If I need 11" WC to get the max of 60,000 BTUs (with no supercharger), is it correct to conclude I can get this if I read 11" with a manometer on the outlet pressure tap on my valve? And would it also be right that I should read 12" on the inlet pressure tap if I have things set right (adjusting the regulator on my brew stand accordingly to achieve this), given the reported 1" pressure drop of my valves? What am I missing?

Given the now apparent risks with a supercharger, I am inclined to optimize the pressures on my set up and call it good. Thanks in advance.

 

[user 125772]

Hmmm, that sounds like a show-stopper for the Nitrous

 

[calgary222]

Quick question JonW, how far in to the venture area does your hose go?

I have a new stand with BG14s and had some flames in the venturi area before I lifted my pots by an inch - seems to have been an airflow issue.

While trying to solve that problem, I read this thread and decided to try it - mainly to try and increase the one way direction of flow through the burners and avoid some of the risks Hockeyman alluded to - this may be misguided, but a quick test by holding up the fans to the air input were encouraging. I am thinking about 3 inches would be about right - thoughts?

 

[JonW]

Given the now apparent risks with a supercharger, I am inclined to optimize the pressures on my set up and call it good. Thanks in advance.

Good luck with that! Please report back your findings as you do your tests.

 

[JonW]

Was there anything indicating fuel starvation is the issue here?

No, only air starvation! It's a problem inherent with the design of these burners when used on low pressure fuel (7" WC).

 

[JonW]

Quick question JonW, how far in to the venture area does your hose go?

I have a new stand with BG14s and had some flames in the venturi area before I lifted my pots by an inch - seems to have been an airflow issue.

While trying to solve that problem, I read this thread and decided to try it - mainly to try and increase the one way direction of flow through the burners and avoid some of the risks Hockeyman alluded to - this may be misguided, but a quick test by holding up the fans to the air input were encouraging. I am thinking about 3 inches would be about right - thoughts?

My air feed only goes into the venturi area about an inch. I understand Hockeyman's concerns, but with such low pressure air and the additional venturi space along with the burner jets, there isn't any way for this to become plugged and force the air back into the gas feed - it's just not going to happen.

I've also tried increasing the orifice size for more gas flow (as Hockeyman suggests), but that just results in a richer flame with a lot of unburned gas. You can't increase fuel flow without increasing air flow - one doesn't work without the other. The bottom line is that the design of these burners does not support sufficient air flow when using low pressure (7" WC) fuel. The higher pressure propane usage on these burners works because the velocity of the fuel pulls in air through the venturi.

My original tests (on my old brew rig) used the exact same gas lines, valves, etc. and only changed the burner from a wok/jet burner to a BG14. Fuel feed was the same, but since the wok burners had 10 tips, that means 10 gas orifice's and 10 venturi's. Each tip is able to mix/burn fuel much more efficiently due to the better air flow at the combustion point. The problem with the jet burners though is that they sound like a jet! I hated the noise, especially when 2 or 3 were running at a time. We now have normal level conversations around the brew rig because the BG14 burners run silent.

Unlike a normal supercharger on an engine, this is not a pressurized system. This is an "air assist" system to get more air up to the point of combustion.

 

[calgary222]

Helpful Jon (and reassuring),
A few final touches then and I should be up and running within the week,

Cheers!

 

[dahlseid]

My air feed only goes into the venturi area about an inch. I understand Hockeyman's concerns, but with such low pressure air and the additional venturi space along with the burner jets, there isn't any way for this to become plugged and force the air back into the gas feed - it's just not going to happen.

...The bottom line is that the design of these burners does not support sufficient air flow when using low pressure (7" WC) fuel.

...Unlike a normal supercharger on an engine, this is not a pressurized system. This is an "air assist" system to get more air up to the point of combustion.

JonW, I appreciate your points here. It has me reversing my thinking about trying the air gun test at least to see if I get more from the same, but I think I will try my optimization first, then test. I am curious, do you evaluate the design of the burners (link posted in #67) I bought to be the same as yours, in terms of not supporting sufficient air flow with low pressure and/or precluding airflow into the gas feed (assuming use of the same design for air assist)?

Thanks.

 

[JonW]

dahlseid, Yes - your burners linked are identical to mine and what is generally referred to as BG14's. On 7" WC NG, you will never get the rated BTU output due to the limitations in air flow & combustion.

 

[Hockeyman]

Thank you Hockeyman for drawing attention to the issues of adequate gas supply and safety concerns that accompany "supercharging" a burner. I have these burners with these valves. They are reported to be designed for low pressure. They are 10" diameter and supposed to deliver 60,0000 BTUs at 11" WC. Presumably, the valve orifice is sized correctly for this.

I have my NG plumbed to a regulator on my brew stand; until the regulator the gas is at the pressure that comes out of the meter to the house. It then goes through 26 to 34 inches of 3/4 black pipe manifold (44 inches total), through a Honeywell valve, to the first through the last of three burners. From the valves, gas goes through a 1/2" appliance line of 18", 24", or 36" to the orifice/valve on the burner.

If I need 11" WC to get the max of 60,000 BTUs (with no supercharger), is it correct to conclude I can get this if I read 11" with a manometer on the outlet pressure tap on my valve? And would it also be right that I should read 12" on the inlet pressure tap if I have things set right (adjusting the regulator on my brew stand accordingly to achieve this), given the reported 1" pressure drop of my valves? What am I missing?

Given the now apparent risks with a supercharger, I am inclined to optimize the pressures on my set up and call it good. Thanks in advance.

To optimize we need a few variables. Shoot me a pm and we will discuss your particulars or start a new thread... Don't want to hijack this one.

 

[Hockeyman]

My air feed only goes into the venturi area about an inch. I understand Hockeyman's concerns, but with such low pressure air and the additional venturi space along with the burner jets, there isn't any way for this to become plugged and force the air back into the gas feed - it's just not going to happen.

I've also tried increasing the orifice size for more gas flow (as Hockeyman suggests), but that just results in a richer flame with a lot of unburned gas. You can't increase fuel flow without increasing air flow - one doesn't work without the other. The bottom line is that the design of these burners does not support sufficient air flow when using low pressure (7" WC) fuel. The higher pressure propane usage on these burners works because the velocity of the fuel pulls in air through the venturi.

My original tests (on my old brew rig) used the exact same gas lines, valves, etc. and only changed the burner from a wok/jet burner to a BG14. Fuel feed was the same, but since the wok burners had 10 tips, that means 10 gas orifice's and 10 venturi's. Each tip is able to mix/burn fuel much more efficiently due to the better air flow at the combustion point. The problem with the jet burners though is that they sound like a jet! I hated the noise, especially when 2 or 3 were running at a time. We now have normal level conversations around the brew rig because the BG14 burners run silent.

Unlike a normal supercharger on an engine, this is not a pressurized system. This is an "air assist" system to get more air up to the point of combustion.

Maybe you'll win the lottery... The chance is there if you want to take it. I'm a licensed gas fitter and this isn't something anyone should do. Buy the correct burner that will work with your available gas pressure.

 

[day_trippr]

No, only air starvation! It's a problem inherent with the design of these burners when used on low pressure fuel (7" WC).

Lol! Admittedly I went very very light with the sarcasm there.
Yes, as I have followed your thread since the beginning and am very familiar with bg14's running on NG, I was well aware of the actual issue...

Cheers!

 

[JonW]

Lol! Admittedly I went very very light with the sarcasm there.
Yes, as I have followed your thread since the beginning and am very familiar with bg14's running on NG, I was well aware of the actual issue...

Cheers!

LOL, yeah, I knew you were being sarcastic. My points were for the benefit of others.

 

[JonW]

Maybe you'll win the lottery... The chance is there if you want to take it. I'm a licensed gas fitter and this isn't something anyone should do. Buy the correct burner that will work with your available gas pressure.

When you get a chance, stop over at the pottery/kiln forums and the metal/forge forums and let everyone there know how dangerous their home-built forced air burners are. I'm sure they'll appreciate it as much as I do.

 

[bsent]

My air feed only goes into the venturi area about an inch. I understand Hockeyman's concerns, but with such low pressure air and the additional venturi space along with the burner jets, there isn't any way for this to become plugged and force the air back into the gas feed - it's just not going to happen.

I've also tried increasing the orifice size for more gas flow (as Hockeyman suggests), but that just results in a richer flame with a lot of unburned gas. You can't increase fuel flow without increasing air flow - one doesn't work without the other. The bottom line is that the design of these burners does not support sufficient air flow when using low pressure (7" WC) fuel. The higher pressure propane usage on these burners works because the velocity of the fuel pulls in air through the venturi.

My original tests (on my old brew rig) used the exact same gas lines, valves, etc. and only changed the burner from a wok/jet burner to a BG14. Fuel feed was the same, but since the wok burners had 10 tips, that means 10 gas orifice's and 10 venturi's. Each tip is able to mix/burn fuel much more efficiently due to the better air flow at the combustion point. The problem with the jet burners though is that they sound like a jet! I hated the noise, especially when 2 or 3 were running at a time. We now have normal level conversations around the brew rig because the BG14 burners run silent.

Unlike a normal supercharger on an engine, this is not a pressurized system. This is an "air assist" system to get more air up to the point of combustion.

Also FWIW, when I built mine out I tested the air pressure where the duct meets the venturi and it's ~1.7" WC (vs. 7" WC where the gas feeds in). Like Jon, my duct pushes into an open venturi. If I could find a way to create a total blockage at the burner, air/gas would simply flow back out the venturi as that is the lowest pressure path.

A check valve might be a good safety addition to any gas appliance, but I have a hard time seeing a practical situation where this setup could create any significant back pressure.

 

[JonW]

Also FWIW, when I built mine out I tested the air pressure where the duct meets the venturi and it's ~1.7" WC (vs. 7" WC where the gas feeds in). Like Jon, my duct pushes into an open venturi. If I could find a way to create a total blockage at the burner, air/gas would simply flow back out the venturi as that is the lowest pressure path.

A check valve might be a good safety addition to any gas appliance, but I have a hard time seeing a practical situation where this setup could create any significant back pressure.

I'm glad you actually tested it as I didn't, but I knew the fan pressure would be less than the gas pressure. I agree with you, and have a hard time seeing where this could create any back pressure into the NG system to create a catastrophic event as has been suggested. It's simply not a sealed and pressurized system.

 

[dahlseid]

Good luck with that! Please report back your findings as you do your tests.

I am using the BG-14 type burner that I got from Brewers Hardware with NG and am using their NG valve/orifice, which has a 1/8" ID. On their site, they report these are designed to run at 11" WC and will produce 60,000 btu; whether this is for NG, LP or both is not clear. I control my burners using a BCS-460 to activate Baso BG1100MAAK-1G furnace ignition control modules that run Honeywell VR8345M valves and direct spark ignition and separate flame sensor. I've been running it for about two years, and it works nicely. After finding this thread, I decided that I would like to get all I could out of my burners as implemented on my current stand.

A little research and some measurements and I learned that, with my valve outlet pressure setting maxed out, I was supplying NG to my burners at 5.5" WC (consistent with valve specs). My NG inlet pressure is 11.7" WC, so I was able to step up my outlet pressure to 7" through 11" WC by changing the NG spring on my value for the LP one. This worked to jack up the flame, for sure, but it also seemed that as I increased the pressure in 1" WC steps that it progressively reduced the number of burner ports that generated/sustained a flame and progressively burned more rich, as evidenced by ever increasing orange amidst the flames.

I'll post below links to short videos of the burn attempts at 7", 9" and 11" WC. In the 7" WC film, you will see that I wave the flame to get all ports to light, which they do but which the burner does not sustain. In the 11" WC, I get ignition but the burner flames out and activates the ignition control shut off.

I seek any insight or perspective any of you might have to share. I have it that, according to tables available to gas fitters, 11" WC with this burner and orifice should be putting me close to 80,000 btu potential, and that I should get 60,000 btu at 5" WC (thanks hockeyman!). I am going to clock my gas meter to see where I am at with all this when I get the time.

For now, I am wondering if I am just throwing more pressure at this burner than it can manage. Clearly, with the pressure set higher (and without a supercharger), the point where gas can ignite is higher. This may require resetting the location of my spark ignitor, and it may be a difficult optimization. It has also been suggested that changing to a pilot light would ease the process of providing ignition to the gas at the higher ignition points that accompany higher pressure.

What do you all think? If I pursue a pilot, I can use the pilot light port already on my valves and would use the intermittent pilot strategy, so I may be asking for advice on how to convert my direct spark ignition/sensing in the most cost effective and reliable way (recognize that cost effective and reliable may be in tension with each other).

Thanks for completing a long read. Fire away...

Seven inches WC

Nine inches WC

Eleven inches WC

 

[dahlseid]

I'm glad you actually tested it as I didn't, but I knew the fan pressure would be less than the gas pressure. I agree with you, and have a hard time seeing where this could create any back pressure into the NG system to create a catastrophic event as has been suggested. It's simply not a sealed and pressurized system.

JonW, bsent has indicated NG pressure of 7" WC. Have you measured what pressure NG you have going to your burners?

 

[JonW]

JonW, bsent has indicated NG pressure of 7" WC. Have you measured what pressure NG you have going to your burners?

I believe I'm right around 7.5" WC.

A quick read of your previous post tells me that you're trying to increase the fuel to your burners, but you're failing to increase the air - which is the whole point of this thread. Since the NG gas flow pressure is so low, there is not enough gas velocity to pull sufficient air in through the venturi. Do a simple test with a mattress inflator or some other air device to give some additional air to the venturi of your burner. You will see the light! (the blue one, lol).

 

[dahlseid]

I believe I'm right around 7.5" WC.

A quick read of your previous post tells me that you're trying to increase the fuel to your burners, but you're failing to increase the air - which is the whole point of this thread. Since the NG gas flow pressure is so low, there is not enough gas velocity to pull sufficient air in through the venturi. Do a simple test with a mattress inflator or some other air device to give some additional air to the venturi of your burner. You will see the light! (the blue one, lol).

Thanks JonW. I agree with your interpretation. I was looking for a few reference points to give me some direction on what to set me outlet pressure to. I want to dial that in first, and that should put me in a good spot to try the air assist. Thanks again!

 

[dahlseid]

I believe I'm right around 7.5" WC.

A quick read of your previous post tells me that you're trying to increase the fuel to your burners, but you're failing to increase the air - which is the whole point of this thread. Since the NG gas flow pressure is so low, there is not enough gas velocity to pull sufficient air in through the venturi. Do a simple test with a mattress inflator or some other air device to give some additional air to the venturi of your burner. You will see the light! (the blue one, lol).

I was able to get some information from Brewers Hardware about the burners I bought from them. They wrote, "The 11” WC is for LPG. The NG burners are the standard 7” WC most all homes have for NG. The manufacturer says this: This low pressure burner that measures 10” in diameter, venturi is tapped for 1/4” FPT for orifice valve installation, burner mounts using four lugs on perimeter which are pre-drilled and tapped and at 11” W.C. consumes 56,500 BTU/hr."

Digging further at the manufacturer's site, it says these produce 52,000 btu/hr with NG and a 1/8" orifice (and no super charger), though it doesn't specify the NG pressure...presumably it is 7" WC.

Have those of you who are running these with ~7" WC NG and a supercharger or air assist clocked your gas meters to determine btu output?

 

[JonW]

Have those of you who are running these with ~7" WC NG and a supercharger or air assist clocked your gas meters to determine btu output?

No, I have not.

 

[bsent]

No, I have not.

Me neither. All of my tests were time to heat typical strike water volume between two known temps. I don’t really care how much fuel it takes ;-)

 

[fosaisu]

I'm interested in trying out a 12v squirrel cage fan. If I'm going to buy this one:
https://www.kr4.us/blower-squirrel-cage-12v.html

any advice on powering it? I don't have a brew stand, so really just looking for a cheap wall-wort that I can strip and attach to the leads on this fan to get it running. I'm not an electrics guy, so any advice would be much appreciated!