Supercharging a natural gas BG14 burner

[dahlseid]

I also had issues with the wiring of my igniters melting some, so I've ordered some fiberglass wire insulation to ensure the leads don't touch.

I'm drawn to the supercharging solution and this thread because I am having related issues, but here I write on a related topic.

The kettles in the current configuration of my stand are causing heat wash onto the wiring of my ignitors and flame sensors, which are mounted in the wind screens (so the wires are on the outside of the wind screens). However, due to the heat wash, they have melted and even caught flame. I'm wondering if you can share what kind of insulation you have used and how effective it has been?

Thannks!

 

[day_trippr]

It'd be helpful to see a picture or two of your stand...

Cheers!

 

[JonW]

My original wire melting issue was due to the wiring being routed inside the front beam of the stand. Since then I have moved the igniters to just below the beam and the wiring being "air cooled" for only about a 3" distance before returning to the beam area. This has been sufficient to keep it from getting super heated. Check out my build thread for pics of the igniter placement.

The fiberglass insulation I used was purchased on Ebay. Search for "Electrical Wire Fiberglass Insulation Sleeving" and you'll see the company I used (or similar results). This has worked well so far. I did order several sizes of the insulation and have it multi-layered over the wiring.

I can tell you that if my igniters were in the rear of my burner shields, that they would still melt due to heat wash, but in the front, they are fine. Knowing what you're looks like might help in determining where the real heat issue is coming from.

 

[dahlseid]

Here is a picture of my stand. The direct spark igniters and flame sensors are mounted 45º off of front center of the wind screens, to one side or the other:



If I could figure out how to post more than one picture, I could show the wires attached to these components, those in best to worst shape, and the photos of the relative position.

 

[dahlseid]

Here is a close up of the igniter and sensor:

 

[dahlseid]

Here is a photo of the challenge:

 

[day_trippr]

Lots of spillage going on, and it isn't obvious how to keep that from happening.
But you could relocate the igniters and their wiring.

I mounted my igniters to the undersize of my bg14s into drilled and tapped holes made directly into the cast iron.
This keeps the wiring under the burner and well below where all the heat is...

Cheers!

 

[dahlseid]

Hey day_trippr -

Any chance you could share a photo of your solution?

Thanks for considering.

 

[day_trippr]

Here's a couple of close-ups of the igniter mounting. I don't have a flame detector but you'd install it the same way.
You could also locate them closer to the center than I did - I don't even remember why I put them that far out on the radius.





The cast iron is very easy to work - indeed, tender treatment during threading is a good idea as it's not as resistant to sloppy technique as say steel or aluminum, and a coarse thread type is advised - but the result is solid. I suppose if you bodged the first shot you could goop in some JB Weld and try again

I should add that my stand has a lot more "breathing room" around the burners as I simply mounted entire Blichmann floor burners in a stand dimensioned to fit them, and those beasts have lots of room for exhaust flow.



So my thermal issues wrt wiring are likely no where near as acute.


Still, routing the wires in the coolest zone is likely your best bet, and that's under the burners...

Cheers!

 

[dahlseid]

Thanks day_trippr. The images are hugely helpful, and that is a mighty fine stand you've got there...

 

[day_trippr]

You're very kind, but in truth it's a mere pretender compared to the plethora of epically fabulous builds you've seen on HBT.



But it gets the job done...

Cheers!

 

[ultravista]

Subscribing

 

[bsent]

So pretty much everyone out there running BG14s on NG must have this same issue.

I have the same issue using BG12's on NG and ran across this thread while researching. Based the results here and my own experiments/research, it does seem likely that many people running burners on NG could probably get more BTU's by pushing more air through the system.

My hunch is that the banjo burner venturi is designed to pull in air based on the pressure and volume of gas coming from the propane regulator (which steps down from high pressure in the tank and is usually adjustable from 0-5psi or 0-10psi). Natural gas sources tend to be much lower pressure(7" WC ~= 0.25psi, 11" WC ~= 0.4psi), so I'm speculating that the blower has two positive effects:

1) Increasing the volume of air in the air/gas mixture
2) Increasing the overall pressure of the air/gas mixture as it enters the burner

Here's what I've learned so far:

1) As shown by the OP, I was able to prove out the concept using an inflator pump I had at home (this was way too strong -- but with creative use of duct tape and other hacks I was able to reduce/direct the airflow to avoid blowing out the flame and prove that this significantly improved my heating time).

2) Using a manometer that I purchased off Amazon, I can see that I'm getting between 6.75 and 7" WC pressure at the orafice. Since my city NG supply runs at 7" WC nominal this seems acceptable/appropriate.

3) Comparing to my use on propane, I can see that the BG12's were running rich (too much yellow) and "low pressure" on NG (flames don't extend as high from the burner), regardless of how high I turn up the gas.

4) At a smaller orafice size, I was able to create a small but efficient flame (all blue). However, with this small flame I could see that the pressure and observed heating power was very low compared to the same burner on propane (very low height, 7G from 64 to 120 took ~30 minutes with NG).

5) By increasing the orafice size, I could get a taller and larger flame but it appeared rich (yellow) and "out of control" (flapping all over the place, extending around the base of the kettle and up the sides if enough gas is added). Note: This is the point where I ordered a carbon monoxide detector from Amazon as well

6) With a slightly larger orafice and increasing both the pressure and the volume of air entering the venturi, I was able to get a nice "clean" blue flame extending a few inches from the burner and significantly improved heating (7G from 64 to 120 in ~10 minutes).

At this point I just need to get this airflow a little bit more adjustable and ducted in a way that's more permanent to my stand. I think I'm going to buy one of the 20cfm squirrel cage blowers that the OP mentioned:

http://www.kr4.us/blower-squirrel-cage-12v.html?gclid=CIei2tblydECFUyAaQodmZ4AkA

Curious if the OP or anyone else has any other tips about this specific blower, what you used for a power source (would be nice to be able to vary the speed), and how you connected the blower to your ducting, etc.

Sorry for the long post -- just wanted to document my experience since I really couldn't find a lot of good info about others experiencing this problem or what they had found.

 

[JonW]

At this point I just need to get this airflow a little bit more adjustable and ducted in a way that's more permanent to my stand. I think I'm going to buy one of the 20cfm squirrel cage blowers that the OP mentioned:

http://www.kr4.us/blower-squirrel-cage-12v.html?gclid=CIei2tblydECFUyAaQodmZ4AkA

Curious if the OP or anyone else has any other tips about this specific blower, what you used for a power source (would be nice to be able to vary the speed), and how you connected the blower to your ducting, etc.

Sorry for the long post -- just wanted to document my experience since I really couldn't find a lot of good info about others experiencing this problem or what they had found.

Yes, I use the same blower you linked. I've since added a second one for my HLT tank. They work pretty good. I tried using a variable speed controller, but the fan didn't respond well with it. I use a strip of duct tape about 3/16" wide that is across the duct tube to lessen the air flow just a little.

I have a stainless tube that is ducted up to my burner so that I can keep the blower motor under my stand with the rest of the wiring stuff. It makes for a really clean installation.

I have thought about drilling out the NG orifice to see if I could get even more gas flow. It would likely no longer work without the blower attached as it would be way too rich, but that's not an issue as I always use the blower.

bsent - please update here with any other tests/findings you come up with.

I personally am very happy with the performance I'm getting now using the air assist. It is nearly equivalent to the wok/jet style burners I previously used, but is silent instead of the incessant load jet engine noise. Also, putting the blowers under the rig also help minimize any sound from them.

 

[bsent]

Yes, I use the same blower you linked. I've since added a second one for my HLT tank.

Awesome. Just ordered two of these myself (one for HLT and one for BK).

They work pretty good. I tried using a variable speed controller, but the fan didn't respond well with it. I use a strip of duct tape about 3/16" wide that is across the duct tube to lessen the air flow just a little.

I had already ordered a variable voltage controller (switch selectable) before I saw this. We'll see how it does. How many amps does your 12v source output?

I have a stainless tube that is ducted up to my burner so that I can keep the blower motor under my stand with the rest of the wiring stuff. It makes for a really clean installation.

Looks pretty. So did you just duct tape the blower output to 1/2" stainless pipe? Can't really tell from that pic what size it is or how it hooks up on the bottom. Unlike yours, my stand is already ugly, so a small shop vac type hose wouldn't appreciably detract from the aesthetic ;-)

I have thought about drilling out the NG orifice to see if I could get even more gas flow. It would likely no longer work without the blower attached as it would be way too rich, but that's not an issue as I always use the blower.

I'll post more later on my orafice size experiments. For my volume/pressure 7/64" seemed to be the right size where at lower needle valve settings I can get a good low flame, and then further opening the valve needs air boost to fully combust. I suspect this is highly dependent on the gas volume and pressure and potentially the burner size, so YMMV.

bsent - please update here with any other tests/findings you come up with.

I will, thanks! And thanks for posting this originally and for responding. As I mentioned, there is very little good info that I could find on this topic, so I think this thread will be useful to others as well. This kind of information sharing is one of the things that makes this hobby so fun!

Thanks,

Blair

 

[JonW]

I had already ordered a variable voltage controller (switch selectable) before I saw this. We'll see how it does. How many amps does your 12v source output?

I have a 3.33A DIN rail mount supply.

Looks pretty. So did you just duct tape the blower output to 1/2" stainless pipe? Can't really tell from that pic what size it is or how it hooks up on the bottom. Unlike yours, my stand is already ugly, so a small shop vac type hose wouldn't appreciably detract from the aesthetic ;-)

It is 1" SS pipe. Yes, the blower is duct taped to the inlet.

I'll post more later on my orafice size experiments. For my volume/pressure 7/64" seemed to be the right size where at lower needle valve settings I can get a good low flame, and then further opening the valve needs air boost to fully combust. I suspect this is highly dependent on the gas volume and pressure and potentially the burner size, so YMMV.

Most NG orifice's are 1/8". That's what I'm running now. I may open it up a bit more to see how it works. Brewers Hardware is real close to me, so if I screw up the valve, I can get another one easily.

I will, thanks! And thanks for posting this originally and for responding. As I mentioned, there is very little good info that I could find on this topic, so I think this thread will be useful to others as well. This kind of information sharing is one of the things that makes this hobby so fun!

Agreed! I post my build threads because I learned so much researching on this forum years ago.

 

[bsent]

Most NG orifice's are 1/8". That's what I'm running now. I may open it up a bit more to see how it works. Brewers Hardware is real close to me, so if I screw up the valve, I can get another one easily.

I was confused by a lot of those conversations at first, then I realized people were talking about two different things -- the orifice size (on the gas valve or input "sleeve") and the gas inlet size (on the burner itself). BG12 uses a 1/8" inlet size, whereas BG14 uses a 1/4" inlet. As for the orifice, the pre-fab ones are usually sold drilled to some arbitrary "average" size that should work for most people. For propane that works fairly well because most propane regulators for this sort of thing adjust to either 0-5psi or 0-10psi. However, on NG you're dealing with much lower gas pressure (0.25 - 0.4 psi). I think that causes three distinct problems that we have to solve:

1) At lower pressure you need a bigger hole (orifice) to allow the same volume of fuel (per second/minute/whatever) into the burner


2) At lower pressure, you also have to find a way to get more air into the venturi and mix it with the fuel to achieve optimal combustion
This is because the venturi design on these burners assumes that the incoming gas pressure will help "pull" the ideal amount of air in to mix with the gas. Natural gas water heaters have regulators, mixers and burners that are better optimized for this purpose. I believe we're trying to force it to work with these common brew burners that are optimized for propane, which is why it requires some extra thought/effort.

3) To generate "max heat" at the appropriate point on your kettle, you need a certain amount of pressure to optimize flame height/intensity
As evidenced by the imprecise language, #3 is more of a hunch on my part. I assume it has to be true, but unlike the other two points I have no backup to support this claim.

Anyway, on to the solutions I tried and what I learned. For #1, you can easily increase the fuel output by "boring out" the orifice. People talk about using drill presses and all kinds of complicated stuff but it's just cutting a damned hole in a piece of brass -- it's not hard and for this purpose it doesn't have to be perfect. Just start small and step it up in small increments (testing in between) until you get what you want. In my case, I ended up intentionally "over drilling" mine so that at lower needle valve settings it would work without the blower (for maintaining a low boil, for example) and as I open up the valve the flame gets sloppy/rich (which i can then resolve by turning on the blower).

As far as needle valves, they're not common on propane orifices (since the regulator has one). I ordered a CVO125 from here:

https://tejassmokers.com/Brass-Fittings-Valves/22#brass7

William's Brewing has a 1/4" one that works with the BG14. It sounds like Brewer's Hardware may have something as well.

Based on some stuff I read on the internet I had them drill mine out to #50, but that turned out to be too small (flame was under control at full throttle, but not nearly enough heat). I kept stepping it up in small increments and ended up at 7/64" for my valve/gas pressure/burner combo (YMMV).

Solving #2 and #3 are where the blowers come in. I think by adding the blowers we are attempting to optimize both the air:gas mix and the pressure. Ideal air to fuel ratio for Natural Gas burners appears to be approximately 10:1 in an "ideal environment". I'm not sure about ideal output pressure for these burners (with the kettle at a specific distance), but I'm fairly certain it's more than what we get with the 0.25psi (and maybe even 0.4psi) provided by most natural gas providers.

Once I get my blowers set up, I plan to play with the fan speed and duct size to try and move the optimal amount of air at the optimal pressure. I'll post a summary of those results in the next week or two.

 

[JonW]

Once I get my blowers set up, I plan to play with the fan speed and duct size to try and move the optimal amount of air at the optimal pressure. I'll post a summary of those results in the next week or two.

bsent - I appreciate your contributions to the discussion here, but you're rehashing what I already know. My point of opening up the orifice (over standard 1/8") is that it will require the forced air at that point to operate properly. Yes, you can use a needle valve to control it for low levels, but once you introduce the air system, you will then need to adjust two flows - air and fuel.

The key thing here is the AFR - air fuel ratio. NG needs to be right around 10:1 for an optimum burn. As you play with the fan speed, duct size, etc. you'll see that your gas flow will have a very limited range where it will work properly at the given (forced) air flow.

If you plan on adjusting your flame during brewing, you'll need to adjust both flows to keep an optimum burn (which will require no forced air for low burner output). I think you'll find that you really don't need a large range of burner outputs for our brewing purposes and picking a fixed air flow and fuel flow will be much easier to work with. This will be especially true if you're going to do any type of automation where your burners are firing on/off to maintain your set temps (as I do).

 

[bsent]

I appreciate your contributions to the discussion here, but you're rehashing what I already know.

Yeah, sorry to have hijacked your thread. Some of that I was trying to rehash both to confirm my understanding and to help document it (since I had so much trouble finding any good info).

I think you'll find that you really don't need a large range of burner outputs for our brewing purposes and picking a fixed air flow and fuel flow will be much easier to work with.

I think you're definitely right on the easier to work with. I do have some concerns about thermal loading though, so I'm trying to come up with an easy enough way to do at least a "low" and "high".

Anyway, I see your point and will definitely take that into account. Thanks again for the help!

 

[dahlseid]

The thread has been quiet for a while, so I would like to ask if some of the last posters have any additional information or data to share? My stand is now complete and has brewed several batches, which I wanted to do before taking on the NG burner BTU output issue. Now I am ready. From what I have read, it seems reliable to plan on using the squirrel cage fans with some pipe to enhance air input to the burner. I already have needle valves on my burners for low pressure NG (from Brewers Hardware), but the thread suggests that I should at least consider that it may be beneficial or necessary to bore out the hole size to gain enough fuel flow. It also suggests that, a variable voltage control for the fan will not be very effective and that I should expect to have to tweak my air flow delivery depending on the tubing size I use and how much fuel I am getting delivered.

So, does anyone have some experience and success to guide me in my efforts? For example, what size (inner diameter) tubing have you found to work best, and with what diameter for fuel delivery and other necessary modifications? Any help will be appreciated!

 

[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.

 

[SleepyCreekBrews]

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.