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03-26-2013, 04:24 AM   #1
bduane
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 Natural Gas Calculations with Banjo Burner?

I've been doing a lot of reading, learning quite a bit, and thought it was about time I ask for help to clarify and confirm.

1. The limiting factor of output of a Banjo burner on natural gas is the air Shutter, correct? We could in theory have a larger orifice for higher volume of Natural Gas and higher BTU/hr, but there is a limit as to how much air can be through the shutter to allow the proper mixture.

2. How big of a supply hose would I need to ensure that the supply hose is not the bottleneck for 2 burners? A 10 foot 3/8" ID hose would have too much pressure drop to supply the volume needed over a 10 foot run, correct, so I need to look at 1/2"?

3. My houses natural gas regulator seems to be adjustable from 7" to 11"WC. I only have a hot water heater and a furnace hooked up to NG, and they are in the same room as the regulator. Any reason not to turn it all the way up to 11"WC to increase the potential BTU output of the burners?

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03-27-2013, 08:31 PM   #2
bduane
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A lot of views but no replies, after doing more research I will try to answer my own questions for others, but don't consider me an expert!

1. I am still under this impression. I have found some additional tips though... you should fine tune your orifice size with your shutter actually closed just a little bit. This way, if you go 1 step too far, you can correct for it by opening the shutter. Also, temperature and other seasonal factors can impact the air intake, so it is good to give yourself a little bit of room to play with at max flow.

2. I think a 3/8" ID hose would work if it was a VERY short distance, but not at the ~10 feet I need, I'm assuming this is due to resistance causing pressure drop. I found a very helpful chart here that will tell you what ID pipe/tube you need for a given length and BTU requirement: http://caloreequipment.com/media/downloadDocument/id/14

3. I can't find a lot of information on people doing this, it seems it is not very common to run NG at 11"WC, not sure why.

Also, the best price I've found on 1/2" NG hose and disconnects was at the same site I linked to above, I ended up going with a 12 foot 1/2" ID hose with a quick connect that has an integral ball vale: http://caloreequipment.com/products/cl/grill/1-2-bbq-grill-connector-kits/1-2-id-ball-valve-quick-disconnect-gas-connector-kit.html

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