Refugee Lp Furnace To Ng


Old 02-14-05, 04:12 PM
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Question Refugee Lp Furnace To Ng

Can you set me right as to the correct orfice replacement to convert an LP furnace used on bottled gas, to NG? I can't seem to make the correct swap.
I don't understand the charts that I have been able to find. The LP orfice is a # 59, and I believe I need a #50,or #51 for NG, but, the chart says that a 51 is just larger than a 1/16" and a 59 is quite a bit smaller. I can slide a 1/16" bit easily thru the #59 that I have. are there different numbers for NG and LP? I'm confused.
any way, the line presure here is 3.5 to 4" of wc. the LP is supposed to flow 12,000 btu
The furnace is a refugee from a travel trailer,forced air burner design from coleman, that I am using to heat my work shop. If I put a stack vent on it, instead of the thru the wall vent, should I use a free breathing setup, like a water heater stack?
Where might I buy numbered drills? What drill size should I use?
If you have answers, or questions, please e-mail me at
email not allowed
Thanks, MIKE

Last edited by Ed Imeduc; 02-14-05 at 04:25 PM.
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Old 02-14-05, 04:32 PM
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Location: San Jose,Ca
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Chart shows for a 12,000 burner on nat gas use a 50 drill size. I would probably use a 51 . When you drill out the orifce unless you are using a drill press and holding the orifice absolutely steady there is room for error. I always go a size small and with an adjustable appliance reg you can clock the meter and adjust as needed. Remember if there are multiple orifices you have to divide the number of orifice into the btu rating and drill accordingly. There is plenty of room for error when making conversions. I would recommend checking for c.o after conversion.
Old 02-14-05, 04:34 PM
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You should go to the maker of the furnace and get a kit for it. In some you have to change the burners also with all the orifice and the gas valve so it has a pressure regulator in it for NTG. THAT #59 LP is for a 12,120 BTU in LP. for the NTG you need a # 50 thats a .0700 drill dia.

AGAIN DONT TRY IT if you dont know gas

Old 02-14-05, 05:17 PM
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Ed-- Thank you for mentioning what I should have said. If you are not familar with gas and gas appliances PLEASE think twice about doing this job yourself. This is one area where you can really mess up.
Old 02-16-05, 08:18 PM
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the orfice seems to only be the tip of the iceberg, LP is OK for now. Thanks for the advice.
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