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General Forestry => General Board => Topic started by: PawNature on April 04, 2006, 12:45:37 PM

Title: Converting furnace from propane to natural gas....
Post by: PawNature on April 04, 2006, 12:45:37 PM
I have a propane furnace and was wondering if anyone here knows if it can be converted to Naturas Gas.
Title: Re: Converting furnace from propane to natural gas....
Post by: Mr Mom on April 04, 2006, 12:54:04 PM
     you should be able to.
     All you need is the orficie (spelling??) for natural gas that if your furnace has them.
     Call a furnace company they should be able to tell you.
     I changed mine from natural gas to propane.



     Thanks Mr Mom
Title: Re: Converting furnace from propane to natural gas....
Post by: TexasTimbers on April 04, 2006, 01:02:59 PM
All you need to do generally speaking is to do like Mr. Mom said and swap the propane orifices (smaller holes tha the NG) for the natural gas orifices. You'll need to swap both the burner jets and the pilot orifice as well, unless it's an electronic ignition. You also may have to change out the diaphram spring in the valve which will give the proper regulator pressure.

Go to your local HVAC guy and give him your model/serial number and brand and he can give you the kit or order it.

Going from gas to propane is not a DIY if you ain't sure you know what your doing, neither is LP to NG but you're less likely to blow yourelf up.  ;D
Title: Re: Converting furnace from propane to natural gas....
Post by: highpockets on April 04, 2006, 10:14:51 PM
In some models (2 each York Units I had) you also had to change the actual burner to.
Title: Re: Converting furnace from propane to natural gas....
Post by: JimBuis on April 04, 2006, 10:29:55 PM
Reemphasizing what has already been said, unless you have had good training and/or experience with gas, do not attempt this.  With that disclaimer, a natural gas unit or propane unit can easily be converted back and forth.  It's all a function of gas and air ratio.  Therefore, the orifice size [controls the amount of gas] and the amount of air are the keys to the process.

Look around inside the furnace.  Sometimes they come with a conversion kit and the installer tapes it up inside one of the covers.

Just an idea.

Jim
Title: Re: Converting furnace from propane to natural gas....
Post by: PawNature on April 09, 2006, 10:28:14 PM
Thanks Guys for the imput.
Title: Re: Converting furnace from propane to natural gas....
Post by: maple flats on April 12, 2006, 06:38:46 PM
On an older cook stove to convert all that was needed was to drill out the orifice to the right size BUT I'll bet a furnace has a lot more to consider and to make sure everything is matched correctly to safely ignite every time and to burn properly and to give the safe BTU level it was designed for. I would think this be better done by a trained technition, not a DIY type project. You must have the correct specs and must change everything needed or you could have a bomb.
Title: Re: Converting furnace from propane to natural gas....
Post by: JimBuis on April 12, 2006, 06:45:20 PM
Back when I used to be in this sort of business, we often drilled out orifices or silver soldered them shut and redrilled.  However, that was done with gas flow charts for reference, precision bits, and measurement instruments for measuring gas pressure in inches of water column.  Done right, this works as well as any factory kit.  However, without the instruments, charts, and know-how, this is the formula for disaster.

Jim
Title: Re: Converting furnace from propane to natural gas....
Post by: woodhick on April 12, 2006, 10:05:24 PM
I picked up a warm morning natural gas stove last summer with the intentions of converting it to propane to heat my shop with.  I have called almost every warm morning dealer and lots of HVAC people to get an orfice to change it over.  No I repeat Not one of them would help me out.  They all said that it was impossible to get just an orfice anymore and I had to buy the whole burner assembly which for my stove was between $300 and $400 bucks. :o :o  They all said it was due to liability and the companies would no longer sell  just orfices' anymore.  I was tempted to due the solder and redrill aproach but bought another heater insted and sold the other.  I guess we can thank the lawyers again. :(
Title: Re: Converting furnace from propane to natural gas....
Post by: logwalker on April 13, 2006, 12:45:24 AM
I have converted two fireplaces to propane from N.G. I could never seem to get the right jets from the dealers so I brazed and drilled. Took a couple trys but came out fine. No soot on the glass in one year. LW
Title: Re: Converting furnace from propane to natural gas....
Post by: Murf on April 13, 2006, 02:58:58 PM
I wouldn't try it in my house, or recomend anyone else do it either for that matter, but I was told that because Propane is hotter than NG, you can just run the propane appliance on NG directly, it just wont put out the rated amount of BTU's.

On a cubic foot basis natural gas has a little less than half the BTU's of propane. Accordingly then a 100k. Propane furnace running on NG would have an output of less than 50k BTU's.

I would want to be sure of things like pilot lights, safety valves, etc., would still work though.
Title: Re: Converting furnace from propane to natural gas....
Post by: Trax on April 21, 2006, 11:15:05 AM
If the furnace is not to old there could be a conversion kit available for it. The kits consist of burner orifices and a spring for the pressure regulator, it is very simply to do. The kits are usually under $50 and will have very easy to follow directions. If it is an older unit  it can still be done by resizing the orifices (you will need a wire gauge drill bit set and a sizing chart)  You will also have to change the gas valve to one that is already set for propane,  if it is old enough to have a standing pilot the orifice in the pilot assembly will need to be opened up slightly which most time can be done with a pin.