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Can you convert a Natural Gas Furnace to Propane?

FarmallMan

Hot Rolled
Joined
Jul 19, 2004
Location
Troy, NY, USA
I was offered natural gas forced air furnace for free. The problem is that where the furnace would be installed, natural gas is not availible from the utility company, so the only source of fuel would be propane. What's involved in converting these units? Anyone done it, or converted from propane to NG? Thanks.

Nick :cool:
 
generally yes. I built a house long time ago where there was no ng, but I figured there would be, so I put in a lp furnace and it was converted a few years later when ng arrived. generally just an orifice needs to be replaced, like a 2 dollar part.
 
GO to your local propane dealer with make and model of your furnace. All that is required is to change an orfice in the gas valve, like changing jets in carburetor. If you can get the right orfice, no problem at all.
jim
 
Sometimes the conversion is built into the gas valve. My new furnace just required removing a plug, reversing it, and screwing it back in.

That, and tightening the orifice a couple of turns.

You would defintely want the owner's manual for your model, though.
 
Like everyone else has said, YES it relativley easy to do. Usualy NG appliances run about .5 to 2 psi (although there are a few higer pressure systems out there) while propane is about ~30 psi.

I converted one a few years back, in that case I hade to enlarge the jet. I just did some research on the the BTU's of each fuel, and the the BTU rating of diff sized jets, and then did some math to get the required jet size, and simply drilled it out to the new size. Depending on the model etc, you may also need to change the pilot flame jet as well.

This is a very std conversion, and most gas fitters would be able to do it quickly, if you dont want to tackle it yourself.

Tim
 
Some conversions require a complete new control valve plus orifices. In my case the Honeywell valve to use NG was $121.00 and I drilled out the orifices to the larger diameter required. The old (but never used) two stage LP control valve sets on the shelf.
 
I had a furnace converted 3 years ago. Most of the newer units will require a different control valve and jets. If it's got electronic ignition, you should add a standing pilot light for safety.

In either case, have a heating contractor do it. Every year I see something about a house blowing up and it's usually because somebody was screwing around with a propane furnace.
JR
 
When you purchase a new unit, Like Armstrong,
it comes with NG installed plus a conversion kit
for LPG. The manufacture, or outlet, can only
sell through an authorized & licenced dealer
( contractor ), and is to be installed by the
same. Which means if you're not licenced, you
can't purchase and install yourself. When the
installer installs your furnace, he must remove
all parts not used. You can't keep them.
I tried to get them to change their minds but
they won't budge on it.
 








 
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