I have a Rheem Classic 90 Furnace. It was originally Natural Gas but was converted when installed to work on LP Gas. Now Natural Gas is coming to my home and I need to convert it back to Natural Gas. I do not have the parts which were changed out the first time. Where can I get the parts? Is there a pre-packaged kit with a part number and instructions?

Contact Rheem and ask them for a conversion kit for your furnace. If your furnace is an older model they would know which current conversion kit would work with that furnace.

Look inside the panel where you can see the burner orifices. The original orifice was replaced with a LP orifice, the old ones may be still attacted in a small strip of metal for future use. I nvere throw them away.

Contact Rheem and ask them for a conversion kit for your furnace. If your furnace is an older model they would know which current conversion kit would work with that furnace.Hey! Just when did you become so d@mn smart about heating?:D

From working at a manufactured home dealership where a lot of new gas furnaces were installed that had to be either LP or natural gas and had to order the conversion kits from the manufacturer. :):D Also the new home installations would involve the natural gas company with accompanying headaches.

Most furnaces as stated by ballengerb1 do come as natural gas and need to be converted to lp, so a conversion kit would be from lp to natural gas, you need to contact a Rheem dealer and order the orifices for natural gas as well as a wiring schematic because the later furnaces when converted to lp have a pressure switch and wiring change added for safety should you run low on lp, these would need to be removed , good luck, Mike