Conversion kits (from propane to natural gas)and vice versa.

Originally Posted By: Robert L Dean
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A lot of gas furnace manufacturers have developed conversion kits for their line of gas furnaces.I have dealt with a few in particular, but I have found it to be a simple matter of orifices when it comes to the differences in them. Each manufacturer has their own type of orifice replacement kit to convert from lp gas to propane or vice versa.

The kits contain the orifices and a spring.The spring is replaced in the gas valve. The way to tell if the system has been converted is the type of gas service piping that is run to the furnace. Generally for propane or LP gas, you would have cast iron piping, and special LP gas and propane fittings. Many natural gas service lines are made of flexible insulated piping.LP gas alone should never be used in a gas furnace that is set up for natural gas because the orifice will be too large, and can cause dangerous overfiring.

I would always inspect the gas lines going into a furnace, to make sure there are no leaks.Bubbles work great for this.Expensive testers may pick up residue from the combustion chamber. This would give false readings.

Also inspect the evenness of the flame when the gas furnace is fired up.This is to ensure the device is working properly.An uneven flame can be a sign of a problem.

Later,I may talk about testing heat exchangers for leaks.Digest this for now.Hope you enjoy.


Robert L Dean


Originally Posted By: ecrofutt
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I would mention that the conversion also changes the pitch of the burners due to the fact that natural gas rises and propane sinks.

In addition, I see lots of black iron natural gas pipes, particularly in older homes. I'm not sure that looking at the line is the best way to tell the difference.

Erby Crofutt
B4U Close Home Inspections
Georgetown, Kentucky

Originally Posted By: Robert L Dean
This post was automatically imported from our archived forum.

Thanks for the additional information. I meant the service connection point. Usually it is different with propane then it is with natural gas connections.At least in Florida it is required by code to be different.The natural gas connection is a flexible stainless steel mesh covered line.Different states have different building codes concerning gas lines though. It’s pretty standard to see black iron pipes for natural gas. When the home is being built these line are installed. If the furnace is to be converted to propane, this must be changed.

Looking at the line itself is not enough. Look for the source of propane,a tank or such. Then you will know for sure.


Originally Posted By: kluce
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In South/East Wisconsin, Central Kentucky and North/West Indiana, black pipe is used alot in the house whether it’s natural gas or propane.

If the heating tech. is good, they would also put a sticker on the gas valve telling that the furnace has been converted to propane. Do not rely on the stickers to determain if it's propane or natural gas. ![eusa_doh.gif](upload://has2a0g32D0AAlDjAwVcrg3HnhX.gif)