How To Furnace Propane Natural Gas Conversion

By | July 28, 2020

How To Furnace Propane Natural Gas Conversion
Converting a furnace to propane from natural gas or vice versa is a straight forward simple process but great care has to be taken because of the possible danger if done wrong.

Converting natural gas to propane or propane to natural gas is the same processes by installing new orifices.
How To Furnace Propane Natural Gas Conversion Size
It involves changing out the the correct sized furnace orifices/jets and the gas valve spring.

The same procedure is done to switch between gas types.

The main difference is that propane gas usually has a regulator at the tank to regulate the gas pressure.
furnace orifices
Many newer furnaces often have the parts (orifice and spring) to convert a system in a small packet somewhere in the control box or with the instructions.

If you don’t have the parts a conversion kit will need to be ordered.

An experienced technician can solder or braze the tips of the orifices and then drill out the correct diameter needed but I don’t suggest this. It is difficult to get the correct diameter needed even for an experienced technician.

Buying the correct propane/natural gas conversion kit and following the instructions for your furnace is key.

Propane burns hotter than natural gas so the orifices need to be smaller allowing out less gas.
furnace natural gas conversion kit orifice size
A furnaces heat exchanger, which is where the flames burn, is rated up to a certain temperature.

If the temperature goes over the rating for the furnace the heat exchanger can become cracked and allow carbon monoxide and other toxic gasses to enter a home.

Example LP Gas Conversion Kit on Amazon
Modine 53080 Gas to LP Conversion Kit for 100K BTU

Steps for Converting a Furnace to Propane Natural Gas (Basic Over)

  1. Turn the gas and power off the unit.
  2. shut furnace gas off

  3. Take pictures and write down the wiring connections to the gas valve.

  5. Disconnect the gas valve.
  6. Disconnect the gas valve

  7. Locate the orifices/jets and with the correct size wrench remove them.
  8. furnace orifice removal

  9. Install the new orifices.

  11. Locate the spring in the gas valve.
  12. furnace spring

  13. Remove and replace the gas valve spring with the replacement.
  14. furnace gas valve spring replacment
    gas spring

After these steps are done to the furnace it should have the pressure set correctly with a water column manometer.

Propane units runs around 9 to 11 inches and natural gas runs around 3 to 4 inches. Again this will depend on your furnace documentation.

Converting from natural gas to propane involves steps that may differ for manufactured to manufacture because of design differences of propane gas valves.

For example, converting from natural gas to propane gas will include changing the regulator pressure, installing smaller main burner orifices, and installing a new pilot orifice, this process may also include changing the ignition control module to 100% shut off module because propane gas is heavier than air.



9 thoughts on “How To Furnace Propane Natural Gas Conversion

  1. willy jochimski

    I need a kit for furnace from natural gas to propane American standard model number ADC18080A9421AD any help out there?

  2. Mary

    Can you tell me what would happen if a Navien boiler was installed but not converted from natural gas to propane gas. Would the boiler still work for a time? And then what would happen.
    We had a Navien boiler installed in May, 2017. It was only used to heat water at that time as it was in the warmer season. But then in November, 2017, my mother and I succumbed to carbon monoxide poisoning when levels reached 1800 in the middle of the night and by the time I heard the alarm, I was already unable to do anything to get help. Luckily, help arrived when my daughter was unable to reach me and suspected something was wrong. We were taken by ambulance and spent 8 hours in a hyperbarrick chamber.
    We suspect that the boiler was not converted to propane gas. Is this basically what would happen if a boiler was not converted?
    Thanks for your help.

  3. Rob Love

    I need a kit back to natural gas. I have a Amana furnace. Thanks

  4. Cory

    I have a Goodman furnace with an Lp valve and need to change it for a natural gas. So what model of gas valve I need and what orifices do I need size of.

  5. Dana

    My water heater blew. My house is natural gas. My dad had an extra water heater, so he brought it over but it’s propane. So we’re going to switch the orifice to match the natural gas in my home. I cannot figure out how to measure the diameter of the port. It looks like 2mm, but I’m scared it won’t be orrect. GE nor Sears could assist me. All I need is a new orifice. Any suggestions on a part number or something?

  6. gene disney

    i have a train model no.ycc060f1mobh and i need a conversion kit

  7. Zach

    I need to conversation kit from natural gas to propan. Tempstar brand. Model number T8DNL075B12A1


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