Need advice about natural gas/Liquid Propane differences for old stove

[STROIL]

My friend who is not so handy asked me if I could help him convert an old natural gas stove from probably the 1930's to propane burning. I think they used to call these things gas "burners". They were frequently in basements in homes way back then, before washing machines, and they were primarily for boiling clothes, or at least making hot water to wash clothes in.

He wants to be able to burn LP gas and use this in his bigtime backyard Bar-B-Q set up. The burners are in fine original condition. I think this thing would probably work perfectly on natural gas, just as it is. But running natural gas to it where he wants to use it is not practical.

I know there are modern furnaces and bar-b-q pits that boast the ability to convert easily from Natural gas to LP gas and vice-versa.

What's involved in the modification from one to the other? Is it as simple as one uses smaller venturis then the other (smaller orifices shooting into the end of the burner)? I would assume LP does use smaller orifices since it is much more pressurized than natural gas. Is that correct?

There are so many smart folks that read this forum, I was hoping some of you might be able to advise. Thanks in advance for any help.

Kinda would like to avoid blowing myself up.

 

[aczlan]

As I understand it, you install smaller orifices, replace the pressure regulator and adjust the air dampers (probably to have a smaller opening).
Going the other way (propane to Nat Gas), you install larger orifices, increase the size of the air inlet and install the proper pressure regulator (if needed).

Aaron Z

 

[Tractor Seabee]

Propane uses a smaller orifice in the burner due to both pressure and BTU content. Orifices are sized by the BTU output of the burner. Orifice sizes for old equipment are hard to find. A propane distributor should be able to help as they often do conversions and they have data tables. The orifice is probably a brass cap on a pipe thread (sometimes they are a pipe plug) with a small hole in it inside the burner throat. They are available as a blank with no hole, again your distributor should have them. The hole sizes are small and use numbered bit sizes. When drilling them out do not leave any burrs. I did a lot of this in Phoenix AZ when NG came in in the 50s but that was easy as we drilled them out bigger. Do some research on the net and you might get lucky. If it has a pilot light you have to do that also. Even if the hole is too big you won't blow your self up; it will probably burn a lot higher and smoke as there is not enough air for the volume of gas. I would take burners and orifices to a gas appliance service place and have them do it. Call them first to make sure they can do it before you run around. If there is a pressure regulator in the gas train of the burner you will need to replace that W/one set for propane pressures also. Propane appliances also have additional safety controls in the gas train than NG appliances as propane is heavier than air and more dangerous, especially in basements. That is how you can blow yourself up and your house (BIG BOMB) if basement fills up with gas. This is not a novice DIY project. I used to do this for a living now many years ago.

Ron

 

[jenkinsph]

I still do these conversions from time to time as a gas plumber. I recommend you get a gas plumber locally to make the conversion for you, he/she should have the needed number drills, jets and charts to do this properly. They should also have the appliance regulators you will need for the conversion. I should mention that your altitude is also taken into account with the btu rating so having the chart is important.

 

[Cord]

I did the conversion once on a water heater. Purchased a factory kit that included a new regulator and a bunch of other parts. Water heater never worked right after that. It would have a delayed ignition that would spit flames out the side. Ended up replacing the unit and the exercise was a waste of money.