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Thread: Natural gas to propane

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    Default Natural gas to propane

    What happens if you go from natural gas to propane without changing out the gas jets in your stove? How about vice-versa? The reason I ask is that many years ago I bought a house that had a 6 burner stove. Two burners and a small oven used wood, the other four burners and a larger oven used natural gas. Based on the age of the stove and the fact that the house was built in the 30's when the area was rural (with no access to "manufactured gas"), I suspect that it originally used propane, yet it always worked fine using natural gas. Any thoughts on this?
    Steve
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    Propane has a higher BTU per cubic foot than Natural Gas. (1030 for Natural Gas & 2516 for Propane). Equipment, (including appliances) are rated for a certain BTU. One way to make sure that BTU rating is not exceeded is to control the maximum supply of gas by a pressure regulator and gas orifice. In most cases the pressure set point remains the same and all you do is install a larger orifice for Natural Gas and a smaller orifice for Propane.

    The magnitude of danger by not changing the orifice depends on which BTU direction you are going, the type of appliance you are using, and how well built the appliance is.

    Going from a high BTU gas, (propane) to a low BTU gas, (Natural Gas) without changing anything just means your appliance will run cooler.

    Going from a low BTU gas, (Natural Gas) to a high BTU gas, (propane) without changing anything could mean you overheat the appliance and burn your house down.

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    KelvinG, thanks for your very informative response, it makes alot of sense. BTW I knew the BTU content of propane was higher then natural gas but I didn't know it was more then double!
    Thanks again.
    Steve
    Tomorrow's a mystery, yesterday's history, today is a gift, that's why it's called the present!
    Approach life like you do a yellow light - RUN IT! (Gail T.)

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    the primary difference is not the BTUs, but the pressure difference.

    Propane is highly pressurized, whereas natural gas is at very low pressure by the time it gets to residential distribution systems.


    Propane should not be used in an appliance set-up for natural gas without conversion.

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    Many gas cook stoves have the ability to convert from nat. gas or propane to the other without changing out individual oriface's at the burners or taking out/changing gas regulators at the gas valves. These stoves have a nut that is behind the control knobs of each burner but back behind the front console. You have to lift the top up to access these fittings. To convert from propane to natural gas or vise-versa, you use a wrench and turn the nut either all the way to the left, or all the way to the right. This adjusts the actual gas flow ( oriface opening size) to the individual burners to match the correct opening for either nat gas or propane. You would need to consult the tech/install information for your individual stove as to which adjustment direction is designed for Propane and Nat. gas..

    To a more specific point on this topic, Nat. gas is typically fed from the Utility gas meter to the house somewhere between 6" and 7" water column. It is then further reduced by the appliance's gas valve to 3.5" w.c to the individual burners.

    Contrast this with Propane, which is typically stepped down with a regulator near the tank to 11" w.c. This is typically fed directly to the appliances gas valve with no further reduction in pressure to the burner orifaces. So propane flows at a supplied pressure rate ( and thus volume ) to the appliance at 3X the rate of Nat. gas ( 11" vs. 3.5" ). Thus a propane oriface can be distinguished from the natural gas oriface by being approximately 2/3 smaller in diameter opening.

    If you have a nat gas appliance that you want to convert to propane, and you only change the oriface's, you may not be able to adjust the regulator in the nat. gas valve high enough to let 11"w.c flow thru it. In that case, the regulator spring must also be changed out to allow the much higher 11"w.c. flow rate. And vise versa- a gas valve's propane regulator may not adjust down as low as 3.5" if converting to nat. gas, and thus would need to be replaced with one that can.

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    Quote Originally Posted by Mr Bill View Post
    Many gas cook stoves have the ability to convert from nat. gas or propane to the other without changing out individual oriface's at the burners or taking out/changing gas regulators at the gas valves. These stoves have a nut that is behind the control knobs of each burner but back behind the front console. You have to lift the top up to access these fittings. To convert from propane to natural gas or vise-versa, you use a wrench and turn the nut either all the way to the left, or all the way to the right. This adjusts the actual gas flow ( oriface opening size) to the individual burners to match the correct opening for either nat gas or propane. You would need to consult the tech/install information for your individual stove as to which adjustment direction is designed for Propane and Nat. gas..

    To a more specific point on this topic, Nat. gas is typically fed from the Utility gas meter to the house somewhere between 6" and 7" water column. It is then further reduced by the appliance's gas valve to 3.5" w.c to the individual burners.

    Contrast this with Propane, which is typically stepped down with a regulator near the tank to 11" w.c. This is typically fed directly to the appliances gas valve with no further reduction in pressure to the burner orifaces. So propane flows at a supplied pressure rate ( and thus volume ) to the appliance at 3X the rate of Nat. gas ( 11" vs. 3.5" ). Thus a propane oriface can be distinguished from the natural gas oriface by being approximately 2/3 smaller in diameter opening.

    If you have a nat gas appliance that you want to convert to propane, and you only change the oriface's, you may not be able to adjust the regulator in the nat. gas valve high enough to let 11"w.c flow thru it. In that case, the regulator spring must also be changed out to allow the much higher 11"w.c. flow rate. And vise versa- a gas valve's propane regulator may not adjust down as low as 3.5" if converting to nat. gas, and thus would need to be replaced with one that can.
    Thanks for correcting my error about the differences in pressure settings. I went back and looked and found that some regulators also have a spacer in them marked LP on one side and NG on the other. That's so you can just flip the spacer to change the spring tension and thus the pressure setting.

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