I have an existing natural gas line that feeds my furnace, water heater, and an indoor fireplace. That's all working fine. I'm considering adding a second line that would feed a new gas range (my current range is electric), an outdoor grill, and an outdoor fireplace. There is a guy coming next week to make a quote for the work, but I wanted to get a jump on understanding the situation.

I understand that the new line has to be sized large enough to support all the load I will place on it, and also the gas line into the house (and up to where the two lines split) has to be large enough to support everything I'm planning.

I can find the numbers for the existing indoor fireplace, water heater, and furnace, but I have not yet purchased the items on the second line (new gas range, outdoor grill, outdoor fireplace) so I'm looking at descriptions online to estimate BTU usages.

The grill seems straightforward, at least this one says 48,000 BTU.

But when I look at gas ranges, it gets complicated. All of the ranges on homedepot.com (like this one) tell me the BTUs for each burner, but not the BTUs for the ovens. And even if I find the BTU for the oven, do I size the gas line so I can run every burner at full power AND both ovens at full power, all at the same time? I guess that's not a totally ridiculous scenario on Thanksgiving ...

What value do I use for BTUs for a gas range when sizing the gas line?

  • At minimum you should size for the single highest BTU appliance. Pragmatically you can size for realistic or anticipated usage. To be absolutely proper and ensure you have enough gas regardless of situation then size it for maximum BTU of all appliances. Regardless of which previous option you choose just make sure to add 1/4 inch for good measure so that you can comfortably add a future appliance.
    – MonkeyZeus
    Commented Feb 11, 2021 at 17:15

1 Answer 1


The size for the range goes back to your cooking style if you use 2 burners all the time or are like my wife uses 2 burners the griddle and one of the ovens at the same time you add all that up but remember you probably won’t be grilling at the same time or the furnace may not need to turn on as often while using the range. It won’t hurt to size everything for maximum flow but the pain may be in the check book when you find you need 1-1/2 lines to do this but only really need 1” for actual use. So if you use all the burners and oven at the same time add them in but then think will you be grilling outside? Or will the heater need to come on? And go from there.

  • Are convenience and usefulness the only factors to consider? Are there code or safety issues involved with having an undersized supply line?
    – izzy
    Commented Feb 11, 2021 at 15:43
  • 1
    I have not had an inspector challenge any of my installs for propane or natural gas. One inspector mentioned the on demand hot water may reduce the pressure in the home but did not ask me to change anything. They usually hit the venting and supply air calculations though.
    – Ed Beal
    Commented Feb 11, 2021 at 15:48

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