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Old 06-04-2007, 07:11 PM
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Default btu to CFH for NG help...


We are having our house supplied with Natural Gas shortly. In order to select the correct pipe sizes for appliance feeds, I need to be able to correlate / convert btus's to CFH.

I understand there is no direct coversion available. In reviewing previous posts here, and limited information elsewhere, I have gathered all relevant available data below in the hopes someone may assist.

Fuel Type: Natural Gas
Inlet Pressure: 2 psi
Pressure Drop: 1 psi
Specific Gravity: .60
Inlet Feed Line I.D. : 1-1/4" plastic (from main to meter)
Inlet feed line length: 175 ft. (from main to meter)

Appliance fuel requirements:

1. Tankless Water Heater: 200,000 btu (5" - 10" wc)
2. Gas Dryer: 50,000 btu
3. Range Cooktop: 56,000 btu (6" - 7" wc)
4. Outdoor Grill: 75,000 btu
5. 16 kw Generator: 250 CFH (5" - 7" wc)
6. Furnace: 125,000 btu

I will be using Sch 40 Black Steel pipe for all runs and need to convert the btu figures above to an approximate CFH for pipe diameter determination on runs.

Any assistance would be appreciated.


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Old 06-05-2007, 05:14 PM
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Default Re: btu to CFH for NG help...

Hi Waterlogged,
You should check with the installer, and with your City requirements. Surely, they will have standards they have to adhere to?
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Old 10-06-2007, 09:54 PM
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Default Re: btu to CFH for NG help...

www propane-generators com/natural-gas-chart.htm
(I had to chop up URL to post it add the . after www and . before com.
Has a whole lot of info!!

I used it to size HP of generator to CFH requirements.
HP to BTU is strait forward.
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Old 11-13-2007, 01:05 PM
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Default Re: btu to CFH for NG help...

There are 1000 BTU's per cf of natural gas.
1,000,000 BTU = 1000 CF =1 MCF
Can't tell you what size pipe you really need everywhere because it depends on how long the lengths of pipe to each appliance.

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Old 01-16-2009, 10:32 AM
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Lightbulb Re: btu to CFH for NG help...

The formula for cfh conversions from btu's changes as you go up from sea level. Contact your local gas company for the exact specific gravity of natural gas in your area to get an accurate answer. The one to one calculation works at sea level only. Also the contractor who is installing your new system will provide you with a drawing of your new system including btu/cfh requirements.
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Old 07-20-2011, 11:07 AM
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Default Re: btu to CFH for NG help...

There are approximately 900 to 1000 BTUs in a cubic foot of gas.
Therefore, ROUGHLY, 1000 BTU/hr requires 1 Cubic foot per hr (1 CFH).
1MBH = 1000 BTU/hr = 1 CFH approximately.
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Old 07-20-2011, 12:29 PM
HerrWarum HerrWarum is offline
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Default Re: btu to CFH for NG help...

You possibly are risking your own life and those of your neighbors.

But, I may be biased because a person in the news recently blew up his own house at 3 AM by a faulty dryer install and had his girlfriend landing on the lawn in her pajamas, burned and having breathing difficulties. The neighbors' houses were also damaged.

On the upside, he is now probably judgement-proof.
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Old 07-28-2011, 06:17 AM
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Default Re: btu to CFH for NG help...

Looks like you have about 741,000btu of natural gas at your home; the 1-1/4" line from the main to the meter at 2psi/1.0psi pressure drop and at 175' can provide roughly 2,444,940btuh of natural gas (spec gravity of natural gas 0.60). I believe the actual number you're looking for is 940. 1CFH = 940BTU's most people use 1,000 for the conversion similar to converting BTUH to MBH (1,000,000BTUH = 1,000MBH or 1,000,000BTUH = 1,063.830SCFH). Hope this helps.
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Old 03-25-2012, 08:35 AM
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Post Re: btu to CFH for NG help...

sir ,
1143.8 cfh covert to kw please con you replay me.
Thank you
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Old 04-24-2012, 02:18 PM
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Default Re: btu to CFH for NG help...

1143.8 cfh = 335 kwh
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