# Natural gas line sizing question.



## 240sx4u (Sep 22, 2008)

I have natural gas in my home. I have a natural gas furnace in the house AND in the garage 45k btu. I use natural gas for my dryer as well. I would like to install a natural gas cooktop in the kitchen but don't want to create a situation where I end up with undersized gas lines running from the meter into the house. Everything plumbing wise is right under the kitchen. My oven is electric.

Is there a table I can use to calculate needed pipe size by btu's used? I am not sure I am up to the task of this installation. I am capable but after seeing someones home vaporized by a gas leak earlier this year I am afraid to do it myself. I just need to know if the run into the basement is going to be adequate or if I should just sell the cooktop I got and get an electric one!

EDIT; This cooktop will draw about 43,000 btu if every burner was on full tilt. 

Thanks guys. 

Evan


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## Jackofall1 (Dec 5, 2010)

What is the furnace btu rating for your house, how about hot water heater?

What is the current line size?

Mark


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## 240sx4u (Sep 22, 2008)

Mark, I knew I forgot something. The hot water heater. I will have to check the BTU rating of those when I get home tonight. 

Thanks!


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## Jackofall1 (Dec 5, 2010)

Need that for both the hot water and the furnace.


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## 240sx4u (Sep 22, 2008)

Can do, thank you.


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## 240sx4u (Sep 22, 2008)

100,000 btu on the furnace and 32,000 on the water heater. 

Thanks.


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## Jackofall1 (Dec 5, 2010)

Approximately how long is the line from the meter to the furthest appliance and what is the furthest appliance.

What is the current line size?

Mark


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## 240sx4u (Sep 22, 2008)

Mark, The order of appliances goes;

H/W heater 12' from meter (looks like 1" pipe)

Furnace (2' from HW to here) (same 1")

Dryer is about 16' further down the line on 3/4", which necks down right after the furnace drop.

Garage heater (60ft of 3/4" pipe including bend calculation if memory serves)


Thanks Mark; Luckily the room that has the gas line run from the meter is drop ceiling so if I need to have that part replaced it won't destroy the house. 

Evan


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## Jackofall1 (Dec 5, 2010)

Ok Heres what I come up with,

Entering pressure (based on normal residential pressure) - 16" WC
Gas SG - .6
OA of pipe - 125' (added 25% for fittings)
Pipe Size Worse Case 3/4" Sch 40 - ID - .824"
Pressure Drop to Last Device 2" WC
Available Gas - 309 CFH
Required Gas - 245 CFH
Pressure Drop at 245 CFH - 1.2"

Results, Line size will not require any modifications.

Mark


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## 240sx4u (Sep 22, 2008)

Thanks for the information Mark! I really appreciate you taking the time to help me out.


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## Jackofall1 (Dec 5, 2010)

I have my own spread sheet to do the calculations but here is a great web site for future reference.

http://www.engineeringtoolbox.com/natural-gas-pipe-calculator-d_1042.html

It has alot of information with all the links in one place, so much so I am suprised its free.

Mark


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## 240sx4u (Sep 22, 2008)

That is some good stuff, thank you.


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