Pipe size is a budget
Every gas appliance has a rated input, printed on its data plate in BTUs per hour. Add up the appliances that could run at once and you have the demand the piping has to deliver. The longer the run from the meter, the more the gas pressure drops along the way, so a long run needs bigger pipe to deliver the same amount.
Most 1950s to 1970s Fullerton houses were piped for a furnace, a tank water heater, a range and perhaps a dryer. That original pipe size may have no room left over. A professional range, a tankless water heater, a pool heater or an outdoor kitchen can push the total well past what the original piping was meant to carry.
Signs a line may be undersized
How a contractor sizes a line
- List every appliance.Furnace, water heater, range, dryer, fireplace, outdoor appliances, plus anything planned soon.
- Read the data plates.Each appliance's input rating goes into the total.
- Measure the run.The length from the meter to the farthest appliance, and to each branch, is measured or estimated with fittings counted.
- Use the code tables.Sizing tables in the applicable code give the pipe size needed for that load and length.
- Check the meter.If total demand rises a lot, SoCalGas may need to confirm the meter and service can carry it.
Common fixes when the line is too small
- IfOnly the new appliance's branch is too smallThenReplace that branch with larger pipe.
- IfThe main run from the meter is too smallThenUpsize the main run, then reconnect existing branches.
- IfThe new appliance is far from the existing pipingThenRun a dedicated line from near the meter.
- IfThe meter itself may be the limitThenContact SoCalGas about a load review before finishing the plan.
What drives the scope
The size of the job depends on how much new demand is being added, how far the appliance is from the meter, whether the existing attic or wall route can be reused, what pipe material makes sense, and whether the meter needs a utility review. A permit and inspection are usually part of new gas piping, so check with the city and get the plan in writing before work starts.
Common questions
Will a bigger connector at the appliance fix it?
No. The connector is only the last short link. If the pipe feeding it is too small, a bigger connector does not fix the shortage.
Who checks whether the meter is big enough?
SoCalGas owns the meter. Your contractor can tell you when the added load is large enough that SoCalGas should be contacted.
Does a gas dryer need much gas?
Dryers are smaller users than tankless heaters or pool heaters, but every appliance counts toward the total the pipe must carry.
Do I need a permit for a sized-up line?
New or altered gas piping usually needs a permit. Check with the city building division.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.