Plumbing advice
Adding a Generator or Grill? Start With the Gas Sizing
The calculation covers everything already connected, not just the thing you are adding. That is where most surprises come from.
Gas smell in the house?
Leave the building. Do not touch switches or use a phone inside. Call the gas utility from outside and let them make the supply safe.
- FIRST CALL
- The gas utility, from outside.
- SIZING COVERS
- Total connected load.
- ALWAYS
- Permit and pressure test.
If you can smell gas, act before reading any further. Get everyone out of the building, do not operate any switch including light switches, and do not use a phone inside the property. Call the gas utility from outside. Everything else on this page happens after the supply has been made safe.
Why adding one appliance is a whole system question
Gas pipe sizing is not a matter of matching a connection to an appliance. It is a calculation across the whole system, covering total connected load, pipe diameter, the length of each run and the number of fittings along it.
The reason is that appliances share the supply. A generator running at load, a furnace calling for heat and a water heater recovering at the same time draw simultaneously, and the pipe has to deliver adequate pressure to all of them at once.
So the honest answer to whether you can add a grill, a fireplace, a pool heater or a standby generator is almost never a simple yes. It is that the existing branch may well be fine while the run back toward the meter is not, which is exactly the finding that moves a quote.
How an undersized line actually presents
Rarely as an obvious gas problem, which is what makes it worth knowing about. The symptom is usually an appliance that appears faulty.
A range that will not reach its rated output. A water heater that recovers more slowly than it should. A generator that struggles under load, or a fireplace that burns poorly when the furnace is running. Each of those gets diagnosed as an appliance fault by somebody who never looked at the supply.
That is why the sizing calculation belongs at the start of the project rather than after the second service call on a new appliance.
| What you are adding | Typical demand | Usual finding | Watch for |
|---|---|---|---|
| Gas range or cooktop. | Modest. | Existing supply often adequate. | Sediment trap and an accessible shutoff. |
| Outdoor grill or kitchen. | Modest to moderate. | New exterior rated run needed. | Correct burial or support, dedicated shutoff. |
| Fireplace or log set. | Moderate. | Usually workable. | Shutoff within reach of the appliance. |
| Pool heater. | High. | Frequently needs upsizing. | Run length to an outdoor location. |
| Standby generator. | High, and simultaneous with everything else. | Often needs upsizing to the meter. | The meter itself may need the utility involved. |
| Tankless water heater. | High, and instantaneous. | Usually upsizing, see tankless conversions. | Venting and condensate as well as gas. |
What a compliant installation includes
Every one of these should be in the job
Ask for the pressure test result and the inspection record at completion. Both should exist, and both are yours.
- A permit, through the City of Austell or the relevant county for unincorporated addresses.
- Sizing calculated from total connected load rather than from the new appliance alone.
- A sediment trap at the appliance connection where the code requires one.
- An accessible shutoff valve at each appliance.
- Correct bonding where corrugated stainless steel tubing is installed.
- A documented pressure test before the system is put into service.
- An inspection, and the record handed to you.
This is the one job on this site where doing it yourself is genuinely dangerous rather than merely unwise. Gas work is licensed, permitted and inspected in Georgia, and it is proved under pressure before going into service. A homeowner installation is both unsafe and unrecorded, which matters again when the property is sold.
The generator case, which catches people out most often
Standby generators have become common in this area after storm outages, and they are the appliance most frequently connected to a line that cannot really support them.
The difficulty is simultaneity. A generator runs precisely when the power is out, which in a winter storm is when the furnace is working hardest and the water heater is recovering. All of that demand lands on the same supply at the same moment.
Where the existing run cannot carry it, the answer is upsizing back toward the meter, and occasionally a conversation with the utility about meter capacity. None of that is difficult work. It is simply work that has to be priced honestly at the start.
The rulebook behind all of this
Water piping in a Georgia house falls under the Georgia State Minimum Standard Plumbing Code, which adopts the International Plumbing Code (IPC) with state amendments. Gas piping and venting fall under Georgia's separately adopted fuel gas provisions.
A job that touches both, which a tankless conversion or a generator connection often does, is inspected against both. The scope and the sequence are set out on our gas line page.
Signs of a problem on an existing system
Any smell of gas means leave and call the utility from outside. That instruction outranks everything else here and there is no version of it that involves investigating first.
Short of that, a burner flame that has turned yellow rather than blue, hissing near a fitting or the meter, or an appliance that has quietly stopped reaching its output are all worth having looked at. The first two should be treated as leaks. Where the appliance in question is a heater, ordinary water heater diagnostics still apply once the supply is confirmed safe.
Where a leak is confirmed and repaired, the system is proved under pressure again before being put back into service. That test is the point of the whole exercise.
Quick answers
Gas sizing questions
Can I just tee off the nearest gas line for a grill?
Not without the sizing being checked. A tee into a convenient branch is easy to make and it is exactly how systems end up unable to supply everything connected to them.
It is also permitted work, so an unrecorded addition creates a second problem later.
How do I know whether my line is big enough?
It is a calculation rather than a judgement, based on total connected load, pipe size, run length and fittings. A plumber can usually scope it from a list of your appliances and a description of the run.
The common answer is that the branch is fine and the run back to the meter is not.
Does the gas utility handle any of this?
The utility is responsible up to and including the meter, and where meter capacity is the constraint they need to be involved. Everything downstream of the meter is the property owner's system.
For a suspected leak, the utility is always the first call and they will make the supply safe.
Is a sediment trap really necessary?
Where the code requires one, yes, and it exists to catch debris before it reaches an appliance's gas valve. It is a small item that prevents a much more annoying fault.
Its absence on an older installation is a reasonable thing to correct while a plumber is already working on the system.
Adding gas appliances to an existing system?
Call and list what you already have alongside what you want to add. That list is the sizing calculation, and it decides the price.