Is there a way to purge air from the gas line?. Pilot won't light.

Sounds like air in the pilot line . If so you need to purge line as pilot is a small injector .

It could be that the gap for the igniter is too big Try lighting it manually There should not be that much air in the line .

Air in gas line needs purging .

When the gas was turned OFF, air got in the line(s) and created an air pocket. This air will need to purged from the system, before the heater will light. It only the shutoff valve on the gas line to the heater was turned OFF, it will be easier to purge. If your Rinnai heater has manual ignition rather than electronic ignition. Holding the control down in the Pilot position, will eventually purge the air. If you have electronic ignition, continually trying to light the unit will do the same thing, but take longer to accomplish. Consulting your Rinnai will also help you with this situation.

Hope this helps you and thanks for choosing FixYa.

You may not have purged out all of the air from the gas line, it does take forever...

you have air in the gas line , the pilot being so small it would take ages to come through , you need to purge the line to get the air out , se if you can undo the pilot line to pruge it

they will be air in the gas line , and the pilot injector being so small it will take ages for gas to come through , you need to purge the gas line undo a union or nut or pilot suppy to purge the line of air test joints after with soapy water .

Hi, What you have to do here, is to take the flex line loose at the flare connection at the hot water control after shutting off the valve 1st. When this is done, open the valve for a few seconds to purge the line of any air that may have been trapped. Re- connect the line and turn the knob to pilot and hold it down until you can smell the gas or hear it. Wait a few minutes and hold it down again and you should have no problems lighting it. If it continues not to light, there may be something in the pilot line at the end of it, and you may have to remove the assembly to clean it out. Very easy to do. Just remove the gas flex at the control, and maybe the nipple that the flex screwed to. The control, pilot and thermocouple will all slide out together along with the burner. If there is a spider web inside donot blow it as it will not blow out. You will need to run a peice of a metal coat hanger or stiff wire through it. Replace it in reverse of taking it out. You will have to purge the air out all over again. Please keep me posted as I know you can do this. I have confidence in you.
Sincerely,
Shastalaker7

When gas is shut off, even for a short period of time, air enters the gas line and must be purged before the pilot will light.

Hold down the pilot light button longer than you think you should have to, then wait about five minutes to clear any gas that might have escaped then try again to relight the pilot. You may need to do this two or three times in five minute intervals.

Hope this was helpful.

The easiest way is simply hold down the pilot lighting button until the gas pushes the air out. The longer the pipes with the air in them, the longer this takes. You are only looking at 4 PSI for natural gas, so a 20 ft line may take several minutes. You do not want a gas build up, so as you are holding down the button, hit the ignitor every 2 or 3 seconds or so. this could take 5 to 10 min solid of holding down the pilot button.

The other way is to loosen the gas line as close to the gas valve as possible to let the pressure push out the air until you smell gas.

That method can be annoying at times, and you will still need to purge the gas valve and manifold. Thus my previous suggestion. Once you statr to smell gas vapors it should light soon after.

It is not uncommon for the pilot to light, burn weakly and go out only to have to be relit a time or two due to pockets of air in the lines.