3/8” gas line into firebox?

[Handyman234]

I'm converting a firebox to have gas logs. All the controls (electronic ignition, gas valve, and quarter turn valve to regulate flame height) will be located outside the firebox. The burner and log set will be 24” size.

The firebox has a prefabricated 1” tube that runs through the side wall. Through that tube I need to run the 1/4” pilot tubing, the main gas line, and the wires for the igniter and ground. To fit inside that diameter, I will need to use a 10” nipple of 3/8” pipe for the main line, whereas all the other piping is 1/2” (or greater).

Will this short run of restricted diameter pipe adversely my flame in a material way? Modifying the fire box to replace side wall tube with a larger diameter would be a big job.

 

[DAKSY]

I assume you have a ZC wood burner that you're converting.
The hole thru the shell should be AT LEAST 3/4" diameter.
There should also be a knock out in the refractory of a similar size.
I'd run 1/2" Corrugated Stainless Steel in to the fire box.
Ward Flex or Trac Pipe or something similar.
It has a smaller OD the 1/2" BIP, & should leave you room
to get the rest of the components thru...

 

[Handyman234]

Thanks, but I may not have made myself clear.

The pathway into the firebox through the refractory is in fact greater than 3/4”—it's a 1” (ID) sheet metal tube. But, it is too tight to fit a 1/2” pipe through it, along with the pilot tubing, etc. Hence, I need to reduce the pipe size to 3/8” where the main gas line elbows to run horizontally into the firebox. A 10” run will give me a stub inside the firebox that I can then connect up to the burner with an appropriate flex.

My real concern is whether whether choking down the gas line to the smaller diameter for 10” will have an appreciable effect on the fire. I'm clueless on gas flow volumes, BTUs, and whatever else affects the “Wow” factor of a gas fireplace.

What can people tell me me about whether 3/8” is still plenty for a 24” log set?

 

[DAKSY]

Natural gas or Propane?

 

[DAKSY]

What burner are you installing?
What is the BTU Rating?
How far & what size gas piping is the run to the firebox?

 

[Handyman234]

Natural gas.

1” run for about 40’ off of 1 1/4“ main (includes branch off for cook top), then 3/4” for another 8’ to feed Robertshaw 712-017 control kit, then 1/2” for about 30” to an elbow where I reduce it to 3/8” to go into the firebox.

Don’t have a burner yet.

 

[Lennox65]

This should have all the info:https://www.edcgov.us/Government/building/documents/Gas Pipe Sizing (Natural).pdf

 

[Handyman234]

The comprehensive pipe sizing website would be good if I were laying out a piping plan for my house, but I'm just looking for some practical guidance.

Whatever the piping is up to the outside of the firebox, it is what it is . I'm just trying to find out whether the restriction of a 10” run of 3/8” pipe would make a difference compared to the big job of making the access into the firebox large enough to accommodate all the piping from the gas valve to be continuously at 1/2” size.

For that matter, does a 24” burner (say 60,000 BTU?) need to be fed with 1/2” or would 3/8” piping all the way from the valve be more than adequate by itself?

 

[DAKSY]

Many gas log sets have a 3/8" gas "whip" running from the hard piping to the gas valve,
& those are usually longer than 2'. You should be good to go with a 10" length.