Reznor gas line size

[70stroker]

I got a helluva deal on a old reznor 120,000 btu I paid 20 bucks and I felt it work before removal. I hung it in the rafters of my 30x40x11, I realize its probably more heater then what I need. But anyhow I need to trench a gas pipe out to the shop. Its about a 100 foot run, would 3/4 be sufficient, or do I need 1 inch?

I tried to get 7 different plumbers out to give me bids on the job and in 2 months noone has showed up, so looks like im going to end up doing the job.

thanks in advance

 

[D45]

I would think 1" would be best, but that's a guess

I have a 70-ish foot run for my 75K heater and used 3/4" pipe

 

[bonneyman]

I'd say 1 inch should be OK.

Here's a chart:
https://www.engineeringtoolbox.com/natural-gas-pipe-sizing-d_826.html

 

[HoosierBuddy]

I ran it on my flow calculator. It shows 100 feet of 3/4 would result in 0.5" Pressure drop at .12 MCF/Hour (about 120,000 BTU). So...if you have 7 inches w/c inlet, you still should have 6.5 by the time you get to the building....of course fittings and additional piping in the building matter too and will result in further pressure loss. Check you heater, but I'm guessing it has a minimum of around 5 inches required?

For reference the same calculation at 1" would only result in 0.2 inches pressure drop in 100 feet.

What's it cost to go to 1"? Another $10?

Phil

 

[70stroker]

I ran it on my flow calculator. It shows 100 feet of 3/4 would result in 0.5" Pressure drop at .12 MCF/Hour (about 120,000 BTU). So...if you have 7 inches w/c inlet, you still should have 6.5 by the time you get to the building....of course fittings and additional piping in the building matter too and will result in further pressure loss. Check you heater, but I'm guessing it has a minimum of around 5 inches required?

For reference the same calculation at 1" would only result in 0.2 inches pressure drop in 100 feet.

What's it cost to go to 1"? Another $10?

Phil

I am using "home-flex" polyethylene pipe underground and black pipe in my basement and up the shop, the home-flex kit is about 30 bucks to bump up to 1 inch and i might have 20-50 bucks in black pipe additionally. To me that is chump change to have the heater perform better, I have no problem bumping it up to 1 inch, just didn't want to hurt it by going to big.... if that's possible. Honestly id like to hire a professional to do this, but no one around here is willing to work on such a small job I guess.

 

[karoc]

I always been a fan of pricing both with you doing work. I bet there's not that much difference in price between 3/4 vs 1". Once your there at heater then you can reduce down to 1/2 or 3/4. I use to install a/c equipment which some were 80k up to 140k btu's all had 3/4 pipe which reduce down to 1/2 which was the inlet size of the gas valve. But none were run as far as yours so to stay on side of caution I would run 1" to bldg up to the heater then using a bell reducer down to 3/4"

 

[HoosierBuddy]

I am using "home-flex" polyethylene pipe underground and black pipe in my basement and up the shop, the home-flex kit is about 30 bucks to bump up to 1 inch and i might have 20-50 bucks in black pipe additionally. To me that is chump change to have the heater perform better, I have no problem bumping it up to 1 inch, just didn't want to hurt it by going to big.... if that's possible. Honestly id like to hire a professional to do this, but no one around here is willing to work on such a small job I guess.

OK...based on that, IIWY I'd run 1" through the building wall, you can reduce down to 3/4" after that. By keeping the long run at 1" you will do yourself some good on pressure. You could run 3/4" after you get into the building without any problems though if you'd like.

 

[70stroker]

Sounds good guys, I really appreciate the help, that is exactly what I'll do,