Propane Gas Line Sizing

[PilotGuy]

Hi,
New to this forum and looking at options for a new pool heater and backyard renovation. We are on propane on our property, 500 gal tank. I currently have a 1 1/4" polyethylene line running ~250' underground to my equipment pad. I need at least 700K BTU at the pad for a new 400K BTU pool heater + fire pit + BBQ + patio heaters, etc. I'm getting some conflicting info about whether or not this existing line will get me 700K BTU.

1 1/4" Polyethylene line run 250' from 500 gal propane tank

This chart says I should have plenty: 4,280K BTU (last chart on the page)

Propane Hose | LP Gas Line Sizing Chart | Propane Warehouse

Refer to our LP gas line sizing chart to equip appliances with tubing for propane tank fittings. Includes copper and polyethylene tubing sizes.

propanewarehouse.com

This chart says I'll be well short: 390K BTU

https://tranesupport.zendesk.com/hc/en-us/articles/7336393268621-Liquid-Propane-Gas-Pipe-Sizing-Chart

If there are any resident experts on LP gas that can explain the difference in these charts to me, I'd really appreciate it. The second link does note, "This chart refers to low pressure LP, after regulation". I did try to search this forum on this topic before posting and only came across posting regarding natural gas, not propane.

Thanks!

 

[Bill1974]

It all come down to what pressure is in the pipe. If the pipe has a few PSI in it it will be fine, if it inches of H2O than your likely out of luck. FYI 2psi is = 55 inH2O. So worst case you need to regulate the line to a few (2-10) PSI then have regulators on each device to regulate down to the 8-10 inH2O of pressure (this may be wrong, i just guessed).

The first chart was for a inlet pressure of 10 psi and a 1 psi drop to the outlet.

The second chart was for 11 inH2O pressure (.397 psi)

 

[JamesW]

One chart is low pressure and one is higher pressure.

10 psi = 277" w.c.

LP Gas flow is given in thousands of BTU/hr.

One cubic foot of LP gas = roughly 2516 BTU

This chart refers to low pressure LP, after regulation

Standard nominal pressure at the burner for Liquid Propane is 11" of water column

Pipe length must include additional length for all fittings

Add approximately 5 feet of pipe per fitting

 

[JamesW]

You can use 10 psi from the tank to the pad and then use a regulator to convert the pressure to about 11" w.c.

 

[Ahultin]

You can use 10 psi from the tank to the pad and then use a regulator to convert the pressure to about 11" w.c.

This
If you look at your tank, chances are you have a red high pressure regulator at the tank (10psi) then a green regulator at the pad (11-13" wc)/or a green with white cover (2psi)
I found that unless you are in an area that the PB predominantly installs on propane, they wont have a clue about a 2 stage system but your propane supplier should be able to provide a wealth of info and will likely even change out your regulators no charge if needed (because they figure you'll be spending your life savings on gas lol)

 

[PilotGuy]

Great, thanks all for the feedback! I don't know anything about how propane pressure works so this info is super helpful. I had a plumber tell me I needed to dig up my 1 1/4" line and put in a 2" line but the pool guy was telling me 1 1/4" was sufficient and I could just swap out regulators. I do need to get my propane supplier onsite to take a look...

 

[Ahultin]

Great, thanks all for the feedback! I don't know anything about how propane pressure works so this info is super helpful. I had a plumber tell me I needed to dig up my 1 1/4" line and put in a 2" line but the pool guy was telling me 1 1/4" was sufficient and I could just swap out regulators. I do need to get my propane supplier onsite to take a look...

Yea, sounds like your pool guy runs accross propane more often, most plumbers and pool builders don't know propane. Take a look at your regulator at the tank and at the house
Red = 10psi
Grey = single body 2 stage regulator 11-13" water column
Green with white cap = 2psi
Green = 11-13" water column


My entire house is fed by a 1 1/4 high pressure line that runs right next my pool equipment pad. Even with the propane company telling him that it would serve the heater fine because it is 10psi, he insisted we need another tank and a 1.5" line. It cost him ( gas supply was in his bid) ~100ft of 1.5" piping and an extra 20ft of retaining wall for the tank location. Cost's me an extra $75 per yr for the second tank rental. Our propane supplier set the tank for free and did the hookup, including the high and low pressure regulator. The plus side of this arrangement is we will never accidently run out of house gas by someone leaving the pool heater running.