Is 1/2 inch Copper Line big enough from 500 Gallon Propane Tank to Cabin

I’m setting up propane at my off-grid cabin and want to sanity-check my line sizing before I finalize things - the 1/2 copper line running from 500 Gallon propane tank to the cabin.

Current setup:
- 500 gal propane tank outside
- approx 80 ft run from tank to cabin
- 1/2" copper line

Inside loads:
- Rinnai RX160iN tankless water heater (~160,000 BTU)
- Gas range (~60,000 BTU total)
So roughly ~220k BTU demand if everything runs at once.

Right now I have these two Regulators:
At tank: red Cavagna-style regulator (appears to be low-pressure ~11" WC, typical single-stage setup)
At cabin: second regulator mounted on exterior wall (appears to be 11" WC / 0.4 PSI second-stage regulator) feeding interior appliances

From what I’m learning, it seems like:
My current setup might be undersized if it’s low-pressure the whole way
A lot of people run a 2-stage system (10 PSI at tank → 11" WC at cabin) to make smaller lines work over distance

Questions for others running similar setups:
- What size line are you running from tank to cabin, and over what distance?
- Anyone using 3/4 inch?
- Anyone using anything else but copper?
- Are you running low pressure the whole way, or a 2-stage system?
- If low pressure, what pipe size did you need to support ~200k+ BTU?
- Any real-world issues with 1/2" line at this distance?
- If you switched to 10 PSI, was it worth it vs upsizing pipe?

Trying to avoid re-running the 1/2 inch copper line if possible, but also want to do it right the first time.

Appreciate any real-world setups or lessons learned.  Thanks!!!

Your distance and the power of gas appliances is greater than what I planned (tiny gas stove to be used in summer only and on demand water heater) and I have used 3/4" pipe after research several years ago.

220k BTU/hour is roughly 6m³/h or 100L/min.
Running that into a pressure drop calculator gives 0.036 bar or 0.53 psi.

Add 0.4 psi you want to keep inside and you get at least 1 psi that needs to come out at the regulator from the tank.
I would probably add a little more for extra margin so the pressure doesn't fluctuate too much.

I have a 330 gallon tank around 80 feet from the house entry, 1/2" copper underground all the way. The regulators and underground piping were installed by the gas company 30-some years ago, and I don't know what the one on the tank is set at; the one by the house is obviously set to standard 11" w.c. It powers the stove and a Polaris water heater which heats the whole house in winter (at least it did until I built my RMH to heat the main floor ).

500 ft is a long run. try this calculator: https://heat-calculator.com/lp-gas-pipe-sizing-calculator.php

Glenn Herbert wrote:I have a 330 gallon tank around 80 feet from the house entry, 1/2" copper underground all the way. The regulators and underground piping were installed by the gas company 30-some years ago, and I don't know what the one on the tank is set at; the one by the house is obviously set to standard 11" w.c. It powers the stove and a Polaris water heater which heats the whole house in winter (at least it did until I built my RMH to heat the main floor ).

Thanks. Your setup and load looks very similar to mine.  Do you happen to know the how many btu your stove and water heater are?  Is the stove a standard 30" four burner with oven?
The calculators say I may need 3/4" or could have problems if both my stove and hot water on demand are running at the same time.  But I've also heard other real life examples like yours that use 1/2" with no problem.

Robert Ray wrote:500 ft is a long run. try this calculator: https://heat-calculator.com/lp-gas-pipe-sizing-calculator.php

My run is only 80 feet (my tank is 500 gal).  Thanks for the link to the calculator. It's giving me a requirement for 1" pipe. That sounds over sized and is the only one that has given that result.

This is from the long long ago, but I recall that ambient outdoor temperature can be a factor. Propane lines can freeze up in very cold temperatures. Skinny lines may be more vulnerable. FWIW

Douglas Alpenstock wrote:This is from the long long ago, but I recall that ambient outdoor temperature can be a factor. Propane lines can freeze up in very cold temperatures. Skinny lines may be more vulnerable. FWIW

Good point.  But my cabin is 3 season so yes it gets cold in Ontario but we won't be out there in the winter.

Realisticaly is the extra cost a problem?
Why not design for all chances?
In Australia there are some 'plastic' pipe varieties that can be used.

We have used 1/2" copper for 45 years with no problems.
Installed by the propane company, the tank has only one regulator, the run is apx 60'.
We have a standard 4-burner stove oven, an on-demand hot water heater, a propane refrigerator, a hardly used 10,000 BTU unvented heater, plus two 15,000 BTU heaters in other buildings. We also have our generator running from the large (250 gal) tank as well.
So quite a few appliances, all easily run by 1/2" copper.
We have never had a supply issue.

I will say that now, they are using either 1/2" black steel, with a bright yellow covering, or, as John mentioned a bright yellow all-plastic line.

John C Daley wrote:Realisticaly is the extra cost a problem?
Why not design for all chances?
In Australia there are some 'plastic' pipe varieties that can be used.

The feedback on this forum has been great and is consistent with what I have found.  If you look at some of the calculators and tables on-line (or ask ChatGPT).  They say I should use 3/4 inch pipe.  If ask people for real world examples, many say they have been running 1/2 inch for years with larger loads and have no issues.

I should have been more clear on my set up.  My 1/2 copper pipe is already in the ground. It was there when we bought the place 1.5 years ago. The owners were running a 10 cubic foot propane fridge, a 24" four burner propane stove with oven, a hot water on demand unit and a propane fireplace.  We ran the place for one full summer (last summer) like that with no issues.  

Last fall we added a larger kitchen on the back of the cabin and will have a bigger gas range (~60,000 BTU total).  I am also replacing the old hot water on demand unit with a larger one (~160,000 BTU).  So roughly 220k BTU demand if everything runs at once.  

We got rid of the propane fridge (we are adding a 20 cubic foot electric).  The propane fireplace will be staying but is rarely used because we don't go in the winter.  We are upgrading the Solar system to accommodate the electric fridge and more small kitchen appliances.

So the net of it is I am adding a larger stove and hot water on demand but got rid of the propane fridge.  These changes have got me looking at the 1/2" gas line.

thomas rubino wrote:We have used 1/2" copper for 45 years with no problems.
Installed by the propane company, the tank has only one regulator, the run is apx 60'.
We have a standard 4-burner stove oven, an on-demand hot water heater, a propane refrigerator, a hardly used 10,000 BTU unvented heater, plus two 15,000 BTU heaters in other buildings. We also have our generator running from the large (250 gal) tank as well.
So quite a few appliances, all easily run by 1/2" copper.
We have never had a supply issue.

I will say that now, they are using either 1/2" black steel, with a bright yellow covering, or, as John mentioned a bright yellow all-plastic line.

I have been watching YouTube videos and see many guys in the US using IPEX 3/4" Polyethylene Gas Pipe and burying it 18-24" without putting a sleeve around it.  Just tracer wire, warning tape on top and metal risers coming out of the ground on each end.  Way cheaper than copper pipe and if I did have to re-do my pipe I would use it.  It meets code here in Canada and in Ontario where my cabin is but not sure if my propane company supplier here would allow it.  They have final say in propane rules.  

Here in California, I used 3/4" plastic pipe designed for flamable gas.  I would suspect that would be far cheaper than 500 feet of copper.  I got it and all the proper fittings from Home Depot.  I do notice though that it takes quite a while for the stove's oven to warm up to 350F, and I think that 1" might have been a better choice.

Talking of fridges, I am off grid in Australia and had trouble with the fridge draining my small battery system.
I found the most efficient fridge made, Hisense, it was resonably priced for Australia $A1200 is about 315 L capacity and uses 25% of the power of other fridges.

Since the tank has a pressure if much greater than 2 PSI, the 1/2" pipe will do fine, just not with the 0.5 PSI regulator. And I expect that a regulator that delvers something around 1-3 PSI is quite a bit less expensive than a new pipe.

1/2 with two stage regulator should work.  Everything is 3/4 these days just because.

I’d be more concerned that the line in the house is big enough if the runs are long. I had issues with a large stove in my last house, and on demand water heaters often need 1” black pipe if they aren’t close to the regulator.

John C Daley wrote:Talking of fridges, I am off grid in Australia and had trouble with the fridge draining my small battery system.
I found the most efficient fridge made, Hisense, it was resonably priced for Australia $A1200 is about 315 L capacity and uses 25% of the power of other fridges.

What exactly is the size of your battery bank?  Is it being fully charged each and every day, even in June?

High-voltage residential panels are getting so cheap now that the single cheapest upgrade you can make to your system is more solar.  If my batteries are fully charged by 9-10am, my arrays are supplying 100% of my power needs for the rest of the daylight hours, with zero battery depletion.  That way I'm operating normally with a far less expensive standard AC frig/freezer.