What size line to run for LP?

[gmwelder86]

I am redoing all the lp lines in our jewel trailer and I am unsure of what sized lines to run, the existing HW heater that was electric only is being replaced by a propane heater. The only appliances in the trailer that are propane are the stove/oven, panel ray heater, hot water heater and a propane light. I was planning on running everything 1/4 type k tubing, but now I am not sure if I should have the main line in 3/8"s and branch off in 1/4 to each fixture. I am just worried about under-sizing the system.

Thanks

[HowieE]

Most trailers have 3/4 line coming off the tanks and branching off with 3/8 to stove, water heater, and refg. 1/4 seams a bit small. I ran 3/8 to my small Olympic heater.

[gmwelder86]

That sounds about right, It just seems weird all the original lines were 1/4 from the regulator back. Mybe a 1/2" main and 3/8" branches might be better.

[overlander63]

Most trailers I've seen start with a 5/8" line to a junction, then 3/8" from there to each individual appliance. An exception would be, say, a gas lamp, which would be 1/4".

[easyride]

OK we are doing gas, not air conditioning,Gas lamp takes 1/8 inch. water heater is 1/4 ",yes your flares are outside pipe sizes,but the pipe is ID. Plumber Dave

[Ganglin]

Your original lines were as Terry mentions according to the early 70's diagram. 5/8 OD main line. 3/8 OD to oven, range, water heater and furnace. 1/4 OD to refrigerator and gas light.

[bobfowler]

We replaced the furnace, fridge, and range in our '72 Argosy 20. (Terry's old trailer) Since we spent all that cash on new appliances, I felt it kinda important that we go ahead and run all new copper tubing - not a fun job. Our trailer has a 5/8" line coming off the regulator with 3/8" tees that feed runs to each appliance. In addition to the new tubing, I installed new gas cocks so each branch can be shut off independantly. The original configuration didn't include a shut off for the range! It was a bit of a challenge running the line for the new fridge, but that was the only difficult hurdle.

BTW - for those who have problems making a good flare connection, this tool from Yellow Jacket makes the job REAL simple. A little spendy compared to the models in the home centers, but worth the price of admission.

[Bob Sheridan]

Originally Posted by easyride

OK we are doing gas, not air conditioning,Gas lamp takes 1/8 inch. water heater is 1/4 ",yes your flares are outside pipe sizes,but the pipe is ID. Plumber Dave

1/2 is to big and 5/8 to small for the two flairing tools I have tried what gives!

[lpgasguy]

Here's the deal with propane line...

Propane line is measured in O.D. (outside diameter) Most trailers, including my Argosy 24, have a 5/8 OD (or 1/2 ID for plumbers) main line with 3/8 OD branching off to each appliance. In most cases that is fine. I have a water heater, range, furnace, and refrigerator all on propane on my trailer. The key to gas line sizing the is load on the system and the length of the run. If you are unsure about line sizing and how to install, please seek out a propane tech for help. Undersized line can be dangerous because if there is not enough pressure you will not get an efficient burn which can produce excess carbon monoxide. Also, the appliances will soot and can cause damage, especially in the furnace where you can't see it without taking it apart.

Hope that helps everyone.

[easyride]

Originally Posted by lpgasguy

Here's the deal with propane line...

Propane line is measured in O.D. (outside diameter) Most trailers, including my Argosy 24, have a 5/8 OD (or 1/2 ID for plumbers) main line with 3/8 OD branching off to each appliance. In most cases that is fine. I have a water heater, range, furnace, and refrigerator all on propane on my trailer. The key to gas line sizing the is load on the system and the length of the run. If you are unsure about line sizing and how to install, please seek out a propane tech for help. Undersized line can be dangerous because if there is not enough pressure you will not get an efficient burn which can produce excess carbon monoxide. Also, the appliances will soot and can cause damage, especially in the furnace where you can't see it without taking it apart.

Hope that helps everyone.

Don`t know where you are getting your info,it doesn`t really make much difference,but the National Fuel Gas code book refers to all sizes in I.D.,wouldn`t think a trailer would be any different. Dave

[Kevo]

FWIW, I just ran all new lines in my 65, Ran 1/2 rolled copper everywhere, but it did branch down to the original 3/8 inch for the Fridge and Water Heater. Pics on my page.

[Splitrock]

Mine is 5/8 to 3/8.

[Aage]

Originally Posted by Ganglin

Your original lines were as Terry mentions according to the early 70's diagram. 5/8 OD main line. 3/8 OD to oven, range, water heater and furnace. 1/4 OD to refrigerator and gas light.

Originally Posted by lpgasguy

Here's the deal with propane line...

Propane line is measured in O.D. (outside diameter) Most trailers, including my Argosy 24, have a 5/8 OD (or 1/2 ID for plumbers) main line with 3/8 OD branching off to each appliance.

Originally Posted by easyride

Don`t know where you are getting your info,it doesn`t really make much difference,but the National Fuel Gas code book refers to all sizes in I.D.,wouldn`t think a trailer would be any different. Dave

I'm wondering if we can all agree on what the size should be?

Does this sound right?

5/8" OD main line (including off the tanks?) and 3/8" OD after the regulator, going to each appliance

Or do we need to use ID measurements, and if so, what would they be?

Thanks. I am replacing my furnace this year, and did my water heater last year, and I want to make sure that I put the proper size in.

Thanks!

[Splitrock]

Originally Posted by Aage

5/8" OD main line (including off the tanks?) and 3/8" OD after the regulator, going to each appliance

This is what mine is.

[worldinchaos]

Originally Posted by Aage

I'm wondering if we can all agree on what the size should be?

Does this sound right?

5/8" OD main line (including off the tanks?) and 3/8" OD after the regulator, going to each appliance

Or do we need to use ID measurements, and if so, what would they be?

Thanks. I am replacing my furnace this year, and did my water heater last year, and I want to make sure that I put the proper size in.

Thanks!

I know this is an old thread, but I am doing some research on LP since I am building a new system, and I just wanted to point out that unless anyone is buying specialty propane regulators, the ones I have seen (esp. the one on VTS that I bought) has an outlet fitting size of just shy of 7/16".

So there is zero reason to go any larger than 1/2" ID or 5/8" OD for the main pipe because you are going through a smaller orifice to get there regardless.--Just in case someone was thinking of going to a larger size to be "safer", it's not necessary.

Yet I still haven't answered the questions I looked through these threads for....

[nrgtrakr]

Resurrecting an old thread just because ...

The size of copper ID or OD, soft (bendable) and rigid sticks, types M, L etc. explained here: https://en.m.wikipedia.org/wiki/Copper_tubing

The size of the gas line used is based on the number of BTUs used at each fixture/appliance.

So for example my 10,000 BTU water heater using type L soft copper is perfectly happy with 1/4" ID, 3/8" OD for a pipe run as long as about 80 feet. Propane Gas - Pipe Sizing

If I add up all of my propane requirements of hot water heater, fridge, furnace and range top I get roughly 60,000 BTU which is more than covered using 1/2" black pipe or 3/8" ID, 1/2" OD type L soft as my main distribution line from tanks under the belly to the entry point up into the trailer.

The two stage regulator near the tanks drops the tank pressure (~200 psi) to 10 psi then 11 inches water column.

Testing a new system or one that has been opened for repair is done first with compressed air - some claim ~3 psi for 10 minutes (11 inches water column is roughly 0.5 psi). Once there are no obvious leaks, the normal annual checks can be made.

Or I could be confused ....

Signed, a retired stationary engineer turned rv mechanic wannabe

[ericpeltier]

Originally Posted by nrgtrakr

more than covered using 1/2" black

Thanks for resurrecting!

Above, I think you refer to the ID of the black pipe being 1/2"?

I need to run black pipe underneath my Streamline.

I suppose there's no harm in running 1/2" black pipe for the branches, too, other than weight?

ERic

[nrgtrakr]

Anytime ...

Mostly my posts are a result of me reviewing things before actually doing them.

Technically 1/2" steel pipe is 0.84" OD and 0.62" ID.

I've read a lot of comments claiming one type of pipe preferred over another. I even attempted to access the RVIA current standards but had the wrong decoder ring.

In practice both are used - all soft copper, or black to point of entry then soft copper.

The underside of my 75 Overlander looks like the cat was playing with it, or someone was using an etch-a-sketch.

I prefer the orderliness of radars, missile launchers, airplanes, etc. Plus the beautification engineer suggested a gas do over after seeing the plumbing job.

So I'll likely run standard Acme nut pig tails to an auto change over dual stage regulator to 3/8" propane hose to 1/2" black from the tongue tank mounts directly rearward to a T then a 1/2" branch to either side of the belly to within stricking distance of the furnace and range curb side, and fridge and water heater street side - each black pipe stub fitted with a flare end ball shut off valve and lots of support clamps for the rigid run.

The nay sayers will claim the trailer flexes too much for rigid pipe. If this proves true, I can always replace the rigid with soft. But then a lot of manufacturers would be swaping rigid for soft also.

The appliances in a home have a flex gas line, similarly and because those residential flex lines aren't suitable for an RV, an RV uses soft copper with flaired fittings to hook up to the appliances.

Hopefully a real RV tech certified for gas will correct any misconceptions in any or all of this. My simple training and experience as a stationary engineer sees nothing scary so far.