# Is LP fuel line distance a determining factor in the pipe sizing for gen. supply?



## kirkdj (Jun 7, 2021)

I have a 500 gal. underground propane tank.......I have to run the gen. supply line around to other side of the house.
I haven't determined which gen. I'll be getting, but it most likely will be 14-17KW and most likely have some load shedding system on it. 

Years ago, I believe I had checked and it would require approx. a 3/4" to 1" LP gas line to supply it. I just measured it and it's actually about 160-170' total from tank to the gen.

I imagine it will be a higher pressure to the gen. then regulated down. Being that distance of 170', does the distance require a bigger pipe size or would it be the same pipe size regardless of the distance?


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## iowagold (Jan 22, 2020)

welcome to the group!
it will all depend where the pressure regulators are located on the system.

some use higher pressure up to the house then drop it to the 11-13 wc...
others run more like 2 psi for inside the house and use a regulator at the point of use for the final drop.

1 inch line at short is ok... you might be larger than that if it is on the low low pressure line for the flow.

you might be better off with a liquid high pressure feed to the gen location and do the 2 regs there plus the internal gen reg
and a smaller dia line as yard buried.

question what is the feed pressure on the main line to the house?


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## kirkdj (Jun 7, 2021)

iowagold said:


> welcome to the group!
> it will all depend where the pressure regulators are located on the system.
> 
> some use higher pressure up to the house then drop it to the 11-13 wc...
> ...


There is a high pressure reg. on the tank now, right above the tank shutoff valve and tank cover.......that line goes to the side of the house ...where there is a step down reg. to supply the house as you said......1" supply line into the house from there. I'm pretty sure the house pressure is that 11-13 wc you mentioned as after entering from outside there are no more regulators anywhere else.

I'm pretty sure I will have to run a separate supply line underground to this gen. but your saying it can most likely be something like 1/2" line at a higher pressure, then at the gen. set another reg., then the gen. itself will have it's own reg. 

Do you know what pressure would be common to use for that high pressure that's 170' long? Just wondering as the installer will do his own thing since he has to make it work.......but I like to know as much as possible sometimes it saves me a few $$$.... 

Thanks in advance for your help 👍👍


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## exmar (Jun 29, 2015)

FWIW, around here, the Propane companies are glad to do that for you, ditching, pipe, supply appropriate regulators, essentially turn key. They're comparable in cost if not less than bringing in a plumber and you'll probably have to deal with them on regulators anyway. However, you may want one contractor to do both electrical and mechanical which kind of puts you at their mercy but at least it's sole source responsibility.


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## drmerdp (Apr 10, 2018)

The tanks red regulator is 10 psi. That’s a good suggestion to contact the propane provider for the gas install. They very well might tee off after the red regulator and bury a sleeved 3/8 flexible copper tube with a green low pressure regulator right at the generator. Gotta trench at least 16” deep, maybe more depending on local code.


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## kirkdj (Jun 7, 2021)

exmar said:


> FWIW, around here, the Propane companies are glad to do that for you, ditching, pipe, supply appropriate regulators, essentially turn key. They're comparable in cost if not less than bringing in a plumber and you'll probably have to deal with them on regulators anyway. However, you may want one contractor to do both electrical and mechanical which kind of puts you at their mercy but at least it's sole source responsibility.


good idea on the gas company......I know about what gen. I want ......I will give them a call when time comes


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## iowagold (Jan 22, 2020)

i bet they can get you setup right!
the cool thing on the liquid to the gen location.
is that you can get more btu on a smaller line.
the LP guys will have all the charts etc. 
all they need to know is the exact btu numbers for the house lp appliances and then for the new gen set.
and yes depending on how large of a gen set it can suck a 500 gallon tank dry fast!
if you are on a long outage....

you might even look in to a second 500 gallon tank just for the gen set!


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## exmar (Jun 29, 2015)

Iowa makes a good point, generator sizing should be the minimum for fuel consumption. 500 gallons sounds like a lot but if you're also using it for heat, cooking, water heating, then throw a large generator in the mix, you'll be amazed at how fast it's used up. So, determine the minimum power you need to make it through an outage. Again, when you talk to your propane supplier they can give you realistic numbers.

Also, a 500 gallon tank only holds 400 gallons of LPG. As a point of departure, Generac (not suggesting them) suggests a 20KW unit will consume 2-3 gallons per hour based on loading.


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## iowagold (Jan 22, 2020)

1000 gallons would be my plan or more on the LARGE gen set.
266 hours of run time at max.
or 11 days.... and is not too large...
maybe even a cross over switch in case you need to draw from the other tank...

a better plan would be to have 2 gens...
one for when you are up and doing things... (big power consumption)
and a smaller gen for just fridge and freezer and security lights...

yea hot summer throws a wrench in there with ac units...
but a good quality dehumidifier helps and consumes less.

grid power and grid fuel is still the lower cost.
but plan for the worst!
always have a plan B and even a plan C!


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