A question about sizing a propane line running underground between a propane tank and the boiler in my house. Plumbing supply house says that a 160K Btu/Hr boiler requires a one-inch propane line; however, the HVAC contractor says that 3/4 inch is just fine. (The existing 3/4 inch line is steel pipe and the installation sits at 7200 feet above sea level.) Can anyone tell me who’s correct and/or how can I determine who’s correct? The boiler is being replaced. Thanks!
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We had two 75K BTU furnaces running fine for several years off of a brass (or maybe copper) line about 1/2" OD. The size requirement depends on the pressure and the length of the run.
Note that propane is generally (much) higher pressure and so doesn't need as large a line as natural gas -- this may be the source of some confusion.
As DanH said, it depends upon the pressure, the pressure drop at the regulator, and the distance from the regulator to the appliance.
It will also depend upon the type opf system you use.
It also depends upon which Fuel Gas Code your jurisdiction enforces.
But according to the International Fuel Gas Code:
- A 10 PSI inlet pressure with a pressure drop of 1 PSI for propane and schedule 40 metallic pipe can use 1/2" pipe for 160K BTU for a distance exceeding 2000 feet in length...
-A 10 PSI inlet pressure with a 3 PS pressure drop can also use1/2" schedule 40 metallic pipe at 160K BTU for a distance exceeding 2000 feet in length...
-A 2 PSI inlet pressure with a 1 PSI pressure drop can use 1/2" sched 40 metallic pipe at 160K BTU up to a maximum of 1800 feet...
-A 11 in WC inlet pressure with a .5 WC pressure drop can use a 1/2" sched 40 pipe is the distance does not exceed 20 feet.... can use a 3/4" sched 40 metallic pipe at 160K BTU up to a maximum distance of 150 feet....or can use a 1" pipe up to a maximum distance of 450 feet..
If you want to know for sure, call your code enforcement office.
Generally speaking, if your run of pipe is less than 150 feet, then a 3/4" pipe will be more than sufficient for a low pressure installation.
Luck.
Thanks to both of you!
The tank has a regulator connecting the tank to the pipe, there is a run of about 40 feet, then another regulator where the propane line enters the house. The entry into the house is less than 4 feet from the boiler. Looking at the boiler literature the minimum propane gas supply pressure is 10 inch water column. I'm interpreting this and the previous two replies as the installer was correct: the existing 3/4 inch pipe is sufficient, and I must have misunderstood the supply house statement. Thanks to both DanH and manhattan42 for sharing the benefit of your knowledge and experience!