Here is a little info on propane.
I have 2 20lb propane tanks. I use it for hot water, cooking stove and oven, and heat.
Most 20lb tanks have an empty tare weight of around 18lbs. You will see your TW printed on the handle (TW18). This tank will hold about 4.7 gallons of LP. At capacity around 430,270 BTU. If you divide that by 58,000 you’ll get about 7.4 hours of burn time wide open. These tanks only have a life span of 10 years. They won’t fill them after that.
Exchange tanks only fill to 15 lbs of fuel. Divide that by the cost of exchange and you’ll get a price per pound.
A filling station might charge a flat amount to fill your tank. They will set the scale for 40lbs and fill. That will be more filled than an exchange tank. TW18 + 2lbs for nozzle + 20lbs of fuel = 40lbs. However, there is usually some fuel left in the tank. I tested that today when I filled a tank. To reach the 40lb scale and cut off it only put 4.1 gallons of LP in the tank. That means 0.6 gallons were still in the tank. However it wasn’t enough to heat the hot water. So…
The best solution is to go to a station that only charges you by the gallon. As of today 05/24/2018 Tractor Supply posted $2.99 per gallon. That means to fill that tank should only cost 4.1X$2.99=$12.26 for a full tank. Exchange tanks with only 15 gallons are around $20. That’s at least an $8 savings per tank. 15gal – 0.6gal = net of 14.4gal of usable LP as opposed to 20gal – 0.6gal = 19.4gal. 5 more gallons to use.
NEW UPDATE 01/15/2022 ON PROPANE INFO:
For calculation purposes, 1 gallon of propane weighs 4.23 lbs. at 60 degrees Fahrenheit. So a 20 lb. tank contains 4.73 gallons Lets calculate this… 4.23 lbs. per gal X 4.73 gals = 20 lbs.
Lets say your (tare weight) TW=18, then 20+18=38lbs for a full tank. Now if you take that tank and weigh it on a scale and the total weight is 27lbs… how much propane do you have in your tank. 27-TW18=9 lbs of propane 9/20=.45 or 45% of capacity.
Tanks made before 1998 didn’t have 80% refill safety feature called OPD or (overfill protection device). Those tanks could not be legally filled after 2002. Now all current tanks have a 3 star shutoff knob that says OPD <–Open Close–> imprinted. So a 20lb. cylinder is sized to hold 20lbs of propane when it’s 80% full. Theoretically is 25lbs. (20/25=.80 or 80%) However, the OPD has a float that prevents you from putting more than 20lbs in the tank.
Tanks are certified for 12 years from the date stamped on the handle/collar. To fill after 12 years you would have to have the tank tested and recertified. But that only is for an additional 5 years.
Don’t forget to have your newly purchased tanks purged. Another good idea is when you buy a new empty tank, put it on a scale and get an accurate weight on an empty tank. Weigh again after filling the tank… do some calculations as shown above.
ALSO for safety keep in mind propane is heavier than air and will sink to lowest points of storage. So it’s not a good idea to store in the basement…
Update. 09/19/2018 I am still using tank one without refill. I plan on filling tank before departing from this camp. It is used for hot water, heater, stove and oven. The power went out for a half day and it switched automatically refrigeration from electric to propane. So it can also run refrigeration.
Update: 09/24/2018. Just ran out of propane tank #1. Switched over to tank #2. (~6 months)
Update: 10/28/2018. Topped off tank #2 at Tractor Supply Company, 1740 North Belt Line Rd, Mesquite, TX. Since the switch over to tank #2 with traveling the past week… used 3.2 gallons @2.69/ gal. Top of the tank cost $8.61. Best place to fill your propane tanks! Thanks TSC. Switched tanks back to tank #1. (35 days)
Update: 11/16/2018 filled tank #1 4.5 gals flat fee $13.00 incl tax. Filled at Barnett’s in Benson, AZ. Switched over to tank #2. Using propane for hot water and refrigerator while on the road and boondocking. Using the heater caused more usage. It’s abit cold in the desert evenings. (20 days)
Update: 11/27/2018 filled tank #2 Benson, AZ 4.5 gals flat fee $13.00 incl tax. Switched over to tank #1. The evenings have been around high 30s low 40s. That’s using the most propane to heat during the night. I also think heating the water from the water tank that is colder causing more usage. The refrig has been on electric while at camp. Moving to a camp about 100 miles west of here and it’s on average 5 degrees warmer. So let’s see if that makes a difference. (11 days)
Update: 12/8/2018 tank #1 ran out last night. It’s been quite chilly. Switched over to talk #2 today. Filed tank #1 Tuesday 12/11 in Casa Grande, AZ at the Tractor Supply store. $2.49/Gal 4.6 Gals. $12.50 including tax. Basically this usage is depleting keeping the heat on at nights. It definitely gets colder at night in the AZ desert. (10 days)
Update: 12/18/2018 tank #2 ran out of propane. Switched to tank #1. On 12/20/18 filled tank #2 at Tractor Supply. 4.6 Gals @ $2.49/Gal plus tax. Total $12.50 (10 days)
Update: 12/30/2018 tank #1 ran out of propane this morning. Switched to tank #2. On 12/31/18 tank #1 ran out of propane. Switched to tank #2. On 12/31/2018 filled tank #1 at Tractor Supply. 4.6 Gals @ $2.49/Gal plus tax. Total $12.50 (12 days)
Update: 1/7/2019 tank #2 ran out of propane. Switched to tank #1. On 1/7/2019 filled tank #1 at Cal-Ranch Stores in Casa Grande, AZ located at 1116 E Florence Blvd. 4.8 Gals @ $2.39/Gal + tax Total $12.53 (7 days)
Update: 1/21/2019 tank #1 topped tank. Switched to tank #2. On 1/21/2019 filled tank #1 at the RV PitStop, Hwy 95, Quartzsite, AZ. 3.5 Gal ~$2.53 incl tax, total $8.85. It has been obviously warmer out here in Quartzsite and decided to top the tank instead of waiting to run out. Part of this reason is, not sure due to the high volume of RVs if there would be enough propane… (14 days)
Update: *** Started tank #3 for propane fire pit. Purchased at Tractor Supply Co. $32.99 plus 4.6 gal full $2.49/gal. $11.45 with tax total $48.53
Update: 2/16/2019 switched to tank #1. Filed tank #2 at Cal-Ranch Stores in Casa Grande 4.5 gal $2.39/gal +tx $11.75 (27 days)
Update: 3/4/2019 switched to tank #2 filled tank #1 at Cal-Ranch Stores in Casa Grande 4.7 gal $2.39/gal + tx total $12.26. (17 days)
Update: 3/27/2019 Switched to tank #1 filled tank #2 at Tractor Supply Co in Casa Grande, AZ 3.9 gal $2.69/gal +tx total $11.46 (24 days) it’s been warming up. And staying at a camp with electric helps. *** Also filled tank #3 for the fire pit. (Last fill 1/21/2019)
Update: 4/13/2019 Switched to tank #2 filled tank #1 at Farm and City Feed, Moab, UT 3.6 gal $3.89/gal +tx total $14.96 (18 days)
Yes the Moab propane gouge! Glad to be out of there!!