I am exploring the idea of switching to natural gas. In doing so I am exploring potential cost savings of natural gas versus propane.
The Blichmann Floor Burner can use propane or natural gas. With propane the Blichmann is rated at 72,000 BTU/hr and with natural gas it is rated at 60,000 BTU/hr.
First propane: one 15 lb. propane refill costs me $20. One lb. propane yields approximately 22,000 BTU. To burn the Blichmann for one hour it will take 72,000/22,000 = 3.27 lbs. of propane. Propane costs $1.33 per lb. meaning running the Blichmann for 1 hour costs $1.333.27 = $4.35. 1179 BTU are required to bring one gallon of water to 212F from 70 F. I boil 7 gallons, so 11797 = 8253 BTU are required to raise the temperature. The Blichmann in propane mode would require approximately 8253/72000*0.8 = 0.14 hours or 8.6 minutes to boil water.
Next natural gas: Based on my gas bill one CCF costs $0.744. One CCF of natural gas has approximately 100,000 BTU. Running the Blichmann for one hour will require 60,000/100,000 = 0.6 CCF which in turn costs $0.7440.6 = $0.45. The Blichmann in propane mode would require approximately 8253/600000.8 = 0.17 hours or 10.3 minutes to boil water. The difference in boil time will add a few cents to the natural gas bill.
My boil times seem too low. I used 80% efficiency. Maybe I should use a lower efficiency. Not sure.
Is the above math correct?
Bottom line it looks very cheap to use natural gas. However, since I would have to hire a plumber to run a gas line in my back yard it would likely take quite a while (I only brew once per month) to recover the upfront costs. I am assuming the plumbing costs would be $200 or more.
Don’t forget the capital cost of hiring a plumber to set up your natural gas, and the possible inconvenience of being hard plumbed to that gas. You could pay for quite a few batches with that cost.
I think it is important to note one should shut off the supply to the house first before attempting any work on the gas lines. No open flames necessary regardless. A pipe wrench and tape usually is sufficient.
Those are best case numbers. You never get all of those BTUs into the water, as the transfer from the flame to the metal is a little inefficient. Those of use that stand around the flaming burner to warm can attest to that.
When it comes to permanently installed gas lines it is best to hire a pro (IMHO). If only for the ability to spread the liability. They have to carry insurance and or bonds to protect themselves and their customers from mistakes. It protects you from burning something down and having your claim denied because the work wasn’t up to code and/or illegally installed.
I converted from LP to NG 3 years ago for my three burner Brutus 10 brewstand using a bbq grill quick disconnect. Even though I don’t have the BTUs of LP, it is really reassuring that I never have to worry about running out of gas during my brew day.
About propane bottle exchanges: Blue Rhino is a rip off. You only get a 3/4 filled tank for nearly double what the price should be. I have 4 20 lb tanks and take them to a local U-Haul station where you only pay for the filled gas amount. Therefore I don’t need to wait for the tank to be completely empty. A completely empty bottle in the North Pittsburgh suburbs costs about $13 to fill.
Where I live the savings is negligible. 15 minute drive for 20% more, or 2 minute drive to the local Home Depot with self-serve kiosk exchange. Fills run me about $17 and exchanges are $16. $0.94/lb compared to $1.07/lb. Factor in the gas and it’s a wash at best. I keep two tanks and run one dry before swapping.
I would fill in the past. I town I lived in had a hardware store with $10-11 dollar fills while exchanges were $20.
Also, they don’t fill the 20lb tanks to capacity, they leave space for expansion of the gas. I think they stop around 4.5 gallons which would be 18lbs.
