reconsidering "why not propane"?

[SapTsunami]

Looking to scale up to a 2'x4' arch and considering fuel sources. It seems the conventional wisdom is that propane is very expensive compared to wood-fired, but I just did some math that made me question that.

The dour view towards propane may be unfairly influenced by:
-backyard boilers using an inefficient turkey fryer setup that is uninsulated and sends most of the heat around the pot instead of into the sap
-the hassle of refilling tiny 20-lb tanks or getting ripped off swapping tanks at Blue Rhino
-backyarders with no RO concentrator who need to boil off every gallon, instead of reducing 4:1 before lighting the flame
-people who don't count their labor and consider firewood to be a "free" heat source. I heat my house with wood and I know it ain't free

I'm looking at this unit from Smoky Lake:
https://www.smokylakemaple.com/product/2-x-4-gas-fired-finisher-evaporator-customize-it/

-Up front cost is comparable to a wood-fired arch
-quick startup and shutdown. 8 minutes to boil is a lot faster than anyone can build a fire. If I get tired I can shut off the burner and go to bed - can't do that with a box full of wood.
-easier for my wife and kids to operate when I'm not around
-I don't have a sugar shack, so more compact off-season storage is appealing

now the math. I estimate I will need to boiloff 180 gallons of 8% concentrate to yield 18 gallons of syrup. The Smoky Lake propane evaporator claims 9 lb LP consumption to boil off 10-12 GPH.
Total 162 lbs of LP over 18 hours total boil time. My local hardware store refills a 100-lb tank for $80.
That's $130 of LP cost to yield 18 gallons of syrup, or $2/quart.
For comparison, a cord of split firewood sells for ~$350-400 locally.
Total cost of LP equivalent to 1/3 of a cord of firewood. There's no way I could boil off 180 gallons of concentrate using 1/3 of a cord. That sounds like a good value to me!

Anything I'm missing? (besides the romance of tossing splits in the fire every 10 minutes?)

[DRoseum]

I use natural gas to fire my evaporator. I made that choice for some of the reasons you stated... not all "costs" are strictly monetary. I highly value my time, the convenience and control of gas, and the automation/safety you can build into the system. No need for splitting and stacking wood and none of the time spent doing all of that or space spent storing it (or the splitting/hauling equipment).

[maple flats]

Check with your local supplier, I suspect you can do even better than the $80/100 lb tank. I have a short bulk tank which holds 40 gal when full. A gal of propane is 4.2 lbs. your 100# tank at full is usually actually 80% full, they don't fill to the top. you might be able to cut your propane bill even more and the propane co will deliver it, no hauling a tank to the hardware store. Just get some prices.
While I don't boil using propane, I have the tank connected to a few things. I have a weed burner torch that is used to light the wood fire, a 2x6 propane finisher, a propane tankless water heater and an 8,000 BTU propane wall furnace in my RO storage room. All of these combined run me between $225 and $250 a year while heating the RO room, heating up 7-8 barrels of syrup (about haqlf 26.5 gal, half 40 gal) up to about 190F to be pumped thru the filter press most years and the hot water, maybe 250 gal/year. While I don''t really have a direct comparison, it might help you.

[SapTsunami]

I will call around

Though it is in line with bulk propane costs (I have a buried 500 gallon tank for home heating)

Propane/fuel oil/electricity is just flat out more expensive here in New England than it is in New York

[Andy VT]

Perfectly reasonable to me.
I would just keep in mind that (I think) 2x4 is about the max available for propane, so if you ever want to expand you might be doing a do-over for fuel.
Either way, weigh it against fuel oil... there are 2x4's that run on fuel oil, and of course any size up from there.
If you don't have your own source of firewood I think fossil fuels make a lot of sense.
If your sugarbush management produces a lot of firewood that would otherwise sit and rot then it becomes a shame not to boil with it.

Nevertheless, this would be a good time to make jokes about how if your time is worth anything to you, do anything but make maple syrup :-D

[maple flats]

When I was picking a propane supplier, I called and got 3 different prices, I just went with the lowest. That was 3 yrs ago. I haven't rechecked since because the one I went with was quite a bit lower. Since then I've just trusted them, right or wrong. Besides, they were 6% lower back then than the next closest, and if I call and need a refill quickly, it's here the same day if ordered by 9:00 AM or next day if ordered later. My previous supplier sometimes took 3-4 days and their depot was only 2 miles from me, and I always paid within the 2/10 discount period.