I would kindly disagree with bill m. The reason being that if you have syrup in a bottler being directly heated, you can have areas where the syrup that is heating up is directly contacting the pan and the propane flame is on the other side of the pan which. The syrup in that area can get above 195 and create sugar sand/niter. If you bring your syrup up slowly under direct flame, you may get by with direct heating. I use propane; however, I have my propane heating some water which causes steam to heat the syrup. It's like a double boiler. When doing it this way, you are assured that you won't create niter and your temperatures stay constant during the bottling process.
Chad
2014: 12 taps, 5 gal buckets
2015: 15 taps on bags
2016: 150 taps: 100 on bags, 50 on 3/16" natural vac, 2x8 AUF/AOF Homebuilt Arch, 2x8 SL Drop Flu & Auto Draw, SL Propane Canner/Bottler
2017: 225 taps: Built Lean to, Added SL hood, preheater, concentric exhaust, SL SS 7" SB Filter Press
2018: 180 taps: Added Shurflo to 50 - 3/16", Auto fill sensor to head tank
2019: No tapping
2020: 175 taps
2021: 300 taps, homemade RO and releaser
2022: 600+ taps