Oxy Propane kit | Model Engineer
That's not really an either/or question. Oxy Propane is a high temperature, but localised flame, and can cause issues by melting tubes or tube plates if not used carefully while propane is a slightly cooler flame, but bigger and with a lot more heat capacity. I would suggest that an oxy propane kit is something useful to have in the workshop for brazing as against silver soldering, but for more heat on a boiler a second propane is probably a better bet and is half the price of the oxy kit. Many of the older designs were produced on the understanding that paraffin blowlamps were to be used and...
Source: model-engineer.co.uk