Hard question to answer Bill when I don't know the size of work you are attempting but several things occur to me. BTW, most of my fabrication & boiler work is relatively small and very large boiler work will present more challenges.
The first thing is that I try to apply the solder 'pallets' before I apply the heat where ever possible. This not only helps to minimise the amount of solder used but also means that you are not feeding solder in and your hand will not therefore get hot! Where I do need to feed the solder in, I do so only once the work is hot enough, so again my hand isn't near the radiant heat for too long, so doesn't tend to get that hot (I don't generally wear gloves either).
However, there have been a few occasions where (even with gloves) things were getting a bit warm and I've got a simple heat shield made from tinplate. It's just a square of tinplate (with a hole in it to poke the solder through) and it's very light to use and certainly helps deflect the heat. Most of the time however, I don't find it necessary.
Regards,
IanT
Edited By IanT on 29/12/2019 12:51:28