Tell us about yourself!
insulating your boiler will increase it's efficiency, but also more heat is more pressure so be careful how high it will get
more practical would be to fill with sand, or even salt would work if you have either of those around. You wouldn't have to wait 30mins or longer; just pack it in tapping your tubing along the way. A long tube may not fit in many people's freezers. I would not reuse the salt for cooking tho! haha