i was in search for a hot tub system where 1000 liter of water was ready in about an hour instead of 3 or 4 hours like most projects i've seen..
also it needs to be a camp fire to sit around with a drink or maybe grill some meat untill the water is warm
i still had in memory how hot camp fires got after placing wood above wood causing massive flames
this all combined is what i came up with..
Step 1: Buiding the Fire Cage
this fire cage is build like a camp fire so it can hold long sticks in place and is feeded trough the top ring
the water will be pumped in the bottom ring and then trough the thin tubes to the top ring
from here it will be led to the tub again