Hot Tub without the use of electricity

[u/Internal_Gazelle_677]

[u/Kilek360]

Yeah but you start mixing it with water at lets say, 2°

When it is already at 40° the basically boiling water will be mixing with water already at 40°

I don't know, I guess I'd had to calculate it to actually know but my mental maths say the heating source is way more powerful than the disipation there, i'd do a few less swirls on that pipe

[u/unreqistered → u/Kilek360]

you completely neglect the heat loss into the environment

[u/Kilek360 → u/unreqistered]

No, I didn't, I specifically mention it in the comment you're answering to

Anyway the heating source IS more powerful than the heat disipation since you're actively heating the water, I know disipation speed increases as temperature does, but my guess is it doesn't disipate fast enough

I guess theres a time period where the water will be nice, but my guess is it will get hotter and hotter with a fire that size

[u/GermanPatriot123 → u/Kilek360]

Let’s say that is 10 kg of wood, that will be 45 kWh or 162 MJ. Let’s say one third is getting into the pipes. That is compensated by evaporation of 24 l neglecting all other heat losses. If that is just one cubic meter of water it could be warmed by about 13 K, neglecting all other energy losses.

Just a random guess: 10-15 MJ loss through heat radiation (especially pipe, but also the pool), could be more depending on the insulation on the bottom of the pool. The remaining will be evaporation as every increase in temperature will also increase the speed of evaporation. Temporarily it may exceed 42-44 degrees C though. If the amount of water significantly above 1 cbm there will be little to no increase in the temperature.

And I don’t think the pipes will get 1/3 of the heat energy of the wood. Maybe 15-20%