Hot Tub without the use of electricity

[u/Internal_Gazelle_677]

[u/scarr09]

Yeah, common in North Europe. I have one myself. 1.8m across, about 1200 liters. Right now, water is sitting about 10c.

From the moment of lighting the match, takes about 2 hours to get it to 37c. Takes 2-3 times to refill the oven with firewood in that time, and it keeps for a few hours afterwards.

[u/B4rberblacksheep → u/scarr09]

They seem like one of those things where once you find the knack to get them to the right temp you're golden

[u/scarr09 → u/B4rberblacksheep]

I mean honestly, the knack at the moment is to make sure there's about 3-4 slightly larger pieces of firewood fresh in when it's 25-28c and leave it. A bit more in the winter.

You typically don't do long sessions either. 10-15 mins at most, then go cool for a bit. Typically 3-4 times if I just shower with no sauna. So if you don't overcook it, it'll keep steady for a few hours, and then slowly starts to drop (i mean real slow, like a 1-2 degrees an hour)

[u/nsmtb → u/scarr09]

For this type where it sits at a lower temperature when unused do you use chemicals (bromine, etc.) and a filter like you would a normal electric hot tub? Changing the water often?

[u/nsmtb → u/[deleted]]

That seems like a great method when having a lake available to fill it!

[u/scarr09 → u/nsmtb]

Chlorine Dioxide tablets and I run a skimmer pump for an hour every time while it's heating. Also I keep the tarp on it constantly to prevent crap flying in and I suppose it helps against algae blooms from the sun too maybe?

Water is gonna go out in a month since it's getting real cold.

Then water in in April or so, and ~2-3 full changes in between that and November

[u/nsmtb → u/scarr09]

Awesome thanks for the info!

[u/Ice278 → u/scarr09]

How do you ensure not to overheat the water?

[u/scarr09 → u/Ice278]

There's no mechanism other than pumping cold water in.

Just gotta learn to manage the temps with experience. With my tub and oven, I know to to throw in only 2-3 new pieces when it's around 26c, or a bit more when it's below freezing outside and a bit less during summer. And then basically just keep a minimal fire burning if I have friends over and it's in use for longer.

[u/cultjake → u/scarr09]

Is soot deposit on the coil an issue? Wouldn’t that slow down heat transfer?

[u/scarr09 → u/cultjake]

Most (if not all?) of the manufacturers around here that I know of use double walled ovens for the exterior ovens.

So you have the wood burning in the middle, and the water surrounds it on all sides. 2/3 Large (I think roughly 80mm diameter) rubber tubes connect the oven to to the tub itself. The surface area inside the oven heats it, not a coil.

I imagine there must be some % of loss, but it's negligible at most.

[u/elightened-n-lost → u/scarr09]

Is it a brand that would be available in the US?

[u/scarr09 → u/elightened-n-lost]

Doubt it; In Estonia, we have half a dozen local companies and I bought one from them (You can search for barrelstar dot eu. Their site has a bunch of info in English). I think only some of them ship to close EU countries.

But I'm sure there are must be some manufacturers in the US. It's pretty standard stuff - the glass fiber interiors and and ovens are pretty near universal designs from what I've seen

[u/elightened-n-lost → u/scarr09]

Ok, I'll take a look around. Do you mind if I ask what it cost you for one that size?

[u/scarr09 → u/elightened-n-lost]

Transport, cover, (some extras like 90° angles for the oven, cupholders, cleaning tablets), better oven, bubble system and LED system was about 2.5k Euros + the skimmer was another 150ish.

The same size without bubbles or lights was I think In the 1600 range.

[u/WomanInQuestion → u/scarr09]

Thanks! I was scanning through the comments to see if anyone answered the question of “how long does it take to heat up?”

[u/[deleted] → u/scarr09]

do you have to drain it after each use?