Domestic hot water from wood stove.

Hello. Trying to do what a lot of people have probably already tried, just wondering if anyone has actually succeeded. I want to heat an openly vented water tank (with a small kettle like cap at end of vent) with a wood stove for my domestic hot water, as well as part of my heat battery for my tiny house.

I plan to run a pressurized cold line to the top of my tank for ease of filling with ball valve in.

The hot out would be:

1 - A ball valve.
2 - 3 way mixing valve with cold coming from above mentioned pressurized cold line.
3 - hand primer.
4 -  12v pump.

Perhaps the 3 way valve and the pump would have to be switched. I don’t think they work without equal pressure on both inputs. And not sure if they work at all on suction. Just didn’t want scalding water entering my pump. Though hopefully it wouldn’t get to the scalding point.

I would like to find a way to control my wood stove better without being inefficient. Has anyone toyed with adding a small air intake fan ( I’m talking a computer cooling fan) to the back air intake of a wood stove? That way I could control the oxygen better so I might bring the water to a desired temperature and then turn take away oxygen thus reducing the heat. I understand the stove would have to be well sealed in order to do this or the pressure may build higher than the pressure inside my house and release gases and smoke inside.

I would also include a ball valve with a drain out of the tank and a thermometer in the tank. That way if the water got too hot to use, I could simply drain out some of the hot water and add
cold. This approach may not be very water friendly, but in the winter time there will be an abundance here.

Any input appreciated, I know free hot water is something humanity has been chasing for a while now so I am wondering if anyone here has attempted anything like this and succeeded.

Cheers,
Dean.

Dean there have been a number of topics on the subject, have you searched for any?

As John suggested, here are some threads that you or others might find interesting:

https://permies.com/t/18701/RMH-hot-water-coil

https://permies.com/t/47521/Wood-fired-passive-gravity-fed

https://permies.com/t/79543/rocket-hot-water-idea

And here are some PEP BB for those interested:

https://permies.com/wiki/106188/pep-rocket/Start-Rocket-Water-Heater-Heat

https://permies.com/wiki/144004/pep-plumbing-hot-water/Unpressurized-rocket-hot-water-system

https://permies.com/wiki/125891/pep-rocket/Build-Tube-Unpressurized-Rocket-Hot

Hi Dean;
I see you are in a tiny house, so space would be at a premium.

From your drawing, it appears you have your super-size kettle sitting on top of a traditional box stove.
I imagine this could work but think of all the wood heat you are sending up the chimney.

Why not consider a Walker-style riserless core water heater?
Your water tank is enclosed in a brick bell, it is open-vented.
The entire water tank is surrounded by the super hot air produced by the riserless core.
Meanwhile, your chimney temps would be at RMH levels of around 200F.
You gain a superb heat-retaining mass and your water stays hot much longer.

Thomas they sound fantastic