Looking to heat your domestic hot water system with your wood cook stove? In these videos, Obadiah’s Woodstoves explains your domestic water heating options and various types of heat exchangers and water coils. We have heated our domestic hot water this way for years, and it works if it sized accordingly.
Be aware! If this is not done properly, it will be *very, very bad.* Water Reservoirs on Wood Cook Stoves are NOT pressurized and cannot be connected to a domestic hot water system. They are fill and drain systems only, which means you fill it with a bucket and drain into a bucket. If you buy a wood cook stove with a water reservoir and it is connected to a water coil when there is a fire in the firebox, there must also be water in the water reservoir, or it will melt. Only the Kitchen Queen has a Water Reservoir that is passively heated and can sit there empty until needed without a problem.
**NEVER DRINK WATER FROM A WATER RESERVOIR**
Instead, use a tea pot and bring it to a boil first before drinking it. Water Reservoirs are a breeding place for bacteria, viruses, and fungi that will make you sick. The best way to do a domestic hot water system if you want a hot shower is to install a hot water tank (such as a Range Boiler) near the stove at the same level or above. You should hook the system up so it will thermospion properly without pumps or electricity.
The key to using this type system is understanding that you cannot install valves to turn off the flow of water, or you will have an explosion when the water boils. When there is fire in the firebox of your stove, some of the BTUs will be going into the hot water tank, so you must have two ways to read the temperatures in the tank. If you don’t have a way to read the water inside the tank, install a temperature gauge on the inlet side of the Thermoloop and on the hot side of the domestic hot water outlet on the tank. This will give you an idea of the temps of the water going in the tank and what is coming out. For example, if the water going into the tank on the Thermoloop side is running at 220 degrees and my hot water coming out is 190 degrees, it means I have 20 degrees to go before the pop off valve will release and all my hot water goes down the drain.
It is a constant monitoring process to make sure you don’t blow your cork and lose the hot water by bleeding off the BTUs inside the tank when you use hot water at the tap, laundry, or shower. We rotated our turns at showers and did our laundry and dishes whenever we needed to use some hot water throughout the day. We’d always drain the tank at night with showers so it would be ready and hot in the morning for those who liked their shower then (there’s nothing worse than waking up to find no hot water because the tank cycled in the middle of the night).
This system works if you’re on a ranch, homestead, or farm, and everyone is around during the day. If everyone is going different places all the time, it won’t work because no one can monitor the water temperature. If that’s the case, the system has to be automated with Auquastats, pumps, and a diversion system to bleed off BTUs into the something like a hot tub. These systems can get complicated quickly and the price can get expensive, so make sure you can run it with a battery back-up in case of a power failure.