You can use an outdoor wood burning furnace in a home that has several different furnaces on different levels or different areas. For example, you might have a furnace in the attic to heat your top floor; another in the basement the heat the bottom floor and even a different one to heat in addition.
You can simply put a heat exchanger in the plenum of each furnace. You would run the piping for the heat exchangers in series.
In this scenario, you would likely run the outdoor furnace at 180°F
The first heat exchanger would yield 180°F water, while the second one would like to be approximately 20° less, or 160°F, while a third one would be approximately 140°F; plenty hot enough to heat up on.
In fact, all of our heat exchangers are rated at 140°F or better.
Doing it this way saves a lot of piping and running extra pumps, which is unnecessary. You would normally run the first pipe from the outdoor furnace to the area needing the most heat (in other words, the largest square footage that you are heating). The last one in the run is likely going to be for the smallest area or a place like a basement, where you don’t need much heat to begin with because it is already 55° or better, being below ground.
You can do the same thing when you are using different types of heating systems. a lot of people utilize a forced air furnace in conjunction with a radiant system, for various reasons. Sometimes one or the other has been added at a later point in time.
You would normally run the first line to the heat exchanger and a plenum because that is where you will need the most heat. Normally a radiant type of system in a floor will be 140° or less, so it is quite fine for that to be at the end of the line. A water to water heat exchanger (sometimes also called a plate exchanger) is used between the outdoor furnace and your radiant system normally uses some type of boiler. You will always need a tempering valve control the water temperature going in the floor, so that the flooring material isn’t damaged.
The same goes true when using a heat exchanger in a Plenum and a side arm heat exchanger on a hot water heater.
In this scenario the plumbing would first go to your heat exchanger in a Plenum and then to your hot water heater (side arm) because that only needs 150°F at the most.
The below pictures shows an example of heating multiple systems: