Pressurized Solar Thermal Space Heating Systems with Storage

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Pressurized solar thermal installations for space heating follow the same solar loop layout as similar systems for hot water. They can use single or multiple liquid tanks or they can use sand as a storage medium.

Traditionally, pressurized systems use a single, large tank to store their heat, with one or more internal heat exchangers to transfer the energy from the solar loop to the tank, and from the tank to whatever equipment is attached. In the case of a combined solar thermal space heating and hot water setup, a separate heat exchanger takes heat from the tank to each destination.

One big advantage of the traditional setup is that it's a lot easier to retrofit to existing heating systems. Additionally, it can be run on a PV-powered solar loop (with a DC pump ) or can use differential temperature controllers (with an AC pump ). Add flexible collector placement options, regulated temperature control inside the home and freeze protection in any climate and you can see why the traditional setup is so popular.

On the down-side, the system requires a diversion or shunt load, especially in warm climates when the collectors will gather too much energy, which must be dispersed.

If you go with multiple heat storage tanks, the water is usually sent directly to the heating equipment if possible, but you can install a heat exchanger in each tank if you prefer – it's easier to install tanks with internal exchangers than to work with external models.

Combination systems with multiple heat tanks need a separate tank for the domestic hot water supply and can get quite complicated and expensive.

If you decide to go for sand as a storage medium, you'll want to read about mass storage systems as an alternative option: they're comparatively huge and have very different requirements.