Simple Solar Heaters with Pumps

The simplest solar heating systems do not use pumps or other controls (Batch ICS solar systems, Thermosyphon solar systems...). But using a pump in a solar heater system adds versatility in terms of designs or even efficiency.

Many solar heaters with pumps use water at the collector level and do not use expansion or drainback tanks; they typically use flat-plate collectors and are called technically active-open systems: active because they use a circulating pump instead of natural convection or gravity; and open because they use water instead of glycol or other non-freezing fluid in the collector.

Elements of open-active solar systems

Simpler open-active solar heating systems involve a solar collector, a storage tank, an electric tank, a small pump, and some valves, controllers and sensors…

The advantage of using a pump (active solar systems)

A solar system with a pump provides wider possibilities in terms of location of the collector or the tanks (the collectors do not have to be placed on the roof). Besides this system can also solve problems with extreme temperatures (risk of freezing pipes, too hot water and related damages).

The pump

Simple solar active-open systems use a small and cheap circulator pump (many of them with just 10 watts), that can be powered by a small and cheap PV photovoltaic module (10-watt) in order to attain an entirely environmentally-friendly solution. Small thermostatically controlled AC pumps can also be used.

Climate

Open solar systems (without anti-freezing fluids and special tanks) are a typical solution for moderate and hot climates.

Solar Collectors

Flat-plate collectors are by far the commonest solar collectors used in simpler open-active solar heaters, though evacuated tube collectors may also be used.

The electric tank

Standard 50-gallon / 200 L electric tanks are common in open-active solar systems. Since the electric element is rarely hooked up, the tank is only a storage tank, feeding another existing backup water heater.

Other elements

Open-active solar heaters include some other minor elements as an air vent at the high point of the collector to purge air, or standard sensors to control the temperature in the tank (standard values usually range between 160ºF/70ºC and 180ºF/80ºC).

The image on left (Credit EERE) includes the components of a closed-loop system with a pump.

The difference between this closed-loop system and the open one described in this page, resides on the fact that open-solar heaters use water at the collector level instead of a freezing fluid.