collection fluid side of the heat exchanger to the cooler solar water storage side. The collection fluid will then complete it's loop by flowing from the heat exchanger, through the check valve, and back to the pump. The job of the expansion tank is to allow for the expansion and contraction of the heat collection fluid as it heats up and cools down. The pump in the solar water storage side loop turns on at the same time as the heat collection loop pump and circulates water

Closed-loop-antifreeze heat collection with in-tank heat exchanger - The closed-loop-antifreeze space heating system consists of two loops; the heat collection loop and the heat delivery loop. Let's first look at the heat collection fluid loop. Starting at the pump (lower left portion of the diagram), fluid will be pumped through the flow gauge and up to the collector panels. Here, the panels will absorb energy from sun and transfer this energy, in the form of heat, to the collection fluid. The fluid will then

return down to the the in-tank heat exchanger. Here, heat will be transferred from the collection fluid side of the heat exchanger to the cooler water in the solar storage tank. The collection fluid will then complete it's loop by flowing from the in-tank heat exchanger, through the check valve, and back to the pump. The job of the expansion tank is to allow for the expansion and contraction of the heat collection fluid as it heats up and cools down. The controller continually monitors he sensors located at the solar

collector panel and the solar storage tank. When the temperature at the collector sensor exceeds the temperature of the solar tank sensor by a pre-determined amount, usually 12 - 20º F, the controller turns the pump on. The pump stay on until the temperature difference between the panel and solar tank sensors drops to about 5º F.

The second loop in this system, the heat delivery loop, delivers heat to the house. When there is a call for heat by the house thermostat, the control system will first check to see if the solar storage tank is warm enough to provide heat to the house. If so, warm water will be drawn out of the solar storage tank and circulated through the heat exchange in the furnace ducting. The furnace fan will also be turned on to distribute the warm air to the house. If the solar storage tank is not warm enough to provide heat to the house, the furnace heat source will then take over and heat the house. Some solar heating systems have the heat exchanger located in the cold air plenum, while with other systems, the heat exchanger is in the warm air plenum. Both methods work. Both have their pros and cons.

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monitors the sensors located at the solar collector panel and the solar storage tank. When the temperature at the collector sensor exceeds the temperature of the solar tank sensor by a pre-determined amount, usually 12 - 20º F, the controller turns the pump on. The pump stays on until the temperature difference between the panel and solar tank sensor drops to about 5º F. When the pump turns off the water in the collector panels drains back into the solar storage tank the air in the storage tank goes up into the solar panels. Allowing the water to return to the solar storage tank when power is removed from the pump is how freeze protection of the collector panels is accomplished. The second loop in this system, the heat delivery loop, delivers heat to the house.

When there is a call for heat by the house thermostat, the control system will first check to see if the solar storage tank is warm enough to provide heat to the house. If so, warm water will be drawn out of the solar storage tank and circulated through the heat exchange in the furnace ducting. The furnace fan will also be turned on to distribute the warm air to the house. If the solar storage tank is not warm enough to provide heat to the house, the furnace heat source will then take over and heat the house. Some solar heating systems have the heat exchanger located in the cold air plenum, while with other systems, the heat exchanger is in the warm air plenum. Both methods work. Both have their pros and cons.

Air system without storage - The warm air collector system collects heat by forcing air over the heat absorption surface of the collectors. The air can then either be directed into a room for space heating or into a heat storage bin for use at a later time. The system shown here is the simplest active air system available. If the sensor in the panels is above a set temperature (usually about 100º F) and the room thermostat call for heat, the fan will be turned on and heat will be delivered to the room. As long as the thermostat calls for heat and the panel sensor is above its set point, heat will continue to be delivered to the room. When the thermostat or the panel sensor drops below its set point, power will be removed from the fan and heat delivery will cease.

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Air system with rock storage - The warm air collector system collects heat by forcing air over the heat absorption surface of the collectors. The air can then either be directed into a room for space heating or into a heat storage bin for use at a later time. The system shown here is uses a rock storage bin to store

heat and is significantly more complex that the system discussed above. When the sensor in the collector panel is about 40º F warmer than the rock storage sensor, the air handler fan will be turned on and dampers #1 and #3 will open. Warned air will be directed to the rock storage bin where the rocks will be heated. If the house thermostat calls for heat and the solar collector panels are above about 100º F, the air handler fan will be turned on, dampers #1 and #4 will open, and the warm air will be directed into the house. At night when heat is not available directly from the collector panels, it still might be available from the rock storage bin. If the sensor in the storage bin is above about 100º F and the house thermostat calls for heat, the air handler fan will turn on, dampers #2 and #4 will open and warm air will be drawn from the warm rocks and directed into the house. Some air systems also incorporate a furnace into the system. The furnace then operates in concert with the solar system and if the solar system cannot provide the necessary heat, the furnace then takes over and heats the house.

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