Collector Flow Rates Balanced
Measure the outlet temperatures of each collector group in the array.
These temperatures should all be within 5 degrees of each other. If not, rebalance
the flow rates between collector arrays.
Balancing must be done on a sunny day when the system is operating. Open all
balancing valves fully. Reduce the flow slightly through the array with the lowest
outlet temperature. Wait three or four minutes, and recheck all the array outlet
temperatures. Continue balancing and waiting until all the temperatures are within
five degrees of each other.
Close the balancing valves as little as possible. Reducing the flow rate
through the collectors reduces their efficiency.
Sensor Wires and Sensors
Check sensor wires for UV degradation. They should be secure and make a
watertight connection where they pass through the roof. They should not be near
sharp edges, or within 1 foot of 120V and 2 feet of 240V wiring or loads.
Make sure the connection to the sensor is still electrically sound. If the connectors
do not appear watertight, replace them.
Make new sensor connections by twisting the wires together, then twisting on small
wire nuts. After installing the wire nuts, fill them with silicone sealant. Tie a knot in
the wires for strain relief.
Unless they are defective, the actual sensors should require no maintenance. Each
sensor must be within 1 inch of the collector housing, well insulated from the outside
air, and protected from weather and mechanical stress.
Sensor testing is described in Section 3.1.7 and replacement is described in Section
6.1 MAINTENANCE PROCEDURES