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Systems with two outlets and one relay inlet
In single installations; with solar power intake for the domestic hot
water and one single heat exchanger, there are two main functions:
1. Start-up and stopping by T between the collectors and
accumulator.
A temperature difference (usually 7ºC) is determined for the pump
to start working, and another difference (2ºC) for it to stop.
2. Temperature limitation in the accumulator. Although the
temperature setting may be approximately 60ºC, on days with
high solar radiation it is preferable to increase the water
temperature in the accumulator to prevent overheating at
the panels.
Systems with two relay outlets
For more complex installations where several pumps or motorised
valves need to run, a regulation system with more relay outlets is
used. The most common functions are:
a) Working a zone valve to divert the flow when the desired
temperature is reached in the accumulator.
b) Diverting the flow to the second heat exchanger in dual coil
storage heaters to improve stratification or with two
accumulators
c) Using two pumps in installations with an external heat exchanger
REGULATION
Correct use of the regulation unit is essential for optimum performance of a forced circulation system.
SOLAR THERMAL CONTROLS
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