Daitsu ELITE 3CSD3000] Manuel D'utilisateur page 56

STALLING AND OVERHEATING
The terms "stalling" or "paralysing" refer to the situation that occurs when the pump stops, either because of pump failure, a power
outage or triggering of a system to protect against high temperatures in the tank with the controller device, causing the pump to switch
off. If there is a pressure and temperature relief valve (PTRV) at the collector inlet or outlet, the temperature will continue to increase
up to the limit set for the valve, when hot water will be discharged from the system. If the collector does not have one of these valves,
steam will collect at the collector outlet. Over time, part of the steam may return to the tank through the return line. The tank relief
valve will open to relieve the pressure or the heat, as required. Under these conditions, the distributor will normally reach a maximum
temperature of around 160ºC/320ºF. Generally, the heat which returns to the collector as steam will not be sufficient to affect the
continued increase in temperature in the tank (i.e. heat inlet < heat loss in the tank).
Under normal working conditions, stalling due to pump stoppage will rarely occur, since power outages tend to occur during storms
and not when it is sunny. The device which protects the tank against high temperatures should only trip when no hot water is used
for several days (at holiday times, for example) and only when the sun's rays are really strong (in summer). If the user is not going
to be at home for a long period of time (more than 2 or 3 days), it is a good idea to cover the collector panel or design the system
with a heat dissipation device or alternative use of the heat, thus preventing overheating of the system and the stalling of the
collector. If the solar panel stalls or is paralysed, it will NOT suffer any damage. However, the insulation on the pipes next to the
distributor inlet and outlet must be able to resist temperatures of up to 200ºC/395ºF (e.g. fibreglass or mineral fibre, with exterior
aluminium foil lagging to protect it from the elements).
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