What action should be taken when the temperature and load increase, requiring another pump to be added online?

When the temperature and load increase and there is a need to add another pump online, it is crucial to open the suction throttle discharge. This action ensures that the new pump can effectively draw in the required fluid. By opening the throttle, the resistance to flow decreases, allowing the additional pump to operate more efficiently alongside the existing system.

Increased loads often require more fluid movement, so creating a pathway for this flow is essential. When you add a pump while maintaining the existing configuration, opening the suction throttle discharge optimizes the system by balancing the flow rates and accommodating the added capacity without causing an overload on the existing pumps.

The other options do not directly support the requirement of adding a pump under increasing temperature and load conditions. Closing the suction throttle discharge would restrict flow, which is counterproductive. Increasing refrigerant flow might be necessary under certain conditions, but without managing the discharge effectively, it could lead to further complications. Reducing the load could be a solution, but it may not address the immediate need for adding capacity with a new pump. Hence, opening the suction throttle discharge is the most effective action in this scenario.