Is an air vent valve required in the piping when an expansion tank is used?

Air vents must be installed in various locations in the piping system to purge air and for sure at the highest point in the piping system. One of the most common problems in water/glycol systems is the presence of air in the condenser loop. In addition, an expansion tank is recommended on glycol systems. The Operation and Maintenance Manual shipped with the unit, or available for download on this website, illustrates typical field piping for a glycol system. How are ambient fans on the heat exchanger controlled? Can they be adjusted? The first condenser fan motor (header end) has a fan speed controller on air cooled units. Secondary and subsequent ambient fans on heat exchangers are controlled by ambient sensing thermostats. These are preset at the factory, but can be adjusted in the field if conditions warrant. To adjust these thermostats, locate he electrical panel on the heat exchanger. The next photo shows the ambient sensing thermostats in the electrical panel. The lower photo ...  more