ERV and Economiser, Athletic Center

[tbedford]

I am balancing a 7 1/2 ton rooftop heat pump appliance (down discharge) with a factory-installed economiser.There is an ERV installed in series with the heat pump ductwork. Appliances are ducted in such a manner that the ERV supplies O/A into the return plenum just downstream of the economiser. Airflow then passes through the ecomiser and then the indoor coil. The ERV exhausts 100% change room and shower exhaust from the facilty. There is a small return air duct from an adjoining exercise room which returns air to the heat pump. Appliances and airflows are matched and there appears to be no influence of fan rotation/speed on each other.

Several questions: Is the economiser necessary? Is there any issue I should be aware of when balancing this situation? Can I calculate the expected energy savings for this installation?

Tom Bedford