Scenario

This case involves a multi-family building with a four pipe heating and cooling system using a chiller for cooling and a gas boiler for heating. The boiler is piped in a primary/secondary arrangement. The terminal unit in each suite provides warm or cool air as determined by a programmable thermostat. The hallway pressurization unit (Make-Up Air unit) has heating and cooling coils controlled by a thermostat in the unit.

Evidence

Monthly natural gas usage was noticed to have doubled compared to previous summers.

Problem

A mechanical contractor was brought in and discovered a failed three-way valve that controls hot water flow to the hallway pressurization unit, resulting in a continuous flow of hot water to the heating coil. The thermostat in the hallway pressurization unit compensated by calling for cooling. Therefore, both gas and electricity were wasted in providing simultaneous heating and cooling.

Cost

The valve had been leaking for six months, wasting 596 GJ of natural gas costing $6,200.

Prevention

The facility profile provided by Arctic Fox Energy Tracking would have allowed staff to see that both gas and electricity usage were uncharacteristically high in the report following the valve failure, permitting immediate corrective action.