Skip to main content


Condensing Make-Up Air Units 


It is required by code to provide mechanical ventilation to buildings in accordance to ASHRAE 62.1. A common method of ventilation for buildings is through introducing fresh air with Make-Up Air (MUA) Units and exhausting building air through multiple exhaust fans located all around the building. If a common exhaust fan exists then a Heat Recovery Ventilator (HRV) should be considered for optimized energy savings.
MUA units will sit on a rooftop or within a mechanical room and supply 100% outdoor air (OA). During the winter months, these units MUST operate to ensure ventilation code requirements are met. This cold OA must be heated up to an acceptable supply air (SA) temperature (typically 65F to 70F) before being introduced into the space. This requirement for a large temperature rise (between the OA and SA temperature set point) during the coldest winter months gives the building owner a significant opportunity to save on utility costs through the implementation of high-efficiency Condensing MUA Units. The significantly higher efficiency (>90%) compared to older equipment (<75%) means that paybacks will be realized quickly.
The condensing MUA units can achieve these higher efficiencies because they remove so much heat from the combustion exhaust gas that it brings the exhaust gas temperature below its dew point temperature. This condenses the water vapour present within the exhaust gas to create acidic water. The equipment has been design to handle this acidic condensation but it needs to be neutralized through a neutralization kit before being drained to prevent deterioration of drain piping.
Patrick Belina
Efficiency Engineering Inc.


Created at 6/22/2012 11:36 AM  by Lauri Alty 
Last modified at 6/22/2012 11:36 AM  by Lauri Alty 
     © 2016 Efficiency Engineering Inc.     225 Pinebush Road Suite 202, Cambridge, ON Canada N1T 1B9 | Phone: 519-624-9965 Fax: 519-624-9316