Many HVAC system designers have realized the benefits of using Energy Recovery Ventilation Fan in commercial and institutional buildings. However, as with many newly adopted technologies, questions of how best to apply this product are being raised. One application issue in particular is whether to apply an ERV as a stand alone unit on its own curb, or as a bolt-on accessory to a rooftop air conditioning unit.
What is the difference between the two systems? Although both systems require an exhaust air stream as an energy source to pre-condition outdoor air, the primary difference between the two systems is where the exhaust air is taken from. The drawings at the right illustrate this difference and help visualize how the ERVs tie into the HVAC ventilation system.
Some system designers may show a preference for the bolt-on ERV. This may be because they perceive that the installation cost will be lower, or they prefer having a single point of responsibility for the ERV/rooftop unit.
Combining outdoor air and exhaust air ventilation functions into a single unit help drive an important practice in good HVAC design-building ventilation balance. In layman’s terms: What goes in must come out. Traditionally, the outdoor air needs and the exhaust air needs were calculated in separate thought processes. The designer would specify the minimum outdoor air and exhaust air volumes required by code, but would stop short of comparing the totals to check the ventilation balance. Frequently, this led to over pressurized buildings where doorways were transformed into wind tunnels. In some cases, buildings became negatively pressurized and infiltration made indoor climate control difficult.
Exhaust fans and outdoor air fans are simultaneously energized so the building operates as it was designed. Separate controls, interlocks, and field coordination to maintain a balanced building are eliminated.
The AMX ERV system has many advantages over the bolt-on system. When considering the total ventilation system, the stand alone ERV offers higher efficiencies, provides a more reliable means of controlling ventilation, minimizes installation costs and enables energy recovery and economizer technologies to be combined for maximum energy savings
No comments:
Post a Comment