Parts List
4 | 5 |
8
6
3 1
Sequence of Operation
Basic Unit
The PVe units are prewired such that when a call for outside air is made (via field supplied 24 VAC control signal wired to unit control center), the supply and exhaust fan are energized and optional motorized dampers open. The PVe is normally slaved (24 volt) to the roof top air handler. When the roof top air handler starts, the auxiliary contactor in the air handler closes to start the PVe.
Summer Operation
1. Supply blower
2
Outdoor air is preconditioned (temperature is decreased) by the transfer of energy from the cooler, drier, exhaust air via the aluminum heat exchanger. The preconditioned air is typically mixed with return air going back to the air handler for final conditioning.
• Forward curved fan
• Adjustable motor mount for belt tensioning
• Adjustable sheaves for speed control
2. Vibration isolators (quantity 4 per blower)
• Neoprene
3. Aluminum plate heat exchanger
4. Supply weatherhood with
5. Exhaust weatherhood with birdscreen
6. Supply and exhaust air filter racks for
7.Electrical control box (standard features)
•Single point power
•Disconnect interlocked with access door
•Motor starters for the supply and exhaust blower
•24 VAC, control circuit with terminal strip Not depicted on this image
8.Exhaust blower
•Forward curved fan
•Adjustable motor mount for belt tensioning
•Adjustable sheaves for speed control
Economizer Operation: Refer to Economizer Application/Operation section.
Winter Operation
Outdoor air is preconditioned (temperature is increased) by the transfer of energy from the warmer, more humid exhaust air via the aluminum heat exchanger. The preconditioned air is typically mixed with return air going back to the air handler for final conditioning.
Frost Control Operation: Refer to Frost Control Application/Operation section.
Other Accessories:
Dirty Filter Sensor: Refer to Optional Accessories section
CO2 Sensor: Refer to Optional Accessories section
VFD on Blowers: VFDs on blowers are often used as part of a demand control ventilation system. This type of system takes advantage of varying occupancy through the use of CO2 sensors to monitor space CO2 levels. If CO2 levels are low in the space, the VFD will operate the blowers at minimum airflow required by code. As the space occupancy increases and CO2 levels increase, the VFD will increase the amount
of fresh outdoor air being brought in to offset the CO2 levels in the space (exhaust airflow is increased proportionally as outdoor airflow increases). As CO2 levels come back down, the airflow will decrease back to minimum requirements.
Model PVe Heat Recovery Unit 25