Replace exhuast fan with ERV?
Replace exhuast fan with ERV?
(OP)
I am upgrading a building’s HVAC equipment with new equipment. There is currently a 5000 cfm fan coil unit supplying conditioned air to the space and a 5000 cfm exhaust fan returning the air back to the fan coil and exhausting a certain amount of air to the outdoors. The return side of the fan coil is ducted to an outdoor air inlet and the outlet side of the Exhaust fan. It is all controlled with pneumatic dampers.
My question is can I remove and replace the exhaust fan with an ERV? My space requires 400 cfm of fresh air and my bathroom exhaust requirements are about 350cfm. Can I remove the 5000 cfm exhaust fan and connect the new fan coil unit’s return air duct to the old exhaust fan’s inlet ductwork and then have the ERV to draw exhaust from the bathroom and supply 400 cfm of outside air into the return duct of the fan coil unit?
The location is Northern, Ontario with a winter outdoor design temperature of -25
Thanks in advance for your responses.





RE: Replace exhuast fan with ERV?
I dont see why not. Add the return duct static (or the ERV staic pressure (if no ERV fan); whichever is greater) to the new FCU ESP. Pay special attention to frost protection options for the ERV.
knowledge is power
RE: Replace exhuast fan with ERV?
Then will add an ERV to for ventilation air instead of using the FCU O/A duct/ EF combo.
RE: Replace exhuast fan with ERV?
RE: Replace exhuast fan with ERV?
just because you found it like that, doesnt always mean it was done right the first time.
knowledge is power
RE: Replace exhuast fan with ERV?
RE: Replace exhuast fan with ERV?
RE: Replace exhuast fan with ERV?
However, if the new FCU's fan comes up short on the pressure requirements, keep the "exhaust" fan and slow it down to be just return, block off/remove the exhaust portion of the duct, add the ERV as originally planned.
My money is on doing as originally intended.
RE: Replace exhuast fan with ERV?
without RF, you would need relief damper somewhere.
I'd look at the control sequence of operation first before changing for the sake of changing without first understanding the purpose of the original design.