Building a larger home near Boston that will need 2 large erv systems.  My hvac contractor doesn’t normally do dedicated ductwork and not experienced in design of dedicated ventilation design and commissioning.  I’ve looked at zehnder to have a well designed dedicated system but cost is about 20k.  Any suggestions for folks experienced in this area as 20k plus install is not affordable and doing a simplified system without dedicated ducts seems like the wrong answer.  

thanks
dave