I see you are returning to the furnace ahead of the air filter. Assume the stale air is coming from the bath rooms? In any case, it is a must that you follow the mfg's instructions on balancing the system. Does the HRV run with the FAU or independently on demand from the baths? If independently, balancing will be a bugger. Gotta pick which condition makes more sense.
I typically returned the fresh air back into the house in the closets, which generally benefit from the fresh air with lower humidity and cooler air gets tempered.
HRV's are great technology when applied properly. Learn and earn! Become the expert and sell em! Lifebreath has some good educational materials, just ask 'em.