In my non-professional and somewhat ignorant thinking, it seems that with all the spot ventilation (3 bathrooms, range, dryer, central vac) a balanced ERV would still leave a house negatively pressurized?

I believe in some cases (winter) negative pressure may be desirable, however the concern would be back drafting (wood fireplace)? Summer might warrant a positive pressure to help prevent moisture being pushed in?

I plan on sizing spot ventilation appropriately, not over sized. Hot water heater will have a Balanced Combustion System. In-floor radiant heating and mini-split ductless AC. Icynene insulation. The only make up air would be from ERV, which would only balance with itself, not the additional spot ventilation. True??

How concerned should I be with a negatively pressurized envelope? Are there ways to maintain a neutral/positive pressurization? Or, is my thinking completely bassackwards?

I am not looking for a specific design (although that would be nice), just some opinions from all you envelope/ventilation experts on how to balance ERV with spot ventilation.

Thanks in advance for educating me.