What size electrical service do I need for a 3000 sq. ft. house with 2 70 amp central heat units 2 50 amp double ovens , 2 30 amp water heaters, 1 40 amp cooktop, 1 30 amp dryer, 3 refrigerators, and all the other 120 volt load for the house.

Is this a new home your are building for yourself or an existing home?

If it is an existing home, what is the electrical service to it now?

Just a suggestion, but please call a licensed electrician to do the load calculation for you.

From the sound of it, unless you are an electrician I would NOT mess with this. This does not sound like a home a DIYer should be wiring.

Off the cuff I would say 400A.