Mech Engineer comes tomorrow...Guidance Needed

[camshaft]

Whats happening: 1100 sq ft new two story addition onto 1600 sq ft existing 70 year old double brick two story home (fully detached) in southern ontario (toronto). Full basement not included in those size numbers. Existing home has hot water gas, no a/c. This is to be removed and forced air gas system installed in entire 2700 finished home.

Mechanical engineer wants to come over to see the existing home and discuss what's involved before he starts the drawings for permits. Existing home will have lathe and plaster walls removed, reframed, and spray foam insulated, new windows, etc to maximize energy efficiency.

Can anyone share some tips for what I should be discussing, asking, etc this fellow? Like possible zoning, types of systems, etc. Any advice would be greatly appreciated. I want to make sure that this job gets done right and it seems to make sense to start with the engineer.

Thanks in advance.

[motoguy128]

You should have a new load calculation done to determine the size of the new equipment. The old home have have different heat loss rates than the new additon, so proper duct sizing and air distrubution will be important so it's well balanced. Zoning can be used for a 2 story home, or 2 smaller independant systems can be used as well. ht eolder home might have limitations where docutwork can be placed.

If the basement is to be heated, it needs to be included in the load calculations.

It can't be stressed how improtant load calculations and proper duct sizing are. If done incorrectly you will have, noisy ducts, warm and cold spots in the home higher bills, and uncomfortable temperature swings.

A good system is transparent, as it's silent and provides even heat throughout.

[camshaft]

The old home have have different heat loss rates than the new additon

Wont the new insulating of the old part of the house have an impact on its heat loss? What will he do estimate heat loss based on the scope and R value of the insulation to be installed?