Ask the seller?

A 70 x 36 range hood?

Insist on access to the installation guide before purchase.

Read the specs. And don't buy no name off brand junk.

Explain the "70" part. I assume the 36" refers to the hood's width side to side, to go over a cooktop that is 30" or 36" wide. But you mentioned depth - do you mean the measurement from front to back?

Can you link the hood you are going to buy at Hoodmart?

Where is your exhaust duct placed? It's typically on the wall, but sometimes on the ceiling.

M Miller, I think the OP is talking about a commercial hood 70” wide and 36” deep. That is the sort of thing hoodmart sells.

Correct. 70" wide, 36" deep, 24" tall.

What about the make up air system? Are you sourcing it from there as well? The heated/cooled MUA needs will be huge. A system like that can empty all the air in your house in about 15 minutes.

Why so big? What is this giant hood going to be put over? And as Minardi mentioned do you have makeup air plans?

The giant hood will be put over a giant range. We have makeup air plans. Apologies if this comes off the wrong way, but I was hoping to get some advice from the experts here on hanging this hood, not have to defend it :-)

You did not answer my question about where the exhaust duct is placed in your kitchen. I'll add that you will need a large exhaust duct for that large of a hood, as well as an MUA. Since you are asking how to hang the hood, I assume you have the duct in place, correctly sized, and that location should dictate how you hang it.

It will be against a wall, with the duct also near the wall. It will be 10" duct.

And vented straight up.

One thing needs to be kept in mind; the recommended air velocity into the hood entry air aperture (90 ft/min from me typically on this forum) may not be needed if the hood is commercial with significant reservoir volume on the cooking side of the baffles. As long as the effluent can get to the baffles without reflecting down and out, and the entrainment air velocity at the baffles exceeds the up-rising plume velocities (e.g., 1 m/s), then containment should be achieved.

So, for example, I have a Wolf Pro Island hood that has an entry aperture of about 12 sq. ft. Using a 1500 CFM rated Wolf (Broan/TnTone) blower I get good capture and containment results with an upward flow rate of (approximately) 100 ft/min. (Careful multi-position measurement and averaging over the entry aperture has not been performed; this is from a sparse sampling of the flow velocity at various locations under the hood.)

With the OP's 17.5 sq. ft. aperture, 90 CFM/sq. ft. requires an actual 1600 CFM that would only be obtained using a blower rated perhaps as much as 2400 CFM, depending on pressure losses. My point is that even 1200 CFM actual might be sufficient with a commercial hood depending on cooking style and assuming the total plumes' CFM did not approach the system CFM, thereby saturating the reservoir averaging process.

“I was hoping to get some advice from the experts here on hanging this hood, not have to defend it :-)”

It seems that way only because a 70” wide hood is unusual. Plus you gave very little information, and the little you‘ve provided has been terse. It is hard to answer your question when there is not a clear picture of what your kitchen is like. It’s like saying “where should I place a window, the room is 20’ wide”, and not saying anything else :-)

As klem1 said, ask the seller or manufacturer. Don't come to a forum and be nasty.

I don’t think the OP is being nasty. I think they don’t know that we need better explanation. For example, what does “with the duct also near the wall” mean? I.e. where is the cut-out for the duct located in your kitchen? Can you provide photos?

I would think mounting to wall or ceiling would be determined by the specific hood. How high are your ceilings?

My hood was mounted to the wall. It was called a wall mount hood.

Here is my hood. Pic is from when house was first built. The hood was actually put up before the cabinets. It has a piece which transitions to a 12 inch duct and goes straight out through the roof.

And what it looks like now:

vinmarks is right - hood will mount to the wall. Depending on where the blower is and how heavy it is it may need additional support, but the HOOD STRUCTURE mounts to the wall unless it's an island hood.