We always suspend attic furnaces from the rafters this way there is no vibration or noise can be heard from the attic units.

You don't say where you're located but putting HVAC equipment in the attic is the worst possible choice because of the extreme temperatures (relative to inside) the ducting and equipment will be exposed to. A basement or a "closet" is a better choice but it does need access to outside air.

If you give priority to function and efficiency of operation, you'll find somewhere other than the attic to locate the equipment (and ducts). If design is your priority, well, then it won't matter where it goes.

What's the problem with putting it in the attic? Can you cite the code?

What about building a conditioned space in the attic?

Is this an electric or gas furnace?

Have you consulted your HVAC contractor?

Do you have a plan that's not all marked up, and showing a bit more of the house?

The location highlighted in green looks like a good place.

This seems 2 obvious.

My 2nd Flr HVAC is in a hall in the entry to my DD's bedroom. On the bedroom side, there is a closet so noise is deadened by clothing in that closet and extra insulation. One end of the HVAC closet is to the outside, so venting is not a problem. It has worked very well these past 34 years!

Somebody does not understand how space works.

Can the furnace be located nine feet above the stair landing (mezzanine level), accessible from the laundry or master closet?

I was going to suggest you take the "open room at the bottom.... take the Laundry room wall all the way to the left below the master closet. Access the space you created from the master closet. Similar to PPF, but take it all the way across. That way you add back the space to the laundry.

I can draw it if that doesn't make sense.

I will try to post a sketch tomorrow.

You should give location as that may help with some options.

What exactly is the code requiring the sprinklers? Could you do a heatpump in an attic? Could you create an attic like area that isn't an attic? For example, why can't bedrooms #2s closet be bigger with a furnace in it?

The size requirements of the furnace depend on a few things. Are you even sure you can fit something in the proposed laundry space? Check out the thread this week from someone who could not despite the plans and the $40k change order he was dealing with over it.

The closet in bedroom #1 as shown will not function well. Clothes hanging on a rod do not turn corners unless it is a wide sweeping curve with at least a 30" radius. There is 7'-6" of lineal clothes rod shown, but you will only be able hang 6'-6" of lineal hanging clothes, with 1'-0" concealed behind the clothes hanging in the other direction.

The closet is 4'-6" wide clear (allowing for drywall); hanging clothes are on the average 2'-0" wide; the door is 2'-6" but projects away from the side wall about 3". The clothes will block 3" of the door opening.

Once clothes are hung in the closet, the clear space to stand in the closet will be about 2'-6" by 3'-0", which is also occupied by the door swing.

It's a fire hazard to put in the attic? LOL so let's cram it in a closet because it's a fire hazard. Out of sight, out of mind -- that must be the goal. If it's a fire hazard in the attic what is going to make a non fire hazard in a closet? Common sense is lost these days.

The mezzanine idea wouldn't be so bad if you had ample room to do it, but because of where this is that is not likely --- not by any stretch of the imagination.

The picture of the furnace with the little arrows representing duct work is not a practical means of displaying return and supply ducting. If you don't have adequate room for ducting, supply as well as return this can have serious consequences later when system is under heavy operating loads.

Then because of this mezzanine sizing likely being barely big enough to squeeze the equipment and ducting into it can you imagine trying to repair the unit when it breaks? Yeah that's not your problem, that's the repair man's problem... until of course you get the repair bill.

The other is code for equipment access. It's in your best interest to do this regardless what the code is in your area. It's best to have at least 36" of space all around the equipment. Current code in my area is 30".

If you cram all this equipment in a tight space it could wind up being costly to repair it when it breaks.

WHOA! you mean HVAC equipment breaks? yeah all brands... every make, model, name brand etc. They all break. This could happen in year 1, 3, 5, 8, 10, 12, 15.

There's probably a few years I missed so pick one. How often they break down can in some instances be related to design of the system.

What is the design of the system? where and how it is placed, the duct system design or lack there of.

The worst idea one could invoke is to put in the HVAC system first and then build the house around it. It should be placed in such a place that it can be maintained adequately and replaced as needed without having to remodel the home every time this is needed.

So if you lack the foot print within the home to include the HVAC system inside the thermal envelope of the home, the money you think you are saving by doing this will all go up in smoke the first time the system needs a repair.

If what you did is causing the need for the repair in some way, it's even worse for you. (I do not do new construction... I only listen to those cry after the home is built and HVAC system is broken.)

Do as you wish (or whatever local codes will allow). The only reason for the post is to warn you what could be coming to a new home near you.

If you plan on locating the mechanical equipment in a space smaller than 10' x 10' with an 8' ceiling, get input from the person that will be installing the equipment. A lesson I learned a long time ago.

Put the furnace in the hall linen closet (size the closet as needed) and find another place for the linens.

What's one more change on that plan...?

I always recommend avoid installing any HVAC equipment and duct work in the attic. The house is large enough to create a utility room large enough to house the equipment and allow it to be serviced.