Thinking about Switching from a Ducted HVAC System to Ductless Mini Splits

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Thinking about Switching from a Ducted HVAC System to Ductless Mini Splits

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I have been looking into purchasing a heat pump for the last few months.

I love DIY, but for this project, I had always assumed I would have an HVAC company do the installation.

My initial impression was that I would replace my existing AC/gas furnace with a Mitsubishi Hyper Heat ducted system.

Recently, I've been reconsidering a ducted system and have been thinking about going entirely ductless with a DIY install.

With the money saved, I could use it for other projects.

I would still use Mitsubishi Hyper Heat units and would implement a combination of ductless wall mounts and ceiling cassettes where practical.

I know Mitsubishi isn't generally considered a DIY install due to the vacuuming required and the loss of warranty, but I feel comfortable enough to do it.

I wanted to see if I could get some general ideas/input, as I'm still at the point where I have a lot of questions.

I feel a bit overwhelmed with all of the options, and any suggestions or advice would be greatly appreciated.

I know that I could save some money by going with cheaper units, but I've been very drawn to the Mitsubishi systems.

I am in southern New Jersey (Climate Zone 4A) and have a 2 story house built in 1984.

It's only about 2200 square feet.

All of the insulation is original, and it seems like it's pretty leaky/drafty.

The upstairs is always so hot, and we end up setting the AC to 68 at night, so that it's somewhat bearable to sleep.

I definitely want to have air sealing done along with blown-in cellulose to make it more comfortable.

What attracted me to using ductless mini splits is that we could target specific rooms depending on use.

When we're downstairs, we pretty much only use the kitchen and family room.

I have Mitsubishi dealers in my area, but I haven't actually had anyone out yet.

I feel kind of guilty wasting their time, if I'm not likely to use them for the installation.

I am on a concrete slab with no basement, so I envision the install costs will be extremely high.

If I do the work, I know I can route the linesets through the ceiling/attic and make it look very clean.

The electrical is no issue.

It will be a lot of work, but I don't mind putting in the effort.

My issue is that I'm not quite sure at the moment on the planning and design (specifically placement, number of units, and sizing).

I was thinking that maybe I could hire some type of energy/HVAC consultant to figure this out, rather than an HVAC installer.

Any guidance in this area would be a huge help.

I would like to use single-zone units as much as possible for efficiency reasons and redundancy, but with 3 rooms upstairs and 6 downstairs, I will probably have to use a multi-split for a few them.

I was thinking that maybe this would be a good idea for the rooms that are rarely used.

Another reason for going ductless is that I have no idea if my existing ducts are appropriately sized for a modern heat pump.

Since I have no basement, the main trunk runs through a soffit in the living room of my house.

All of the ductwork is in the ceilings, and one room has a flex duct running through my garage attic.

The accessibility is very poor and would require extensive drywall removal.

I also have a two room addition in the back, and the HVAC has never been great in those rooms.

My only hesitation is that when reading and watching YouTube, it seems that HVAC tradespeople and those in the building science/green industry are obsessed with ducted systems.

They spend a lot of time on the ventilation aspect, and many of the designs include an ERV/HRV.

I watch Matt Risinger's channel, and he always has these elaborate systems that seem somewhat unnecessary for most people.

On the HVAC installer side, I constantly hear them saying how you'll humidity issues and that nothing beats a "properly" ducted system.

Most of the central systems seem poorly designed, and if possible, I wouldn't mind ripping out my air handler to free up space in my small laundry room.

I know this post was long, and I apologize.

Any advice, suggestions, or input are greatly appreciated!.

TL;DR - I currently have a ducted AC/natural gas system.

I had planned to replace this with a ducted Mitsubishi Hyper Heat air handler.

I'm now considering going fully ductless to give me better individual control and make my upstairs more tolerable.

I would do all the work myself to save money.

My preference is to use mostly single-zone units for efficiency and redundancy purposes, but I probably would use a multi-split for lesser used zones (to reduce the number of condensers outside).

I do plan to air seal and replace the insulation in the second floor attic, so that my house is tighter.

I'm unsure if I would be making a mistake as most of the building science and HVAC people are obsessed with ductwork (ie.

you need clean air and good ventilation, you'll have humidity issues, nothing beats a ducted system, etc.

).

Question from user cai24 at heatpumps at reddit.

Answer:

It will take a long time before you recoup costs necessary to have an installation that you will be satisfied with.

Answer from user Sweatycamel at heatpumps at reddit.

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