Split AC vs HVAC system

31 Replies


I have a 15 year old HVAC systems in my multifamily duplex and I think both the units have reached end of life.i came across mr cool mini split 24k btu on sale for $1500 and thinking about replacing my old HVAC with this newer split ac units.

My apartment size is about 1300 square ft ,its a 3bed 2ba. Is it a good idea to replace?

Also I want to if they are good for heating here in midwest.appreciate your inputs


@Peter Morgan it is going to be more expensive then just straight HVAC if you have ducting.  You need to have the heads run to each of the different rooms.  Are you only looking for AC or is the for heat too?

@Peter Morgan

I am planning to sell home but both my HVAC units are broken and now I am confused if I should have them repaired or replace with new ones.

Peter, I would agree with what Colleen has said. I can't speak for the Mid West market specifically but if you already have ducting in place then it would be cleaner and potentially cheaper to install a conventional split system. For your space, I would recommend installing atleast a 3 ton unit. I always slightly oversize as a rule of thumb- these units will be running for a long time and it's better to have AC/heat than having a unit not be able to keep up. There are Sq Ft to BTU calculators online that you can use to find out the min requirement. If this is a duplex and each side is 1300 sq ft then that would be a 3 ton on both sides, however if your space is 1,300 sq ft total then you can do two ton units. What is your current heating setup? If you don't have furnace gas lines already ran, then you can install a heat pump which does both heating and cooling.

Mini splits don't distribute air very well, so they work best when used in small spaces. We've installed 8 of them, the only complaints were on a two bedroom unit that didn't get warm in the winter.

A regular split unit is better for a unit this size. The information on sizing isn't correct, the worst thing you can do is oversize the units because they won't control humidity and they won't last as long. If you are selling you might not care... except that larger units are generally more expensive. 

Originally posted by @Peter Morgan :

@Zee Abbas

Are conventional split systems and heat pumps one and the same? There is a gas furnace already with duct work already there.

 A heat pump is an air conditioner run in reverse. Instead of removing heat from the inside it brings heat from the outside in. The new models work well in the cold. They can replace your furnace, or merely augment it when it's not below freezing. 

@Peter Morgan Since you already have furnace lines set up and you are selling the property, go with a regular split system. Also, I have to disagree with Seth on his humidity comments in this situation. He is correct that humidity will be a problem if the unit is grossly oversized. However, in this case, 24K BTU is undersized for this space and 36K BTU ranges from appropriate to slightly large. If you were to install a 24K unit, it would continuously run and drive up your energy costs. Of course there are other factors to consider such as insulation, local weather patterns, occupancy, void space, etc.

@Zee Abbas

Thank You Abbas!

Any specific models or brands that you can recommend? How much can a 36k BTU

cost me?

If I understand this correctly there will be two components to this system right?, one component sits outdoor (36k btu component) and the other one is the head component which I am assuming will be installed on a a per room basis as needed right? Is the head component also called heat pump?

Sorry for asking very basic questions I am new to this system and trying to wrap my head around all the components

@Peter Morgan

I owned rentals in the Midwest, and opted for the mini-split AC units, and they leaked very often in the summer.  This was not due to improper installation, but because the Midwest gets to be very humid in the Summer months(even in the fall too).  Just my experience.

@Peter Morgan best bet with ducts in place is a heat pump not mini-split, probably most cost effective.  What does the competition have?  If you are selling in a market where AC is going to bring you money  of course include. If HVAC without AC is more common I would look at what money it brings in to have the AC and make sure the cost above a straight furnace is worth it. 

I think what is being referred to as a regular split system is the same as a heat pump. If you install a heat pump you use the ducts you have and just put the unit where the furnace is, no need to have 1 head per room, you use the normal returns you already have.  A minisplit has heads and a part outside as well as something on the wall in the main room minimum. 

@Colleen F.

Thank you very much Colleen, this was very helpful.I guess there is just one thing I need to make sure whether heat pumps can generate sufficient heat during winters here in midwest.

@Peter Morgan your welcome ,  and whether it is sufficient is all about brand I think because they use heat pumps up in canada and  I think you have to be warmer then up there. 

@Peter Morgan Residential HVAC systems have two components (hence "split"): an indoor unit (evaporator coil) and an outdoor unit (condenser coil). Typical "conventional" (central) split systems provide cooling using the condenser's compressor and heating is generated via a furnace that is mounted alongside the indoor unit. A heat pump system uses the compressor to do both cooling and heating. The heating can still be aided with a furnace. The "indoor" units are generally located in an attic or closet and the "outdoor" unit is located on a pad next to or in the rear of the property. The indoor unit feeds into an air handler which uses a fan and ducts to distribute the air to each room. So visually speaking, heat pumps and conventional systems essentially look the same. Since you already have gas lines, it would be cheaper to install a conventional split system that generates heat through a furnace. I also echo what Colleen is saying- look at your market. Do homes have heat pumps in your area?

Mini-splits are also "split" systems but since there is no ducting, you need to have a air handler (what you call head) in each room. Otherwise there is no way to have air in that space. If you're looking on the cheaper side, Goodman is generally affordable. Lennox, Trane and Carrier are more expensive. For pricing, I suggest calling your local HVAC wholesale supply store or looking online. In NYC we have suppliers like United Refrigeration and Johnstone Supply. Most places will require a "business" account to purchase from them - you'll only know if you reach out. Supplier catalogs are online, find the unit part #s and reference those. And at the very least, it will help you figure out how much your contractor is up charging you when you get a quote :0

@Zee Abbas

Thank you so much this was very helpful.

I did not come across any heat pumps in my local area, most of them have conventional hvac systems.

@Kevin Manz   I  am curious on what point you don't you agree with @Zee Abbas .?  Your comment above doesn't help @Peter Morgan or offer him differing advice or where you think Zee is wrong.  I am thinking for sizing and install  Peter would be contacting HVAC companies but the general gist is mini-split isn''t the best idea and a conventional furnace or Heat pump could meet his needs.  

Originally posted by @Peter Morgan :

@Zee Abbas

Thank you so much this was very helpful.

I did not come across any heat pumps in my local area, most of them have conventional hvac systems.

There is a good reason for that.  For cold temperatures, heat pumps struggle to keep up because it is harder to extract heat from very cold outside air than from warmer outside air.  Typically, heat pumps will have electric backup heat strips (“auxiliary heat”) that will kick in when the heat pump cannot keep up anymore.  THAT backup heat is very expensive (unless you are in one of those rare places that has dirt cheap electricity).  So, if the backup system has to kick in often, your electric bills will skyrocket.  
Now, it IS true that in very recent years, heat pumps have been improved significantly, so that they have indeed become more feasible for many colder climates.  Perhaps there are a few folks in Canada brave enough to install them, but I can’t imagine that being a cost effective solution up there (unless you live in Western BC).

Since you have a gas line already available, you do have the option of installing a heat pump with a gas furnace backup.  In my opinion, this will give you the most economical operation overall.  However, the upfront cost will be higher.  For this reason, it may not make sense for you as you are planning on selling the property.

In fact, given that you are selling, your best bet might well be to repair the current system and just let the buyer deal with it.  Depends on how much it costs to repair, of course, but generally, I don’t believe in replacing appliances just because they have “reached the end of their lifespan”.  If they run, they run.  Even if they are 10 years past their expected lifespan.  Some HVAC systems can last 25 years, some will bust in 5 years.
Finally, I do agree that for your situation, a mini split is likely NOT the way to go.

@Zee Abbas

Sorry, I should have elaborated, your 1st post mentioned going with a 3 ton per side, 1300 square feet per side. That is way to big. So many issues with oversized equipment. I now see you have wrote a few more post, and do agree with the 2nd 2 u have wrote. I don't like seeing people ask hvac questions on here, so many wrong answers. As u mentioned in 2nd post, oversized equipment will cool so fast, won't run long enough to pull humidity out. Another problem I always see is returns not being big enough. As u mentioned, I agree, being already set up for with ductwork and mechanicals, a traditional split is going to be this owners best bet. Sizing is very important for alot of reasons, and best left for the contractor bidding for a lot of reasons, location, being 1 of the many critical factors. Wish u the best

@Peter Morgan

If you already have central air, just replace your equipment like for like.

Split systems are designed to last for 15-20 years, and are much better at their job.

Mini-split systems are essentially toys, designed to fail at about year 7, and should only be used in situations where ductwork isn’t possible.