Mini Split vs Central Air (1 Viewer)

[FBG26]

We currently have central air that is nearing the end of its life. Considering swapping it out for a mini-split system and am curious if that's crazy. Haven't talked to any HVAC companies yet, but am curious if anybody here has mini-spits or installs them (@ChiefD ?).

We're located in MN. We have hydronic radiant heat. House was built in 1960 and central air was added sometime after. Pic of the setup is here. The condenser outside was installed roughly 2000 (assuming the same for the air-handler). The air-handler is in the attic and does a good job cooling the bedrooms. But the system really struggles to cool the kitchen level and the family room level. If I want to cool those areas to a reasonable temperature, the bedrooms are then freezing. Plus, the air handler takes up a huge space in the attic, so I have a large uninsulated area above the bedrooms, which isn't great during the winter.

We thought about adding a mini-split to the kitchen level to help cool that area. But since the central air system is 20+ years old and will likely need to be replaced soon, we thought about going with mini-splits everywhere. is that crazy? What sorts of things should I think about or ask when I have people come look at our setup?

 

[ChiefD]

We currently have central air that is nearing the end of its life. Considering swapping it out for a mini-split system and am curious if that's crazy. Haven't talked to any HVAC companies yet, but am curious if anybody here has mini-spits or installs them (@ChiefD ?).

We're located in MN. We have hydronic radiant heat. House was built in 1960 and central air was added sometime after. Pic of the setup is here. The condenser outside was installed roughly 2000 (assuming the same for the air-handler). The air-handler is in the attic and does a good job cooling the bedrooms. But the system really struggles to cool the kitchen level and the family room level. If I want to cool those areas to a reasonable temperature, the bedrooms are then freezing. Plus, the air handler takes up a huge space in the attic, so I have a large uninsulated area above the bedrooms, which isn't great during the winter.

We thought about adding a mini-split to the kitchen level to help cool that area. But since the central air system is 20+ years old and will likely need to be replaced soon, we thought about going with mini-splits everywhere. is that crazy? What sorts of things should I think about or ask when I have people come look at our setup?

Where is the ductwork? I’m assuming in air handler attic and the attic above the kitchen and living room area?

Do the duct runs for the family room go down the walls somewhere from the air handler attic?

 

[FBG26]

We currently have central air that is nearing the end of its life. Considering swapping it out for a mini-split system and am curious if that's crazy. Haven't talked to any HVAC companies yet, but am curious if anybody here has mini-spits or installs them (@ChiefD ?).

We're located in MN. We have hydronic radiant heat. House was built in 1960 and central air was added sometime after. Pic of the setup is here. The condenser outside was installed roughly 2000 (assuming the same for the air-handler). The air-handler is in the attic and does a good job cooling the bedrooms. But the system really struggles to cool the kitchen level and the family room level. If I want to cool those areas to a reasonable temperature, the bedrooms are then freezing. Plus, the air handler takes up a huge space in the attic, so I have a large uninsulated area above the bedrooms, which isn't great during the winter.

We thought about adding a mini-split to the kitchen level to help cool that area. But since the central air system is 20+ years old and will likely need to be replaced soon, we thought about going with mini-splits everywhere. is that crazy? What sorts of things should I think about or ask when I have people come look at our setup?

Where is the ductwork? I’m assuming in air handler attic and the attic above the kitchen and living room area?

Do the duct runs for the family room go down the walls somewhere from the air handler attic?

Yes, you are correct.

Ductwork for the family room and office come down from the air handler through two of the closets in the upstairs bedrooms.

Ductwork for the bedrooms is directly above in that attic.

Ductwork for the kitchen and living room runs from the air handler to the other attic. All of the vents are in the respective ceilings.

 

[ChiefD]

Ok. This one is easy then. You don’t need a mini-split.

You need dampers. So, with your AC being 22 years old, its basically time to replace it. When you do that, have the install company put dampers in your supply runs. You can then balance your house a heck of a lot better.

What is happening now is that those bedrooms are closest to the air handler. Which means your air velocity is the strongest in those rooms because your velocity will always go the path of least resistance.

With dampers in those supply runs, you can shut those down part way and force air to the other areas of your home. Since this is basically an air conditioner system only, I would only install dampers in the supply runs that serve those bedrooms.

Heck, you could do that now before you replace that system. This should cost you less than $1000. If someone tells you its more tell them to pound sand.

 

[The Z Machine]

Ok. This one is easy then. You don’t need a mini-split.

You need dampers. So, with your AC being 22 years old, its basically time to replace it. When you do that, have the install company put dampers in your supply runs. You can then balance your house a heck of a lot better.

What is happening now is that those bedrooms are closest to the air handler. Which means your air velocity is the strongest in those rooms because your velocity will always go the path of least resistance.

With dampers in those supply runs, you can shut those down part way and force air to the other areas of your home. Since this is basically an air conditioner system only, I would only install dampers in the supply runs that serve those bedrooms.

Heck, you could do that now before you replace that system. This should cost you less than $1000. If someone tells you its more tell them to pound sand.

Aren't there some size limits on where you can put dampers? If the runs are in constricted spaces, that might make it difficult, no?

 

[ChiefD]

Aren't there some size limits on where you can put dampers? If the runs are in constricted spaces, that might make it difficult, no?

Not really. I think in his situation it sounds like there is a main trunkline that probably goes from the air handler through the (2) attic spaces. And then supply runs coming off of that that are then in the ceiling of the respective rooms.

And for the family room/office room area, if they went through closets it sounds like a couple runs that drop into the ceiling of that room.

So those runs coming off the trunkline are more than likely 6" runs. A company should be able to put dampers in there right where they come off the trunkline. Even if the supply runs are 7" or 8" they should be able to do it.

And yeah, it depends on how tall that attic is, but if the AC was added after the fact and they were able to run ductwork up there there should be plenty of room to access those lines where they come off the trunk.

Truthfully, they may only need to add dampers for those bedrooms runs, since they are taking most of the velocity anyway. Shutting them down halfway will allow more air to push to those other locations.

 

[Van Dyman]

$1000 just to put in a few dampers? Seems high. We had it done at my first house for better balancing. Maybe I'm misremembering but seems like it was not expensive at all, like $200 or so. How hard is it...what's the process? @ChiefD

 

[ChiefD]

$1000 just to put in a few dampers? Seems high. We had it done at my first house for better balancing. Maybe I'm misremembering but seems like it was not expensive at all, like $200 or so. How hard is it...what's the process? @ChiefD

Just depends on how many there are. If he has ten dampers at $100 a piece it adds up quick. I'm also factoring in a guy crawling around an attic. Attic works normally takes quite a bit longer.

But yeah, if all he does are the dampers for the bedrooms - probably $200 - $400 depending on how many there are.

Edit to add: It all really depends on what's up there and how the trunk lines and supply lines are installed. All I was saying was if it was more than $1000 to get another bid.

 

[FBG26]

Ok. This one is easy then. You don’t need a mini-split.

You need dampers. So, with your AC being 22 years old, its basically time to replace it. When you do that, have the install company put dampers in your supply runs. You can then balance your house a heck of a lot better.

What is happening now is that those bedrooms are closest to the air handler. Which means your air velocity is the strongest in those rooms because your velocity will always go the path of least resistance.

With dampers in those supply runs, you can shut those down part way and force air to the other areas of your home. Since this is basically an air conditioner system only, I would only install dampers in the supply runs that serve those bedrooms.

Heck, you could do that now before you replace that system. This should cost you less than $1000. If someone tells you its more tell them to pound sand.

This is good stuff. Thanks Chief! I'll be sure to ask about dampers when we get people out here for quotes to replace the unit.