New Home HVAC System

kf4uda · Feb 10, 2021

We are in the planning stages of building a new house. My original thought was to have a standard central air and heat ducted system using heat pump with propane backup. We also will have non vented fireplace with gas logs for supplemental or backup heat if the power goes out.

In talking to a friend who retired from the HVAC world he suggested looking at a Mitsubishi Multi Zone Mini Split System. Multi-Zone Cooling and Heating Outdoor Units | Mitsubishi Electric

Are any of you guys using a system like this in your house or have any knowledge of it? I have studied it some and it certainly looks interesting. I like the idea of each room/area temperature being controlled independently. I also like the idea of no duct work as well.

EddieWalker · Feb 10, 2021

I'm not a fan of them. I've worked on quite a few homes that people have added them to an existing system for rooms that where converted from storage areas, like attics and garages, into living areas. They work OK in those areas, but you can tell the difference when you want through the house and into those areas. I've also been in small homes where they had three units for the entire home. Each room had one. In those cases, it was a lot of money for basically what a window unit does. I was told the advantage was in saving money on electricity over window units, but in both of those homes, they didn't stay there long enough to make back what it cost to buy them.

I would never contemplate replacing a central unit with a bunch of mini split system when building a new home.

If you are planning on living in this house the rest of your life, I would still factor in what resale value will be if something comes up in your life that you never imagined happening. It happens a lot. How much money will you lose when selling the house because of the mini split systems over a central HVAC system?

pjigar · Feb 10, 2021

Resale is the only problem with mini-split HVAC. We built our forever home in the country and opted for individual mini-splits rather than multi-zone mini-split. The single units are more efficient and cheaper to replace when they break plus you won't be without HVAC in the whole house when they break. There are added benefits of mini splits: Your house would have fewer air leaks, Rodents can't chew the ducts!

We have 5 units: 2 for living areas and one for each bedroom. Bathrooms have fan heaters for winter. Remember to upsize the living area units. Our units are 21 SEER and I paid less than $5000 for the material. You may feel the temperature difference from room to room but it's a feature to me rather than a downside.

PS: Multi-units were cheaper since I installed them myself. If you pay someone then multi-zone might be cheaper. They were way easier to install DIY than ductwork would have been.

forgeblast · Feb 10, 2021

we have the Mitsubishi mini splits with the heat pump. Life changer especially in an aframe that has no windows upstairs. We use it all year long. I cannot say how much it has improved our home.

wagne223 · Feb 10, 2021

I don't think I would choose mini splits in lue of a central system. A central ducted system is great at moving air throughout the house and seems to balance temp good.

That said, mini splits have their place and I really like them.
I have 3 in addition to the central system for the following reasons.
- They are DIY friendly.
- They are great assist to central in rooms that have a high sun load.
- at night I can keep the Master bedroom cooler and comfortable for sleeping without having to keep the whole house that cool.
- They are Generator friendly. During power outage from Hurricanes I can run the 3 minis, the fridge, lights and TV on a 3500 watt inverter generator.
-should the central fail, you can take your time and shop around. It is not an emergency even if it is 100 degrees out.

Buppies · Feb 10, 2021

I agree with Eddie we have two units one up 2 ton heat pump 16 seer. Downstairs 3 ton heat pump backed with propane 18 seer. These units are 5 years old even air flow works well when propane people do not let me run out

dodge man · Feb 10, 2021

For a new house I would go with some form of forced air, but that is my preference. Tennessee is far enough south heat pumps are probably viable. Better yet look at geothermal. There were and may still be some very big tax breaks. We also pay a few cents less per kilowatt hours for our geothermal. A HVAC guy with the right software can break down each system and the return on investment for geothermal.

Popgadget · Feb 10, 2021

It’s hard to beat the mini splits. They are very high efficiency, generally over 20 SEER, extremely quiet, inside and out, and much better zoning than you would get with ductwork and dampers.

As far as multiple outdoor units vs multi head, that depends greatly on the installation and how the line set would run. Multiple units give you redundancy, which is a good thing.

riptides · Feb 10, 2021

Really depends on your floorplan. I have on 960sq foot building with a minisplit wide open floor plan. Works perfect. House with multi zoned HVAC...works as advertised.

I like the minisplit better. I could probably replace my downstairs zoned HVAC as the floorplan is only three rooms.

jk96 · Feb 10, 2021

No reason you can't zone your home with a central air system. We have geo. 2 units, total of 6 zones with independent thermostats for each zone. Now with scroll compressors that can ramp up or down on demand zoning has gotten even easier. Also btw sensi makes a nice wifi tstat if you are running multiple zones. I have the 6 tstats on the house and 4 more for my business all at my fingertips in an easy to use app.

Rustyiron · Feb 10, 2021

Mini splits are amazing. Both heating and cooling. Look at the performance numbers, they are real. Then look at the losses of your average installed ductwork systems. That alone will make up your mind. They have become the standard up here in Maine and the HVAC contractor's norm. Pricing a m/s setup for my daughter's home in the mid Atlantic region, those guys are still pushing the basically antiquated traditional ducted h/p with a huge high amperage and very expensive to run resistance heat for backup and were unfamiliar to say the least with a ductless mini split system and therefore out of their comfort zone and very expensive for the install.
With any luck, you'll find a contractor that is aware of this relatively newer (to the US) technology and is familiar with its highly reduced labor for installation and you get a good bid from them.

IXLR8 · Feb 10, 2021

We have mini-split system and love it. Our house is small, it costs about $1/day for heating in the winter, until temps get below 20dF then we go to the wood stove. Ours is one of the older Mitsubishi Mini-splits that the efficiency drops off fast below 20dF. New ones are good to below -5dF. In the summer it costs about $0.50/day for cooling. If I was building new, Geothermal would be my first choice, mini splits second, central air heat-pump last. Biggest issue with Mini splits is the WAF of the interior units. At least one of the mini split makers has units that recess into the ceiling and don't look any different than a central air duct.

DrRobM · Feb 10, 2021

We renovated our 2,500sqft clinic and decided to rip out the old electric forced air system with fiberglass ducting and replace it with a Mitsubishi Mini Split w/ hyper heat here in northern Wisconsin. We have 8 in-ceiling cassettes, a junction box, and two outside condensers. We are very happy with our decision. Our heating costs were cut by 60% in winter and cooling costs are next to nothing. Independent room temperature control is great. When I know there will be an infant on the schedule or some of the older women I can turn just that room up. It’s also very nice to feel the heat or cold coming out of the indoor unit and not hearing any noise with it. We were concerned about heating capacity, but even with the -0 temps we’ve had this week there have been no problems maintaining room temperatures. The system wasn’t exactly cheap at around $35k installed but we’ve already saved around $7k in heating and cooling costs in the past year and a half. We plan to use the same thing in the home we’re building this year and expect that system to be far less costly since there was a significant amount of labor associated with removing old equipment and working on a remodel. There was also about $8k worth of costs on government mandated add-ons since it’s a commercial property.

Popgadget · Feb 10, 2021

IXLR8 said:
If I was building new, Geothermal would be my first choice, mini splits second, central air heat-pump last.

Actually mini splits can exceed the efficiency of a closed loop geothermal system, and get close to an open loop. In various buildings I have an open loop geothermal, air to air heat pump with propane furnace, and mini splits. If I were to build a new house, I’m nearly certain that I would use multiple mini splits.

kenmac · Feb 10, 2021

Instead of using mini split, you could use a VRF unit and run to multi heads. You can run longer line set with VRF than mini split.
only issue going with one unit is, If the unit goes down, you have nothing.
Multiple mini ODU's would prevent you from losing everything should the single unit go down

Had I built this home new. I would have installed VRF with multi heads /zones.
Since my home was already built and had a conventional ducted system. I installed a VRF, with a matching AH.

In most cases, people with a normal HP will have to have supplemental heat. Not so much with these units. I think mine is rated at -20 deg . I have never had an issue with heating my home.

Another thing is, a conventional unit will either be all on or all off. When On, it's at 60 HZ.. Not with these units. Mine idles along most times around 18-20 HZ. and will ramp up when xtra heat, or cooling is needed.

Energy requirements are increasing, and pushing the conventional units out.

Tractor Seabee · Feb 11, 2021

Biggest problems with mini-splits are poor air filtration and lack of outdoor air input capability. If you have allergy's or asthma/opd you really need the electronic air cleaning and fresh air intake capable with central fan systems. With mini-splits the coils run colder so they lower humidity with all re-circulated air to below the comfort/healthy level of around 50%.

Ron

rademamj1 · Feb 11, 2021

We have been using three Mitsubishi minisplits with heat pumps for 12 years now and are still doing good. We are using them at our rural Texas ranch, which is completely off the grid. Entire lithium battery bank provides power and is fully dependent on Solar and Wind for recharge. Each minisplit provides AC or Heat to specific parts of the ranch house, and we typically run only one minisplit a time. For example, at night there is no need to cool the living room while we are sleeping at night in the bedroom. This greatly reduces our total electrical power needs over what a Central Air System would need.

Frankenkubota · Feb 11, 2021

kf4uda said:
We are in the planning stages of building a new house. My original thought was to have a standard central air and heat ducted system using heat pump with propane backup. We also will have non vented fireplace with gas logs for supplemental or backup heat if the power goes out.

In talking to a friend who retired from the HVAC world he suggested looking at a Mitsubishi Multi Zone Mini Split System. Multi-Zone Cooling and Heating Outdoor Units | Mitsubishi Electric

Are any of you guys using a system like this in your house or have any knowledge of it? I have studied it some and it certainly looks interesting. I like the idea of each room/area temperature being controlled independently. I also like the idea of no duct work as well.

I'm finishing my new house and garage/shop/studio apt. right now. I put in a Trane heat pump for the house, 1400 sf rancher. That will be more than enough but i might get a pellet stove just cause i love them!

My shop is on one end of the garage and the apt is on the other, both about 400 sf. 2 car parking in the middle. I put in the mini splits you refer to, 1 for the apt and 1 for the shop.

$6K for 2 mini splits. I hope they are the solution, i didn't want window mounted units.

Bocephous · Feb 11, 2021

We had a single zone Fujitsu ductless heating/air conditioning unit installed in our living room last spring and have nothing but positive things to say about it. We ran the a/c all summer and our electric bill was significantly lower than the bills we had running a 12,000btu window unit, and the unit was almost silent. Maybe a $10-$15 more monthly versus not running an a/c.