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FREE Definitive Guide "Air Conditioning Systems Compared: What Are Your 4 Best Install Options To Get Mills & Trump To Pay For It"
Throughout this guide, we address the pros and cons of each unit and system to help you make the best decision for your home's ductless heat pumps, mini-split heat pumps, ductless mini-splits, and mini-splits installation.

Summer is approaching and humidity levels are rising, making it easy to see why air conditioning is a home comfort necessity.

There are four main types of home air conditioning units and systems that function based on removing heat from your home. 

Results vary between systems and units in ways like efficiency levels, aesthetics and the ability to provide comfort. 

Throughout this article, we address the pros and cons of each unit and system to help you make the best decision for your home.

Contractors must be able to provide quality estimates of payback periods to educate homeowners on the value of mini-split systems. 

The limited labor involved in mini-split systems allows for installations in as little as a day or two for single-zone systems.

In this regard, ductless mini-splits offer an excellent solution for additions to existing homes.

How Does A Heat Pump Work
Many variations of this term exist in published literature, including ductless heat pumps, mini-split heat pumps, ductless mini-splits, and mini-splits. 

A heat pump heats your home by collecting heat from the air, water, or ground outside and concentrating it for use inside. It does double duty as a central air conditioner by collecting the heat inside your house and pumping it out. What's fantastic is that Heat pumps can be used for both home heating and home cooling.

However, ductless mini-split heat pumps connect one or more indoor coils (often referred to as "heads" or "fan coils") to a single outdoor unit (i.e., the condenser), with each head having its own refrigerant loop. 

Conditioned air is provided directly to the rooms in which the heads are located, without the use of ductwork. 

Mini-split systems with more than one indoor head (sometimes referred to as "multi-split" systems) enable specific zones to be conditioned independently because each indoor unit has its own thermostat. 

A common recommendation is to provide one indoor unit per floor, with the downstairs unit mounted in the main living space and the upstairs unit installed in a central hallway. While warm air from a single downstairs unit naturally rises, cool air does not, resulting in a hot upstairs during the summer in a home with only a downstairs indoor unit. 

Most Commonly Used Type
Ductless mini-split heat pumps are air-source heat pumps that can be installed in homes or additions with-out ducts. Small in size and flexible enough for zoning or heating and cooling individual rooms. 

Geothermal (or ground-source) heat pumps transfer heat between your house and the ground. Because they move heat that already exists, geothermal heat pumps are among the most energy-efficient heat pump. Only wood is more efficient. 

Heat Pump Tips 
• Do not set back the heat pump's thermostat manually if it causes backup electric-resistance heating to come on. This type of heat is more expensive. 
• Install or have a professional install a smart or programmable thermostat with functions suitable for a heat pump. 
• Maintain the system according to the manufacturer's instructions, which most likely will include cleaning or changing filters once a month or sometimes as needed.

Home Cooling 
Air conditioner options include room air conditioners, ductless mini-split or multi-split air conditioners, and central air conditioning.  Look for ENERGY STAR certified.

According to the Northwest Ductless Heat Pump Project (an initiative by the NEEA to displace zonal baseboard heating with mini-split heating in existing homes), the average installed cost of a 1-to-1 mini-split system is $3,000– $5,000 (NEEA 2012).

There are definite benefits to mini-splits, but there are some variables that cannot achieve the same level of performance of a traditional ducted split system. 

The most common non-thermal issues reported by homeowners with mini-splits are aesthetics and fan noise of the wall-mounted indoor units; some homeowners also report being annoyed/distracted by the blowing air from the indoor units (CARB 2010b, Baylon et al. 2012). 

As with all heat pumps, the capacity and heating efficiency of mini-splits decreases with lowering outdoor air temperature, so performance in frigid climates is a concern. 

Limited information exists regarding the ability of ductless mini-splits to adequately dehumidify homes in extremely humid climates.

One distinct disadvantage of ductless mini-split systems is the inability to mix air in an ample space or multiple rooms. Because the discharge is from a single source, and consideration must be given on the exact location of the indoor unit. 

The need for humidity control varies throughout the country but is often an important consideration in overall comfort. Mini-split systems do a good job removing humidity but do not have the ability to add humidity. The recommended humidity range in buildings is typically between 30%-60% relative humidity (RH). In low humidity areas of the country and winter time in cold climates a stand-alone humidifier would be required to raise humidity levels.

Maintenance and Service
The filter and condensate pan are located within the indoor unit therefore each indoor unit requires filter maintenance and condensate pan/drain line cleaning. Multiple indoor units will need this regular maintenance for each unit resulting in increased labor costs. 

Now entirely "plug and play" from the end user's perspective. Modern automation controls is a primary reason the system is more efficient. However, troubleshooting these systems can be more complicated and time-consuming.

Indoor Air Quality (IAQ)
According to the National Institute of Occupational Safety and Health (NIOSH), inadequate ventilation accounts for 53% of indoor air quality problems. Most ductless mini-split systems cannot address this due to the inability to introduce outside air; however, ventilation systems canbe designed separately. Because current building codes and/or construction methods often produce envelopes with higher air tightness values, air will stay circulating locally around the indoor units.

Ductless mini-split systems have one or more indoor units, and typically hang high on the wall near the ceiling. It isn't the most appealing look for a permanent installation, but not as unsightly or inconvenient as a window unit. New mini-split designs have recessed and concealed registers that offer better aesthetics than the typical wall-mounted evaporator units. If aesthetics is an issue for the retrofit, manufacturers do offer options for addressing the location and appearance of the indoor unit.

Noise Levels
Interior units of ductless mini-split systems must be installed in the rooms where conditioned air is provided, which will add to the ambient noise levels of the space. This additional indoor noise varies with fan speed and can be similar to or slightly higher than what is expected from ducted systems.

The installation is limited only by the distance of refrigerant piping. However, one drawback to mini-split systems in retrofit applications is finding a practical and aesthetically pleasing way to dispose of the condensate created in cooling mode.              

Ductless mini-split systems are a high performing HVAC technology that incorporates independent and integrated controls and offers increased efficiency. Even at almost double the costs versus packaged terminal air conditioners (PTAC) or window-type air conditioners, the increases in efficiency and comfort make these systems an attractive option in smaller homes, retrofits, and additions.

At the current average residential electric rate for the Pacific Northwest (approximately 9¢/kWh – based on data from the U.S. Energy Information Administration's State Energy Data System; EIA 2013), this equates to a savings of $270 per year.    

Split-System Air Conditioners and Heat Pumps 
The most common central equipment type that uses electricity as the energy source for cooling and heating is air-source heat pumps, typically split systems. 

Heat pumps may use a gas furnace or electric resistance to provide supplemental heating when outside air temperatures are low and the heat pump cannot meet the entire load. Electricity is also used for central air conditioners for cooling only, often integrated with a furnace to provide heating with a shared fan. 

All three major U.S. HVAC manufacturers mentioned in the Conventional HVAC Systems section offer split-system air conditioners and heat pumps with nominal capacities from 1.5 to5 tons (typically available in 0.5-ton increments). 

Typical single-stage units have advertised seasonal energy efficiency ratios (SEERs)13 for the air conditioners from 13 to 21; the heat pumps have advertised SEERs from 13 to 12.

Cooling energy savings could also be achieved in homes that were using window-mount air conditioners with less-efficient cooling than a mini-split. 

However, this study only considered heating energy savings. 13 SEER is the total amount of cooling provided by an air conditioner or heat pump over the cooling season (in Btu) divided by the total electrical energy used to provide the cooling (in W-h). 13 19 and heating seasonal performance factors (HSPFs)14 from 8 to 9.5. 

Ductless Mini-Split Air Conditioners
Ductless mini-split air conditioners are meant to cool older homes without ductwork, as well as smaller homes and add-ons where ductwork shouldn't be added. 

Benefits of Using a Ductless Mini-Split Air Conditioner
Mini-split air conditioners provide flexible cooling to individual parts or rooms of your home through a smaller and more energy efficient system. It's as close as you get to a central air conditioning system, and you don't need to tear up your ceiling and walls to install ductwork. Also, mini-splits are a type of heat pump, so they can provide home heating during winter months.

Ductless systems also operate as quietly as a typical fan. Because the compressor is located outside, the unit is much quieter than a window or portable units. Plus, with no need to obstruct the window with AC equipment, you get better home security, a view to the outside, and the ability to operate your window when you want.

Disadvantages of Using a Ductless Mini-Split Air Conditioner
Keep in mind that ductless mini-splits cost more than window or portable units. Not only that, but you need to hire a professional to perform the installation, which includes drilling a three-inch hole in the wall to connect the indoor and outdoor components. You should also keep interior design considerations in mind, as the unit mounts to the wall or ceiling.

Central Air Conditioning System
Central Air systems distribute cooled air throughout ductwork with return and supply registers in each room to comprehensively cool your entire home. The components are all located outside, except for the air handler, usually shared with the furnace. If you have the ductwork in place and are looking for whole-house cooling, this is the most popular system.

Benefits of Using a Central AC System
Central AC systems are a more effective way to keep your home cool. You can expect lower energy bills and better indoor comfort, with cooler temperatures and lower humidity throughout your home. Also, with all the components located outside, you stay cool with a virtually invisible, silent system.                                                                                   

If you already have existing ductwork in your home, installation is straight forward for our trained professionals. And since a central air system is a permanent fixture in your home, it is a valuable investment.

Disadvantages of Using a Central AC System
Central air conditioning systems require annual maintenance to remain in tip-top shape for years. You should prepare for higher upfront costs and extra charges if you need ductwork installed. However, replacing an old central air conditioning unit is cheaper than installing a new ductless mini-split.

Finally, you will need to decide what size air conditioning system to install. If you install a small unit, it won't keep your home cool on the hottest days. Oversized units can short cycle, which wears out parts faster and doesn't give the unit a chance to dehumidify your home.

When you choose either a central home air conditioner or a ductless mini-split, a licensed professional contractor will size the unit to meet the needs of your home perfectly. It's just another reason to get a professionally installed home air conditioning unit.

Ductless mini-splits are gaining popularity due to their higher seasonal energy efficiency ratio (SEER) ratings and ease of installation. 

The basic ductless mini-split cooling only system includes an outdoor condensing unit, very similar to conventional split systems. The outdoor unit contains the condenser coil, the compressor, and the fan motor to remove heat from the refrigerant in the coils. 

If heat from the system is needed, most manufacturers offer heat pumps as an alternative. Heat pumps work by extracting heat from the outside air and transferring it via the refrigerant to the indoor unit. This option provides year-round solutions for most of the country. In the northernmost climates, upsizing the system capacity may be an option, or use of another source of heat for supplemental heat may be required.

Mini-split systems can also include "mini-ducted" systems that incorporate short runs of ductwork that often allows for a traditional look with only grilles visible. This is done only when accessible attic or under floor space is available. Mini ducted systems can also be used effectively for retrofit projects either for a single zone application (such as a master suite bedroom) or as part of a multi-zone system.

Energy Efficiency
Ductless mini-splits are gaining popularity based on their high efficiency ratings. Governor Janet Mills is encouraging Heat Pump installs by offering big cash rebates. And Trump will throw in a $300 credit as well. 


Ductless mini-splits currently have one of the highest SEER, EER, and coefficient of performance (COP) rating ranges in the industry, so it can be a wise choice for high performance homes. Advanced inverter and heat pump technologies achieve greater efficiency and energy-savings. This will result in long term savings by way of reduced electricity bills.

Most ductless mini-split systems have hand-held remote controls that adjust the temperature and fan settings. Most have functions similar to thermostats, but with individual control—each indoor unit can be operated independently to deliver air comfort only to rooms where needed.

ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) defines thermal comfort as "that condition of mind which expresses satisfaction with the thermal environment." 

Ductless mini-split systems 
When using multiple indoor units provides the ability to control the temperature in each space. Each indoor unit has its thermostat and can be set to different setpoints based on one's own preferences.

SEER = Seasonal Energy Efficiency Ratio, 
EER = Energy Efficiency Ratio, 
HSPF = Heating Seasonal Performance Factor

Window Air Conditioners
Window units have been around for a long time. They've always been kinda ugly sitting there in some double- and single-hung window. 

Because window air conditioners are smaller and more portable than most other units, they are fairly easy to install.  They're a cheap alternative.  Models today claim 30 percent more efficiency than those back in the day. Warranties give people peace of mind because they can go out for as long as five years.

Those little buggers likely can't cool your entire home unless you're living in one of those cute mini houses or perhaps a small apartment you could get away with just one. 

And you know it's nice to look out your windows to see what your neighbors are up to. You just can't get a clear view of the Jone's place. 
I like the humming sound of that compressor to put me to sleep and drown out noise to keep me in dreamland.

Perhaps you're a powerlifter and have a darn respectable deadlift. Good- you'll need it to hoist that large window unit to install during the summer and remove during the winter. 

Portable Air Conditioners
The unit draws in hot, humid air, removes the heat and moisture, and vents cold, dry air into your home. The warm, moist air is vented out a window through an exhaust hose. This option is only better than a window unit if you have windows that cannot hold a window unit, or are nervous about lifting and installing a more large window unit.

Portable units are easier to install than window units. The floor unit rolls around on casters so you can place it quickly and effortlessly. The exhaust hose runs out the window without blocking your view, and it can be removed easily in beautiful weather!

According to Consumer Reports, portable air conditioners generally deliver half the cooling capacity they claim, so you feel hot and sweaty even when the unit is running. 

Most portable units are also more expensive and less efficient than similarly sized window units, which means higher purchasing and operating costs. 

Noise can be a factor, and portable units usually have a water reservoir that removes humidity from the air but needs to be emptied manually.

Bottom line: Save A Bundle
In conclusion, a combination of proper insulation, energy-efficient windows and doors, daylighting, shading, fans, and ventilation can often keep homes cool with a minimum of energy use in all but the hottest climates. 

Heat Pumps are the most efficient form of electric heating, providing up to three times more heat than the energy they use. In fact, your electricity use for heating through a heat pump will be approximately 50% less compared to electric furnaces or electric baseboard heaters. 

For more information or to request a FREE Heat Pump Installation Estimate, Call (207) 553-3833 or book Tuesday a "COVID-19 Safe" online meeting w/ Tony Colón below. 

Click the following link to book an informational session w/ Tony

Further Resources

Audit Your Home's Energy Use

Building Performance Institute:

Home Energy Saver:

Home Energy Score:

Home Performance with ENERGY STAR:

Residential Services Network:

Weatherize Your Home

"Attic Air-sealing Project." ENERGY STAR. Accessed May 2017: cfm?c=home_sealing.hm_improvement_attic

"Attic Insulation Project." ENERGY STAR. Accessed May 2017: cfm?c=home_sealing.hm_improvement_attic_ insulation

"Basement and Crawlspace Air Sealing and Insulating." ENERGY STAR. Accessed May 2017: sealing.hm_improvement_basement

"A Do-It-Yourself Guide to Sealing and Insulating with ENERGY STAR." (2016). ENERGY STAR. Accessed May 2017: pubdocs/DIY_Guide_2016.pdf?1cb1-bbd4

"ENERGY STAR Certified Homes." ENERGY STAR. Accessed May 2017: newhomes

"A Guide to Energy-Efficient Heating and Cooling." (2009). ENERGY STAR. Accessed December 2016: partners/publications/pubdocs/ HeatingCoolingGuide%20FINAL_9-4-09.pdf

"No Regrets Remodeling, 2nd Edition." (2013). Home Energy. Accessed May 2017: building_america/no_regrets_remodeling_ ornl.pdf

"Recommended Home Insulation R-Values." ENERGY STAR. Accessed May 2017: hm_improvement_insulation_table

"Savings Project: Attic Stairs Cover Box." Energy Saver. Accessed May 2017: energy. gov/energysaver/projects/savings-project-attic-stairs-cover-box

"Savings Project: Insulate and Air Seal Floors over Unconditioned Garages." Energy Saver. Accessed May 2017: projects/savings-project-insulate-and-air-seal-floors-over-unconditioned-garages

"Savings Project: Seal Air Leaks with Caulk." Energy Saver. Accessed December 2016:

"Savings Project: Weatherstrip Double-Hung Windows." Energy Saver. Accessed December 2016: savings-project-how-weatherstrip-double-hung-or-sash-windows

"Sealing Behind Window and Door Trim." ENERGY STAR. Accessed May 2017. hm_improvement_window_door_trim

"Zero Energy Ready Home." U.S. Department of Energy Building Technologies Office. Accessed June 2017. buildings/zero-energy-ready-home


"Applying Plastic Over Windows Project." ENERGY STAR. Accessed June 2017.

"Savings Project: Install Storm Windows." Energy Saver. Accessed December 2016:

Financing, Incentives, and Assistance


203(k) Rehab Mortgage Insurance. U.S. Department of Housing and Urban Development. Accessed June 2017: portal. offices/housing/sfh/203k/203k--df

Database of State Incentives for Renewables and Efficiency (DSIRE). Accessed December 2016:

HomeStyle Energy. Fannie Mae. Accessed June 2017: homestyle-energy

"Find Product Rebates & Other Special Offers." ENERGY STAR. Accessed June 2017:

"Renewable Energy Systems & Energy Efficiency Improvement Loans & Grants." U.S. Department of Agriculture Rural Energy for America Program. Accessed June 2017.

"Where to Apply for Weatherization Assistance." U.S. Department of Energy Weatherization Assistance Program. Accessed December 2016: where-apply-weatherization-assistance

"Veteran's Administration Energy Efficiency Mortgage: VA pamphlet 26-7." RESNET. Accessed June 2017: lenders/va_26_7

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