Sizing a Ductless Air Conditioner

Properly sizing your mini split air conditioner or other ductless system is a relatively easy task. I get asked daily by consumers what size air conditioner is right for me? Whenever you purchase a ductless air conditioner make sure to get a unit that can handle the area that needs to be cooled with a few variables thrown into the equation. The worst thing that could happen is that you purchase the equipment and everything gets installed properly, but the unit doesn’t live up to expectations.

Remember first that ductless air conditioning equipment can only cool or heat areas that can be reached by the expelled air. Like a fan, if you close doors to rooms surrounding the indoor evaporator, those rooms will not feel the effect of the circulated air. Most ductless mini split systems will have fan settings from relatively low to high speeds. A higher speed, of course, will help the room air circulation.

For larger areas it is a good idea to check the evaporator fan’s Cubic Feet per Minute (CFM) output in the specifications. The higher the CFM, the better the circulation.

Let me start with the basics of ductless sizing for the best case scenario. For every 12,000 btu., an average of 600 square feet can be cooled or heated. If your air conditioner produces 18,000 btu.’s the coverage improves to 900 square feet.

For me, best case scenario means a square room with 8 foot ceilings, no windows in a climate of 72 degrees. Now let’s look at some of the variable that reduce the amount of square feet covered by a ductless air conditioner

6 Variables that Reduce an Air Conditioners Useful Area:

1. Climate: If you live in an area of the world that has seasonal temperatures in excess of 90° F. Increase 30%
2. Windows: If you have south facing windows in your designated area, or if you have large windows. Increase 20%
3. Ceiling Height: High ceilings increase a room’s size reducing the air conditioners effectiveness. Increase 20%
4. Appliances: Heavy kitchen appliances and electronics increase the heat created in an area. Increase 20%
5. People: The more people in the area the more heat produced. Increase 20%
6. Insulation: Poorly insulated homes are much more difficult to cool or heat. Increase 30%

Taking into consideration the above variables we can form a good estimation on the size of air conditioner needed to do the job. We know that 12,000 btu.’s can cool 600 square feet or a room approximately 25’ x 25’. If any of the 6 variables from above are a factor we will not be able to maintain a comfortable environment for your area. So we need to move up to a higher btu. ductless air conditioner.

If our area is a 16’ x 16’ room (256 sq. ft.) in Orlando, Florida (Increase 30%) with south facing windows (Increase 20%) you would need an air conditioner that can cool a 384 sq. ft. area.

There are only a few basic sizes produced in the ductless air conditioning industry, so it makes it easier to find the unit that will work best for you.

Standard Sizes of Ductless Air Conditioners:

1. 9,000 btu. Coverage area 450 sq. ft.
2. 12,000 btu. Coverage area 600 sq. ft.
3. 18,000 btu. Coverage area 900 sq. ft.
4. 24,000 btu. Coverage area 1,200 sq. ft.

If you come close to the maximum square feet numbers listed above after adding in your variables make sure to bump up to the next higher btu. system. I have never seen a problem of over-sizing a ductless air conditioner. The thermostat is always in the area being cooled, so if you have a larger system expelling more cool air, the system will run less often.

These numbers have worked great for me in the past, and I hope they help you find the right size air conditioner in the future.

Join the forum discussion on this post - (1) Posts

How to Find a Ductless Mini Split Installer?

“Many of the contractors that install mini split air conditioners will be able to do both the electrical and HVAC portions.”

So you have made the decision to purchase a mini split air conditioner, and now it is time to figure out how to install the equipment. There is some basic information that you will need to know before you flop open the five pounds of yellow pages. First thing you should do is have a good idea of where you want to mount the evaporator or indoor portion of the ductless mini split.

Wall mounted air conditioners attach to a bracket about 10” below the ceiling. This high installation lets the air flow downward in the room. All the wiring and lines will run out the back of the unit so find a place that has enough room to hold the minimum dimensions of the evaporator.

Find a nice flat area near the exterior of the building to house the outdoor condenser.
A cement slab is ideal for a mini split air conditioner or purchase a plastic pad approximately 24” x 36” to place on a level surface.

Let’s keep it legal and make sure we pull the appropriate permits. Mini split air conditioners are hard wired into your fuse box, so you will need an Electrical Permit along with a HVAC Permit. Electrical permits on average are $40.00 and HVAC permits are approximately $75.00. Contact your local city hall for more information. Many times the installer you find will pull the permit for you, but to be safe I always pull them myself.

Time to make the call to find your friendly local contractor to do the dirty work. I no longer receive the yellow pages which is a shame because it worked as a great booster chair for my daughter! The best way I have found is to go online and search the yellow pages. I use www.yellowbook.com but there are many directories to choose from online.

Type in “Air Conditioner Contractors” into the Product / Service box and your city and state into the Location field. Most likely you won’t find anything that resembles the terms ductless air conditioner or wall mounted mini split air conditioner, but trust me 80% of all residential contractors have installed a mini split air conditioner.

I like to use the “mom and pop” companies because it seems I receive better pricing from smaller companies; Jay’s Heating and Cooling and such. If you have already picked out the brand and style of wall mounted air conditioner, you will have to supply the contractor with some basic information before they come to your home.

5 things to know before contacting a contractor:

1. Brand: They usually like to know the brand of the equipment but it doesn’t really matter because 99% of the equipment is installed the same way.
2. Size: Speak in btu. (British Thermal Units) to help them understand how large the unit will be. Example: 12,000 btu. or 1 ton.
3. Power Requirement: Does your unit require a 110 volt line or 220 volt line. Make sure to read the specifications beforehand or have them handy.
4. Type of Refrigerant: Does the unit use R22 or R410A refrigerant? They will need to know this to have extra refrigerant on hand when charging your system.
5. Length of the Run: Have a general idea of how far the indoor evaporator will be from the outdoor condenser. The farther away the two units are, the more expensive it will be to install, because of longer refrigerant line-sets and added refrigerant.

Many of the contractors that install mini split air conditioners will be able to do both the electrical and HVAC portions. Make sure to have a spot available for a dual pole circuit breaker in your electrical box. I ran into this problem when I was installing my own ductless air conditioner.

Check the breaker size in the specifications of your mini split air conditioner to find out the amp size needed to run the equipment. Most single mini split systems use a 15 or 20 amp circuit breaker. Make sure that the new air conditioner runs on its own circuit breaker.

I hope this information gets you on the right path to work with a qualified HVAC installer, and you can enjoy your ductless mini split system as much as I do. If you have any additions or comments feel free to share them in the Savings Forum.

Join the forum discussion on this post - (1) Posts

Mini Split Condensation Pumps

A mini split condensation pump is a small pump that is used to pump the condensation, or water, out of the reservoir of your indoor evaporators drain pan. The basic function of an air conditioner is to remove moisture, or humidity, from the air creating a cooler environment. As moisture is removed it is deposited in the evaporators drain pan at the bottom of the unit.

When a wall mounted mini split is installed properly, the drain pan can empty its contents out the back of the unit through a plastic drain line outdoors. Most mini split air conditioners have a ½” drain line. All condensate water will drain, with the assistance of gravity, outdoors or to an interior drain below the unit.

Most condensation pumps use a float switch to activate the pump when water reaches a designed level. Condensation pumps require either 110 volt or 220 volt electricity for operation. Make sure to purchase a pump that will operate with your existing power configuration.

Mini split condensation pumps are ideal to use when the evaporator is installed in a basement or area that is below the outdoor drain level. Condensation pumps can help drain water up to 30 feet above the pumps location.

Condensation pumps are self-priming, water-cooled and water lubricated.

All mini split condensation pumps have two components:

The Pump Body: This includes an electronic circuit board and the pump motor.

The Reservoir: This contains the switching mechanism to activate the pump and the filter. Make sure to occasionally check the filter to make sure that it is clean and the float switch is operational. Dirty filters can clog the float switch and water may overflow the drain pan. The reservoir must remain level to operate effectively.

Please check out the article ‘Condensation Pump Installation Styles” for more information on types of installation for condensation pumps. As always please feel free to leave comments on this article.

Join the forum discussion on this post - (1) Posts

R22 Versus R410 Refrigerant

“9 out of 10 contractors I spoke with would rather repair and install R22 air conditioners.”

The great refrigerant debate continues. Well, it’s not so great anymore. R22 refrigerant is dead -all hale R410A! In 1992, the international environmental agreement named Montreal Protocol amended its worldwide phase-out of to include ozone-depleting hydrochlorofluorocarbons (HCFC). There’s a triple score scrabble word for you!

R22 is a greenhouse gas and the manufacturing of it results in the by-product HFC23 that is a contributor to global warming. On January 1st, 2010 manufacturers will not be able to manufacture air conditioners using R22 refrigerant. In preparation, air conditioner manufacturers have started supplementing other refrigerants in place of R22 like the new and improved R410A.

R410 refrigerant is a combination to two gases that does not contribute to the depletion of the ozone layer, but like R22 still contributes to global warming. We’re making some progress.

If I am looking for a new ductless air conditioner which refrigerant do I choose?

It’s obvious, isn’t it? R410A. Not so fast, 90% of the window and through wall air conditioners are only available in R22. R410A still doesn’t have the excellent track record that R22 has and is proven to be less efficient at higher temperatures.

R22 will be around for a very long time. It will still be manufactured for the replacement and repair market until 2020. After 2020, manufacturing of R22 will be finished, but recycled refrigerants will still be around to service your air conditioner.

If I was purchasing a window unit I would still purchase a R22 unit. There is a minimum of 15 years of life for R22 and I’m pretty sure R22 will out live my air conditioner.

9 out of 10 contractors I spoke with would rather repair and install R22 air conditioners. They have worked with it longer and they do not have to mix chemicals to create the R410A. If there is a leak in a R22 air conditioners contractors add refrigerant. If there is a leak in a R410A air conditioner they have to vacuum the system and re-pressurize with new refrigeration at the correct mixture.

I’m sure R22 refrigerant will increase in price little by little as manufacturing is reduced but most R410A window air conditioners are more expensive than R22 air conditioners.

If I am purchasing a ductless mini split air conditioner I would lean towards the R410A unit. There are enough contractors who have worked with it over the past few years installing mini split systems that I feel comfortable recommending it for split system air conditioners.

Both refrigerants have positives and negatives for ductless air conditioners consumers and all indications show that R410A will be the next generation of R22. Let’s hope it has the consumer life span of R22.

Feel free to leave questions or comments about this article.

Join the forum discussion on this post - (1) Posts

Saving Money on Mini Split Installations

“If you have any technical ability and some extra time, you can complete most of the installation of the mini split air conditioner yourself.”

Air conditioning installations can be expensive, but there are a few things you can do to help save money. First, I would make sure you shop around for a brand of ductless mini split air conditioner that fits your budget. When shopping always contact the seller to make sure adequate technical support is available for the product being sold.

There are many different brands of mini split air conditioners. Make sure warranties are available for the air conditioner you purchase. Most warranties should be approximately five years on the compressor and one year for parts and labor. If you are purchasing a wall mounted mini split online make sure the seller uses trucking companies for delivery.

Companies like UPS, FedEx and DHL are well known for their destructive habits delivering heavy and awkward sized equipment. Truck-line companies deliver everything on pallets and you must be home at arrival to inspect the equipment. If you have a residential address shipping companies will require a lift gate to lower the pallet to the ground. Lift gate service is usually an additional fee approximately $30.00. Finding a commercial address will save you that additional expense.

It is always good to open the boxes at the time of delivery to make sure nothing is damaged. If products are damaged, the truck line will take responsibility for returns. If you wait three weeks to open your mini split boxes, they could have been damaged during shipment with no recourse.

If you have any technical ability and some extra time, you can complete most of the installation of the mini split air conditioner yourself. Many people choose to let the professional HVAC installer handle the whole job, but most of the mini split installation cost is labor intensive.

First thing I would do is to locate a place you would like to hang the indoor evaporator. The installation manual will be supplied with the equipment. Evaporators should be hung approximately 10” from the ceiling.

Next, I would remove all of the equipment from its packaging and check that everything was shipped properly and nothing is missing. There is nothing worse than having the installer show up and a main component is missing for the installation. More time, more money.

Follow the directions to properly mount the metal bracket that holds the indoor evaporator. You will need to drill a hole through the wall to fit the refrigerant line set, wiring and condensation tube. Usually, it will take a 3” hole, but check with the installation instructions. Make sure you are not drilling through a stud or other electrical wiring, or you may make a shocking discovery!

Find a hard flat surface outside to place the condenser. Try to keep the outdoor condenser near the position where you will install the indoor evaporator. The longer the distance between the two will add refrigerant, line set and wiring costs.

A concrete slab or plastic air conditioner pad is ideal for the condenser. Make sure the area is level and place the condenser on the chosen area. If you have the wiring and refrigerant line set you can run them through the wall.

Fill the hole you made for the line set and wiring with some socks or insulation until final charging takes place.

The outdoor condenser will need power so make sure an electrical disconnect is located next to the condenser.

At this point I would call your certified HVAC installer to come vacuum the line sets and charge your mini split air conditioner to the proper pressures.

When the HVAC installer finishes charging the system you can fill the 3” hole around the line set and wiring with silicone to prevent moisture within the wall.

By completing these few easy steps you can save yourself hundreds of dollars in basic labor costs. I hope this article can save you money on your mini split installation. Your comments and installation stories are always welcome.

Join the forum discussion on this post - (1) Posts

Wall Mounted Mini Split Savings for Higher SEER Air Conditioners?

“Does saving $30.00 a year justify the increase in price for higher SEER air conditioners?”

In January 2007, the federal government raised the minimum Seasonal Energy Efficiency Rating (SEER) for split system air conditioners from 10 SEER to 13 SEER. Any equipment manufactured after 2006 for sale in the United States must be at least 13 SEER. The Air Conditioning, Heating and Refrigeration Institute (AHRI) is working on special certification grouping for ductless mini split systems, but until that happens ductless equipment has been thrown into the same group as central air conditioners.

Since the minimum SEER has been increased manufacturers are using more expensive components to reach higher efficiency. Thanks in large part to inverter compressors, ductless mini split equipment has become available in efficiency numbers surpassing 21 SEER. The increase in the component costs are passed directly to the customer and mini split systems have risen in price dramatically. Ductless mini splits have also increased in physical size to house the larger compressors. So how much money does an increased efficiency air conditioner save you?

I have broken down one example of the savings between a 13 SEER and 16 SEER mini split air conditioner.

Operating Hours: 1600 annually or approximately 4 hours a day
Operating Temperature: 75 degrees Fahrenheit
Seasonal Energy Efficiency Rating: Increasing from 13 SEER to 16 SEER
British Thermal Units (btu): 12,000 or 1 ton

Survey Says:
Ding…..

Yearly savings: $42.00

Seeing that most ductless split system air conditioners are used for cooling smaller additions and rooms, a 12,000 btu. system is the most popular size sold in the United States. $42.00 is nothing to shake a stick at, but that is at 1600 hours. What about all the other areas that use the ductless systems seasonally? Does saving $30.00 a year justify the increase in price for higher SEER air conditioners? Not to mention the fact that high- efficiency compressors run hundreds more for replacement.

Many consumers are paying an average of $500.00 more for a more efficient 16 SEER air conditioner instead of a 13 SEER unit. With the efficiency saving air conditioner it could take 15 years to break even.

Many consumers like the idea of monthly savings and reducing energy usage. My hat is off to you, but my wallet is staying put.

Join the forum discussion on this post - (1) Posts

Easily Hide Your Mini Split Line Set

For years I have looked to find a product that can easily and cost effectively hide the refrigerant line sets of a wall mounted split system. I found a company that distributes the SlimDuct Line Set Ducting System. It seems like such an easy fix, but it has been very difficult to find products like these.

With all of the wiring, condensation tube and line sets coming through the exterior of the wall, the SlimDuct Ducting System seems the best way to maintain the ascetic appeal of your home. SlimDuct products encase the unsightly items for added UV resistance, fire resistance, abnormal weather and hungry living critters.

Standard colors include ivory, white and brown but I went all out and painted my line set covers the same color as my house. The basic pieces needed to finish off my mini split installation were a 78” length SlimDuct cover, a 90° wall inlet and a 90° end outlet. Not bad.

SlimDuct also offers 45° fittings, couplers for joining two or more of the 78” straight lengths and a variety of other pieces to get around windows and corners of your home.

There are three different dimensions of piping that can be ordered from SlimDuct.

1. SD-77: 3” x 2 ½”
2. SD-100: 4” x 2 ¾”
3. SD-140: 5 ½” x 3”

When I spoke to SlimDuct they told me that the SD-77 was sufficient for a standard mini split installation that uses a 3/8” x 5/8” line set, ¾” drain hose and 14 gauge wiring.

They were right. The SlimDuct components were easy to cut to size and now look great on the exterior of my home.

To purchase SlimDuct line set covers please visit our SlimDuct Sales Page at Clearance AC.

Join the forum discussion on this post - (1) Posts