The correct line set size depends on your mini split system. Always refer to the manufacturer’s specifications to ensure compatibility.
Measure the distance between your indoor and outdoor units
When in doubt, choose a longer line set. Most systems require a minimum length of 15 feet to function correctly, while exceeding the manufacturer’s maximum limit can cause performance issues.
For more information, check out our complete guide to line sets for mini splits
What voltage do I need?
The voltage you need depends on your home’s electrical supply and the requirements of your mini split system.
Before installation, make sure your home’s available voltage matches the voltage listed for the unit.
Most mini split systems require either 115V or 208–230V power. Using the wrong voltage can cause performance issues or damage the unit.
If you are unsure, consult a licensed electrician before installation.
Experience intelligent, all-season comfort with the Optima Series. This 9000 btu mini split ac heat pump is engineered to deliver reliable warmth in extreme temperatures as low as -13°F. Fully compatible with Amazon Alexa and the Della+ WiFi app, it offers seamless voice and mobile control. With a leading 24 SEER2 rating and Energy Star certification, it dramatically reduces energy costs and may qualify for government rebates. The system is backed by a lifetime warranty for ultimate peace of mind.
How Long Will It Take for My Order to Ship? It normally takes us 1 business day to arrange the shipment. During peak seasons, it will take 2-4 business days to arrange the shipment. We provide free ground shipping, so there are no additional charges for shipping and handling.
How Do I Track My Order? Log into YOUR ACCOUNT, and you may see each individual order that you’ve placed with us. Select one that you want and you’ll be provided with all the details you need about the order.
Once your order is on the way you will receive a notification email.
What Should I Do If I Haven’t Received My Order? Please contact us immediately.
For the full shipping policy, click here to view our shipping policy. Return
We offer return guarantees to ensure your satisfaction with every DELLA purchase.
DELLA provides comprehensive assistance for all orders within 30 days of purchase. If you're not satisfied with your product within 30 days of purchase from dellahome.com, you can return the product for a full refund.Products must be returned in their original operating condition, including all accessories and packaging.The customer is responsible for return shipping costs.
If a product defect is confirmed, DELLA will, at its discretion, provide the necessary replacement parts free of charge. DELLA will also cover all shipping expenses for the delivery of replacement parts.
Need to Start a Return? To initiate a return, call us at (800) 863-4143 or contact our live chat team.
For full return terms, click here to view our return policy.
Standard Warranty (1 Year): Products are covered by a 1-year limited warranty from the date of purchase.
Extended Warranty Program: Customers whoregister their mini split unit within 100 days of purchase will receive complimentary lifetime parts coverage.
Registered Product and Non-professional Install: If a product defect is confirmed, DELLA will, at its discretion, provide the necessary replacement parts free of charge. The customer is responsible for all shipping costs.
Registered Product and Professional Install: If a product defect is confirmed, DELLA will, at its discretion, provide the necessary replacement parts free of charge. If, after parts are replaced, the customer’s unit is still malfunctioning and the customer has a licensed HVAC tech's defective report, Della will take care of the customer at its discretion. In any event, the customer is responsible for all shipping costs.
Unregistered Product: If a product defect is confirmed, DELLA will, at its discretion, provide the necessary replacement parts. The customer is responsible for the costs of all parts and shipping.
Optima: Cold Weather’s Greatest Rival. Efficiency’s New Standard.
Engineered with cutting-edge Hyper Heat technology, the Optima mini-split delivers reliable, high-performance heating even when temperatures plummet to -13°F. With an industry-leading 23-24 SEER2 rating and ENERGY STAR® certification, it’s designed to slash your utility bills while keeping your sanctuary cozy year-round. Whisper-quiet, smart-connected, and built for the extreme—Optima ensures your comfort (and savings) never freeze, no matter what’s happening outside.
Powered by MightAir X
Top performance, energy smart design
65% more efficient energy savings
Cleaner air, healthier living
Durable design, lasting comfort
Reliable Performance in Extreme Weather
Engineered to deliver dependable heating and cooling through intense summer heat and freezing winter conditions, helping maintain consistent comfort when outdoor temperatures become more demanding.
6 modes for max comfort
Auto mode
Maintain a comfortable indoor temperature by automatically switching between heating and cooling as needed
Auto mode
Maintain a comfortable indoor temperature by automatically switching between heating and cooling as needed
Wherever you are
Control your comfort, your way
Set schedules and timers through the Della+ app to match your daily routine.
Take control your way through the app, remote, or voice. Award-winning remote design makes every interaction seamless.
Your comfort adjusts automatically as you come and go.
Get help anytime with live chat or call, directly in the app.
Control your AC hands-free with Alexa.
Which series is right for me?
Model
Efficiency
HSPF2 Rating (Region IV)
Refrigerant
Climate Range
Energy Rebate
Shop Now
DELLA Optima Series 9000 BTU 23 SEER2 Ultra Heat Mini Split AC - Up to 400 Sq.Ft.
SEER2 23
9.5
R454B
-13°F - 131°F
DELLA Optima Pro Series 9000 BTU 25 SEER2 Ultra Hyper Heat Mini-Split AC - Up to 400 Sq.Ft.
This unit uses R454B refrigerant. This unit comes pre-charged with R454B refrigerant for up to 24.5 feet of lineset. If your installation does not exceed this length, no additional refrigerant is needed.
R454B is a new-generation eco-friendly refrigerant that complies with EPA regulations. It can replace the original R410A models, offering better performance and greater energy efficiency.
Yes, you can purchase a longer lineset separately. If you buy it together with the Single Zone Mini split system, you’ll receive a 10% bundle discount. Please note, if the extended lineset is longer than 25 feet, additional refrigerant will be required. Make sure to consult a professional HVAC technician for proper installation.
In auto mode, the unit automatically switches between cooling and heating to maintain the set temperature. You can adjust the target temperature manually—typically between 60°F and 86°F —depending on your comfort.
The mini split condenser and lines are not pre-vacuumed. You will need to vacuum the system during installation to remove air and moisture before releasing the refrigerant—this is essential for proper operation and longevity. You can use our Rental Kit Service, which includes all the necessary tools for vacuuming and installing your mini split.
Talk to an HVAC expert
Not sure which system is right for your home? Our experts can help with sizing, installation, and product selection.
Technical support: Mon - Fri, 8 AM - 3 PM (PST)
24/7 live chat for general question
I installed the unit in a standard 12x12x12x12x12 pentagon with two floors, 11’ ceilings! The floor, walls and roof are treated with spray foam for an ideal space to cool. I have the unit set to “dry out mode. In 5 1/2 days the unit has removed 11 mop buckets of moisture. The bottom floor (foamed) suffered several heavy rain showers…. I drilled holes in the subfloor to allow the unit to extract that trapped moisture. Overall, I am quite pleased with my Della unit! I would give it a 5, but feel like that would be a chump move. Statesboro Georgia is, in legendary Coach ERK Russel’s words, the gnat capital of the world. Gnats love heat and humidity, so does my Bella Della!
Bill Thomas
Ex officio Mayor
William L.4/5Verified
I am truly impressed with these Della split units. This was the perfect choice for the space being used. I ordered everything needed to make for a great installation. Wall bracket (keep it off the ground and keep it clean) line sets (well packaged and protected) line set covers (good product for fair price). The inside units are a nice looking unit and their sizing is common to all others out there. Well done Della! Thank you!
Jeff W.5/5Verified
Thai review comes while I'm currently in a heatwave with a heat index of around 110 degrees.
This unit is incredible. Ice cold air, even when it's brutally hot and humid. The up-down/left-right louvers are great.
Indoor unit is attractive. Honestly I feel like my 9k Della has more cooling power than my 12k Mr.cool.
Installed it myself. Everything went well
Samuel H.5/5Verified
Very easy DIY install. And so quiet inside and out!
Donald W.5/5Verified
I brought the DELLA mini split mainly because of the rental kit to make the installation much easier. The vacuum pump, torque wrench, and for me the best feature the plastic tubing you put inside the copper tubing to help you from bending the copper tubing.
John S.5/5Verified
I ordered the 9000 btu 230v system w/25' lineset. The equipment arrived three days after I ordered it. I also rented the installation kit for the diy install. To purchase the needed equipment would have been between $250-300. I watch the recommended Youtube videos and several others. I installed both the indoor and outdoor units following the video instructions, and the written instructions in the manual, using the rental equipment. At the coldest setting it blows 40 deg air. At the warmest setting it blows 140 deg air. This awesome little system will make my home office much more comfortable to work in during the winter and summer.
Paul H.5/5Verified
It is 20° outside right now and it says it feels like 11 and the room is staying warm. The only issue is the installer had to make a lot of modifications compared to my last unit, but he got it in.
Kimberly C.4/5Verified
Unit works great. My issue is interior fan runs all the time in AC mode with compressor on or off fan runs constantly. So fan runs 24/7 in Arizona.
Richard C.4/5Verified
This company is absolutely unbelievably incredible. The HVAC technician more than likely cross-threaded the liquid line service valve nut. The nut had to be cut off, which completely destroyed the valve. I contacted DELLA, who requested pictures of the damage. In complete amazement, they did not send a new valve but instead replaced the outside unit, AT NO CHARGE!!! This is after I told them I would pay for all parts and replacement costs. I even emailed them and stated the damage was not due to the manufacturer's defect, and I told them I was not seeking any warranty or compensation. This is a truly great company, and I highly recommend them if you want a mini split and want a company that stands behind its products. I have always wanted to add a mini split to my upstairs rooms, and after this wonderful customer service, it will definitely be a DELLA.
Adrian G.5/5Verified
We have 4 now in our home, and my husband installed them himself. They work great! Just like having central air in the summer, & so far keeping rooms warm this winter. Seems good on the electric bill, too!
Best part is you're able to control air & heat for each room.
John F.5/5Verified
This is a great unit. worth every penny. Pro install recommended.
Joe N.5/5Verified
Easy install! Wish I had leased the install kit and just returned it to get the longer warranty. I already owned all required equipment, and I did not realize it would affect my length of warranty.
Ricky C.5/5Verified
This is my second Della mini-split install and it was a breeze. The order was delivered in just a few days and installation went easily. The first unit (18K) has been running for 2-1/2 years without any issues. It heats and cools quickly, is quiet and quite efficient.
If you are mechanically inclined and can follow instructions, there should be no problem doing an install of one of these units. The only concern I had was in vacuuming the lines, as I don't have experience in that. But, it was pretty straightforward and went without a hitch.
I'd recommend Della to anyone.
Joe B.5/5Verified
Pretty easy install. Make sure to order the line set.
In Louisiana is hot one day and cold the next. I recommend this mini split for anyone who can’t keep a room comfortable. It works like a charm.
John S.5/5Verified
This is my third Della Mini Split we have purchased and installed. I am very pleased with the operation of these units. I would give 5 stars, but the order process had a flaw in that it allowed me to order this unit without a line set.
I previously had to purchase a longer line set for the second unit we installed because it came with a 16 foot line set which was not long enough. When I purchased that unit, it automatically came with the 16 foot lines and I did not see an option to change that.
That worked out for me because this time, I was supposed to choose a length for the line set. It was a drop down menu that I did not see. This should have been set up so that if I truly did not want to include the line set, I should have had to choose that as an option. Instead, it let me order with that field blank. If I did not happen to have an extra line set, I would have been unable to finish my install.
A second observation...I installed one of these in my shed, which is intended to be a work shop for my wife also. In normal circumstances, we would only like to heat it to about 45 degrees. The lowest setting on the Della is 61 degrees. I was unaware of that when we purchased it. This may not be important in most installation scenarios, but someone else may have a similar need and it might help you to know that.
Overall, we are pleased with the Della units. Very straightforward installation and we have had zero problems with them. Incredibly quiet inside and outside. You can stand right next to the outside unit and have a normal conversation. Truly impressive. Change the order process Della so someone cannot accidentally order without a line set and it will be a five star experience.
