Della Optima 18000 BTU Review: 23 SEER2 Hyper Heat Mini Split
Della's premium Optima series in a 1.5 ton size: 23 SEER2 and 10 HSPF2, hyper heat to -13F, soft indirect airflow, 34 dB mute mode and Wi-Fi with Alexa.
By Daniel Brooks
Updated October 19, 2026
The Della Optima 18000 BTU is Della’s premium 1.5 ton mini split, built around two ideas: hyper heat that keeps working down to -13F, and soft, indirect airflow that does not blow straight at you. It is ENERGY STAR certified, lists 23 SEER2 and 10 HSPF2, and covers up to 1000 square feet on a 230 volt circuit. In our single-zone mini-split air conditioners category, it has a 4.2 out of 5 average from 245 ratings.
Our Verdict
The Optima 18000 BTU is the Della to buy for a large bedroom, family room or open apartment in a region with real winters. It combines high efficiency with cold-climate heating, Wi-Fi and Alexa control, an I Feel remote sensor and a pre-flared 16.4 ft line set. The soft airflow design is a genuine comfort upgrade for people who dislike drafts.
It costs more than Della’s Vario series, it needs a 20A circuit and professional installation with vacuuming, and at 115.7 pounds for the system it is a two-person job to handle.
Della Optima 18000 BTU Hyper Heat Mini Split AC
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Key Specifications
| Feature | Specification |
|---|---|
| Brand | Della |
| Model | TPX-18K2V-23S-I+O (Optima Series) |
| Type | Single-zone ductless mini split heat pump |
| Cooling Capacity | 18000 BTU (1.5 tons) |
| Heating Capacity | 19000 BTU/h |
| Room Size | Up to 1000 sq ft |
| Power | 230 volts, 20A fuse |
| Rated Wattage | 1390 watts |
| Efficiency | 23 SEER2, 10 HSPF2 |
| Heat Pump Range | Down to -13F |
| Noise Level | 34 dB in Mute mode |
| Refrigerant | R-454B |
| Line Set | 16.4 ft pre-flared, 1/4 and 1/2 inch |
| Certification | ENERGY STAR, AHRI listed |
| Weight | 115.7 pounds |
Cooling Capacity and Room Size
Della rates the Optima 18000 BTU for up to 1000 square feet, matching the 700 to 1,000 square foot band on the ENERGY STAR chart below. It fits a large primary suite, an open living and dining area, a finished basement or a small apartment where one air handler can reach most of the floor.
ENERGY STAR publishes this general guide for matching cooling capacity to floor area:
| Room Size (sq ft) | Cooling Capacity (BTU/hr) |
|---|---|
| 100 to 150 | 5,000 |
| 150 to 250 | 6,000 |
| 250 to 300 | 7,000 |
| 300 to 350 | 8,000 |
| 350 to 400 | 9,000 |
| 400 to 450 | 10,000 |
| 450 to 550 | 12,000 |
| 550 to 700 | 14,000 |
| 700 to 1,000 | 18,000 |
| 1,000 to 1,200 | 21,000 |
| 1,200 to 1,400 | 23,000 |
| 1,400 to 1,500 | 24,000 |
| 1,500 to 2,000 | 30,000 |
| 2,000 to 2,500 | 34,000 |
Adjust for your room: reduce capacity by 10 percent for a heavily shaded room, increase it by 10 percent for a very sunny room, add 600 BTU for each regular occupant beyond two, and add 4,000 BTU if the unit cools a kitchen. Source: ENERGY STAR.
Hyper Heat Down to -13F
The Optima’s heat pump is rated to operate down to -13F, and its heating capacity of 19000 BTU/h is higher than its cooling rating. Della credits its Gold Fin coil coating for durability in harsh conditions. For most homes outside the coldest northern states, that is enough to make the Optima the main heat source for its zone, and it can sharply reduce the use of costly baseboard, oil or propane heat.
As with any heat pump, output falls as the outdoor temperature drops, so a drafty room may still need help on the coldest nights. For a well-sealed space, the Optima is one of the most capable 18000 BTU systems we cover.
Efficiency
At 23 SEER2 and 10 HSPF2, the Optima is among the most efficient single-zone systems on Amazon, and it carries ENERGY STAR certification. Higher HSPF2 matters as much as SEER2 if you heat with it, because it measures how much heat you get per unit of electricity over a heating season. Della lists 1390 watts of rated power and four power levels.
Soft Airflow and Noise
Instead of aiming a stream of cold air across the room, the Optima uses a soft, indirect airflow mode that spreads air more evenly. Della describes it as a no direct draft design, which suits bedrooms, nurseries and offices where people sit in one place for hours. In Mute mode, Della lists 34 dB.
Smart Control
The Optima connects to the Della+ app and works with Alexa, so you can schedule pre-warming before you wake up or keep the room comfortable for pets while you are out. The I Feel sensor in the remote reads the temperature where you sit. Della’s Wi-Fi uses the 2.4 GHz band.
Installation
The Optima is pre-charged, but Della specifies vacuuming and a 20A fuse, and professional HVAC installation is recommended. The kit includes a 16.4 ft pre-flared copper line set with 1/4 and 1/2 inch lines and a drain hose, so your installer should not need extra trips to the supply house. Della also offers a rental tool kit for vacuuming and 24/7 live support.
Warranty
Della offers lifetime parts coverage when you register within 100 days, with enhanced coverage for licensed HVAC installs. Labor is not included.
Planning the Install
The Optima’s outdoor unit should sit on a level pad or a wall bracket, raised above typical snow depth in cold regions so it can breathe and drain during defrost. The indoor unit goes high on an outside wall with open space in front, and the 16.4 ft pre-flared kit covers most direct runs through the wall. Have an electrician confirm a 230 volt circuit with the 20A fuse Della specifies before the HVAC visit.
Maintenance
Clean the reusable filters seasonally or more often in heavy use, keep the condenser clear of leaves, snow and ice, and book a yearly coil inspection. Della also highlights its PureClean fresh air and defrost protection features, which help keep the coil clean and heating steady through the winter.
Optima vs Vario
Della’s Vario series is the brand’s mainstream line, with heat pump operation down to -4F and efficiency around 21 SEER2 in the 18k size. The Optima adds hyper heat to -13F, higher 23 SEER2 efficiency, ENERGY STAR certification and soft airflow. If you live where winters regularly drop below zero, the Optima is worth the step up. In a milder climate, the Vario gives you most of the summer comfort for less.
Pros and Cons
| Pros | Cons |
|---|---|
| Hyper heat down to -13F | Premium price |
| 23 SEER2, 10 HSPF2, ENERGY STAR | Needs 230V and a 20A fuse |
| 19000 BTU/h heating capacity | Professional installation required |
| Soft indirect airflow | Heavy system to handle |
| Wi-Fi, Alexa and I Feel | Wi-Fi supports 2.4 GHz only |
Who Should Buy It
| Who Should Buy It? | Who Should Look Elsewhere? |
|---|---|
| Cold-climate homes | Mild climates on a budget |
| Large bedrooms and family rooms | DIY installers |
| People who dislike drafts | Homes without 230V capacity |
| Smart home users | Rooms under 700 sq ft |
For more options, see our picks for the best 18,000 BTU mini-split air conditioners and the best smart mini-split air conditioners.
Final Verdict
The Della Optima 18000 BTU is a premium, cold-ready mini split for spaces up to 1000 square feet. It heats down to -13F, runs at 23 SEER2 and keeps the air gentle and quiet. You can check the current price and details for the Della Optima 18000 BTU Hyper Heat Mini Split AC.
Frequently Asked Questions
How cold can the Della Optima heat?
Della rates the Optima heat pump for operation down to -13F.
What size space does it cover?
Della rates the 18000 BTU model for up to 1000 square feet.
Is it ENERGY STAR certified?
Yes. It is ENERGY STAR certified and AHRI listed.
Does it work with Alexa?
Yes. It works with the Della+ app and Alexa.
What voltage does the Della Optima 18000 BTU need?
It runs on 230 volts and needs a circuit protected by a 20A fuse, as Della specifies in the listing.
Is the line set included?
Yes. The kit includes a 16.4 ft pre-flared copper line set with 1/4 and 1/2 inch lines and a drain hose.
About the author
Daniel Brooks is a home cooling editor at WikiCooling, covering window, portable, through-the-wall and mini-split air conditioners, fans, and dehumidifiers. He researches cooling capacity, energy efficiency, noise levels, installation requirements, and buyer feedback to help homeowners choose the right unit for their room size, climate, and budget.