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Is the MRCOOL DIY 5th Gen single zone worth the extra money?
Short answer: Sometimes. A MRCOOL DIY 5th Gen single zone costs $960 to $1,430 more than a DIY Select of the same size, and in a cooling-mostly climate the power savings won't pay that back. It earns the money when your run needs the 25 ft line set it includes, the 36K size, a 5-year parts and 7-year compressor warranty, or long heating seasons where its higher HSPF2 adds up.
The DIY 5th Gen is MRCOOL's top single zone line, and it carries the top price. This guide runs the efficiency math against the Select, then covers the parts of the 5th Gen that are easier to put a value on.
What do you get with a 5th Gen single zone system?
Each 5th Gen single zone complete system comes with the indoor wall unit, the outdoor unit and a 25 ft pre-charged Quick Connect line set. Here are the five sizes and the room size MRCOOL rates each for (prices as of November 2026).
| Size | Power | Rated for up to | Price, from | More than a Select |
|---|---|---|---|---|
| 9K | 115V | 350 sq ft | $2,329 | $1,080 |
| 12K | 115V | 550 sq ft | $2,359 | $960 |
| 18K | 230V | 800 sq ft | $2,909 | $1,219 |
| 24K | 230V | 1,050 sq ft | $3,329 | $1,430 |
| 36K | 230V | 1,550 sq ft | $3,769 | No Select at this size |
On top of what every MRCOOL DIY system has (R-454B, the app, Alexa and Google, 18 dB(A) silent mode), the 5th Gen adds:
- SEER2 of 18.0 to 23.6 and HSPF2 of 8.5 to 11.5, depending on size.
- Leak detection, Follow Me and a Gold Fin coated outdoor coil.
- DIYPro armored cable between the indoor and outdoor units, so that run needs no conduit.
- Outdoor sound of 54 to 60.5 dB(A).
- Parts coverage for 5 years and the compressor for 7, plus a lifetime compressor option with registration and MRCOOL's paid Care program.
Does the higher efficiency pay for itself?
You can work this out with your own bill. For cooling, divide the BTU of cooling the room needs in a season by the SEER2, then by 1,000, to get kilowatt-hours.
Take a 12K unit running the equivalent of 1,000 full-output hours a summer, which is 12 million BTU. We used 15 cents per kWh as an example rate; swap in yours.
| SEER2 | Which unit | kWh for 12 million BTU of cooling | Cost at 15 cents per kWh |
|---|---|---|---|
| 16.5 | Lowest Select | 727 | $109 |
| 17.5 | Highest Select | 686 | $103 |
| 18.0 | Lowest 5th Gen | 667 | $100 |
| 23.6 | Highest 5th Gen | 508 | $76 |
Best case, the top 5th Gen size saves about 219 kWh, roughly $33 a summer, against the least efficient Select. At the other end, a 5th Gen at 18.0 next to a Select at 17.5 saves about 19 kWh, or $3. With a $960 price gap at 12K, cooling savings alone take decades to pay back.
Heating changes the math
HSPF2 works the same way: BTU of heat divided by HSPF2 gives watt-hours. Say the room takes 20 million BTU of heat over a long northern season.
At the Select's lowest 8.3, that's about 2,410 kWh. At the 5th Gen's best 11.5, it's about 1,739 kWh, a difference of 671 kWh, or about $100 a year at 15 cents. That's real money, though it still takes close to ten years to cover the 12K price gap on power alone.
Two cautions. The SEER2 and HSPF2 numbers vary by size, so look up your exact unit on the specifications page. And your hours could be half or double ours; use your own.
Our take: count the power savings as a bonus on top of the reasons below. If none of them apply to your room, the Select or EasyPro is the better buy.
What else does the extra money buy?
A 25 ft line set in the box
The Select and EasyPro ship with 11.5 ft, and going farther means buying a longer pre-charged line set for them. With 25 ft in the 5th Gen box, the outdoor unit can go around a corner, away from a bedroom window or to the side yard. Bought on its own, a 25 ft 5th Gen line set is from $264, so that part of the price gap is easy to see.
The 36K size
No other MRCOOL DIY single zone goes past 24K. The 36K is rated for up to 1,550 sq ft, which suits a big open great room or a large shop. Our 36K review covers when one large unit beats a 2-room multi-zone.
Armored cable
The DIYPro armored cable between the units is built to run without conduit. That's one less thing to buy and fit, and one less question for your inspector, though local code has the final say.
The warranty
Five years on parts and seven on the compressor, against one and two on the Select. If a part fails in year four, that difference alone can cover a good share of the price gap. Coverage is for the original owner and includes a DIY install once you register.
Next: Should you buy one single zone or a multi-zone for your home?
How do you choose the right 5th Gen size?
- Measure the room. Length times width gives square feet. Compare it with the ratings in the table above, then adjust with our sizing guide for high ceilings, big windows, sun and insulation.
- Check your power. The 9K and 12K run on 115V; 18K, 24K and 36K need 230V. Each needs its own circuit, sized per the installation manual for your unit.
- Measure the line set run. If 25 ft reaches, you're done. If not, separate line sets come in 35 and 50 ft, and up to 75 ft with a coupler kit. The pipe size has to match: 1/4 x 3/8 in for 9K and 12K, 1/4 x 1/2 in for 18K, 3/8 x 5/8 in for 24K and 36K.
- Think about winter. The 5th Gen keeps heating down to −13°F outside. Below that, keep a backup heat source or size up, and call us for cold-climate sizing.
Watch how the 25 ft line set and the armored cable are routed from the indoor unit to the outdoor unit.
What if the 5th Gen isn't a clear fit?
What if my run is only 8 ft?
The line set is pre-charged and can't be cut, so you'd coil the extra 17 ft neatly behind a cover or near the outdoor unit. If that's the case and you don't need the other 5th Gen features, an EasyPro with its 11.5 ft set may be a cleaner fit.
What if I mostly cool?
In a southern house that heats a few weeks a year, the payback math above points to the EasyPro. Its 18.9 to 20.2 SEER2 is close to several 5th Gen sizes.
What if I'll want more rooms later?
A single zone 5th Gen stays a one-room system. If you're planning three rooms over the next few years, look at a 5th Gen multi-zone from the start.
Who should buy the 5th Gen single zone, and who shouldn't?
Buy it if you need a 36K unit, the longest warranty in the DIY family or the best heating efficiency for a long season. A run of 12 to 25 ft tips it further, since the 5th Gen covers that in the box, and it suits owners who plan to stay ten years or more.
Skip it if the room is cooled most of the year, the outdoor unit sits right behind the wall, or you might sell the house in three years. In those cases, put the difference toward the electrician.
What to do next
Measure the room and the line set path, then pick your size. If you're between two sizes or two lines, call us at +1 (844) 999-9725, Monday to Friday, 9 AM to 5 PM EST, with the square footage and your town. For the full side-by-side, read the Select vs EasyPro vs 5th Gen buying guide.
