MrCool DIY 5th Gen vs 4th Gen: What Changed

The Short Answer

The 5th Generation MrCool DIY mini split is a meaningful upgrade over the 4th Gen in almost every measurable way — better efficiency ratings, lower noise levels, improved WiFi connectivity, and a sleeker indoor unit design. If you're buying new, there's no reason to pick the 4th Gen. If you already own a 4th Gen, whether an upgrade makes sense depends on your situation.

Let's break it all down.

Efficiency: The Numbers That Hit Your Power Bill

This is where the 5th Gen pulls ahead most dramatically.

What does that mean in real terms? SEER2 (Seasonal Energy Efficiency Ratio) is the key metric for cooling efficiency. Going from 22 to 24.6 translates to roughly 10-12% lower electricity costs during cooling season. In a state like Texas or Florida where your mini split runs 8 months a year, that's $80-$150 in annual savings on a single zone.

HSPF2 measures heating efficiency, and the jump from 9.5 to 11.0 is even more significant proportionally. If you're using your mini split as a primary heat source in a moderate climate, this upgrade pays for itself faster than you'd expect.

The 5th Gen achieves these gains through an updated inverter compressor and redesigned heat exchangers — more surface area, better refrigerant flow, same physical footprint.

Noise Levels: Genuinely Quieter

The 4th Gen was already quiet by mini split standards — about 35 dB on the indoor unit at low fan speed. The 5th Gen drops that to 32 dB on the 9K and 12K models, which is functionally silent. For reference, 32 dB is quieter than a whisper from across the room.

The outdoor condenser also got a noise reduction — from around 56 dB to 52 dB. Your neighbors will appreciate that.

Why It Matters

If you're installing in a bedroom or home office — which many people do — every decibel counts. The difference between 35 and 32 dB might not sound like much on paper, but human hearing perceives it as a noticeable reduction. Zomg the Handyman specifically recommends the 5th Gen for bedroom installations because of this improvement.

WiFi and Smart Home Integration

The 4th Gen required a separate WiFi adapter dongle (about $60) to enable smart features. The 5th Gen has WiFi built in — no dongle, no extra cost.

Both generations work with the MrCool SmartHVAC app for iOS and Android, giving you:

• Remote temperature control
• Scheduling and timers
• Energy usage monitoring
• Multiple unit management from one app

The 5th Gen adds native compatibility with Google Home, Amazon Alexa, and Apple HomeKit (via the app bridge). Voice control works out of the box: "Hey Google, set the bedroom to 72 degrees."

Design and Build Quality

The 5th Gen indoor air handler is noticeably sleeker. MrCool reduced the depth of the unit by about an inch and softened the lines — it looks more like a modern European design than the somewhat boxy 4th Gen.

The louver mechanism also got an upgrade. The 4th Gen occasionally had issues with louvers getting stuck or making a faint clicking sound during oscillation. The 5th Gen uses a new motorized system that's smoother and more reliable.

The outdoor condenser looks similar between generations, but the 5th Gen unit has improved corrosion-resistant coating on the coils — marketed as a "Gold Fin" coating — which extends the life of the unit in coastal or high-humidity environments.

Installation: Same DIY Simplicity

Here's the good news if you loved the 4th Gen install process: nothing changed. The 5th Gen uses the same Quick Connect line set system with pre-charged, pre-flared connections. No vacuum pump, no manifold gauges, no HVAC license.

The mounting bracket is compatible between generations, so if you're replacing a 4th Gen indoor unit, you can often reuse the existing bracket.

Line set lengths and sizes remain the same across comparable BTU ratings. The electrical requirements are also unchanged:

• 9K and 12K: 115V / 20A dedicated circuit
• 18K, 24K, and 36K: 230V / 30A dedicated circuit

Operating Temperature Range

The 5th Gen expanded the heating range. The 4th Gen could heat down to about 5°F (-15°C). The 5th Gen pushes that to -13°F (-25°C) on select models. That's a massive improvement for homeowners in northern climates who want to use a mini split as a primary heat source.

For cooling, both generations operate up to 122°F (50°C), which covers even the hottest desert climates.

Warranty

Both generations carry MrCool's standard warranty:

• 7 years on compressor
• 5 years on parts

No change here, though the improved build quality of the 5th Gen should mean fewer warranty claims in practice.

Should You Upgrade from a 4th Gen?

If your 4th Gen is working fine and you're happy with it, there's no urgent reason to swap it out. The efficiency gains are real but modest — it would take 5-8 years to recoup the cost of a new unit purely through energy savings.

If your 4th Gen is aging or having issues, absolutely go with the 5th Gen as a replacement. The better efficiency, lower noise, built-in WiFi, and expanded cold-weather heating range make it the clear choice.

If you're buying your first mini split, there's zero reason to hunt for leftover 4th Gen stock. The MrCool DIY 5th Gen Bundles are the same price or very close, and you get a better product across the board.

The Bottom Line

The 5th Gen isn't a revolutionary redesign — it's a refinement of an already excellent product. MrCool took everything people loved about the 4th Gen DIY line and made it measurably better in the areas that matter most: efficiency, noise, and smart connectivity.

If you're ready to buy, check out the full lineup of MrCool DIY 5th Gen Bundles. Use code SUMMER100 to save $100 at checkout.

Shop 5th Gen Bundles →