Real-World Experience with Midea MULMI0513B Multi-Split Compressor?

overkillxx on 05/02/2025 - 21:44
Last edited 05/02/2025 - 21:49

Hey guys,

I’m in the market to replace my aging ducted heating system, which is on its last legs. I plan to take advantage of the current government rebate program, and so far it looks like the most common quotes I’m getting are for Midea and Rinnai multi-split systems.

Premium brands (in my opinion, the “Rolls Royce” would be Mitsubishi Electric—not Mitsubishi Heavy Industries) are coming in at more than double the price. While I do like Mitsubishi, it’s hard to justify spending over twice as much when Midea (or Rinnai) are substantially cheaper.

From what I can tell, the compressors in both the Midea and Rinnai units are essentially the same. Specifically, I’m looking at the Midea model MULMI0513B, which is listed with a:

Cooling capacity: 13.5 kW (range: 1.71–16.75 kW)
Heating capacity: 14.8 kW (range: 1.78–18.15 kW)

On paper, this compressor seems capable of modulating down to around 1.7 kW, which sounds impressive—especially compared to the larger Midea MULMI0618B, which apparently bottoms out at around 4.57 kW.

Planned Setup:
I’m considering pairing the MULMI0513B unit with five indoor heads: 1 × 2.6 kW, 3 x 2.0 kW & 1 × 8 kW. My thinking is that if this unit really can run down to ~1.7–1.8 kW, it shouldn’t cycle on/off too frequently if, say, only a single 2.6 kW head is running. If I used the bigger 18 kW outdoor unit (MULMI0618B), I suspect it would cycle more often at lower demands, wasting energy.

So, on paper, it looks good—but I’m not an HVAC expert, and I’d love to hear real-world feedback from installers or people who already use the MULMI0513B compressor in a multi-split setup. Is it really as efficient and smooth at low loads as the specs suggest? Any insights on reliability, actual performance in heating/cooling mode, or whether you regret not going with a premium brand?

Home & Garden Air Conditioner

Comments

Ltsmash on 05/02/2025 - 22:14

Curious as to why you don't rate the Mitsubishi Heavies?

In terms of split systems it's all I've ever used. Relatively good experience with them so far.
They've also been rated the best on ProductReview.

https://www.productreview.com.au/c/split-system-air-conditio…

But keen to hear your insights.
- MS Paint on 05/02/2025 - 22:48
  
  While I do like Mitsubishi
  
  Huh!
- Jolakot on 06/02/2025 - 01:31
  
  +2
  
  Heard from a few installers last year when planning out my system that the quality of MHI has gone downhill in the last few years, and dealing with their local warranty team is like pulling teeth.
- overkillxx on 06/02/2025 - 09:25
  
  I co-own a small, boutique data center where every data room is equipped with Mitsubishi Electric (ME) split systems that run 24/7. When we expanded the facility to include two additional data rooms, we opted for Mitsubishi Heavy Industries (MHI) units. After about ten months of continuous operation, the first MHI unit failed. Three months later, the second one went down. Despite multiple service calls, more issues persisted, so we replaced all the MHI systems with ME units. That was over 16 months ago, and we haven’t had any problems since.
  
  Although many people speak highly of MHI, this was my firsthand experience. In terms of reliability, I would say Mitsubishi Electric is definitely superior to brands like Midea. However, in my own home—where I don’t plan to stay for more than five years—it makes practical sense to choose a cheaper unit such as Midea, especially since it comes with a seven-year warranty.
  - JIMB0 on 06/02/2025 - 12:26
    
    I worked at a place that has dozens of Mitsubishi Electric systems. They'd been running 24/7 for over 10 years with no failures. I was sold.
bargaino on 05/02/2025 - 22:55

+1

Why multi-split? Are you short of space to put separate outdoor units?
Does it save much money?
- JIMB0 on 05/02/2025 - 23:21
  
  +1
  
  You're putting all your eggs in one basket getting one big outdoor unit running the whole lot. If it fails you'll have nothing. Can't you get seperate split systems on the rebate. I'd rather have 2 or 3 Mitsubishi Electric units then a 5 head Midea.
  - Jolakot on 06/02/2025 - 01:40
    
    You'd need 5 outdoor units to replace a 5 head Midea, why do you think you'd need less?
    
    Plenty of reasons to get a multi-split; better power efficiency, less noise, cheaper to maintain and repair, and most importantly aesthetics because who wants 5 ugly outdoor units when you can have 1.
    
    Multi-split is also cheaper after the rebate, for us it was $1500 more to have individual splits. No-brainer.
    - JIMB0 on 06/02/2025 - 12:30
      
      I meant just install regular split systems. That way you'd have redundancy. It would also be more efficient as the pipe runs would be much shorter, the unit wouldn't have to cycle with a single head running and you'd have more heat exchanger area on the outdoor units.
      - Jolakot on 06/02/2025 - 13:19
        
        @JIMB0: The power overhead for each individual unit would outweigh the efficiency loss from shorter pipe runs.
        
        More expensive to service 5 units than 1, costs more to install 5 units than 1, takes up far more wall space, the only real benefit is redundancy.
Jolakot on 06/02/2025 - 02:59

We ended up getting the MULMI0618B with 3 Venus heads (1x 3.6kw, 2x 8kw), which is overkill as we only really needed 2x 3.6kw and 1x 8kw, but somehow it ended up being $300 cheaper after rebates to get the oversized system. Didn't make much sense to me, but apparently the VEU rebate is larger for bigger systems, and the additional cost for the larger system was less than the additional rebate.

We had concerns about the modulation as well, because the 3.6kw is the only one we usually run at night, but some napkin math put the worst-case wastage at around $18/year for 3 months of aircon + 3 months of heater each night with a 5% efficiency loss to COP and EER by running under-capacity (40kWh wasted for cooling + 35 kWh wasted for heating = 75 kWh total). The installer said 5% is pretty conservative for a modern inverter, seemed to think it'd be a few bucks a year at most, no way to know without actual efficiency curves I guess.

Pretty happy with it, I'd make the same choice again.
- overkillxx on 07/02/2025 - 10:01
  
  It's interesting that you mentioned opting for larger head units is more cost-effective due to the rebate structure. However, I'm encountering some issues when I request the 2.0 kW head units. I've been told that they aren’t available—only the 2.6 kW units can be provided—and it's unclear whether that information is accurate.
  
  Additionally, I was informed that the compressor might not be sufficient to run all the head units in my setup. While it's true that the compressor wouldn't operate at full capacity with every unit on simultaneously, I rarely have all the head units running at once anyway.
  
  What really puzzles me is their outright claim that my configuration won't work, especially since the product literature clearly states that a 5-head combination paired with a 13.5 kW compressor (as mentioned in my original post) is a supported configuration.
  
  The installer is scheduled to call me at 10:30 to explain why they believe it won’t work, and I'm curious to see what they have to say.
  - Brick50 on 09/02/2025 - 13:45
    
    They probably want to avoid the low 2kw units because they offer a much smaller rebate and people don’t understand that they are paying more money for a smaller system
    
    Going from a 3.5kw to 2.5kw head will reduce the rebate by $100-$200 I believe so they probably have a hard time selling people on the idea of paying more for less.
    
    I have done a lot of research over last 3 months and am ready to settle for the MULMI0618B 18kw system. Only bad things I have heard are from people who install Japanese brands or are critical of “Chinese” products.
    
    No one who has the Venus heads has mentioned anything bad about them that I can see

Real-World Experience with Midea MULMI0513B Multi-Split Compressor?

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