Seeking Opinions on Daikin Quaternity Ductless Heat Pumps
I’ve read many times about the independent humidity control of Daikin’s Quaternity models. I’ve even found myself jealous of them after installing a Mitsubishi and feeling muggy in my house on a mild spring day when there is little need for cooling, and the dry mode makes us feel too cold. There are illustrations and videos on the web showing how it works — the indoor coil is split into two parts, one of which can be hot and one of which can be cold (at the same time), which allows for dehumidification without cooling. That’s great, but in all my perusal I don’t recall ever reading a single personal experience with how well this actually works in real life. Does it really maintain a stable humidity level year-round? How much is energy use increased by this additional dehumidification function? And why are these not hugely popular considering all the talk I’ve seen about latent loads being such an important issue in high performance homes?
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try setting the fan speed manually to very low, and the temperature lower than the desired setpoint. I will act more like a dehumidifier
Keith, isn't that what dry mode already does?
I don't trust the machine to do what I want, it has a mind of its own.
Well, the main issue with dry mode is not that it doesn't dry, but that it has a slight cooling effect, which gets uncomfortable and causes us to turn it off. Running cooling mode on low would have the same problem.
Umm, I guess you could assume that is true or do something radical like trying it............you can change both temp and fan settings to see if something works better than the stock setting
From posts on other forums I'm led to believe that the Quaternity has a dehumidistat, but does not in fact (as implied) dehumidify without at least some sensible cooling, nor does it dehumidify in heating mode as I had previously been led to believe. There may have been a design revision, altering the operation function of their innovative split coil & valving in the indoor unit that allowed dehumidifying in heating mode , or completely without sensible cooling, or maybe there was confusion early on.
Beats me, but it does not dehumidify in heating mode, and there will always be some sensible cooling, though the latent/sensible cooling ratio will be different in DRY mode than in DRY COOLING mode, and it's not clear that it responds to the temperature setpoint in DRY mode.
In the engineering manual it implies that in DRY mode (as distinct from DRY COOLING mode) there is less sensible cooling as it approaches the humidity setpoint, but that's not the same as no sensible cooling. See the notes at the bottom of P49 (p50 in PDF pagination):
http://www.daikinac.com/content/assets/DOC/EngineeringManuals/EDUS04-906_b%20Quaternity%20Heat%20Pump%20Engineering%20Data.pdf
The coil & valving diagram on p.8 (p.9 in PDF) implies that the coil really is split, and operates differently in DRY mode.
If the internet-scuttlebutt about how well it works is true, the primary distinction between the way the Mitsubishi & Quaternity works in dry-mode may be that the Daikin's dry mode is under dehumidistat control, and stops when the RH hits it's setpoint, whereas the Mitsubishi keeps running until you put it in heating or cooling mode. But they allege there is at least some re-heat when in DRY mode.
100% aware this is a 7-yr old thread, but would love to hear if this is still Dana’s thinking on the Daikin Quaternities (humidistat control confers some slight advantage in handling latent loads without sensible cooling, split coil/reheat not so much?).
If what they say is true, it seems like the Quaternity is the runaway best choose for a minisplit in a humid zone...
Ditto! I have the same question, and I would love to hear from anyone who has tried using the Quaternity primarily as a dehumidifier.
I'd like to see a detailed financial analysis of the expensive Quaternity vs a typical AC plus dehumidifier.
Bumping this thread to see if anyone has any thoughts on the Daikin Quaternity, as I'm considering it due to its humidity control functions. It looks like the implication in the engineering manual mentioned by Dana above (that there is some sensible cooling and does not dehumidify in heat mode) has not changed. Just wondering if anyone has any practical experience with the unit and can comment on how well it functions.
I would love to know, too!
I just installed a 12kBtu Daikin Quaternity for the specific purpose of dehumidifying. The installed cost was $4850.
It is too soon in the year to know how well it will dehumidify. We had one muggy day, and I was pleased to see that the "Sarara" drying mode did hold the RH at 50% when set on "Low" (i.e., a low RH setpoint). We collected about 1 gallon of water from the discharge.
I will post again after I have more operating data.
Mark, what climate zone are you in? Curious what your outdoor dewpoints are and how well the Daikin will do.
Also, once it gets to full dehumidification season, can you let us know how much cooling the system provides when you are primarily trying to dehumidify? For example, if you want your indoor temp to be 76 but your RH to be 50%, is the Daikin going to end up overcooling by several degrees to reach the desired RH?
While the Quaternity is specifically designed to dehumidify without overcooling, it's a good question just how far it can go - can it dehumidify down to zero sensible load?
All I know is that with my Mitsubishi FH09, during high humidity, mild temperature days in fall/spring, the humidity in my finished space can get up to 60% or more when the indoor temp is 72 or 73. Sure, turning on dry mode drops the humidity, but it also lowers the temp way down to about 68 or less. I stopped using dry mode completely and just got a standalone dehumidifier.
Would love to know how the Daikin performs under similar temp/humidity scenarios.
I had a chance to try out my Daikin Quaternity for dehumidifying. We had muggy weather that kept the unit running more-or-less continuously, with the Sarara (dry-only) set to "Lo" humidity. With outdoor dew point at 71 deg F, and operating with indoor air at 68 deg F, the Daikin held the indoor RH at roughly 53% (= dew point of 50.3 deg F). It produced 4.3 gal/day of water and consumed about 15.1 kWh/day of power. It did not change the room temperature to any notice-able degree.
The Daikin replaced a Whynter 70-pint portable dehumidifier. Operating under roughly similar conditions, the Whynter produced 4.5 gal / day and consumed 14.3 /kWh / day. However, the Whynter was rejecting the heat of vaporization to the conditioned space, and I estimate that it required another 7.7 kWh / day for the air conditioner to remove that heat. So the total power consumption for the Whynter was about 22 kWh / day.
More to follow . . .
In other tests, with less challenging moisture loads, the Daikin consumed less power and produced less water. The minimum power consumption I saw was in a low-moisture load situation (outdoor dew point = 50 deg F) with the humidistat set to "Standard". The Daikin held the indoor RH at 54% while consuming 4.8 kWh / day and produced 0.4 gal / day of water. I think this is likely the minimum power consumption, basically what is needed to run the indoor fan.
The Whynter portable had died after two summers, and I was glad to see it go. It sounded like a lawnmower! My main reason for installing the Daikin was to solve the noise problem. But I also gained some energy efficiency and the increase in annual cost was (by SWAG) only $100 or so.
If I had installed a mini-split system for my main HVAC, as I wish I had, I would have been well set with a Daikin Quaternity. The Sarara Drying feature works, and it is quite useful for a tight house in a mixed climate like mine.
Nice data. Using your numbers and some other assumptions (everyone's will be different), I get about an equal purchase + operating expense for a Quaternity (high purchase price) vs a dehumidifier (lower purchase price, even when accounting for a short lifetime). I'd expect the Quaternity to be much less expensive in Florida.
What price to you put on reliability? I find that standalone dehumidifiers are hard to keep running.
Mark, Thanks for the information. I look forward to hearing more about how it operates.
Bought the 9k Quaternity for the main floor as supplemental heat. Didn't plan much cooling. This unit has no "fan only* mode so we set it to 90 degrees cooling with the breeze option. Humidity hit 60% yesterday so I pushed the dry button and it went down about to 57%, still learning about it. Live in Western Oregon was about 92 high yesterday.