Hi, I just had a Daikin Quaternity installed this past weekend. The AC and heating functions are working great. However, when I put the unit in "drying mode", the humidity does not change. The info reads temperature 59 F, and humidity 70% constantly. The unit displays that it is in "drying mode" and the fans are continually on, but the humidity does not change and absolutely no moisture is extracted. I even placed a plastic cup underneath the PVC pipe, and it was bone dry. I called Daikin technical support this morning, and they told me that "drying mode" does not dehumidify very well when the temperature is cold. Then he recommended that I put it in "dry cooling" mode, but then said that even that wouldn't work because I was below the operating AC temperature of 64F. Essentially he told me I was out of luck because of the cold temperature. I was really confused by this because I thought that the Daikin Quaternity was could dehumidify at a constant temperature by toggling between heating and cooling. Additionally this particular Daikin technical support representative didn't seem very knowledgeable - it seemed like he attended a weekend training session based on the operation manual. So I wanted to ask the experts on this forum as well as other Daikin Quaternity owners. Should the Daikin Quaternity be able to dehumidify in "drying mode", when the temperature is 59 F? I live in a foggy area of SF, which is why it is both cold and humid. Thanks in advance for your help. Thanks, Alex

You may have to add a conventional dehumidifier, some of which claim to work down to 40F.

Additionally this particular Daikin technical support representative didn't seem very knowledgeable - it seemed like he attended a weekend training session based on the operation manual.

Anything can happen, but that's a very different experience than I have had with Daikin representatives. Not only are they knowledgeable, but if you bring up anything they don't know about, it gets escalated to someone who does.

Should the Daikin Quaternity be able to dehumidify in "drying mode", when the temperature is 59 F?

How is that going to work? You can't dehumidify air by heating it. It's 59F outside and you want to have it blow even colder air into your home?

temperature 59 F, and humidity 70% constantly.

Heat that air to 72F and it will be a comfortable 47% humidity.

A conventional portable dehumidifier would probably work in the short term while you get it figured out. My basement had a leak not long ago and it was about 60 degrees down there. I turned on my dehumidifier to dry up the water. It took longer to fill up the tank than in the summer when it's 70 degrees down there but it worked.

You do have a challenge on your hands. Warming up the house would help. You may have to augment in the bumper seasons.

The thing wasn't really designed to dehumidify a basement, thus I'm not surprised it isn't pulling a lot of moisture out if it's heating the place to only 59F.

The Quaternity doesn't dehumidify by toggling between heating and cooling. The coil on the interior head is split into two sections and has a separate valve to be able to use half the coil for dehumidifying even while the other half is actively heating or cooling to be able to control the temperature of the exiting air to meet the sensible heating or cooling needs while dehumidifying. The valving that separates / joins the two parts of the coil may be togging (or modulating) to adjust the moisture content of the exiting air as best it can while still heating/cooling the exiting air to an optimal temp, but the basic mode at the compressor end is not toggling. IIRC the dehumidistat control only affects the state of the valving at the split coil.

If you're using it strictly as a dehumidifier normally you'd be better off in cooling mode, where both parts of the coil in the head are engaged rather than just part of the coil. But if the room temp is below the minimum operating point for the unit in cooling (which is designed to operate at more typical conditioned air temperatures, not 59F- what are you a BRIT or somethigh? ;-) ) it won't be able to do much for you.  I'm sure it could be done with a firmware change on the control system, but it isn't currently designed to do anything other than heat when the incoming air temp is 59F.  If you run it in heating mode at it's minimum temperature setting and turn the humidity setpoint to 50% or something it might be able to do some dehumidifing though (just a guess), even if the room is still 59-60F.

I had a Quaternity installed around the same time as the OP. Similar issues, though I have it installed in a daylight, finished basement that has two bedrooms. The unit seems to dehumidify sometimes, sometimes not. I'm still trying to work things out and really figure out how it operates. The times that it has worked, the room is 68 when I turn it on drying, then the output air is 41%, 79F. If the room gets too warm, it'll shut down until the room cools down. If the unit is operating at night, it'll keep the room at 72F, 52%. However when the room gets more ventilation during the day (bedroom door opened), the room cools down to 64 and the unit doesn't dehumidify anymore.

For the OP, I would suggest heating the room to 68 with the Quaternity, change setting to drying mode, and set the humidity to cont. I was disappointed that there is not a % set point, rather you have your choice between Hi, Std, Low, or Cont. It seems that this unit has the technology to be able to set a temp and RH and cycle between its three functions (heat, cool, drying) to maintain.

I believe Daikin should have put some sideboards in their manual about operating temperatures. If the unit cannot dehumidify below 65 degrees, I never would have bought the very expensive unit, and perhaps the OP wouldn't have either. I'm fairly frustrated with a company that is highly regarded for making excellent products.

Many of my customers operate their radiant floors in the basement slab, (stapled right on the XPS foam by the way), as i do, year-round. RH is the key. If infiltration is controlled and the upper floors are properly cooled--this would imply RH below 50%--then all is well.

There are few methods for keeping a basement in cold climates from being damp and cold by moving air. A dedicated--dare I say; ducted?--dehumifier is the only other practical option.

I've been looking at whole house dehumidifiers. The specs break out the moisture removal at 60, 70, and 80 degree breaks, and even at 60F it can remove quite a bit of moisture. Most the ones I looked at also have operating temps, and optimal temps, starting in the upper 50's. This would work for me, though I would have to get Daikin to take their unit back and refund my money first. I'll continue to work with Daikin and the company that installed the unit, but its not sounding like this unit will work for me.

The minisplit market and the VRF technology is growing quickly in sales and application. Like any product boom there will be bandwagon installers (Hey ya'll we should get us a piece of the pie).
We see it a lot in geo. Word of caution to those looking at these systems for specialized application- Research and find the best installer in your area and you'll be fine. Presume all splits are equal and all installers are equal and you might be sorry.

Posted By CoosBayBrew on 05 Apr 2014 06:59 PM
I had a Quaternity installed around the same time as the OP. Similar issues, though I have it installed in a daylight, finished basement that has two bedrooms. The unit seems to dehumidify sometimes, sometimes not. I'm still trying to work things out and really figure out how it operates. The times that it has worked, the room is 68 when I turn it on drying, then the output air is 41%, 79F. If the room gets too warm, it'll shut down until the room cools down. If the unit is operating at night, it'll keep the room at 72F, 52%. However when the room gets more ventilation during the day (bedroom door opened), the room cools down to 64 and the unit doesn't dehumidify anymore.

For the OP, I would suggest heating the room to 68 with the Quaternity, change setting to drying mode, and set the humidity to cont. I was disappointed that there is not a % set point, rather you have your choice between Hi, Std, Low, or Cont. It seems that this unit has the technology to be able to set a temp and RH and cycle between its three functions (heat, cool, drying) to maintain.

I believe Daikin should have put some sideboards in their manual about operating temperatures. If the unit cannot dehumidify below 65 degrees, I never would have bought the very expensive unit, and perhaps the OP wouldn't have either. I'm fairly frustrated with a company that is highly regarded for making excellent products.

In Coos Bay the outdoor dewpoints are nearly ALWAYS low enough to dehumidify primarily with an HRV by bumping up the ventilation rate. (Pull up a dew point history graph on WeatherSpark and scale it to cover an entire year.)  The mean mid-summer outdoor dew points are in the low 50sF in an average year. Last summer was exceptional with weeks where dew points averaged in the low 60s, and it even nose over 70F a couple of times, but in cooling mode there should be no problems managing those latent loads with the Quaternity.

The months of December through February the outdoor dew points average around 40F and even the exceptional peaks are in the mid-50s.  The dew point of 65F/50% RH air is ~45F, the dew point of 70F/50% RH air is ~50F, so only on the days when it's north of 50F outside with "Oregon mist" type rain would you need to use something other than ventilation to hold the line of the interior RH at about 50%

The notion of installing a whole house dehumidifier in a house in Coos Bay (or really anywhere in the Pacific Northwest), is a bit bizarre- like going after no-see-ums with a sledgehammer.   From September through May it can be completely controlled by ventilation rate, and during the summertime peaks dialing back the ventilation rates and dehumidifying with the Quaternity (and maybe a standalone room dehumidifier.) 

Dana1 -

Thanks for your reply. What I am understanding from your message is that on an evening like tonight, when the outdoor temp/humidity/dew point is 53F/100/52 is that if I open windows (better yet, an HRV) and reheat that air, it'll be drier than my 64F/65% indoor air? And once the outdoor temp equals or is less than the dew point, then I should close the window?

My house is rather sealed, so the idea of ventilation makes sense, though I've never thought about it in that manner.

I met with the Daikin install company's tech guy on Monday. He had a Dealer Information packet that in his opinion was still pretty vague, however it did make mention that the AC portion of the unit and the Dehumidify portion of the unit will both only work between 70 - 109 F, outdoor temperature. Shall I repeat that? The dehumidify (drying) function of the Quaternity unit will only work when the outdoor temp is between 70 - 109 degrees F. Unbelievable that the company doesn't publish that info ANYWHERE that a consumer can see that when doing research on the unit. That means for the OP and I that have this unit installed to dehumidify, it won't function in that except for the few days its above 70 in our climates.

The tech guy is going to call Daikin to see if there is anything that can be done on the circuit board to bring that 70F limit down lower. He said on some Daikin units, their company folks can tell them what jumper to cut on the circuit board to bring the cooling range down from the standard (say down from 70 to 40), when applied in rooms that require year-round AC like computer server rooms. It doesn't void or change the warranty, he claims, as Daikin suggests the modification.

I'll update when I hear something back. Otherwise the company has hurt its reputation by not disclosing the simple operating temperature of one of its functions. All the sales materials claim you can "Set your preferred humidity and Quaternity will do the rest!!" Yeah, but only if its 70F or greater outside.

CoosBayBrew,
Why aren't you mad at the guy who sold you the thing? He's the one who misapplied the unit. Daiken used to train new dealers, if they still do then this info should be known to whoever you bought it from, if they weren't trained, then they are still responsible.
Anyone who gets how dehumidification works, could see this coming.

I agree that the dealer should have known, and there is some anger directed there, but after looking through the dealer manual and seeing how broad it is, Daikin could have made things clearer. In the pamphlet for the unit is listed the operating range for the outdoor unit for both heat and cooling. Strangely enough, AC is listed from 16 to 109F, different from the 70 to 109f listed in the dealer manual, and how the unit operates. This gives me hope that the outdoor unit can do AC or drying mode down to 16f, but with circuit board modifications.

I disagree that anyone that knows how dehumidification works could have seen this coming. Simple portable $200 dehumidifiers can work down to 50 or below, just less efficient. A personneeds to know much more about mini splits, head pressure, etc to see that it may not work. Thats the manufacturer and dealers jobs to list operating ranges for units so dealers and researching consumers can easily see what will and will not work for them.

When you change the temperature of 52F dewpoint  outdoor air to 65F, the RH is 62%, which isn't a mold-inducing level (though dust-mites will still be able to reproduce at that humidity.)  Raising that air to 70F drops the RH is 53%. 

I'm a bit surprised that Daikin would have designed the thing to dehumidify in heating mode, but only when the outdoor temp is 70F or above (when there is NO heating load.)  Are you sure there wasn't something that was lost in translation, and that the tech really has it right?

The Quaternity cannot dehumidify in heating mode. The four selections you can choose from are heating, cooling, dry cooling (just slows the fan to maximize warm air contact with a cool coil), and drying. Drying mode splits the coil into an upper heating portion and lower cooling portion, to try to keep the room air where it started.

I hope things were lost in translation, but I know for sure that when the outdoor temp is below 70, it doesn't dehumidify. On days when the outdoor unit was in a microclimate that was 70+, it did pull moisture out of the air and dump it outside. Once the outdoor temp dropped though, it just ran the fan to move air, but the coil wasn't cooling or heating. Thus the ambient moisture in the room slowly rose over time.

I haven't heard from the tech yet. I'm out of town, so I hope to make contact tomorrow or Friday.

The tech said when he talked to Daikin, Daikin told him that the unit could dehumidify down to 50 F outside temp. Not sure I believe that, from my experience. He tucked the outdoor temperature probe inside the unit to try to gain 5 - 10 degrees to keep it working when the outdoor temp drops below 50. I'll try that for a week and see what happens. Of course today was fantastically nice, with an unheard of 34% humidity today, so I may have to wait a bit until we get normal outdoor temps and humidities to see if this fix works.

I'll update when I hear something back. Otherwise the company has hurt its reputation by not disclosing the simple operating temperature of one of its functions.

From my experiences with Daikin, I GUARANTEE you that was not their goal. If deception or ignorance was involved, it was an error or due to your local installer.

After many back and forth conversations with my local installer, the operating range for drying mode was found on page 9 of the operating manual, on the page about setting the clock. Note that this is the only place that there is an operating range for the drying mode, of 50 F to 108 F. This range is not noted in the product brochure provided on the website and to customers (heating and cooling temperature ranges are listed), nor is it listed in the Engineering Manual, though there are 9 pages dedicated to heating and cooling specifications. There is also a graph, with indoor and outdoor temperatures, showing the continuous operation and cool down range, but only for heating and cooling. It really seemed like this would have been a great place to put the limitations of drying mode which is much less or a range than either heating or cooling. Now that its summer (day temps 70, night temps 50), the unit will run in dry mode 24/7 and keep the humidity at 50%.

I'm still frustrated with Daikin, and not even sure if they still make the Quaternity. I feel that the operating limitations should be listed in more places that one (perhaps everywhere the heating/cooling specs are listed??) Their new website (daikincomfort.com; with the 12 year warranty stuff) doesn't have any info about Quaternity under ductless systems. My installer is a trained Daikin installer, and it was not made clear to them about this specific operating range. I believe that this is a great unit in a year-round warm climate, or a climate that only has humidity problems in the summer. In the Pac NW, we have humidity issues all year, but especially in the mild winters, where 40 and raining is common, and ventilation doesn't work. My local installer made things right, providing me with a whole house dehumidifier which is very efficient and pulls quite a bit of water.

However, let those that are thinking about a Quaternity, there is a limited outdoor operating range, so buy very carefully.