Are whole-home dehumidifiers or portable dehumidifiers better value?
I need to plan for supplemental dehumidification for my whole house (~1600sq ft, 2 story slab on grade duplex, zone 4a) and am trying to decide what kind of dehumidifier to buy and where to put it.
Option 1: buy a typical portable dehumidifier for like $300
Option 2: buy a ducted, whole-home dehumidifier like Santa fe or aprilaire e80, which are like $1500
I’m sure the santa fe and aprilaire units are better built & last longer, but the efficiency boost only looks marginal (ENERGY STAR Certified Dehumidifiers | EPA ENERGY STAR) (they’re all between 2 and 2.35 l/kwh). Will they really last 5x as long? Are there other ductable units that are better options?
The biggest problem with the portable units is where would I put it? Autodrain is crucial for me. And I don’t see a great option out in the open somewhere. I have a small mechanical closet on the first floor it could go in conveniently and autodrain (and it would dampen noise a bit), but I worry it wouldn’t dehumidify the rest of the house very well. Is there a way I could ventilate that closet sufficiently to make it work?
Thanks for any input!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
If you're only trying to deal with some excess humidity in a basement or accessible crawlspace, a portable unit is probably fine. If you are trying to control your indoor humidity levels during seasonal transitions or in a humid area, then the whole home unit is a better way to go. I'd be more concerned with the application here than I would the efficiency. Portable units are not the best option when you have large amounts of humidity to deal with over extended periods of time.
Portable units are more likely to fail if you run them a lot. The permanently installed units tend to be more robust.
Bill
Thanks. I've been trying to gauge how much dehumidification I'll need, but with the home under construction, lack of insulation, and attic partially open, it's hard to tell. I'm definitely looking for "controlling humidity during seasonal transitions in a humid area" though, so your point about portable units breaking down if run a lot is helpful.
Any advice on how you would duct it? Would simply finding a way of pulling from upstairs and blowing out downstairs work? Or is ensuring distribution by integrating with hvac supply ducts worthwhile?
You won't be able to gauge things until you're dried in and air sealed. In my own home, a lot of the humidity comes in from the to-be encapsulated crawlspace, which I have partially done but never seem to have the time to completely finish! I have two of those, one is done, the other I have the materials but need to install everything.
Air leaks are going to bring in moisture if you're in a humid environment. Your dehumidifier will constantly be fighting how ever much leaks in through those air leaks. That's what will ultimately decide how much dehumidification you need. Homes that are very well air sealed will do better than more leaky homes.
I have a protable unit running right now. It's my third one. The first came with the house, an old GE unit, and it ran for years. The second was something from the blue store, and it ran another 3-4 years or so then started flashing an error code and running intermittently. The new unit is something from the green store. So far it's going strong, but it's not even 1 year old yet. It runs very nearly continuously through the summer, cycles maybe to 50% or so in the winter.
The usual whole-home dehumidifiers are installed with the HVAC system, and use the same ducts. I know that at least some of the Aprilaire units can operate standalone, and could be ducted seperately from the rest of the system. If I were to install one that way, I'd draw from the upper level and exhaust to the lower level. Moist air rises, so ducting things this way would make stratification work for you.
Bill
Thanks. And yes, capturing the most humid air is good for the dehumidifier & I was also thinking that depositing the warm air from the dehumidifier downstairs would be good to help even out temps in the house.
Do you see any issues with just letting the dehumidifier exhaust air into the mechanical closet in which it would sit? (air would be supplied through a duct pulling from upstairs, and I would make sure there were sufficient undercuts or I would insert some louvers in the closet doors to make sure air could find its way out). I ask b/c space is really tight, and configuring separate ductwork out of there will be tricky.
I don't think you'd have an issue exhausting air into the mechanical closet, since the air from the dehumidifier should be pretty dry. You would want the closet to be vented (put some slats in the door), and you would be adding additional heat to the closet. Aside from that, I don't see any issues.
Bill
I've always been curious about the Daikin Quaternity. It's a minisplit where the head has two coils. You can have both heat, both cool, or one heat and one cool -- which is what a dehumidifier does. It would seem to have a lot of advantages, it's built-in like a whole-house dehumidifier and it does double duty as a minisplit.
But I've never seen one installed. It uses R410A for the refrigerant, which is being phased out at the end of the year, and I haven't seen an R32 version, which makes me think that Daikin might be discontinuing it. So there must be a downside.
yeah sounds interesting. Would be nice to have the versatility in one unit
The best units from Santa Fe and other units of their parent company ThermaStor are disqualified from the energy-star lists based on a stupid rule that a cartel of other manufacturers managed to get in the book: To qualify for energy star, it needs to be physically small, but the extra technology ThermaStor uses makes them physically larger. If you compare the numbers for the best SantaFe units they are fantastic. But the best tech is in a different ThermaStor brand, Quest.
Can you wait until 2025 to buy it? The rule limiting refrigerant global warming potential in dehumidifiers starts in Jan, so you should have a bunch of new models available, which will likely have better performance as well as lower climate impact.
Yes, I could wait until 2025 to buy one. So that's good to know that some new units should be coming out. Curious which santafe units you are referencing, though? A couple are listed on energystar, such as the ultra98. And it is efficient at 2.21 L/kwh, but many portable units are 2.01 L/kwh and there are some Aprilaire units at 2.35. Looks like santafe lists the efficiencies at the older 80deg/60% humidity levels on their website, so they are higher there.
The main difference betwen the ThermaStor units vs the portable are that you can duct the ThermaStor. If you need ductwork, go with the ductable units. If you don't, you are correct -the portable units are FAR less expensive.
While I appreciate the ThermaStor units, my experience is that I'm on my third unit in less than 3 years. ThermaStor has worked with me on replacing them via warranty, but that still has a cost, and there is a cost to get rid of the old unit. There is no possibility of getting the unit repaired if it fails as you can't find anyone willing to work on it. A nearby home has 2 of ThermaStor's built in wall units; one was shipped back to Thermastor and was returned repaired 3 months later; it has since failed again. The other one failed and they decided not to deal with it and bought a portable unit.
I love the idea of the ducted and built in units, but they are costly, there is no way to get them repaired locally, and based on a sample of two households, they are not as reliable as I would like.
In your case, I would install the ducting for the ducted, so you can do that direction if you need, but initially I would go with portable units.
Yeah, I would be pretty disappointed if I bought one of those units and it proved to be that unreliable.
Another complication I'm experiencing is that virtually none of the ducted units come in a vertical orientation like the portable ones, and due to space restraints with trying to fit it into a closet, I haven't figured out a good way to duct it yet w/o choking the flow. The "compact" ones also tend to be shorter but nearly as long, which doesn't help the limiting dimension.
Key question with portable is how to get adequate air circulation to dehumidify the house...
>"Key question with portable is how to get adequate air circulation to dehumidify the house..."
You can set your regular HVAC system's fan to run periodically just to "stir" the air. That will help to even things out throughout the house.
Bill