Sizing a Dehumidifier for 600 sq ft basement

D107 · May 28

My 50 pint Frigidaire FFAD5033W1 dehumidifier has bit the dust after only three years. Previous GE unit lasted 7. Maybe lost refrigerant? Anyway, I think I need a unit that basically stays on all the time. The basic basement humidity when humid outside is about 55. This unit emptying capacity is 50 pints, but generally empties 2 gallons a day (16pints), and is rated for 4500 sq ft. Seems way to big. I had this on a timer off and on, perhaps that did the unit in.

A smaller 22 pint capacity unit would seem better—or even smaller. Rated for 1500 sq ft 3 fan speeds. Bucket holds 1.7 gallons, about my usual condensate. I usually set humidity at 40% so since that will stay the same, seems smaller than this will result in smaller bucket which I'll have to empty more than once a day..

ratio · May 28

Any reason why you don't go with a unit with an internal pump, so you don't have to empty the bucket every day?

D107 · May 28

This one does have a hose drain option (not sure if that's a pump or just a gravity drain) into slop sink which I did for years with the previous dehumidifier. However the easiest way to do that was to keep it in the boiler room—near the slop sink—about ten feet from the main room. A real pump unit would allow me to keep it in main room and run a pex? line into slop sink, a bit more set up work. Also I found that the constant drip drip into the slop sink fostered some sewer flies. That pump option —more expensive and possibly another thing that could break down—WOULD allow me to size the unit purely for the correct capacity of dehumidification (about 2gallons a day) rather than have to factor in the bucket capacity. But since dehumidification req and bucket size are about the same, maybe no issue there except having to empty it daily. Also this smaller unit would seem to emit less heat than the prior 50 pint unit. The low speed CFM on this unit is 97 vs 167 for the larger unit, so it would work slower with less off and on.

I also see Midea has a very high efficiency rated unit 20 pint capacity. It's lowest speed cfm is 215; I'd prefer half that so that it would stay on longer but overall this seems smarter and easier to clean. The Frigidaire bucket has many intricate surfaces and is very hard to clean—and mold will form there several times during a summer. Noise is measured in Sound Pressure not DB, but SPL is 48, which from 20 ft away shouldn't be bad.

https://www.amazon.com/Frigidaire-FFAD3534W1-35-Pint-Dehumidifier/dp/B0BHCC5VDJ/ref%3Dasc_df_B0BHC5P5TZ?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80608063550906&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584207598498525&th=1

https://www.amazon.com/Midea-Dehumidifier-Ft-Compact-Basements-Medium-sized/dp/B08ZMY8BC8/ref%3Dpd_lpo_sccl_3/147-8217505-2461108?pd_rd_w=42cRr&content-id=amzn1.sym.1ad2066f-97d2-4731-9356-36b3edf1ae04&pf_rd_p=1ad2066f-97d2-4731-9356-36b3edf1ae04&pf_rd_r=KZNPT7JQ36BT1GPBDZZF&pd_rd_wg=LNYkE&pd_rd_r=ae732f9e-80bf-4d07-a563-ba275fde08a5&pd_rd_i=B08ZMY8BC8&th=1

ChrisJ · May 28

I use a condensate pump behind mine.

When I replaced the dehumidifier this year I kept the same pump. I try to get the one without the safety switch but it doesn't matter either way you just don't hook it up in this case.

https://www.amazon.com/Little-Giant-554405-Condensate-Horsepower/dp/B000AHT78O/ref%3Dmp_s_a_1_1_sspa?crid=2OQGHPUH1Q4Q7&dib=eyJ2IjoiMSJ9.MehZW7EKXcxXgpeZhIaVxv0Qm6QpUUKowOcNoHP02sbDFxOCrde7qYoayI6Ha9Zlm6ce-eIf4ORwTlySF1Vwf7WbZX2eupxJhm0CVlrnIo8d8mNt-SNhX0BCUNjj53YJ4dKcnBi9v_alm6iq3dYh9zcCcwyaAZFgdcIjUfKkTt2EE17vAdrKYAzMkKkRzg6wX_akDg82EOZmLkSRbt6lZQ.r7JtTcwxiyxQJZq-nL3cSNyMQzw-yjageohlrsX1LYE&dib_tag=se&keywords=condensate+pump+little+giant&qid=1716863525&sprefix=condendate+pump+little%2Caps%2C100&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRm&psc=1

D107 · May 28

One difference between the Frigidaire and preferred Midea is the low speed fan CFM. Frigidaire is 97 vs 215 for Midea. The 97 would seem to result in less recycling, but by how much? X more cycles per day? My current dead Frigidaire low speed was 167cfm which worked too fast. Ideal for this space is probably 50 cfm with the same 20 pint capacity.

jumper · May 31

My choice is two small ones if you can find some small enough. Almost all the time need only one. Stagger humidistat so that second goes on when primary takes a vacation. If I can I install a rack above sink. Above advice is important for vacation homes so one can shut off A/C.

ChrisJ · May 31

I had a Frigidaire last 12 years.

Now I have another and it seems good but it has the same exact issue the last one does. It's built in humidistat senses the humidity from inside the machine and causes it to turn back on pretty soon.

Makes me wonder where the sensor is, and how easy it would be to relocate it a foot or two from the machine.

JakeCK · May 31

https://forum.heatinghelp.com/discussion/comment/1802903#Comment_1802903

I have the same problem. It is most noticable when the tank in mine fills up. The humidity with skyrocket to 80% but that is just the humidity coming from the tank its self and the coils. The sensor for mine is located on the back right where the filter is.

D107 · May 31

I bought the 22pint Frigidaire unit, set it for 40% and with medium fan speed (115cfm) and heavy humidity outside, it easily maintains 43%. (When outside humidity is 30% as now, inside keeps 36%.) Bucket size is 1.7 gal, a little small but not a problem. For this unit —unlike prior 50 pint unit––I will not attach a timer to turn off every hour or so to save electricity or compensate for the fact that the capacity was too large for 600 sq fr and dehumidified too quickly—that on and off might have aged the prior unit prematurely. New unit on medium speed is very quiet, and I'm hoping will give off much less heat. Refrigerant is R32 which is supposed to be more efficient.

Makes me want to get a 50 pint unit for the main floor; would probably save money with less air conditioning (just north of NYC.) Will have to convince the wife to allow yet another gadget in the house. 1500 ft reach would probably cover both upper floors if I could locate it close to both.

kenjohnson · June 12

I've tried both smaller and larger dehumidifiers, different dehumidification set points, running on timers only overnight (continuously) or cycling it (letting it do its thing) in a similar size basement and I find that no matter what I do the dehumidifier is dead in three years.

D107 · June 12

Good to know and that was my most recent experience, but I refuse to pay for that extra insurance they offer you. My prior GE unit lasted for 5-6 years which I find acceptable. If this Frigidaire goes only 3 years again it will be my last Frigidaire. But this time around I've been setting it at 35%, low fan speed and I think because of its size is giving off less heat and keeping humidity at 35-40%. Time will tell.

JakeCK · June 12

https://forum.heatinghelp.com/discussion/comment/1803857#Comment_1803857

I had the same dehumidifier for over 10 years and it would run nonstop for 7 months of the year. I only replaced it because of the foul smell I couldnt get out of it even after cleaning the coils. Idk why people burn through so many of them. :s My current one is almost 3 years old.

ChrisJ · June 12

https://forum.heatinghelp.com/discussion/comment/1803869#Comment_1803869

I had one go 12 years.

I suspect both of us were very lucky and we're the oddballs here.

Get ready to start replacing is the feeling I've got.

jumper · June 12

Too long ago I tried to make my own dehumidifier from an electric fan; a timer; and an old refrigerator. I think an hour a day sufficed for 1200 sq ft basement during notoriously humid Toronto spells.

Larry Weingarten · June 12

Hi, This is likely too strange an idea, but heat pump water heaters make great dehumidifiers. Just install your HP water heater in the space. 😜 It would be a nice twofer.

Yours, Larry