2021 12v Peltier dehumidifiers experiences anyone?

[Franziska]

Hi,

in the past we have used the classic salt bag dehumidifiers.

With the new electric setup we would like to add an electric 12v dehumidifier to run this winter season when not on board.

We are not plugged into shore power and I do prefer not to run an inverter constantly when not on board.

A compressor based system draws to much to be left on permanently I guess.

We have 1200w solar, so power is not an issue.
If it's not running during very rainy days it's not a desaster, neither are the few days here where it will frost up.
Humidity is low when it's freezing anyway.

The unit will be placed in the metal kitchen sink and drain overboard.

I know that there have been threads on this before, but I like to hear from folks who have used them in the last 2-3years and what their experiences are.
Please indicate which model you have.

Our boat is a 35ft plywood/epoxy catamaran based in Brittany, France.

Thanks!

[OzeLouie]

Originally Posted by Franziska

Hi,

in the past we have used the classic salt bag dehumidifiers.

With the new electric setup we would like to add an electric 12v dehumidifier to run this winter season when not on board.

We are not plugged into shore power and I do prefer not to run an inverter constantly when not on board.

A compressor based system draws to much to be left on permanently I guess.

We have 1200w solar, so power is not an issue.
If it's not running during very rainy days it's not a desaster, neither are the few days here where it will frost up.
Humidity is low when it's freezing anyway.

The unit will be placed in the metal kitchen sink and drain overboard.

I know that there have been threads on this before, but I like to hear from folks who have used them in the last 2-3years and what their experiences are.
Please indicate which model you have.

Our boat is a 35ft plywood/epoxy catamaran based in Brittany, France.

Thanks!

Hi Fran, Although I am a qualified refrigeration tech I have never had anything to do with Peltier system humidifiers, but have been involved with so-called Peltier refrigerators enough to know how hopelessly inefficient they are. Expect to consume 3 to 5 times more power than a compressor system to do the same job!!!

I would suggest that you explore these things further and perhaps get a small 12VDC compressor system with cross finned cooling coil and digital thermostat to cause defrost automatically. This would be an easy build for a local fridge tech.
Cheers Louie

[Chotu]

I’m looking at the same thing.

It makes sense to me that they would work. The water extraction fins don’t need to be cold like an air conditioning unit and the Pelletier effect is quite capable of that type of temperature (which is why they don’t do so well as refrigerator and air conditioning).

I see thousands of satisfied customers on the reviews of the products.

I’m looking at getting one to keep mold down in the RV. Was thinking it might be good for a boat too. But you might need multiple units for larger spaces like that. They are somewhat limited in the volume of air they can dehumidify.

[rsvmille]

Have you looked into desiccant dehumidifiers?

I used peltier 12v and none had enough power and they would last only a few months under constant use.

I have since switched to a desiccant style. It uses more power and mine is AC not DC but much, much less than a compressor model... and vs the 12v models the one I have works extremely well and I've had for several years now.

I think the one I have is the Ecoseb 122 Classic.

[redneckrob]

Originally Posted by rsvmille

Have you looked into desiccant dehumidifiers?

I used peltier 12v and none had enough power and they would last only a few months under constant use.

I have since switched to a desiccant style. It uses more power and mine is AC not DC but much, much less than a compressor model... and vs the 12v models the one I have works extremely well and I've had for several years now.

I think the one I have is the Ecoseb 122 Classic.

According to https://www.dehumidifierbuyersguide....lassic-review/

"How does this dehumidifier’s energy efficiency compare to that of compressor based units? The answer to this question largely depends on the size and capacity of the compressor based dehumidifier we’re comparing it to. Small capacity 30 pint/day compressor based units draw on average 300 to 400 watts of power. Large capacity 70 pint/day units draw on average 700 to 800 watts of power. Note that these are maximum power draw averages and so we need to compare them to the DD122EA-Classic’s maximum power draw of 615 watts. Clearly, the EcoSeb is less energy efficient than both small capacity 30 pint and large capacity 70 pint compressor based dehumidifiers. It removes half as much moisture per day (15 pints vs 30 pints) as small capacity compressor dehumidifiers but uses about twice as much energy to do so (615 watts vs 300 to 400 watts). It removes more than 4 times less moisture than large capacity compressor dehumidifiers and uses only slightly less energy to do so (615 watts vs 700 to 800 watts).

A major factor here is the time it takes for a dehumidifier to dehumidify a particular room. A 70 pint unit may draw more power than a 30 pint unit, but, it also dehumidifies at a much higher rate of speed. Thus, it needs to draw its maximum amount of power (700 to 800 watts) for a much lesser period of time to dehumidify the same quantity of air. A 70 pint unit may need to run for only 2 hours to dehumidify the same space that would take a 30 pint unit 6 hours to dehumidify. If this is the case the 70 pint unit is more cost effective as energy is billed per kilowatt hour, not per kilowatt. 700 watts times 2 hours is less expensive than 300 watts times 6 hours.

These same principles apply when assessing the cost of running the DD122EA-Classic on different settings. It may only require 330 watts of power to run on economy settings, but on these same settings it will take a much longer period of time to dehumidify the same space than if you were to run it at maximum power for maximum moisture removal. The bottom line is that despite the fact that it’s capable of running at very low power levels, the DD122EA-Classic is not necessarily a more energy efficient dehumidifier on these settings (as compared to maximum power draw settings) and as we clearly demonstrated above is also not more energy efficient than a compressor based dehumidifier."

Curious how their analysis is off? I would love to get something actually more efficient than my compressor based system.

[rsvmille]

That's really surprising to me and I'd be interested to evaluate if I look again. The desiccant doesn't have as much "action" so it made sense to me that it would be less as claimed.

I did a side by side comparison of some of the 12vs a couple years ago but not the larger. Manufacturer claims *way* off the mark. The best 12v I found extracted a pint from 80% plus humidity, 70deg over 24hrs. Some of the big names got 1/8- 1/4.

Would be cool to do the same and I'll be glad to pony up my ecoseb for a few days for a side-by-side if I happen to be near anyone interested or if I get my hands on a compressor model for a bit ill do it.

I guess in my situation, I run the dehumidifier in a small space not a house and while the same principles apply, and the link may be accurate, again I havent tested but I had size and power constraints and needed cold weather. I can run the Ecoseb off my 12v and inverter and the size while not of the 12vs is decent, smaller than the compressors I looked at and I love the turbo mode. Only problem I have had is (not having the automatic model) I have dried out a space too much leaving it too high for too long and cracked some wood.

[doublewide]

We tried a 12V Peltier unit (name unknown; about 12” tall) in the tropics, and its output was minuscule when compared to the desiccant pots we used simultaneously.
Cost over $100. We thought it was not very useful, even if you have limitless battery capacity. We don’t recommend it.

[Bill O]

We looked at these for our boat and they don't work well in colder temps. Off the top of my head, somewhere ~40F (4C) was the lower practical working limit.

[redneckrob]

Here's another interesting post on dessicant dehumidifiers on a boat mv.VikingStar: Things that . . . work: EcoSeb DD122EA-CLASSIC Dehumidifier

Sounds like they also create heat, so if you're already heating then they may be more efficient than having both a heater and a compressor style dehumidifier. Also they appear to be quiet, which compressor dehumidifiers generally are not. Unfortunately I only run mine in the summer when I'm not on the boat, so not great for me. But for a winter liveaboard north of FL it sounds like they may have some real benefits.

[Franziska]

Thanks to all.

We do not heat the boat when not on board.
The boat is on the hard in winter.
Noise does not matter as we will use them only when not on board.

We used the desiccant bags many years, but now that we have plenty of solar we'd prefer running an electric dehumidifier (or two).

Therefore we'd love to hear from you about actual real life experience of folks who are using them.