Dehumidifier

Any recommendations on dehumidifiers for a 45' trawler would be appreciated.

Watching this with interest myself

I have a vessel about the same size and as I am only aboard once a month or so she smells musty when opened up...

Ventilation is the key to a nice smelling boat.

Boats seal up tight, and most have no ventilation.

We live in mold, and condensation country, but using ventilation we have neither.

Fans lots of fans

Cheap to run and effective. If you have air conditioning running it will dry your air. Some units have a cycle for dehumidify by running for short duration automatically.

I use a small dehumidifier that is about the size of a loaf of bread. It works on the Peltier Effect so the only moving part is the fan. I put a drain tube in the collection tank and let it drain into my galley sink. If I didn't put the drain tube in, I'd need to drain the tank every couple of days.

how about some of the rechargeable silica containers, like this one:

900 Gram Rechargeable Silica Gel Dehumidifier

Best used in closed compartments like bilges and cabinets.

I use the Eva Dry unit pictured by Hop Car, works on both European and North American power. I drilled a hole in the tank for the water to drip out into a sink.
Previously used a larger marine dehumidifier made by JD Products. It was a stainless steel box without a tank. The marine dehumidifier was great except it would not work on 50 hertz.

Use a dehumidifier OR ventilate.

The choice is yours , but you cant do both together.

Leaving the kitchen door open in winter my father used to say,

you cant heat the universe.

Same with water removal, you cant get an acceptable level of dry with the windows open.

We use a wind powered rotating vent,in SW Florida

on the Eva Dry EDV-2200 after adding the drain. The power supply also felt hot to me so when we leave the dehumidifier on, I put the PS on a cookie sheet.

LarryM, re the drain in your Eva Dry, Great Minds Think Alike. That's just what mine looks like.

I have used the one below for about 9 years it works well but is very heavy and bulky, we don't bring it while cruising. I may look at a couple of the Eva Dry units for the future. I could keep one in the aft head where the shower is and one in the galley year round.

HopCar said:

LarryM, re the drain in your Eva Dry, Great Minds Think Alike. That's just what mine looks like.

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Will the Eva-Dry continue to operate with the water drawer removed? If so, could it just be placed in a sink?

FlyWright said:

Will the Eva-Dry continue to operate with the water drawer removed?...

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No. The water tank has to be installed.

Larry M said:

No. The water tank has to be installed.

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Thanks!

Rainy season (hot and wet) on the way here, so this thread convinced me to order the Eva-Dry 2200. And great minds showed me a tip for putting in a drain tube! It was $79.60 on Amazon, including shipping. Might could have looked around a lot and perhaps found one a little bit cheaper, but that price is OK with me.

I purchased a dehumidifier from Home Depot this winter to have on our Tollycraft 44 here in the PNW. It seems to work pretty well. It is amazing how much water it produces. It seems to be pretty noisy, but I can't compare it to others. It has a normal and high settings and I wish it had a low setting. Even on normal it will usually get the humidity down to 35% in a few hours which is where it shuts down.

Al, you could just drill a hole in the Eva Dry tank and sit the unit in the sink.
I just drilled a hole and stuck a piece of aquarium air hose in it. It is a tight enough fit that it doesn't leak. No hardware or sealant needed. I lead the hose directly to the sink drain.

Are you guys familiar with the Peltier Effect that these dehumidifiers use? It's pretty amazing.

Peltier effect (physics) -- Encyclopedia Britannica

Just when you thought that there could not possibly be a question on TF that has not already been asked (many times), I will bet here is one:

For maximum efficiency, should a dehumidifier be put up high, or put down low? Or is the moisture in the air so evenly distributed that it doesn't make any difference?

jwnall said:

Just when you thought that there could not possibly be a question on TF that has not already been asked (many times), I will bet here is one: For maximum efficiency, should a dehumidifier be put up high, or put down low? Or is the moisture in the air so evenly distributed that it doesn't make any difference?

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I'll venture a thought on this. The same amount of water in the air indicates as higher relative humidity in cooler air. So rather than looking up or down, i'd try for the coolest location that works.

Put the dehumidifier in a cool location. Some of the energy used is to cool the air to the saturation point (dewpoint) and the rest of the energy is used to condense the water. The cooler the location, the less energy is used on the first part of the process. This assumes the air in the boat has at least some circulation.

OK, with two votes for the cooler location, I'll go with that. Since hot air rises, as I understand it, that would mean the lower the better (so long as above deck,I mean).

John, I think it's more a function of temperature than elevation. The chart below shows the effect on relative humidity with a change in temperature or pressure. As the temp decreases 10C, (from State B to State A) the RH increases 17%. This higher % of water per volume of air is easier to remove using the dehumidifier.



I use calcium carbonate pellets to dehumidify my boat during periods of non-use in the winter. I notice more water in the water collectors when the heat is turned off than when I run the heaters in my absence. I attribute this to the lower RH with the heaters on.

We use two large household sized dehumidifiers we bought at Home Depot. As our boat is compartmentalized into fore and aft sections below decks, we needed two. And as we live and work aboard 24/7, we wanted large capacity. Running them each about 4 hours every few days takes A LOT of water out of the air. A few gallons a week at least.

We also use the H2Out reusable dehumidifiers throughout the boat. Here's a video we made on the Pittman award-winning Space Dryers: H2Out Space Dryers

Started using an EvaDry 2200 this past fall. It has worked great. I was going to install a drain, but since we check the boat every week, I've never had it more than half full when I empty it. That may change over the summer. The advantage over a compressor dehumidifier is size and noise. The evadry is light and very queit. however, compressors will remove a lot more moisture. The 2200 seems fine for our 34 foot tug, but for a 45 foot boat you would probably need to run two of them. Practical sailor gave a positive review of the evadry where a large compressor model wasn't necessary. The chemical desicants may be fine for small compartments, but are not really feasable for an entire boat. Lastly, our AC does have a dehumdify mode, but I don't like leaving it running during the week when we are not around becuase I worry about it sucking up debris and burning out the pump.

I'll bump this thread. We had more "Pineapple Expresses" go through the PNW last year than I can ever remember. The "Dries Air" chemical anti-desiccants were overtaxed. I just purchased a Garrison dehumidifier: 28 pint (13 litre) 298 watts (3.2 amps). I have it running at home in the basement right now and it removed 1 litre in about an hour. I intend to set it on the Galley counter and run a hose into the sink (through hull above the water line). Another option is to set it in the companion way between the staterooms and have the hose run into the sink in the amidships head.

We just got back from a trip with guests and found that the bottom bunk in the guest state room was quite wet under the mattress. I intend to get some of that Hypervent mesh to put under the mattress. Expensive stuff at $14Cdn a linear foot!

Jim

As an aside to the discussion, I was told that the water collected from a dehumidifier if the collection is clean can be used as distilled water for battery use.

Is this true?

SCOTTEDAVIS said:

As an aside to the discussion, I was told that the water collected from a dehumidifier if the collection is clean can be used as distilled water for battery use.

Is this true?

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Yes. In theory...if the collection is clean. Dust and other airborne contaminants could be an issue. Given distilled water is cheap, I wouldn't be using reclaimed water from the dehumidifier.


Jim
Sent from my iPad using Trawler Forum

Guys

My wife read somewhere and put it in the boat and it works!!!!!
It is CHEAP, you can change it whenever you want and you can find it everywhere.

Get yourself a wicker basket, cover it with absorving paper and cover it up with wood charcoal. (the one you put in your BBQ pit.)

Use as many baskets as you want. The charcoal will absorve most of the air moisture.

Try, don't be shy

Portuguese said:

Guys

My wife read somewhere and put it in the boat and it works!!!!!
It is CHEAP, you can change it whenever you want and you can find it everywhere.

Get yourself a wicker basket, cover it with absorving paper and cover it up with wood charcoal. (the one you put in your BBQ pit.)

Use as many baskets as you want. The charcoal will absorve most of the air moisture.

Try, don't be shy

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Fernando, have you got pictures of this? Sounds like a perfect solution if the footprint is small. That's why I like Dri-Z-Air.



I buy calcium chloride pellets that are sold online for ice melting in less fortunate climate areas. During the summer, this stuff is dirt cheap. Just try not to order during blizzards. They really price gouge in the winter.

Charcoal briquettes in a basket sounds much better!!! Do you need to place the baskets in a sink or on a platter to catch water like the Dri-Z-Air does?