12v mini dehumidifier?

[chrisbitz]

Just seen this in todays Maplin email for £40 http://www.maplin.co.uk/p/22-litre-mini-dehumidifier-a59kx

It uses 70w at 12v = 5.8 amps, so supposing I ran it for 2/3 hours between visits to the boat, or something like that, would it have any effect, or do they need to be on for 24h a day or something?

 

[TSB240]

I bought one from Aldi when they were on offer.

Firstly you will be wasting your money if you are only going to use this without any form of heating on your boat. It works on a peltier principle which is not very efficient at best but is lousy at low temperatures.
It would need to be on all the time to be of any use.
Only once have we seen the water container anywhere near full between weekends.
I am happy that the boat and bedding is kept nice and dry.
This is probably more because of the heating provided by an oil filled radiator and ventilation!

 

[jwilson]

Peltier anything = very inefficient. In a few hours running it might collect an egg-cup-full.

If you don't have shorepower you'd probably be better just with lots of ventilation. On shorepower an electric dessicant dehumidifier like the Meaco DD8L will give you a really dry boat: run it a few days to start on full welly then turn it's humidistat down to low to mid range. Obviously seal all vents or you will be trying to dry the whole county. On most mid-sized boats a Meaco or similar will collect a few gallons in the first few days running, much of it out of the upholstery, which will suddenly feel warmer and dryer.

I get onto lots of boats and the owners who swear by ventilation alone have boats that in winter always still feel slightly dampish - until you have used a decent dehumidifier you won't know what a dry boat feels like.

 

[owen-cox]

I have one in my caravan in my drive and it works very well indeed I get a full tank every week if its raining and I have no heat in there. Well recommended.

 

[sarabande]

a waste of money in a boat.


It is rated at 70 Watts - that is one old fashioned light bulb.

Think how much difference the warmth of a single light bulb will make to the air volume of a medium sized boat in the water. So then ask about the efficiencies of the humidity extraction process, which is probably down to about 50%. And then think about the amount of fresh air (with water vapour) that creeps in through ventilators and gaps in the washboard, etc.

Any difference will be imperceptible.

 

[neil1967]

I have just purchased a Meaco DD8L and it is amazing how much water it is extracting. Our (40') boat is on the hard at the moment, but with two of us on board at the weekend and the hatches closed to keep the heat in, that's a lot of moisture. Doesn't really answer the question, but having seen the effect of a 200-400W mains dehumidifier, I cannot see how a much lower powered one would be effective, unless it is drying a really small volume.

Neil

 

[the_branflake]

I also agree - we got one from Aldi and to be honest its doing very little. My idea was to also test it on the boat but having seen it in action at home with the heating on i dont think it would do anything on the boat other than use power.

 

[lw395]

I inherited one with a boat.
It might make the difference between condensation and no condensation, if your boat is already fairly dry and well sealed.

 

[jwilson]

Re Owen Cox - full tank = 2.2 litres after running a week - as I said an eggcupfull over 2-3 hours if you are lucky. Presumably you leave it on, which the OP probably can't do if running on battery power alone. You'd have to have a monstrously big big battery bank to sustain 5-6 amps for a week.

 

[Poecheng]

I have just purchased a Meaco DD8L and it is amazing how much water it is extracting. Our (40') boat is on the hard at the moment, but with two of us on board at the weekend and the hatches closed to keep the heat in, that's a lot of moisture. Doesn't really answer the question, but having seen the effect of a 200-400W mains dehumidifier, I cannot see how a much lower powered one would be effective, unless it is drying a really small volume.

Neil

+1 (well actually +3 as I have three of them: home and boat)
These are the best IMHO.
They have a humidistat, variable humidistat, ability to run constantly if you have a drain point (easy attachment of drain tube), if the power supply is interrupted then they reset - as they were - once power resumes (very important), they work in far colder temperatures than even compressor dehumidifiers (important in cold boat/boatyard). They extract lots of moisture and do so quickly and I thoroughly recommend them. They work on the desicator principle which requires some heat to extract the moisture and you get a (variable) small amount of heat blown around which is a considerable advantage. I read the reviews and they were correct.
I paid £128 plus VAT and got a three year guarantee and excellent courier delivery: energybulbs.co.uk
No connection etc. just happy. Transformed our house over winter.

I saw the peltier ones and thought "Oh that will be good for my daughter" in her flat share. I was all set to go to Aldi/Lidl as one had them on a special offer. Did the research - especially reviews from users - and concluded I would remove more humidity by burning the banknotes to heat up the air.

 

[rubbishman]

I bought a Meaco dd81 due to this forum,great piece of kit.

 

[owen-cox]

Re Owen Cox - full tank = 2.2 litres after running a week - as I said an eggcupfull over 2-3 hours if you are lucky. Presumably you leave it on, which the OP probably can't do if running on battery power alone. You'd have to have a monstrously big big battery bank to sustain 5-6 amps for a week.

Yes I agree that running it all the time is required but he does ask that question in the OP and I would imagine 2.2 litres of water in a week is rather better than having it in the air for a week. Thats quite a lot of condensate that would otherwise be damaging the boat???

 

[lw395]

Yes I agree that running it all the time is required but he does ask that question in the OP and I would imagine 2.2 litres of water in a week is rather better than having it in the air for a week. Thats quite a lot of condensate that would otherwise be damaging the boat???

Indeed.
If you can stop condensation, you stop mould on the whole.
These things won't make up for rain leaking in, but they will stop condensation on the deckhead in the coldest part of the night if the boat is dry during the day and well sealed to damper air.

 

[Halo]

De-humidifier on shore power is great. You can leave the sleeping bags, sails etc on board throughout the winter and the bags of crisps and biccies just get crisper with time. The best thing is that you simply dont get the mould marks forming on oilies and life jackets. As someone said before - dont think any ammount of ventialtion is as good because it is not.
Second thing is to put a couple of low watt heaters on board each with a plug type thermostat set at 5 C
I get very little power consumed with this arrangement and it helps preserve the boat.

 

[padge]

I forgot to put the latch across on my companionway hatch and didn't check for a month - the strong winds opened it a couple of inchs , lots of rain later everything was soaking and getting mouldy:disgust:

Bought a dessicant dehumid on fleabay it's brilliant after a week it's all nice and dry , just run it now at night on E7

Pielter is as much use as a chocolate fireguard

 

[RIBW]

Just seen this in todays Maplin email for £40

Hi, I bought the Aldi version (£35) at the end of January and tried it in my boat partner's house. It worked extremely well - to the extent that we bought a second unit for the boat. This unit was installed, as an experiment, last weekend such that it runs between 12:00 and 17:00 but only when the temperature in the (deck) saloon is above 5degC (reportedly the minimum advisable for this type of unit). Currently, the boat is afloat (sea temp 10degC), has no ventilation, no leaks and feels pretty dry. The Ebers is run for about 12 hours/fortnight. We use passive dessicant containers extensively. If, after two weeks, there is significant accumulation of condensate, we will wire it in as a pluggable option.
I am happy to post the result of the test, (but will probably need a PM to remind me).
Regards
Bob

 

[William_H]

I bought one from Aldi when they were on offer.

Firstly you will be wasting your money if you are only going to use this without any form of heating on your boat. It works on a peltier principle which is not very efficient at best but is lousy at low temperatures.
It would need to be on all the time to be of any use.
Only once have we seen the water container anywhere near full between weekends.
I am happy that the boat and bedding is kept nice and dry.
This is probably more because of the heating provided by an oil filled radiator and ventilation!

Of course any inefficienices and there are a lot in a peltier device will appear as heat from the device. So most of the 70 watts will come out as heat for the cabin. Mind you the end effect may not be much better than a 70w lamp heating the cabin. Of course where you could get 70w for continuous use from 12v is a big question. Only from shore power and if that is the case why not a proper mains powered dehumidifier. olewill