Dehumidifiers

[Simonboatshift]

Hi all,

Just a post to find out what people use and to see what is preferred to deal with condensation inside Windows etc whilst on board.

 

Do you use a small or large electric dehumidifier or the crystal type collecting water in a container?  I have seen on eBay some that look like small bean bags and wonder if anyone uses these?

 

look forward to seek what the general consensus is.

 

thanks,. Simon.

[Vaughan]

Ventilation. Adequate fixed ventilation. Can't beat it.

By the way Simon, a warm welcome to the forum!

[Simonboatshift]

The problem we have is the number of us sleeping in a small boat! Anything to stop the downpour from the front windows would be good... 

Met have a small electric unit that doesn't really seem to work all that well and is also noisy running at night when it's otherwise so peaceful.  Wondered if the crystal units work?

[Simonboatshift]

And a big thanks for the welcome!

[BroadScot]

Hi Simon, welcome to the NBN Forum  Quite a few members I believe use the Karcher window cleaner to soak up the moisture.

Iain

[Bound2Please]

Simon from me and the wench (some call her Inge). We use the crystal ones from the firm that does pest control. The name slips me for a second (old age) but they contain a large salt ring? and collect moisture in a tray beneath 

Charlie

[ranworthbreeze]

8 minutes ago, Simonboatshift said:

The problem we have is the number of us sleeping in a small boat! Anything to stop the downpour from the front windows would be good... 

Met have a small electric unit that doesn't really seem to work all that well and is also noisy running at night when it's otherwise so peaceful.  Wondered if the crystal units work?

Hi Simon,

We have the water traps (Morrisons sell a good moisture trap, we then buy the replacement crystals in bulk locally) in various locations on the boat, we also have one of the small mains units that we tend to leave running overnight in the galley. In the morning we use the Karcher and cloths.  As already stated leave windows and roof vents open.

Regards

Alan

[Vaughan]

3 hours ago, BroadScot said:

Hi Simon, welcome to the NBN Forum  Quite a few members I believe use the Karcher window cleaner to soak up the moisture.

I tell you what, these are marvellous! Someone told us about these on a thread over last winter, and called them "window sucky cleaners". I bought one online, for our camper van, which we use for coming back to England. When I get up early to carry on driving, one sweep of the windscreen with that, and I am ready to drive off. A real luxury!

[tjg1677]

hello all,

yes lots of ventilation and an old but very cheap trick, bowls of table salt dotted around, it is amazing what that absorbs.

When I bought my first boat, a norman 23, I had terrible trouble with window condensation in the mornings, get a bag of cotton wool, tease it out into long strips and place it at the bottom of the windows either on the sills or wedged into the frame area, has to be done every night with fresh cotton wool but it does work and stops those annoying cold drips - oh!, and it's cheap  

 

ttfn

trev.

[Jim]

We never have condensation probs in our Falcon cabin and I think that has a lot to do with the carpet trim on the roof. The helm area is worse in the mornings but once you open a section of the canopy, it soon clears. We use the dessicant stuff you can get over the winter months which has always been good.

The first boat we hired in 1979 was an Elysian from Southgates in Horning. She had a hard lining on the cabin roof so when you woke up in the morning, you had to dodge the cold drips!  

[LondonRascal]

If you (or anyone) for that matter considers getting a plug in dehumidifier for use on their boat when on shore power (such as your marina berth) please do not get a condenser powered type - which are the most prolific when you look into purchasing them.

Instead get a Desiccant Dehumidifier. 

Desiccant Dehumidifiers are smaller, lighter, quieter and more efficient and cheaper to run than a compressor driven dehumidifiers but it is not the above which is why they really are so much better suited to on board boats - it is because they work in low temperatures (right down to freezing).

See this graph:

As you can see not until the ambient temperature gets up to about 18c does the compressor based Dehumidifier actually begin to extract any meaningful moisture from the air - they will be running, consuming the same amount of electricity but not absorbing hardly any moisture.

Because you tend to get a lot of moisture on damp, dark autumn and winter days (when it is cold)  compressor powered Dehumidifiers are the most inefficient form of moisture removal when it happens to also be the most chilly in such conditions. They just stop working at below 5c too.

A compressor driven Dehumidifier would be great in a warm, damp house - but in a boat that may get to say 10c on a good day in the autumn or winter not at all wroth while.

Desiccant Dehumidifiers might not be able to extract as much volume of water (once the ambient temperature rises) but will be more efficient at moisture ceremonial when the ambient temperature is low. 

Desiccant dehumidifiers use a desiccant material, typically Zeolite, which absorbs water moisture from the air in a similar way to silica gel. A fan draws air into the dehumidifier and passes it through a section of a slowly rotating wheel which holds desiccant which dries the air. A small heater warms the Zeolite as it rotates, drying it and meaning it is ready to remove moisture at a constant efficiency. The collected moisture is collected in a water tray at the bottom of the unit or through a continuous drain system. 

An alternative to Dehumidifier may be something like a Kampa Damp Buster. These are large bin like collectors that you fill up with crystals and collect many litres of water in the bottom.  Great to leave on a boat, but hellish to knock over once they have a couple of litres of water in them!

For small individual cabins or lockers, simple ones you can get in the likes of Lathams for a couple of pounds are ideal.

 

[ZimbiIV]

If the vents on Zimbi were big enough (5mm too narrow) I would fit 2 of these, 1 extracting 1 intake.

http://www.sunshinesolar.co.uk/prodshow/Solar_Vent_or_Fan__Day___Night_Operation___Low_Profile/SSS224.html

If someone can tell me how to enlarge the opening by 5/10mm please do a hole cutter will not work, tried it.

paul

[tjg1677]

4 minutes ago, ZimbiIV said:

If the vents on Zimbi were big enough (5mm too narrow) I would fit 2 of these, 1 extracting 1 intake.

http://www.sunshinesolar.co.uk/prodshow/Solar_Vent_or_Fan__Day___Night_Operation___Low_Profile/SSS224.html

If someone can tell me how to enlarge the opening by 5/10mm please do a hole cutter will not work, tried it.

paul

Hi Paul,

I had one of these fitted to my last narrowboat and they are really good, very quiet and move a far bit of air over a 24 period considering that the fan only runs relatively slowly. Best suggestion for enlarging a hole by that much is make a card template to the size you need. use it to draw around the existing hole, then once you have the line, cut out very carefully and patiently with a fine small jigsaw blade in a fast running jigsaw.

 

hth

ttfn

trev.

[BuffaloBill]

The simple answer to windows dripping on you on the inside is to fit a quilted cover on the outside.

I was told this about 5yrs ago and had one made. Fantastic! Fitted with press studs so comes off easily in the mornings and for cleaning. Never had drips since.

Can't remember the cost but worth every penny!! Just get one!

[Bound2Please]

Just remembered the name of the dehumidifier's we use they are "uni bond 360" work a treat. Mind so does the £8.95 mini water vac (karcha copy) off ebay, after you have any conensation on the windows,  neither have let us down this year.

Charlie

[Baitrunner]

We have a couple of the Unibond units. 

Fyi Robert dyas have the refills half price at the moment. £4.99 for a pair. Expensive but very convenient. 

We also run a dehumidifier when not on board and it uses very little electricity and seems to work in all weathers. No idea if it's a compressor one or not. 

[ExSurveyor]

I have a bit of knowledge of dehumidifiers and condensation and Robin makes some good points based on his research ,,  however, in practice compressor type units will work well on a boat.  Use a timer and buy one that will continue to operate if the timer turns off and then on again,  not all units will.  

They will extract at around 8 degrees and work best with a small heater. 

I have used compressor types on both boats for years with complete success. 

Remember to cover larger vents in something bright to restrict airflow but obvious enough to see to remove when onboard. 

Small,  less than 100 pound units are not worth the power to run them ..

Crystal units are great for cupboards but not ideal for a boat that is left for 3onths over winter. They may be the only option without power available .. 

Anyway,  Winter is months away 

[LondonRascal]

I would disagree about compressor based dehumidifiers working well on a boat - sure they work, but not as efficiently as desiccant based types, as Mark says they work well with the addition of a small heater,  However, in terms of efficiency you running a compressor and a heater - the heater to help warm the ambient air, to allow the Dehumidifier to extract as much moisture as possible and that is of course an  inefficient way of doing the job.

The optimum temperature for extracting the most moisture from air for compressor based Dehumidifiers is high - around 30ºC. It is why even on a hot humid day while they wont' cool the air in a room it can make it more comfortable to have a dry heat than a humid heat.

 

Compressor based Dehumidifiers will not work at the same efficiency between  0ºC to 5ºC because they work on the same principal as a fridge (or air conditioner).  One side gets cold (evaporator coil) and the other warm (condenser coil). 

 

Moisture laden air is drawn in over the Evaporator coil - being cold the moisture condenses on this, and drips down through a collection channel to the water tank in the base of the machine.  The dry cold air is then passed over the Condenser coil - taking with it the waste heat, returning such back to the room at the same ambient temperature it came in (or a little higher temperature than ambient air).

 

So the colder air is to begin the less it will condense on the cold Evaporator coil - thus it is less efficient.  Once you are above 10c the efficient begins to improve and at 15c to 25c is extracting a good proportion of moisture from the air.

 

The Desiccant based Dehumidifier on the other hand can run from 0ºC to 30ºC with a constant and stable intake of humid air, the consistency means it is more efficient at lower temperatures at doing its job - to remove moisture from the air. . Despite the Desiccant based Dehumidifiers only being able to extract 7 litres in every 24 hours,  it will actually be more useful because the stability and the fact it will extract the same amount of moisture from the air, be it an ambient air temperature of 0c or 30c.

 

The other benefit is their light weight since they have no compresses motor in the base and the associated Evaporator and Condenser coils which add to the weight of the unit too.  A Desiccant based Dehumidifier simple has a slow revolving drum of moisture absorbing material, a fan and a small heater element.

 

This is why I maintain that a compressor based Dehumidifier is great for the home, but not as suited to far colder boat interiors left for weeks or months on end on moorings.  I also wonder how many people knew the difference between the two methods, because by far the most common products for sale are the compressor driven types - since most people of course would benefit from such in their home but boaters are a different kettle of fish.

 

[Baitrunner]

And if in doubt....I am sure Robin read this earlier

http://www.dehumidifiersuk.com/boat-dehumidifier

Does sound like the desiccant ones are the future, but I wont be throwing my one away if it is a compressor one as it works brill. And I know it doesn't heat so assume it is a compressor. It has worked all winter with no heat on. No idea if a desiccant one would be better, but it works for me. So there 

Not sure if they still sell dehumidifiers, but I bought mine many years ago from Norfolk Marine and the fan packed up after about 10 months. They initially were going to get it repaired, but in the end they replaced it and that was years ago. Cant beat that.

[Baitrunner]

And to sort of contradict, well maybe not, but proves desiccants might not be the be all and end all:-

Brian Wards do one of each - http://www.brianwards.co.uk/catalogsearch/result/?q=Dehumidifier

Desiccant - works 1-40C, 390-620W power consumption and 7l per day removal

Compressor - works 5-35c, 300W power consumption and 12l per day removal (if I have read this correctly).

So, take your pick folks - they both work some slightly better than others depending on temp but power consumption might be a decider?

[ExSurveyor]

I pay about 50 pounds over winter for electric,  that's battery charger,  engine heater to come on at 3 degrees,  cabin heater set to  come on at 5 degrees and a compresser dehumidifier on a timer between 10 am and 4pm.  

I guess changing to a dessicant unit might save me 15 pounds a year but I will have to buy a unit at over 100.pounds more. 

I do measure the atmospheric moisture levels  using my hygrometer with the dehumidifier running and it is kept below 60%. 

I know a dessicant unit would work better but the additional cost is not justified. 

It works well,  why pay the extra. 

I have had no mould or mildew formation in five years and I leave all soft furnishings onboard for occasional use. 

A dehumidifier works well as a dryer if put in the heads with wet clothing  .

[Baitrunner]

Likewise here Mark.

I don't run a heater, but large battery charger and dehumid left all 24x7 all year when not on boat - even with leccy use when we are on the mooring I dont spend that much on leccy.

Leave all the doors open when not on board and like you no mold.

When the current one goes pop I may get a desiccant model, but they don't seem to be cheaper to run, no doubt due to the heater element in them.

[RayandCarole]

We have used a Maeco DDL 80 junior for the last 2 years and find it works very well, it also generates a useful amount of heat in the cabin which is a bonus as the thermostatic heater rarely comes on

just my ten pennorth

Ray & Carole

[tjg1677]

9 hours ago, Baitrunner said:

And to sort of contradict, well maybe not, but proves desiccants might not be the be all and end all:-

Brian Wards do one of each - http://www.brianwards.co.uk/catalogsearch/result/?q=Dehumidifier

Desiccant - works 1-40C, 390-620W power consumption and 7l per day removal

Compressor - works 5-35c, 300W power consumption and 12l per day removal (if I have read this correctly).

So, take your pick folks - they both work some slightly better than others depending on temp but power consumption might be a decider?

The ultimate power consumption will depend in the duty cycle. i.e. how many minutes per hour the units run.

I am not familiar with the dessicant type so I dont know if they run constantly or cut in and out ( cycle ). The compressor type however, do cycle, so in theory a 50% duty cycle will only consume 150w of power per hour - bargain !!

Trev,

[Mowjo]

I have a Karcher Window Vac copy that came from Aldi, that is always kept on the boat and is the dogs for getting rid of the condensation on the windows, and for winter when we arn't on the boat much I have two Adli condensation traps about the size of a small shoebox that came with two refils about £5 each, and they see me right throught the winter, with me going down to empty them once,,