Dehumidifiers

paultallett

paultallett

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Sorry for such a predictable title, but I thought I'd get my question in first before you all get sick of them!!!

With leaving my boat in the water this winter I'm beginning to think about arrangement with a dehumidifier. Normally when we are away from the boat I do try to leave internal cabin doors open and have the small vents locked open a jar to keep the air circulating.

When the dehumidifier is running, should I shut the vents so it dries out the internal air in the boat without any extra natural circulation??

Regards Paul.
 
Anyone got any recommendations on good models to buy? I've been looking usual places (Argos, B&Q, etc) but none state they have drain pipes, just tanks which are a bit useless if you don't visit regularly.

Also, is it best to use in conjunction with a thermostatted (sic?) heater or just on it's own. I use a Dimplex Latitude heater set to low temp to keep damp at bay and have been wondering whether to get a dehiunidifier as well.

Thanks, and sorry to hijack thread but thought better than starting another one on the same subject.
 
wattsn said:
Anyone got any recommendations on good models to buy? I've been looking usual places (Argos, B&Q, etc) but none state they have drain pipes, just tanks which are a bit useless if you don't visit regularly.

Also, is it best to use in conjunction with a thermostatted (sic?) heater or just on it's own. I use a Dimplex Latitude heater set to low temp to keep damp at bay and have been wondering whether to get a dehiunidifier as well.

Thanks, and sorry to hijack thread but thought better than starting another one on the same subject.
Click to expand...


Yes, if you do a search I recieved loads of excellent info when I replaced mine earlier this summer. I asked for recommendations and got them in spades
 
David2452 said:
Lock it up tight, otherwise you'll be dehumidifing the rest of the marina.
Click to expand...

Are you sure???
If the dehumidifier is running all the time there is something wrong with it.
I would only get one with an adjustable humidistat, but even the cheaper fixed type ones are not designed to draw water out of normal 'air' levels.

Whilst I wouldn't leave extra ventilation open (as you need the air to be reasonably warm for a dehumidifier to work efficiently) I wouldn't go to the the lengths of sealing the boat.
 
I have never used a dehumidifier on the boat, and have never had any problems.
I do believe (rightly or wrongly) that they will pull in damp air from outside of the boat through any vent or air space possible.
People i know who do use them always say about how much their electricity bills go up when using them.
 
seanbeagley said:
I have never used a dehumidifier on the boat, and have never had any problems.
I do believe (rightly or wrongly) that they will pull in damp air from outside of the boat through any vent or air space possible.
People i know who do use them always say about how much their electricity bills go up when using them.
Click to expand...


You are right that a dehumidifier is not required if you have a good supply of fresh air - air that is allowed to change on a frequent basis.
Think about it for a while... If the outside fresh air stops condensation, how can the dehumidifier pull the damp air in from outside?
It's true that moisture spreads from damp air to dry air, like oil on water, but the moisture levels required to grow mold in your boat are higher than that in the air - it requires a build up of moisture in the fabric and on surfaces.
You either need enough change of air to keep the surfaces and fabrics dry, or heat to get the moisture into the air, and a dehumidifier to get it out.
I can't believe that anyone can make their boat airtight, so in daylight hours the air in the boat will get warmer and expand, then at night will contract and bring in the cool moist air. - It is a continuous process that needs to be controlled by one method or the other, and not caused by the dehumidifier.
Yes they cost money to run, but the cost of mould smells and damage will be higher. Anyway, it's down to individual choice and the arguments will never end. - The dehumidifier works for me, and that's all that really matters :-)
 
I have always run dehumidifiers on my boats. I do not like them with a drain as I will never know how much water has been taken out.
I just close all hatches/windows and the main entrance door/patio doors. Open all cupboards, internal doors, etc. set for 5 degrees with 50% humidity and “hey presto” it cuts in and out dehumidifying happily. After the first couple of days you have to keep emptying the tank but then it settles down and I was getting 3/4 of a tank after leaving the boat Sunday to Friday through the winter (1/2 litre a day approx). You can leave all bedding, soft furnishings set out with no damp feeling or condensation. I run the reverse cycle aircon as normal for winter heating and still the de-humidifier kicks in now and again. Never had any issues re static/electric shocks which is what you will get if it is too dry. No shrinkage to doors or wood never been an issue. As mentioned earlier you have to get a unit with a heater as the air has to be 4-5 degrees in order to condense through the compressor. I use a De-Longhi about £400 B&Q or same thing was £200 Costco (With a built-in heater) or you will need a separate heater on a stat.
PS I dont seal any vents but then its only a small one.
 
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I can recommend this one

http://www.meaco.com/proddetail.asp?prod=XDry

Its very affordable, has a continuous drain and will restart itself if the power is cut off through someone removing your shore power lead. A lot of them won't do this so that is a key feature for me. I used mine all throough last winter with no problems and the boat was lovely and dry in the Spring.
 
We have winter storage dehumidified for over 5 years with a desicant type & have been very impressed with it.
The Amberdry we use has now been superceded by this X-Dry,

http://www.aircomfortcentre.com/productdetail.aspx?pid=5f981757-3431-4d55-843b-03fc34e9b5b6

Better lower temperature opperation than a compressor version but with the added bonus of heat output.
Would highly recomend these new types as they are ideal for boats etc & even specify this in their sales literature.
The higher running costs are a myth as the unit doesn't opperate for 100% of the time, only on when the relative humidity exceed's the level set by the user.
 
seanbeagley said:
I have never used a dehumidifier on the boat, and have never had any problems.
I do believe (rightly or wrongly) that they will pull in damp air from outside of the boat through any vent or air space possible.
People i know who do use them always say about how much their electricity bills go up when using them.
Click to expand...

I do not think the unit will 'pull in' damp air from outside - yeh the boat is not sealed and the interior volume is quite large to allow some circ. We leave bedding in place and I always find the boat feels like new still whenever we board after leaving it for a period. You can smell the wool from the carpet and cotton from the sheets. The humidity gauge I leave in place shows the highs and lows and my boat is 'stored' between use at 50/60% RH. Without the winter heating on it costs peanuts to keep the boat dry.

When my last unit packed up I could tell as soon as I boarded that something was up and it was not working as it had been..........Speak as you find.
 
I was chatting the the owner of Meaco (there is a link to one of their units above) and he was telling me that above 68% Humidity (RH) mould will grow, below it it will not. The average RH of the UK is 80%. If you open the windows to ventilate the boat the chances are you will introduce air at >68% RH and so you may flush out the smell but you will get mould.

He said I should buy this one: http://www.meaco.com/proddetail.asp?prod=DD122FW it his his best seller by far he said.
 
PEJ said:
I was chatting the the owner of Meaco (there is a link to one of their units above) and he was telling me that above 68% Humidity (RH) mould will grow, below it it will not. The average RH of the UK is 80%. If you open the windows to ventilate the boat the chances are you will introduce air at >68% RH and so you may flush out the smell but you will get mould.
QUOTE]

There is a little more to it than that... If there wasn't then everything outdoors would be mouldy.
The humidity has to be high enough, but the surface needs to be wet enough for a long enough period too.
That is why you get mold mainly growing on the north side of objects that do not dry out in the winter sun.
You are wrong about the ventilation - If you have sufficient airflow through the boat (without letting rainwater in) the boat will not get mouldy.
As I said in an earlier post, you cannot make your boat airtight, and the moisture will come in with the air that changes as the temperature in the boat fluctuates causing the air to expand and contract.
Click to expand...
 
wattsn said:
Anyone got any recommendations on good models to buy? I've been looking usual places (Argos, B&Q, etc) but none state they have drain pipes, just tanks which are a bit useless if you don't visit regularly.

Also, is it best to use in conjunction with a thermostatted (sic?) heater or just on it's own. I use a Dimplex Latitude heater set to low temp to keep damp at bay and have been wondering whether to get a dehiunidifier as well.

Thanks, and sorry to hijack thread but thought better than starting another one on the same subject.
Click to expand...

We sell two models- both desiccant type, which works well at lower temperatures unlike a refrigerant model. They also slightly warm the air. Both models have drain hoes included and auto restart when used on a timer. There's a good thread at http://www.ybw.com/forums/showthread.php?t=214354
and also extenisve details on our website at http://www.boatsheen.com/dehumidifiers.html
 
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