Which Dehumidifier?

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hoped4

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Our 31ft yacht is moored in a marina with shore power. I'm trying to choose a dehumidifier to run through the winter. We plan to spend a few weekends on board and get a bit of winter sailing in too. I have seen the mini dehumidifiers advertised that have a 250ml tank & promises to extract 250mls a day (I suppose in warm conditions) and which can be overidden DIY to run into the sink. It's no bigger than a shoebox. The alternatives seem to be much bigger models that promise to extract up to 10l a day, have humidity control dials and have a sink drainage facility buit in.

My question is, the mini seems to be sold by on line chandleries but is it really up to the job? Or should I go for the bigger , more difficult to store when sailing versions knowing that they will do a propoer job? Any suggestions on models?
 
I would get one of the larger 10l dehumidifiers. Those little ones are really pretty much useless on a boat, unless you just want to keep a locker dry or something.

I use a homebase one on my boat. The newest B&Q ones are suprisingly compact, and I use mine with a pernament drain hose so that its left on and does not need to be emptied, It has a tank but it fills it quickly. Leaves the boat lovely and dry. No damp anywhere.

The chandleries do sem to like the small one, i guess as they are 12v they can stick a marine badge on it and bump up the price, but as most of them aren't boaters probably, they dont realise how power hungry they are. They advertise 250ml per day, but one i had would be lucky to get that much in 4-5 days.
 
I'm curious about dehumidifiers on boats- do you have to seal all the ventilation? If you don't, dos'n't a load of damp air simply get in? For old, deep keeled boats like mine, which always seem to have a bit of bilgewater at the bottom of the sump, would this be a real problem?
 
I suspect you have to be very careful with a wooden boat, where excessive dehumidification can do damage. My house is very old, stone built with no damp course, so tends to be damp. We run a dehumidifier for an hour or so every day in winter on the landing upstairs. It is very noticeable that whereas in summer the floorboards are solid and do not make a sound, by the end of winter they are quite loose and creak whenever we walk on them. Just a thought.
 
During the 'damp' season I run a household-type dehumidier 24x7 aboard my boat - makes a HUGE difference to how dry the bedding and clothes stay, even if left aboard all winter. Mine has an external outlet allowing it to drain permanenetly into the sink as opposed to using the tank.

Being NZ I don't think the make/model will be of much use but just in case it's called a SUKI.
 
Possibly a silly question, but we have one of the B&Q 10l dehumidifiers on the boat, and I can't get it to continuously drain. It just fills the internal tank then switches off. Anyone got any ideas?

I took the plug & bung out of the continuous drain hole & put some garden hose on it, led down to a seacock (the boat is out of the water and I've disconnected the sink) so the hose is lower than the outlet. But the outlet is at the top of the tank, which doesn't make a lot of sense. Nothing in the instructions that I could see.

???
 
You need to make sure it is level - I discovered on our B& Q machine last year that if it is tilted slightly, the water will fill up the tank rather than flow out of the drainhole. The machine will then cut out once the tank is full.

I use a small spirit level and then pack it with assorted paper/card until it's level.

Works for me....
 
I use a large (7ltr/day) dessicant type called a Prem-i-air DD122FW and it's very good. It has a 2/4/8hr timer and low/high/auto settings and in low it's so quiet you can sleep with it on. It also has an ioniser built in. There is a 2ltr integral tank, or it drains continuously into the sink.
BTW - I have no connection with the company.
 
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Paleyma said:
Possibly a silly question, but we have one of the B&Q 10l dehumidifiers on the boat, and I can't get it to continuously drain. It just fills the internal tank then switches off. Anyone got any ideas?
???
Click to expand...

I had this trouble with my B and Q dehumidifier. Unlike Beancounter, I found that tilting it back a small amount, I'd guess 5 deg or so, seemed to do the trick. I think the important thing is that it doesn't tilt forward at all.
 
Ventilation and a little background heat. You will need to look at old wooden boats though to find out how to ventilate a fibreglass one properly. You need a gentle air flow from end to end.
Once I had fitted proper dorrade vents fore and aft all I have needed to keep the boat and its furnishings dry and liveable all winter has been a tubular low wattage heater. Far less trouble than messing about with dehumidifiers that also need the boat to be hermetically sealed - otherwise you are trying to dry the entire global atmosphere as it blows past.
 
We just put a small electric fan heater on board with the thermostat dial set to a low heat. The theory was that trying to keep moisture out is a never-ending task but just drying the air will always work. May be unscientific but it works for us.
Any comments?
 
Paleyma said:
Possibly a silly question, but we have one of the B&Q 10l dehumidifiers on the boat, and I can't get it to continuously drain. It just fills the internal tank then switches off. Anyone got any ideas?

I took the plug & bung out of the continuous drain hole & put some garden hose on it, led down to a seacock (the boat is out of the water and I've disconnected the sink) so the hose is lower than the outlet. But the outlet is at the top of the tank, which doesn't make a lot of sense. Nothing in the instructions that I could see.

???
Click to expand...

Did you then put the bung from the continuous drain into the drain to the tank?
 
johnsail said:
Did you then put the bung from the continuous drain into the drain to the tank?
Click to expand...

I thought that you just slung the bung into the tray....

I have the same one.... it bleeding better work as I am not down until December again....
 
I work in a chandlery....and would definitely recommend picking up a 10l dehumidifier from B&Q and attaching a permanent drain hose.

One thing to note, we couldn't get ours to drain properly until we made sure the 'out' end of the hose was lower than the 'in' end (like a siphon, it's a gravity pump), which meant hoiking the thing up onto the dinette table
 
I would definitely avoid the ordinary dehumidifiers - the quoted drying rates apply to normal temperatures only. You will find that in winter conditions they hardly work at all. Please look at the dessicant varieties - one of the best is the X-dry (?sp) which is hardly affected by low temps.
 
BelleSerene said:
We just put a small electric fan heater on board with the thermostat dial set to a low heat. The theory was that trying to keep moisture out is a never-ending task but just drying the air will always work. May be unscientific but it works for us.
Any comments?
Click to expand...
Fan heater does not "dry" the air. What it does is heat the air which allows it to hold more moisture for the same relative humidity. This moisture comes from somewhere so probably less condensation and dampness. If you then vent the warm air it is replaced by cold air at the same relative humidity but lower specific humidity and the cycle continues.

Lidls are selling 3 packs of silica gel and a holder for about £5 - claims to dry 35 cubic metres and is rechargeable in your (preferably electric) oven.
 
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