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12v marine dehumidifier


snooky jo
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Hi

 

im have pretty good ventilation but do often still get quite a lot of condensation on my windows.

 

i was thinking maybe getting a dehumidifier but have no knowledge of any.

 

im running on 12v electric, with 2x 220amp hour batteries, with on 90w solar panel providing a pretty good continuous feed of 1 to 2 amps as well as the engine alternator.

 

at present i have not had to turn the engine on to top up the electric as the panel has kept me going well.

 

i would consider getting another panel.

 

what i dont want is a monster of a dehumidifier that will gobble up all my batteries or one that is so small that it does not really collect any moisture, does such a thing exsist?

 

shore power is not an option.

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Hi

 

im have pretty good ventilation but do often still get quite a lot of condensation on my windows.

 

i was thinking maybe getting a dehumidifier but have no knowledge of any.

 

im running on 12v electric, with 2x 220amp hour batteries, with on 90w solar panel providing a pretty good continuous feed of 1 to 2 amps as well as the engine alternator.

 

at present i have not had to turn the engine on to top up the electric as the panel has kept me going well.

 

i would consider getting another panel.

 

what i dont want is a monster of a dehumidifier that will gobble up all my batteries or one that is so small that it does not really collect any moisture, does such a thing exsist?

 

shore power is not an option.

 

I can't answer your question about 12v dehumidifies directly, but can offer some other thoughts:

 

Most dehumidifies have a fridge-like compressor system. Trouble is they stop working as the temperature gets down to about +5 because the mechanism runs below ambient temperature and freezes up. Desiccant-type dehumidifies work right down to freezing and below, and emit air slighlyt above ambient temperature (ie there is a slight heating effect). These are ideal for a boat left empty on shore power - we got one recently following some advice on this forum and it is great to come back to a dry boat in winter (wooden doors not sticking, no sign of mould etc) after it has been empty for some time, at a cost of £2 or 3 per week electricity or so. That is no good for you though!

 

Condensation will form on a cold surface such as a window when the local temperature of that surface gets down to the saturation point of the air. The air in the rest of the boat might be quite warm, and so have a fairly low but comfortable relative humidity (too low is uncomfortable). How low the relative humidity in the boat has to be to prevent window condensation depends entirely on the temperature difference between inside and outside the boat. To guarantee no condensation when it is really cold outside, you have to have uncomfortably dry air in the boat and expend a lot of energy removing the water. Therefor dehumidifying a warm boat is not the answer.

 

I would suggest that your best solution is some form of removable secondary glazing for the colder months, that will stop window condensation and cost no electricity to run, and as an added advantage will reduce heat loss from the boat.

Edited by nicknorman
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Hi

 

im have pretty good ventilation but do often still get quite a lot of condensation on my windows.

 

i was thinking maybe getting a dehumidifier but have no knowledge of any.

 

im running on 12v electric, with 2x 220amp hour batteries, with on 90w solar panel providing a pretty good continuous feed of 1 to 2 amps as well as the engine alternator.

 

at present i have not had to turn the engine on to top up the electric as the panel has kept me going well.

 

i would consider getting another panel.

 

what i dont want is a monster of a dehumidifier that will gobble up all my batteries or one that is so small that it does not really collect any moisture, does such a thing exsist?

 

shore power is not an option.

 

I think you'll find they don't exists - - - As Nick suggests - get secondary glazing instead - even the annual application of a temporary variety will be better than nothing . . . . and make sure your ventilation is excellent,

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im have pretty good ventilation but do often still get quite a lot of condensation on my windows.

 

Even with half a decent dehumidifier you'll more than likely find condensation on your windows, it may be better to use other methods to insulate the windows (I will find the link) rather than use a electric method.

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After reading the other replies I think I can offer you some goods news, as I have seen positive mention of a 12v dehumidifier in a CC'ers blog. He reports favourably on its performance, and it was recommended to him by a boat owner, so that's at least two people in the community who have found 'it did it for them'.

Now then, who and where.

IIRC, Bruce's blog 'Living In Sanity Again' was where I read about it. BruceinSanity is a member of this forum, but I'm not sure whether he will pick up this mention.

I'm not sure what the qualifying criteria is on this forum for Member searching and PMs; it might be 5 posts, in which case you are OK.

 

I've previously tried Searching his blog, but found the facility inadequate. Don't let that stop you trying though, as it might have been operator error on my behalf.

 

HTH

Edited by Davidss
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True, they do exists: http://www.ecrater.co.uk/p/13028591/large-dehumidifier-air-dryer-portable

 

I have one of these - small, not tiny like some though, and pretty damn good, we run it in the bedroom after we are up and about to get rid of condensation and does the job really well. It doesn't seem to use anywhere near the watts it is quoted as using. V. quiet too.

 

Neil

Edited by snigsnig
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  • 9 years later...

So absorbing 120ml of water will make a significant difference in a boat, will it? Then you  drive it back into the atmosphere from the microwave.

 

They may do something in an enclosed small volume space like a cupboard but I think a stove and  a few open vents would do more on a boat.

 

Thy are not even 12V, just a bag of dehydrated crystals. Try an open bowl of salt.

Edited by Tony Brooks
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On 13/04/2012 at 13:58, Davidss said:

IIRC, Bruce's blog 'Living In Sanity Again' was where I read about it. BruceinSanity is a member of this forum, but I'm not sure whether he will pick up this mention.

Typing @BruceinSanity will let him know his name has been mentioned the next time he logs in.

Jen

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  • 2 weeks later...
On 12/08/2021 at 08:15, MartynG said:

Sounds like you need more ventilation and/or  better air circulation

 

I have  a small USB desk fan which is surprising effective at circulating air. Perhaps a few of them in a narrowboat?

https://www.homebargains.co.uk/products/15429-status-coolbreeze-4-usb-mini-fan.aspx

We've got a 50ft, cruiser stern. Plenty of ventilation. I always wonder if a dehumidifier, once it has dried the air in the boat, will pull in outside air and try to dry out the canal 🙄. For years we have relied upon dehum crystals - two trays - and a couple of those disposable ones the same size as washing capsule boxes. We've got big windows which do steam up when cooking but soon clears. Stove for cold weather. Have recently added an Aero device which seems to also collect stacks. Never had any concerns or problems with mustiness, mould or damp.

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  • 2 weeks later...
On 13/04/2012 at 11:38, snooky jo said:

Hi

 

im have pretty good ventilation but do often still get quite a lot of condensation on my windows.

 

i was thinking maybe getting a dehumidifier but have no knowledge of any.

 

im running on 12v electric, with 2x 220amp hour batteries, with on 90w solar panel providing a pretty good continuous feed of 1 to 2 amps as well as the engine alternator.

 

at present i have not had to turn the engine on to top up the electric as the panel has kept me going well.

 

i would consider getting another panel.

 

what i dont want is a monster of a dehumidifier that will gobble up all my batteries or one that is so small that it does not really collect any moisture, does such a thing exsist?

 

shore power is not an option.

 

Are your windows single or double glazed ??  If they are normal single glass ports or windows, before playing with dehumidifyers that use a lot of power, see what happens when you fit cheap perspex, (Or other clear plastic), sheets over the glass parts. Cheap perspex is rather difficult to cut without cracking, so if you don't like that idea, just try flexible clear plastic that is at least 2mm thick and then glue it into place with clear bathroom sealant, (assuming it's not a stainlees frame). That's a cheap option that I know will work, although I use more expensive but 20 times tougher clear ploycarbonate sheets that can be ordered already cut to size with holes etc all for mounting.

 

A limited amount of through flow of fresh air is important, as lack of it can cause mould or condensation rates to accelerate. Keeping the bilges dry can also help reduce humidity in some cases.

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  • 3 months later...

I must say that my boat is remarkably dry,  no black mould.

The sf stove runs 24/7, the windows have lined curtains, the lower metal on windows are covered with draught excluding tape. The stove has a back boiler, distributes warm water through airing cupboard, bathroom radiator and a wide pipe in bedroom. 

Webasto to two radiators, kicks in when outside temp about 0 degrees and inside thermostat about 18 C. 

I have heavy full length curtains near  the bow doors but keep the rear doors uncurtained in order to keep a large mass of air fairly cool air except in extreme weather when I will stop draughts with pool noodles or similar. 

Ventilation is fairly efficient. In winter I remove the grids under mushrooms, this improves ventilation,  the vents holes are sprayed white, makes the boat lighter. 

I run the shower fan to remove steam when needed. Dry towels near fire for an hour or so if they are to be re used. 

The portholes get a bit of dampness, removeable with paper towel.

I think the stove keeps the air dry, I would expect most problems in a small boat with more people and more showering, but keeping the stove on, and circulating air by opening doors and windows  is critical. Good foam insulation of course. I remove any condensation on windows every day, often not necessary. 

I used greenhouse tube heaters when on shore power, quite efficient. 

Edited by LadyG
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If you want to reduce the humidity inside a boat, try insulating it correctly. This is more important if you have a steel or alloy hull than a plastic or wood one.

  Although I'm still building my alloy lifeboat, (Salvaged hull up project), I'm going to place fire resistant good quality bubble bubble wrap against the hull and secure it in place with strips of wood, with oak below the waterline and red wood or pine above for C of G reasons.

  Obviously you can solve the issue by heating, but that is one expensive solution for a large canal boat.  The Portholes or glass windows are best insulted with cheap Perspex, as the tougher and easy to cut Polycarbonate is fairly expensive. It's possible to find folks of Fleabay that do pre cut Perspex etc.

Perspex Disc Plastic Circles / Laser Cut Acrylic Disc - ALL SIZES / Cut to Size | eBay

It's also possible to fit Perspex that has a mirror finish if you don't like curtains, or just use a one way tint sheet on top.

 

Never, ever use a foam insulation that is not fire proof. If it burns it creates a very dangerous toxic gas that kills people that smoke in bed every year. Cheap bubble wrap is flammable put at least it burns without producing smoke.

  Most of the foam or alloy bubble wrap insulation advertised as fire proof or resistant and made overseas is not. The roll I bought said fire proof, but it burnt slowly when I tested it, so it is in reality fire resistant. 

 

Edited by TNLI
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41 minutes ago, LadyG said:

I must say that my boat is remarkably dry,  no black mould.

The sf stove runs 24/7,

Plenty of heating and ventilation such as in your case  is just as good at controlling condensation as any dehumidifier . By keeping your heating on full time you are minimising the conditions that result in condensation.

 

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47 minutes ago, TNLI said:

Most of the foam or alloy bubble wrap insulation advertised as fire proof or resistant and made overseas is not. The roll I bought said fire proof, but it burnt slowly when I tested it, so it is in reality fire resistant. 

 

There is a huge variety of specifications to cover 'fireproofness', one of the most common ones being the American UL (Underwriters Laboratories)  specification 94. covering plastics.

 

There are the following ratings :

 

Test done with the specimen hanging vertically in a (specified) flame -

UL94.V0 which is basically it does not propgate flame, will not 'burn' and just shrivels up. It must self extinguish within 10 seconds.

UL94.V1 which means it must not propogate flame  and must extinguish within 30 seconds.

UL94.V2 which means it is allowed to propogate the flames by dripping flaming drops but must self extinguish within 30 seconds

 

And for the 'lowest' specification the sample piece is held horizontally across the flame and it will continue to slowly burn with continuous flaming droplets.

 

Your bubble warp could quite easily be UL94 compliant but like many things without the full detail (which rating) is misleading and confusing.

 

 

Part of the reason for the loss of life on the ships hit by missiles in the Falklands was that the military had specified HB and V2 rated cable ties on the cable tray, this meant that once burning flaming drips could drop down from one layer of cable trays to another lower down and spread the fire. The specifications were changed and we supplied Vo cable ties in future.

As the cable ties burnt and melted, the cables dropped off the cable tray (they are strapped to the underside of the tray) which caused further problems that the escape routes / walkways became a mess of tangled cables and the sailors, blinded by smoke and fumes, could not escape. We subsequently developed a range of steel fixings which could take the shock loading of an exocet missile and were completely fireproof. It was interesting watching the G-Force testing machine simulating an Exocet missile hit.

 

We had a similar issue with cable ties 'off-shore' where HB rated nylon 11 or Nylon 12 cable ties were specified, these were changed to stainless steel cable ties, but there was then corrosion and crevice corrosion problems between the stainless steel and the galvanised cable tray, we resolved this by coating the stainless steel cable ties with a V0 rated 'Macropol' coating.

I had many breakfast meetings at Shell offices in Lowestoft, London and Aberdeen (and with Lloyds register) getting the necessary approvals.

Edited by Alan de Enfield
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1 hour ago, MartynG said:

Plenty of heating and ventilation such as in your case  is just as good at controlling condensation as any dehumidifier . By keeping your heating on full time you are minimising the conditions that result in condensation.

 

The othe reason I keep boat warm and air clean is that I have asthma, which is aggravated if it is really cold and damp indoors while sleeping. 

So the best thing ever about boat living is being cosy 24/7, I think the total cost of heating and cooking is similar to my one bed flat, where I used to have an electric overblanket plugged in all night to keep my shoulder muscles relaxed. 

I have yet to perfect a clean and efficient way to deal with the coal, essentially I half empty a bag onto the well deck and fill a coal scuttle. I just need a better coal scuttle! 

Although bottled gas has gone up 15% this year, my solid fuel has not, and I am paying maybe 15% more for diesel, I don't think I am as hard hit as landlubbers. 

Edited by LadyG
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1 hour ago, LadyG said:

 

Although bottled gas has gone up 15% this year, my solid fuel has not, and I am paying maybe 15% more for diesel, I don't think I am as hard hit as landlubbers. 

It will be next year when most  landlubbers like myself are really hit by gas and electricity price increases. 

At the marina - where the  price cap does not apply - our shore power electricity cost per unit has doubled starting  from December 1st 2021.  It does focus the mind on ways to reduce energy consumption but there is only so much that can be done.

 

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