Dehumidifier draining

[KompetentKrew]

Not true. A dehumidifier makes a huge difference in our non airtight AWB.

+1

I'm so tired of the "dehumidifying Hampshire" trope. It's observably untrue,

 

[wonkywinch]

Bumping this thread as winter approaches. I've used Ebac dehumidifiers in my home for many years and have been very impressed. I'm thinking of putting one on the boat (marina based with shore power) but due to it being slightly larger than the chandler sold types, it would be more convenient to leave it under the saloon table and poke the drain hose into one of the thumb holes in my sole boards above the bilge pump (which I always leave on auto to catch any fridge condensate or rainwater that might have found it's way in.

If the power failed, the whole lot would turn off, if the bilge pump failed, the dehumidifier wouldn't produce enough water between boat visits to get very far.

I'd appreciate the pro's and con's from the knowledgeable & experienced people here.

Plan B would be to stand on the worktop and drain into the sink but that's more cumbersome.

 

[RupertW]

We’ve always had ours on the worktop and drained to the sink. That seems much more resilient to outages and breakages and doesn’t inconvenience us even when living on board as the dehumidifier (Maeco Junior) has a fairly small footprint.

Personally I really wouldn’t want it draining into the bilge as that means a permanently wet bilge even if the pump is working and ours can pull litres of water a day, although that would imply a lot of damp air and water ingress if that kept happening.

 

[ChromeDome]

Make sure you get a device that will start up and continue on a set % and program if power cuts out and returns.

Had a DDB that failed, now on a EEESE that just works. Model "2509 Adam" - probably sold under other labels.

Also has a maintenance mode where it reaches the set %, stops, waits, starts to check and stay on if needed.

 

[RupertW]

Make sure you get a device that will start up and continue on a set % and program if power cuts out and returns.

Had a DDB that failed, now on a EEESE that just works. Model "2509 Adam" - probably sold under other labels.

Also has a maintenance mode where it reaches the set %, stops, waits, starts to check and stay on if needed.

Those two reasons are exactly why I bought the Maeco Junior. The ability to choose the fan power setting and the required humidity and then to go back to those settings after a power outage.

 

[B27]

Bumping this thread as winter approaches. I've used Ebac dehumidifiers in my home for many years and have been very impressed. I'm thinking of putting one on the boat (marina based with shore power) but due to it being slightly larger than the chandler sold types, it would be more convenient to leave it under the saloon table and poke the drain hose into one of the thumb holes in my sole boards above the bilge pump (which I always leave on auto to catch any fridge condensate or rainwater that might have found it's way in.

If the power failed, the whole lot would turn off, if the bilge pump failed, the dehumidifier wouldn't produce enough water between boat visits to get very far.

I'd appreciate the pro's and con's from the knowledgeable & experienced people here.

Plan B would be to stand on the worktop and drain into the sink but that's more cumbersome.

To my mind, the whole point of the dehumidifier is to have a dry bilge.
I'd suggest either buying a smaller dehumidifier or running it with a tank and putting some effort into eliminating those rain leaks.

Maybe you could raise the dehumidifier on a box or something and have it drain into a 25 litre can or something?
Or do you have a shower sump which will get the water overboard?

 

[Alex_Blackwood]

To my mind, the whole point of the dehumidifier is to have a dry bilge.
I'd suggest either buying a smaller dehumidifier or running it with a tank and putting some effort into eliminating those rain leaks.

Maybe you could raise the dehumidifier on a box or something and have it drain into a 25 litre can or something?
Or do you have a shower sump which will get the water overboard?

If you use a container it has to be air tight or the condensate will just try to fill the space it has been taken from. If you have a drain in the boat it will let humid/moist air in from outside. All sort of defeats the purpose of dehumidifying, I think! Could be wrong

 

[B27]

If you use a container it has to be air tight or the condensate will just try to fill the space it has been taken from. If you have a drain in the boat it will let humid/moist air in from outside. All sort of defeats the purpose of dehumidifying, I think! Could be wrong

A container would need to restrict the air flow, but it needs to vent air out to let water in, the internal tank of a dehumidifier works well enough without being actually air tight.
I used a 25 litre can in my workshop.

 

[wonkywinch]

I don't believe having a closed container makes any/much difference. It's all to do with surface area/temperature differential vis dew point etc which is how this machine pulls a large volume of air across cooled coils to condense the water out.

There may be a small amount of evaporation from an open container, but not enough to be concerned (unless you were draining it into a 2 sq m baking tray).

 

[Momac]

I use the dehumidifiers built in tank.
On a low setting it takes the best part of a week to fill the tank, if the vents on the boat are blocked.
The low setting is enough to keep the boat acceptably dry.
But I can get to the boat easily to empty the tank.

 

[Gsailor]

I appreciate it’s been covered, and I’ve read many threads already, but I’m a newbie looking for some certainty!
I’ve got a 30yrold 32footer, in a marina and thinking of getting a dehumidifier (plus some 80w bar heaters) and letting it drain into the heads or galley sink and keeping that seacock open. I have no through hull above the waterline.
I’m away from the boat for up to 2/3weeks at a time.
Before inviting lots of warnings, I’d appreciate your knowledge and experience.
Thanks

Have not read all replies- what about a small bilge pump in the dehumidifier collection tank that is either auto or works via a an electronic water level sensor (water witch is one brand) - you could set the water level sensor to half way up the reservoir tank?

 

[Tranona]

I thought the idea of a dehumidifier was to get the water out of the boat and water in the bilge is a major source of moisture. So passing it through the dehumidifier into the bilge rather than down the sink does not seem like a good idea even if the pump does remove some of it. First thing to do is have dry bilges, then the need for the dehumidifier is reduced. next remove the moisture from the air in the boat to the outside as quickly as possible.

 

[wonkywinch]

I thought the idea of a dehumidifier was to get the water out of the boat and water in the bilge is a major source of moisture. So passing it through the dehumidifier into the bilge rather than down the sink does not seem like a good idea even if the pump does remove some of it. First thing to do is have dry bilges, then the need for the dehumidifier is reduced. next remove the moisture from the air in the boat to the outside as quickly as possible.

The bilge has a deep trough about the shape/size of a vertical brick, there is always water in there surrounding the pump as the level switch inside the pump doesn't fully drain the bilge so the dehumidifier draining won't add to the surface area of water present in the bilge since the pump will run whenever the level rises enough to trigger it (still contained within the brick shaped cavity).

I'll try laying some paper towel around the bilge area surrounding the pump and see if it ever gets wet there draining the dehumidifier, otherwise countertop next to the sink which will gravity feed out to a drain above the waterline rather than relying on another mechanical device to clear it.

Thank you all for your valued comments.

 

[[2574]]

I confess I haven’t read every one of the above comments from 2021 - so apologies if I’m duplicating - but I’m always surprised that there’s not always mention of a desiccant dehumidifier being better than a compressor type when used for this purpose. They work more effectively at lower temperatures.

Our dehumidifier has now been running on board for about a month. At first it was using about 15kw per week, however having now dried the boat out its down to 8kw per week - or about £4/wk cost. Much more expensive than it used to be of course.

 

[RupertW]

If you use a container it has to be air tight or the condensate will just try to fill the space it has been taken from. If you have a drain in the boat it will let humid/moist air in from outside. All sort of defeats the purpose of dehumidifying, I think! Could be wrong

Most people drain into a sink so no outside air will get in and even moisture through the tiny pipe is going to be minimal.

 

[14K478]

Ex wooden boat owner getting used to GRP.

I visited the boat in lay up yesterday and found everything either wringing wet (grp surfaces) or very damp (everywhere else)

We have had had a week of rain and little wind. Up to now I have relied on the wooden boat technique - establish a howling draft from end to end and all will be well - but I now see that this doesn’t always work with plastic.

I think I need a dehumidifier. However the galley and heads sinks are hand pumped overboard - a system that I like, when afloat - so a dehumidifier cannot drain into them.

I suppose I could, with a good deal of bilge diving, lead the drain hose through the bilge drain plug hole, which is just above the encapsulated ballast in the keel.

I’m assuming that a dehumidifier should be placed low down?

 

[Graham_Wright]

I confess I haven’t read every one of the above comments from 2021 - so apologies if I’m duplicating - but I’m always surprised that there’s not always mention of a desiccant dehumidifier being better than a compressor type when used for this purpose. They work more effectively at lower temperatures.

Our dehumidifier has now been running on board for about a month. At first it was using about 15kw per week, however having now dried the boat out its down to 8kw per week - or about £4/wk cost. Much more expensive than it used to be of course.

15kw weeks is an awful lot of electricity.

 

[jwilson]

I normally run a dessicant dehumidifier with pipe into the sink, but as you cannot do that I suggest into a 25 litre plastic can with a tussue or rag jammed into the cap holding the pipe in place. Evaporation from that will be truly minimal, and you can empty it every week or two. Re water in bilge sump: if it is at all reachable you could dry it out for once.

 

[B27]

Ex wooden boat owner getting used to GRP.

I visited the boat in lay up yesterday and found everything either wringing wet grp surfaces) or very damp (everywhere else)

We have had had a week of rain and little wind. Up to now I have relied on the wooden boat technique - establish a howling draft from end to end and all will be well - but I now see that this doesn’t always work with plastic.

I think I need a dehumidifier. However the galley and heads sinks are hand pumped overboard - a system that I like, when afloat - so a dehumidifier cannot drain into them.

I suppose I could, with a good deal of bilge diving, lead the drain hose through the bilge drain plug hole, which is just above the encapsulated ballast in the keel.

I’m assuming that a dehumidifier should be placed low down?

I don't think there is any particular need for the dehumidifier to be low down. It may help air circulation a bit though.
Unless you are neglecting your boat for months at a time, a 25 litre can should collect all the water?
If you can run a hose through the bilge (I assume you're boat is ashore!), it's maybe still worth collecting the water in a big can, to see how much there is, We used to run the the drain pipe through the speed log fitting on my mate's boat.

I am leaving my boat on the mooring this winter, I've just removed most of the cushions, cleaned and dried the bilge, it's not doing too badly. I open the boat when I can if the weather is dry. I have a couple of small rain leaks to work on.
When the weather is cold and damp, firing up the heater and allowing moderate ventilation helps a lot.

 

[V1701]

Key things are:
1 - If you're using it in winter on an unheated boat use a dessicant type dehumidifier not compressor. Compressor type do not work well at low temps.
2 - Don't put it on a timer because they have a shutdown cycle.
3 - Seal boat as best you can, however it's a myth that unless you hermetically seal the boat 100% you'll be trying to dehumidify the planet...