Dehumidifier draining

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Coxsimon

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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
 
Think about an inline, quick blow, fuse below the rating of the device.
Just in case something goes wrong. A damp boat is better than a burned boat.

Drain into the sink, not the heads.

If you are really clever you can put it on a timer or a thermostat and run through the warmer parts of the day.

We left the boat for nearly 6 months with this set up.
 
Gwylan said:
Drain into the sink, not the heads.

If you are really clever you can put it on a timer or a thermostat and run through the warmer parts of the day.
Click to expand...

I've done that for 20 years. My dehummer is old school and doesn't defrost itself so I use a timer to switch in on and off every few hours. Any ice formed melts that way. Without that it creates an iceberg big enough to counteract sea level rise (or maybe make it worse if the boat is afloat :) ).
 
After 10+ years, I consider a dehumidifier with humidity control draining into the galley sink, plus tube heaters on thermostat (or better, Thermotxt) so they maintain a constant temperature, as one of the best maintenance investments perhaps after Coppercoat.

No mould, no smell, no damp, and significantly less corrosion and/or green e.g. in window grooves. When buying, you can spot boats that had this, from those that did not, from a mile.
 
Sandy said:
Unless the boat is air tight you will using a lot of power to make a puddle of water in the galley sink.
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Yes, but that waters better draining from the galley sink than feeding mould in the headlining. (I hope the cushions are ashore in the dry).

Close down as much ventilation as you can, but you'll never get any boat airtight (exception made for the grey funnel line)
 
I have mine draining into the sink currently but in other years I have often drained it into the bilges, leaving only a small gap and pumping it out regularly. The bilge method works perfectly well and quite a lot of water is removed initially, even though you might think that this water would just be circulated.
 
Sink is best option. Make a note not to shut the seacock.
Make sure the drain tube has a steady fall so it does not air lock
Use t towels to block vents and put cling film over head so you don’t dry it out.
De humidifier is a great asset. Use it!
 
FWIW, I've used a dehumidifier, draining into the sink, every winter for the last 20 years or so. Nothing bad has happened yet.

I do not: block up the various vents; wrap the toilet in cling-film; take off the cushions and bedding; use it when I'm sleeping on board; worry about the open sea-cock or fire while I'm away; do any maintenance on the dehumidifier itself; spend very much money on running it. I do: have it running on a timer - for about six hours from 18:00 to 24:00 each day; have it set to "normal" rather than "extra dry"; ensure the drain pipe is properly fitted and runs down all the way into the sink; power the unit direct from the marina supply rather than through the boat's shore-power system. As a result, the boat is perhaps drier inside during the winter months than it sometimes is from April to October, when it's on its swinging mooring.
 
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I live on board full time, in the winter a dehumidifier makes a huge difference to on board comfort. Make sure you get a dessicant one, the compressor ones are ineffective at low temperatures. I have to say I'd be loath to leave it running whilst I'm not on board but I'm probably overly paranoid about such things, plenty of people do it. I think Gwylan's suggestion of an inline fuse is a great idea...
 
Another one for the sink.

If you use a desiccant dehumidifier they make a bit of heat and you don’t need the tube heaters.

they are more expensive to buy and run than a compressor dehumidifier, but work at lower temperatures, are quieter and don’t have a habit of catching fire.

I leave the beds made up in winter with the dehumidifier on, and enjoy comfortable impromptu boating.
 
Elessar said:
Another one for the sink.

If you use a desiccant dehumidifier they make a bit of heat and you don’t need the tube heaters.

they are more expensive to buy and run than a compressor dehumidifier, but work at lower temperatures, are quieter and don’t have a habit of catching fire.

I leave the beds made up in winter with the dehumidifier on, and enjoy comfortable impromptu boating.
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That's interesting, I haven't heard that the dessicant type are less prone to catching fire before, is there any data that you're aware of on this?
 
Halo said:
Sink is best option. Make a note not to shut the seacock.
Make sure the drain tube has a steady fall so it does not air lock
Use t towels to block vents and put cling film over head so you don’t dry it out.
De humidifier is a great asset. Use it!
Click to expand...
A survey on the HR owners’ page a year or two ago showed that socks were by far the most popular items for blocking vents.

Further to #10, desiccant dehumidifiers don’t take kindly to having their power cut off as they need to go through a closing-down cycle. The occasional power cut hasn’t harmed mine but it is something I avoid if possible. I used to put my old compressor type on a timer but one model defaulted to ‘off’ and wouldn’t restart. I leave my current desiccant type on its wettest setting and lowest fan and this seems fine.
 
Another +1 for dehumidifier drained into the galley sink, been doing it for years.

The bar type heaters as another mentioned are also good for keeping the temperature just above ambient, always have one in the engine bay on a timer.
 
I’ve been experimenting with a different approach, I’ve bought a big fan and I’ve put it by the door so it keeps the air moving about and I’ve kept it on a timer and kept the ventilation open , so far Its kept the boat very dry , ive used dehumidifiers in the past on other boats but still had mould problems, , this seems to be working for me ,
 
Restoration man said:
I’ve been experimenting with a different approach, I’ve bought a big fan and I’ve put it by the door so it keeps the air moving about and I’ve kept it on a timer and kept the ventilation open , so far Its kept the boat very dry , ive used dehumidifiers in the past on other boats but still had mould problems, , this seems to be working for me ,
Click to expand...

Thats an interesting take on it. One other reason for the tube heater/dehumid combination is to keep ambient temperature sufficient to protect engine and avoid fully draining water pump each time.
 
There seems to be two reasons for a dehumidifier.

One is to stop mould. Ventilation works for some on this and we’ve had forced ventilation described. Sounds good.

The other is to keep the boat feeling nice so it can be used in winter. That’s why I leave my desiccant dehumidifier on 24/7. Beds made up and clothes in the wardrobe. Ready to go. It isn’t cheap but it is worth it for me.
 
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