Dehumidifier

[captbuddy]

Has anyone ever used the units they sell in West Marine. Was reading on the box of the one that is round about 12" across and about 3 or 4" tall. All it does is run air through it and heat the air up before blowing the warm air out. I've been told there is some that you set on the counter and run the drain hose into the sink. These type units actually take out moisture. Any experience with either units will be appreciated.
Thanks,
captbuddy

[Will]

The round ones from West Marine seem to work only slightly better than 100 watt light bulbs. You'll need something better if you have to deal with really damp conditions. I've tried 3 of them on a 43' in the San Francisco area and still had problems with condensation.
Will

[captainwjm]

I use the round one from West Marine; can't say that I notice any significant difference than when I only had a ceramic heater set on low in the same area [still use the ceramic heater]. On the other hand, like so much of what we do as "preventive maintenance", the absence of a problem is reason enough to keep on using it.

[Fanfare]

I've had better luck with dehumidifiers that use a small refrigeration compressor. They aren't big enough to cool the air, but they can cool a fan-operated air handler enough to cause the moisture to condense onto a coil, then drip into a pan which can be emptied into a nearby sink drain. This gets the water out of your boat. I've used three on my 50MY, one in the galley, one in salon dumping into the bar sink, and one in the aft head ( block the head doors open, don't let them move). Even so, I'm hard pressed to say that they do a great job. There is so much moisture in the South! (Our boats are surrounded by it!)

Last year a friend of mine in Florida invented and patented a system which removes virtually all of the bilge water. I installed his system last Feb. and it's been running all year. I'll be down in two months and can't wait to see if I'm met by "that Hatteras smell." I'll report as soon as I get there.

[eze2bme]

I have a dehumidifier that's sold at Sears ... has settings to allow it to run at 3 hour or 6 hour intervals ... has a digital humidity setting ... and HI and LO fan settings. I plumbed the discharge to a thru hull fitting and have been very pleased with the performance. A side product of the dehumidification cycle is heat ... which is an assist in the Winter months. During the Summer months I leave the vent in the cabin door slightly open to releave the heat from building up in the salon. I leave the unit set to run at 3 hour intervals on HI at 45% humidity ... year round.

My only suggestion on the discharge issue would be to have the drain discharge very near the water line as the discharge water may stain/discolor the fiberglass. I'm in a fresh water environment but the discharge water is often golden in appearance which I'm assuming comes from minerals.

Happy Holidays ... maybe Santa will see your "wish list" on the humidifier!!

[Maynard Rupp]

We have been using a standard old home type dehumidifier for years. We use it on our 35' racing sailboat. When the boat goes in the well in spring, the dehumidifier goes aboard and runs 24/7. We only haul it off,(they are heavy), when we are leaving for a race. We have been told that these things actually keep the hull from holding water in the laminate. I am not sure about that, but we can lay out lots of soaking wet sails and they are dry the next day. We just use the pan that holds about 2 gallons. The other secret is to close the boat completly. If you don't you are trying to dehumidify the entire city. Detroit isn't a real humid place but I still empty about a gallon every 2 days. We have never felt the need for one on our Hat. We run the AC for a couple hours in summer and it seems to dry it out fine. Spring and fall we use the heat feature for the same purpose.

[Genesis]

The little ones sold at West are just heaters - heat air, the dewpoint remains the same, the RH goes down. Duh. Does NOTHING.

You want a REAL dehumidifier, which is basically just an AC unit with both the evap and condensing coils in the same place. The evap cools, water condenses on the coil, drains off just like your AC unit, and the heat is rejected back into the room from the condensor coil. You have a net GAIN of heat (the energy consumed goes into the room) but you REALLY DO get drier air this way.

Of course you have the deal with the condensate doing it this way.

If the AC is running, you have a dehimidifier. If not, then this is the way to go; if you're running heat but still getting too high of an RH, the dehumidifier will contribute to the heating and also get rid of the water.

[REBrueckner]

As Gensis posts, unless there is a means of causing moisture condensate which can then be collected or drained, you are not lowering relative humidity.
In NY in winter, with heat set at about 45 degrees to prevent freezing, I find that once the weather turns cold, say mid December thru end March I can set my dehumidifier at about 55% and it doesn't run too much; in milder weather at that setting it runs a LOT.

[Genesis]

50% RH is ideal.

Its also basically impossible to maintain in the summer on board a boat.

[captddis]

I have a dehumidifer that has been on the last two boats. The boat is in FL and I have never had mold problems. in the winter when it gets into the high 40s, I turn it off as the coils freeze into a solid chunk of ice. How do you keep yours ice free in the winter? Dave