Best application for using a dehumidifier

[ralexa6808]

Ok, I did a search before posting this question and although it has been answered before in other posts, the answers were not exactly addressing these questions.

The PO used a portable dehumidifier (which they did not leave behind). The boat is located in the Southern US, and until the Admiral retires consistent use of the boat will be sporadic. Any advise would be appreciated, thanks.

Questions:
1. Portable or permanently installed dehumidifier (pros and cons either way)?

2. On a 58' YF would the best location to place a portable dehumidifier be in the companionway just forward of the guest bathroom so it can discharge water via the shower drain (that is where the PO had located theirs)? Do I also need a dehumidifier for the Main Salon/Helm Area?

3. If permanently installed where would be the best location?

4. Apart from leaving the door to the bedrooms open, should the engine room doors be left open too?

5. Is it a good or bad idea to temporarily block the ER room vents?

6. Is the above a waste of time, effort, and money? I noticed while reading through the older posts, it had been mentioned more than once that dehumidifiers were not being used all that much in the Southern US.

 

[saltshaker]

If you don't have digital controls for your AC units, you should consider upgrading. If you do the salon and the master stateroom only that may do the trick but I would eventually do them all. If you have digital controls there is a dehumidify feature. When my boat was in Fl we left them in humidity control and the boat was always dry and no odors. We live in NJ so the boat was left for extended periods. If you use a portable dehumidifier, I would think it be best to have one in the salon and one in the lower section of the boat, maybe in the companion way? Fans will help a lot too. If you keep the air moving you'll have less of an issue with dampness. I wouldn't close the ER vents for this reason. We do it up here but only in the winter months to help keep the cold air out.

 

[carolinacoast]

The AC system on our boats, properly maintained, IS a big dehumification system. The prior post is accurate, you may need the 'dehumidify' feature to run the compressors to keep things bone dry. We program that to run more often in the salon while away than a below deck unit, since hot humid air rises. Maybe start with a checkup from a well regarded AC tech.

 

[ralexa6808]

Thank you both for the advise. I know one of the AC control units has a digital display. I will check next month when we are onboard and look into upgrading the remaining "analogue" controls.

 

[Pete]

I am a believer in portable dehumidifiers on an unattended boat and for that matter even when on the boat if the temperature and humidity make it difficult for the onboard air conditioners to run without turning the boat into a cold storage locker. So let me make the case for leaving the onboard air off and running portables during your absence.

Take a look at the air conditioning system. No other system on these boats has more hoses and sea water connections, not even the main engines. Every time the AC starts in any cabin, a sea water pump starts pumping through all these connections, hoses, heat exchangers, and thru hull fittings. So much opportunity for leak, and loads of sea water in the wrong place, with no one checking on the situation. On the other hand, what if the water circulating system clogs due to jelly fish, vegetation, clams, or anything else. Now you have one or more compressors cycling on the high pressure switch, unless your controls do a shut down under this condition, leaving the boat to turn into a mold colony. Why look for a problem when a simple solution is available (KISS).

On our 48 LRC I have two portable home dehumidifiers. One in the salon/galley, and one in the master stateroom on the lower level. The upper unit sits on the galley counter and drains into the galley sink drain. The lower unit is mounted on a table for some height and drains into the master head using the bath tub drain. This causes the drain sump pump to cycle which is good and should that fail the water will overflow into the bow bilge and that pump will discharge it, so a backup exist. Simple, easy, and the chance of anything going wrong is as close to zero as you can get. I also use several fans to constantly circulate the air throughout the boat. Setup works great in my opinion in eastern NC.

One lesson I have learned is to not get digital electronic controls on the dehumidifiers as when the shore power goes up and down as it always does, the units do not restart. For this reason, make sure to only acquire manual control units if you go this way.

That is my story and I am sticking to it. BTW, our boat is docked behind our house and thus I have put up with the electronic controls. If the boat was somewhere else I would have definitely gone for two different dehumidifiers with manual controls.

Pete

 

[rsmith]

I am a believer in portable dehumidifiers on an unattended boat and for that matter even when on the boat if the temperature and humidity make it difficult for the onboard air conditioners to run without turning the boat into a cold storage locker. So let me make the case for leaving the onboard air off and running portables during your absence.

Take a look at the air conditioning system. No other system on these boats has more hoses and sea water connections, not even the main engines. Every time the AC starts in any cabin, a sea water pump starts pumping through all these connections, hoses, heat exchangers, and thru hull fittings. So much opportunity for leak, and loads of sea water in the wrong place, with no one checking on the situation. On the other hand, what if the water circulating system clogs due to jelly fish, vegetation, clams, or anything else. Now you have one or more compressors cycling on the high pressure switch, unless your controls do a shut down under this condition, leaving the boat to turn into a mold colony. Why look for a problem when a simple solution is available (KISS).

On our 48 LRC I have two portable home dehumidifiers. One in the salon/galley, and one in the master stateroom on the lower level. The upper unit sits on the galley counter and drains into the galley sink drain. The lower unit is mounted on a table for some height and drains into the master head using the bath tub drain. This causes the drain sump pump to cycle which is good and should that fail the water will overflow into the bow bilge and that pump will discharge it, so a backup exist. Simple, easy, and the chance of anything going wrong is as close to zero as you can get. I also use several fans to constantly circulate the air throughout the boat. Setup works great in my opinion in eastern NC.

One lesson I have learned is to not get digital electronic controls on the dehumidifiers as when the shore power goes up and down as it always does, the units do not restart. For this reason, make sure to only acquire manual control units if you go this way.

That is my story and I am sticking to it. BTW, our boat is docked behind our house and thus I have put up with the electronic controls. If the boat was somewhere else I would have definitely gone for two different dehumidifiers with manual controls.

Pete

Glad you said it. I'd never leave the boat with the A/C running. I can't say how mant times I got up in the middle of the night to clear a plastic bag out of the strainer. The pump gets red hot,the Compressors get red hot.Not a good thing for the compressor life no less the possible fire hazard. Not to mention the sink risk. The tubing connections where the cooling hoses connect are thin. I was on a boat offshore that had the line snap off where the hose ended. We found it quickly but it put quite a bit of water in the boat first. I have a house hold unit strapped in up in the Fwd stateroom.

 

[captddis]

I have a White Westinghouse dehumidifier that I bought 19 years ago. I put it on top of the stove and run the drain out into the sink. Never had any mold and is much safer than running the AC's. I don't want hi amp loads and water pumps running while I am away.
The dehumidifier is also much, much cheaper than running the ac's.
The down side is you have to take it down when you are going to move the boat.

 

[ralexa6808]

Thanks all, I appreciate all the experience and input..... aside from upgrading /standardizing the A/C controls, I'll also get two portable units and put one on each level.