Electric dehumidifier for a dry boat

[Rick]

Three years ago I bought a dehumidifier to keep the inside of the boat dry, especially in the winter. Even though the hull itself has an “insulated” core the hull-to-deck perimeter is not and at times it drools water down the inside all around the boat merely from that relatively small area.

It is a Whirlpool model AD25BBL2, a 25 pint per day unit with an adjustable humidistat measuring 13”W X 15”D X 234.5” H. It has a steel case and is about as heavy as I could lift and move by myself and, therefore, I did not casually move the unit in the summer when I don’t need it.

The bad news is that it wll NOT remove much water when the ambient temperature is below 60 deg. F. In fact, near 55 deg. F it doesn’t appear to work much at all! I discovered that at maximum humidistat setting when the temperature was above 60 deg. F with an electric infra-red heater on the space that a large block of ice developed on the front grille blocking the air passage. I had to spend some time and mess defrosting the unit and playing with the humidistat setting until I got it to work under my relatively low temperature conditions. The BEST that I could do is achieve 65% relative humidity with that unit.

THEN I read that Sean had a Soleus Air dehumidifier rated to operate down to 36 deg.F. I immediately ordered one. This unit works great! I can get the humidity down to 50% when the temperature is 59 deg.F, which was my goal. According to the allergists dust mites do not reproduce at relative humidities at or below 50% and I am allergic to dust mite “dust”.

The Soleusair is smaller 14.5"W X 9.25"D X 21"H, lighter weight, has a plastic case that can be bumped into the teak without a problem and has a lifting handle making it easy to remove from the boat or move around without breaking my back. It is QUIET, even on the “high and dry” setting.

Let’s compare the energy details between these two units both operating under the same conditions of 60 deg. F, 67% initial relative humidity, 30.8 inches of mercury:

Whirlpool
340 W peak power, 207 W average over days, 63% relative humidity the lowest achievable, 112VAC (sagging voltage on the dock), 0.7 power factor, 4A, 445 VA.

Soleusair CFM-25E (rated at 25 pints per day as is the Whirlpool)
202W peak observed, 171W average over long time, 50% relative humidity achieved, 1.41A, 0.95 power factor, 111.7 V (sagging voltage on dock), 157VA with 150W observed. At “idle” when the compressor is not on the unit draws 24W at a power factor of 1.0!

As an engineer I am very impressed at such a low power factor with a compressor. Most compressors are very inductive thereby creating a circuit breaker heating effect much greater than the actual amount of real power consumed would do without the inductive effect. All such inductive loading effects on the boat (like with most battery chargers) add up to decrease the effective real power that one could draw from say a 30A shore breaker without tripping the breaker.

I did notice that at 121VAC input the Soleusair powerfactor is 0.90 increasing to 0.95 at a lower voltage of 111.7VAC. Regardless, this unit is very efficient and practical for use on a boat.

[ssullivan]

Of course, I agree completely with Rick's detailed product review. Once you get one of these units, you develop a sort of passion for it. I had originally found them after searching high and low for a dehumidifier that was small, did its job and was energy efficient. I couldn't find anything better on the market.

Without having taken the unit apart, I am suspecting it has a sort of "rotary" compressor, since that spinning fan seems to be pretty integral to the whole system. Also, the size and dimensions of the unit suggest that there isn't room for an independent compressor and drive motor. I think (guess here) that they are running the fan and a rotary compressor off the same drive axle.

Man, I LOVE this thing.

[Amfivena]

Looked at buying one recently and the various consumer ratings were interesting. Seemed to score mostly 5 stars all around except for a significant minority who apparently received a non-functioning unit and didn't feal the love with customer support.

We will be getting one this Spring. Just have to remember to confirm operation before throwing the box away or letting it sit for 2 months before using. Have made both mistakes with other things in the past.

[S/V Elusive]

Amfivena - boy do I feel the pain on those issues! LOL - I can't tell you the number of times that I've purchased something (usually on deep discounted sale) and it sat around for a few months (okay 9 months?) or didn't have a place to stash the box, only to find a problem and was then stuck.

Keeping ON topic - I have a Sears Dehumidifier (Kenmore #5130 (30 pint)) I do NOT have all the technical specs on it, but it does draw 4 amps when the compressor is engaged. I've had this unit since April of 2001 and it has worked like a charm. I can easily pull down to 40% at temps between 55 and 60 degrees F. It doesn't get much colder than that onboard where I'm at, so I don't know about lower temperatures.