Boat and RV Dehumidifier FAQs

Answers to frequently asked questions (faqs) you may have about or Boat and RV Dehumidifier.

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FAQs

Where can I find support and warranty information?
Why doesn't my unit start?
What is the recommended rh setting for the dehumidifier?
Where is the best place to locate the dehumidifier?
Why doesn't the unit collect and drain moisture?
Who is the manufacturer?
What kind of maintenance is required on the unit?
Is there a filter on the unit?
What do I do if a UPS package I received is damaged?
Why do you say better than AC for humidity Control?
Why can't I just use my AC for humidity control?
I just bought a portable AC unit end of story. No need for a dehumidifier.
What's wrong with using desiccants or silica gel packets?
The dehumidifier uses refrigeration principles won't this cool down my cabin even further in mild weather?
I note that the dehumidifier uses 150 watts while running. Can you tell me, in watts, what its starting current is? I need to know in order to purchase an inverter of sufficient capacity to start and run the unit.
What kind of inverter should I use?
Why shouldn't I use the dehumidifier in the bilge?
Why can't I just use an off the shelf dehumidifier?
I rotated the drain pipe and now it leaks?
Questions concerning winter time operations in below 50°F.
More Questions concerning winter time operations in below 50°F
More Questions concerning winter time operations in below-freezing temperatures.
I am interested in your dehumidifier Dehumidifier but can't find the quantity of water removed per day (capacity) in the specs so I can compare to other units. Can you provide this info?
I have a 42' sailboat and want to know if one of your units is big enough to handle the entire boat.
I am interested in knowing whether the dehumidifier is available in 220 volt.
What is the height of the unit excluding the control knob and handle? I have a step that is 11 ½ high by 10" wide I want to place the unit in that area.
Information on your website indicates the DH-5-1 is constructed from stainless steel. Does the DH-10 have any non stainless steel or copper parts such as screws, nuts, or bolts that could rust?
Our understanding from your website is that water removed from the air is supposed to drain out the drain tube and not into the cabinet (base).

Where can I find support and warranty information?

Support and warranty information can be found in the support page.
Why doesn't my unit start?

You just plugged in the unit and it doesn't run and you know that you have plugged the unit in to a good outlet. This is what you do. Turn the humidistat level to 60%. If it doesn't start turn the knob all the way to on. It should kick in then. Set the humidistat at the recommended 60% RH. The unit will power on and off automatically at the level which you preset. back to top of page
What is the recommended rh setting for the dehumidifier?

The recommended relative humidity (RH) setting for the DH-10 is 60%RH.

Set the humidistat on the unit at 60%. At settings lower than 50% woodwork may become dried out. For different applications see the other usage table for the recommended RH setting. back to top of page
Where is the best place to locate the dehumidifier?
Locate the unit in the galley, berth, or head, or where the air is stagnant or where mold and mildew has formed in the past. Direct the exhaust airflow towards areas where moisture is a problem - v berth or head.
NOTE: Do not operate the unit in the bilge, engine, or fuel storage room where combustible vapors may accumulate and therefore pose a risk of explosion.
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Why doesn't the unit collect and drain moisture?

First check the humidity. At a low humidity and low temperature the amount of moisture that can be collected is greatly reduced. back to top of page
Who is the manufacturer?

The manufacturer of the DH-10 dehumidifier is the McIntire Company
This division is called Arrow Dryers by McIntire

The DH-10 has been manufactured in the USA since 1993. back to top of page
What kind of maintenance is required on the unit?

Other than keeping the unit clean and free of dust, the unit was designed to be maintenance free under normal operating conditions.

Cleaning Involves: Occasionally checking the evaporator (water collection coil at the air intake, (control knob end)) and the condenser. If it is contaminated with dust and dirt, have the dehumidifier cleaned by a boat or RV service man. A dusty or dirty evaporator coil or condenser reduces the units efficiency.

Clean and dry out the drain pan and hose occasionally, since a dirty, moist drain pan or hose is a breeding ground for mold, mildew and bacteria.

Inspect the hose for blockage caused by kinks, dirt or mold and mildew. Clean and straighten as necessary. back to top of page
Is there an air filter on the unit?

No. back to top of page
What do I do if a UPS package I received is damaged?

If you receive a damaged package, please contact us and we'll handle the damaged shipment/claims process. back to top of page
Why do you say better than AC for humidity Control?

First we want to make it clear that we agree, that while you are in your boat or RV, by all means turn on the AC. I don't know if anyone can survive hot humid weather in a boats cabin without the AC running especially if you are at anchor or dockside. There is a time however, that we do recommend you give the AC system a break and turn ON the dehumidifier. Namely: 1. while you are away from your boat, 2. during mild weather to reduce condensation (you don't want the AC cooling you any more than you already are), 3. or for humidity control.
1. While you are away from your boat: the AC system is designed to cool you down and while doing so humidity is also removed. However, If you will be gone all week and want to return to a fresh boat on the weekend, there is no need to keep an unoccupied boat cool. Give the AC system a break, and your pocket book too, the shore power bill on typical 16k BTU system adds up after a while. At 150 watts our DH-5 will consume less electricity than the typical 16K (1440 watts) central air in your boat. Even the more smaller AC units draw some 528 watts of electricity. Turn on the dehumidifier, its designed to remove humidity without the added cost of cooling the unoccupied cabin plus it was built with power efficiency in mind.
2. During mild weather to reduce condensation: naturally you won't use the AC system in cold weather. The DH-10 returns room temperature air.
3. For humidity control: An AC system was designed to keep you cool and comfortable while on board, but it was not designed for efficient humidity control. The dehumidifier was designed for efficient humidity control. The DH-10 has settings of 20%RH - 80%RH humidity level selection. At settings between 50%RH and 60%RH most humidity related problems (i.e. Mold, condensation) can be taken care of. back to top of page
Why can't I just use my AC for humidity control?

Question 10 is similar to this question so please see question 10 for the answer.
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I just bought a portable AC unit end of story. No need for a dehumidifier.
By all means do whatever you need to do to stay cool and comfortable during hot humid weather. However if your goal is humidity control, may I suggest a dehumidifier. See question 10 for more information on this. back to top of page
What's wrong with using desiccants or silica gel packets?

Nothing, but when you start going through bucket loads of the stuff its time to get a dehumidifier. back to top of page
The dehumidifier uses refrigeration principles won't this cool down my cabin even further in mild weather?

This is a concern for those of you in LiveAboards, Houseboats, and Motor Homes, with no off season you must endure mild weather and condensation.
Some of you are concerned that the DH-10 dehumidifier will lower the temperature in your live aboard even more, since it operates on the same refrigerated principles as an air conditioner unit. Relax. We have taken room temperature readings at 70°F at both ends of the dh-5 dehumidifier and the temperature is about the same. How is this so? This is so because damp cabin air flows over the evaporator coils (cold) and is cooled down; true, but the same cool air blows over the condenser (hot) coils and is heated back up again and is exhausted back through the other end into your cabin. So your cabin temperature remains the same, though, drier. back to top of page
I note that the dehumidifier uses 150 watts while running.
Can you tell me, in watts, what its starting current is? I need to know in order to purchase an inverter of sufficient capacity to start and run the unit.

The starting current or draw is 1.62 AMPS (RLA 1.62) RLA stands for Running Load Amps. This in watts is 194.4 watts. I would recommend buying an inverter of at least 300 watts since the inverter itself will draw some 30 watts or so. If you plan to connect a laptop, cell phone or medical device to your inverter, you might want to consider an inverter that uses a pure sine wave. Our dehumidifier is not as picky and so it will run on either a pure sine wave or a Modified sine wave inverter. The more watts the inverter is rated for the more appliances you will be able to connect to it. back to top of page
What kind of inverter should I use?
see question 15 back to top of page
Why shouldn't I use the dehumidifier in the bilge?

You may drain water into the bilge but we don't recommend placing the dehumidifier in the bilge. First, the dehumidifier could easily be submerged in water in the bilge. The DH-10 has not been designed to be submerged in water neither has it been designed to be used in the bilge.
Secondly, we don't recommend placing the DH-10 in the bilge because according to most boat safety courses gasoline or diesel fumes may also accumulate in the bilge which may cause an explosion. Use only equipment in the bilge that has been designed for use in the bilge. back to top of page
Why can't I just use an off the shelf dehumidifier?

Off the shelf dehumidifiers were primarily designed for home use and not marine use. There are several factors that must be taken into account in designing a marine dehumidifier; the harsh marine environment, humidity, salinity, space consideration and power consumption. These factors translate into features that distinguish a marine dehumidifier from a home type dehumidifier. There's a whole page in our website that compares the two. Follow this link to see the comparisons.
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I rotated the drain pipe and now it leaks?
Note: The newer version of our dehumidifier the Dh-10 doesn't use a grommet so this is not an issue in the DH-10.
If a leak develops after rotating the drain pipe:
The grommet is notched on the inside of the drain pan. The notch must remain horizontal or leaks may occur. If you rotate the elbow barb to the opposite direction and a leak develops its probably because the grommet has rotated along with the elbow barb. To stop the leak the grommet needs to be reset to where the notch on the grommet is horizontal.
See the setup portion of the manual for complete details

Note: Newer Dh-5's and Dh-10s don't have the notch on the grommet
TIP: To prevent the grommet from turning hold down the grommet with one hand while turning the elbow barb with the other hand.
TIP: If leaking persists:
Use a dish drain tray/pan (like the kind used under a dish drain rack) under the DH-5 to catch undesirable leaks. back to top of page
Questions concerning winter time operations in below 50°F. Your model DH-10 dehumidifier looks perfect form my needs. I have a 35 ft sailboat in the pacific northwest. During our winters most boats are still in the water and semi-winterized (Not sailed, but at the dock) I’ve tried the "air heater" types and it’s just not keeping the interior dry. I just discovered a serious mold problem in the floorboards around the base of the mast and center bilge. However, you state on your webpage that,

"we don't recommend for unattended operation in below 50°F temperature. Our customers around this time are on liveaboards and motor homes, where the indoor temperature is set for personal comfort (70°F), so the temperature for them is within allowable usage limits."

In the pacific Northwest, the air temperature in the winter is around 45°F, but can go as low at 35-40°F at times. This is the time we need the humidifier most, not in the summer. So, 1) will this dehumidifier work adequately in our winter environment? And 2) if not, what other solutions are there to keep the humidity down under 45°F outside of a heater which is a fire hazard unattended.

In answer to your question, the dehumidifier may not work adequately in the situation you described. However, you might want to try a combination of the dehumidifier + your "air heater" (as long as it is a safe heater (unattended) and designed for boat or marine use and for your particular situation) to raise the temp inside your boat. Perhaps the two together might be the solution. (as long as it is a safe heater (unattended) and designed for boat or marine use and for your particular situation).
A second option might be to use a dehumidifier that is rated at a lower operating temperature. Such a dehumidifier will have a defrost feature or have a crank case heater or other heating element to keep the evaporator from frosting.

see also question 21 and 22
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Questions concerning winter time operations in below 50°F I have a 35 ft sailboat in the Pacific NW. The average cabin temp during the winter is 45-50°F. Last winter I had a severe decaying mold that got into my floorboards and destroyed several panels. At the time I was just using 2 small "saucer" dehumidifiers and a heater that didn't do the job. On the advice of local boat owners, I bought your DH-5-1 dehumidifier to keep the boat dry, but had concerns about the low ambient temperature. They said it didn't matter since the unit generated enough heat to keep the cabin warm. Well, I'm not so sure that was good advice.

I started at 90% humidity. After 2 days of use in 50°F temp I was able to drop it to 80%, but the coils are frozen, and it seems the unit is running constantly. I assume the unit isn't very efficient at the lower temperatures. So my questions:
1. Is it ok to run the unit 24 hrs a day in these conditions, or is it just not efficient and should go to another system?
2. Should I be able to get the humidity down to 50-60% when the temp is 50°F?
3. Is it Ok to make it more efficient by getting a space heater to heat the cabin temp?

In reply to your question:
Our customers around this time are on Liveaboards and motor homes, where the indoor temperature is set for personal comfort 70°F, so the temperature for them is within allowable usage limits. The unit doesn't generate enough heat to warm up your cabin temperature. It returns warm air but at the current room temperature. see question 14 for more about this

1. Is it ok to run the unit 24 hrs a day in these conditions, or is it just not efficient and should go to another system?
The Dehumidifier becomes inefficient at lower temps. especially at 50°F. It will still remove moisture but not efficiently. Furthermore, running the unit constantly in these conditions could result in the unit breaking down. Its advisable that you use a unit that has a lower operating temp. range.

2. Should I be able to get the humidity down to 50-60% when the temp is 50°F?
Like the above question, it is probably not possible given the limitations of the DH-10. Look for a unit with a hot gas defrost feature or one which which will operate down to 33°F.

3. Is it Ok to make it more efficient by getting a space heater to heat the cabin temp?
It is a good idea, to warm up the cabin temperature using a heater, as long as it is a safe heater (unattended) and designed for boat or marine use and for your particular situation.

Below is more information that covers this topic:

The manufacturer does not recommend using the DH-10 dehumidifier below freezing temperatures for two reasons
1. The refrigerant in the evaporator will become slushy and will cause a low pressure build up. In other words the compressor will not function properly and may breakdown.
2. The dehumidifier is not rated for outdoor usage (below freezing weather). In other words outdoor refrigerated appliances have a crank case heater or other heating element to keep the evaporator from frosting or freezing.

As for a risk of fire, the compressor is thermally protected so it will shut down if it gets too warm.

see also questions #20 above #22 below
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Questions concerning winter time operations in below-freezing temperatures. I am considering buying your marine dehumidifier to protect the boat that I am about to buy. However, I see no information on your web page on how the unit will react to below-freezing temperatures.

I live in Georgia, near Atlanta. Winters are relatively mild here, water is not freezing solid, and I expect to keep my boat in the water all year long, with your dehumidifier inside, turned on. While the temperature during the day is above freezing on most days, it goes below freezing during many nights in winter. How will the unit react if it is left operating? I understand that it will not remove moisture during that time, and it is OK with me. But, is there a risk of a break-down, or even
worst, a fire? It is crucial for me, because I will not be able to monitor the operation of the unit for days at a time.

The bottom line answer to your question is, we don't recommend for unattended operation in below 50°F temperature. Our customers around this time are on liveaboards and motor homes, where the indoor temperature is set for personal comfort (70°F), so the temperature for them is within allowable usage limits.

As for operation in freezing weather the manufacturer, doesn't recommend using the DH-10 dehumidifier below freezing temperatures for two reasons
1. The refrigerant in the evaporator will become slushy and will cause a low pressure build up. In other words the compressor will not function properly and may breakdown.
2. The dehumidifier is not rated for outdoor usage (in this case below freezing weather). In other words outdoor refrigerated appliances have a crank case heater or other heating element or defrost feature to keep the evaporator from frosting or freezing.

As for a risk of fire, the compressor is thermally protected so it will shut down if it gets too warm.

Although dehumidifiers are not designed for freezing weather, some dehumidifiers (with a defrost feature or other heating element to keep the evaporator from frosting or freezing) have a lower operating temperatures range to 33°F

Here's some more info on the temperature limitations.
Temperature Limitations: the dehumidifier will not operate properly at temperatures below 50°F. Some customers have reported frosting can begin at 50°F. The dehumidifier will definitely not operate at temperatures below 32°F. Water freezes at 32°F so any condensation on the coils will freeze or frost. We have tested and ran the dehumidifier in outdoor temperatures as low as 58°F with no problems and moisture being removed just fine. Please note that the colder the temperature gets, the less efficient the unit becomes. In other words as the temp. reaches the low operating temp. range of 50°F the less humidity the unit will be able to remove.

Temperature Limitations based on humidistat:
Operating Temperature Range (efficiency based on, and limited by the nylon ribbon sensing element in the humidistat)
50°F to 125°F (10°C to 52°C). In addition frosting on the coils begins around 50°F which further limits the ability of the unit to remove moisture.
see also questions 20 and 21 above
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I am interested in your dehumidifier, but can't find the quantity of water removed per day (capacity) in the specs so I can compare to other units. Can you provide this info?

The capacity of the DH-10 is 10 pints per day, adequate for boat and RV Applications.
I have a 42' sailboat and want to know if one of your units is big enough to handle the entire boat.
Mr. Brown, (formerly) the owner and manufacturer of the Arrow Dryer DH-10 dehumidifier,
has replied that:
"It will do a 54 ft boat". Mr. Brown owns a 54 ft. boat.
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I am interested in knowing whether the dehumidifier is available in 220 volt.

I have an English boat and I am docked in the US hooked to a 220 (50 AMP) supply. This feeds my charger and my AC outlets on the boat and works fine. My appliances are 220 Volt and both 50/60.

I would plan on running the dehumidifier hooked to boat's internal AC outlet which is the 220 (60HZ) which is the supply in Connecticut.

any possibility of a custom manufacture?

No, the DH-10 Dehumidifier is not available in a 220 volt configuration. The DH-10 runs on 115 volts AC power. At this time the manufacturer doesn't do any custom conversions to a 220 VAC model or such like.
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What is the height of the unit excluding the control knob and handle? I have a step that is 11 ½ high by 10" wide I want to place the unit in that area.
Note: This question refers to the older version DH-5-1
In reply to your question:

height not including handle or control knob 10 1/2 "
height to knob 11 1/4 "
height to handle 11 1/2 "

On the DH-10 the handles are flush with the side of the panel. The dimensions for the DH-10 are:
Height: 12.5", Width: 12", Depth: 15.5"

Note: on the DH-5-1 the handle is riveted to the cabinet.
I'm not sure how your setup looks, but additional consideration are "Is there a suitable drain nearby, for continuous draining? and make sure that you allow enough space for airflow in and around the unit.
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Information on your website indicates the DH-5-1 was constructed from stainless steel. Is the DH-10 constructed of stainless steel, and does the DH-10 have any non stainless steel or copper parts such as screws, nuts, or bolts that could rust?

The DH-10 cabinet has a textured powder coated steel cabinet with an all stainless steel base. But other parts like the compressor, condenser, fan blades, and evaporator are constructed of other types of metals that may rust or corrode, but this is minimal and doesn't affect the life or function the dehumidifier.
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Our understanding from your website is that water removed from the air is supposed to drain out the drain tube and not into the cabinet (base).
Note: This question refers to the DH-5-1
The new design for The DH-10 has the entire stainless steel base of the dehumidifier act as a drain pan. The base is tapered in 4 places to force water to drain through the center of the base and out the back of the cabinet. This design will be less prone to clogging and an added lip around all four sides of the base will prevent water that has accumulated in the dehumidifier base from spilling out of the side of the cabinet.

The result: water is collected and drained out more efficiently.

If you have an older DH-5-1
Yes this is true, the evaporator is positioned over the drain pan so that the condensate drips into the drain pan. Know that there is a small drain pan that collects a little bit of water before it starts flowing out the drain hose.
Nevertheless, under certain conditions, some condensation occurs in other parts of the dehumidifier (CPV valve, tubing to the evaporator, compressor) so some water will drip inside the cabinet base. On a level surface the water should flow towards the drain pan. If you have too much water dripping into the cabinet, or too much back flow, consider tilting the unit so water flows towards the drain pan. We found that using a towel to tilt the rear end works well and helps to absorb some sound and noise. Older models had holes in the base which could cause the water to drip on your counter top. If you still have one of these older models and this is a problem for you, use a dish drain pan to collect excessive water.

The unit must sit on a level surface and the drain hose must not be higher than the unit otherwise water will back flow back into the cabinet.