How to choose the right dehumidifier for your garage

How to choose the right dehumidifier for your garage?

When choosing the right dehumidifier for your garage, there are several options to consider. Here, we will look at the different alternatives and provide you with the information you need to choose the right dehumidifier for your garage.

You need to consider things like:

• type of technology (Condensation / desiccant rotor / sorption with exhaust)
• temperature (more than 10 degrees / 10 to 0 degrees / risk of frost)
• how to get rid of the water?
• budget

CONCLUSION:

Below, you can read a lot about dehumidifiers in the garage, if you want to delve into the background. If you want the conclusion right away, here it is:

The best option is to use a sorption dehumidifier that exhausts moisture as wet air. Here are the alternatives:

Arida S12 is a small dehumidifier that can still be suitable for a garage. If you have a garage with minor moisture problems, or a garage that is rarely used, this can be a good alternative. If wet cars enter every day, it will take a long time to dry the garage. It may not be able to get the garage completely dry before new cars arrive the next day.

Arida Pro S19 is a modern dehumidifier with an upgraded heating element that provides excellent drying capacity relative to power consumption. This dehumidifier also has Wi-Fi, which offers many possibilities.

A simpler alternative is to use a desiccant rotor dehumidifier that converts moisture into liquid water.

Remember that this water must be emptied or drained away. These dehumidifiers are often for indoor sporadic use and are not really suitable for continuous use in a garage.

Arida Sandefjord is a freestanding dehumidifier that can be used in all temperatures down to zero degrees. It has good drying efficiency, but is often still too small if wet cars enter every day. Arida Sandefjord has rotating louvers, so it supplies dry air to larger parts of the garage. This provides more effective and faster dehumidification.

Meaco DD8L is a freestanding dehumidifier. It is as good as Arida Sandefjord, but lacks swivel louvers and uses more power per liter of water. For this model, you can purchase a wall mount to place it higher on the wall.

Read on here, for those with special interest:

Why the right dehumidifier in the garage?

There are many good reasons to use a dehumidifier in the garage:

• The car rusts less. If you keep the humidity below 50% RH, you almost stop all rust. 
• Tools and other items in the garage rust less.
• The car dries inside and you avoid condensation inside the car. This assumes you open the car windows when you park overnight.
• The building benefits, with less mold, rot, mildew, and similar issues.
• Less odor in the garage and less odor in the car (if you open the car windows)

What alternative dehumidifiers are available?

Compressor-based dehumidifier / condenser dehumidifier:

Most dehumidifiers available on the market today are compressor-based dehumidifiers. These are also called condenser dehumidifiers. If you need a dehumidifier in your living room or laundry room, this is a good choice. However, if you are going to use it in the garage, we do not recommend this type of dehumidifier. The reason is that condenser dehumidifiers have very little effect in low temperatures. They work fine at 20 degrees, but below 10 degrees, they perform poorly. Manufacturers state that they work down to 5 degrees, and some even claim down to 1 or 2 degrees. This is technically true, but the effect is so small that you would need a very large dehumidifier to compensate. Such a large dehumidifier uses a lot of electricity, takes up a lot of space, and is expensive to purchase. If your garage is always above 10 degrees, or you only need to dry in the summer, then you can certainly use a condenser dehumidifier. Most others should use a desiccant rotor dehumidifier or a sorption dehumidifier. 

Also, remember that you need to get rid of the water. A condenser dehumidifier converts moisture into liquid water. You are therefore dependent on a drain or emptying the water tank yourself. Read more about this here. Also, remember that if you can get frost in the garage, the water can freeze and damage the dehumidifier. Read more about this here.

It is important to choose the right dehumidifier for your garage. Examples of good compressor-based dehumidifiers for use in heated garages are:

• Arida Desert Super 20L
• air&me Rohan

Desiccant rotor dehumidifier (Sorption dehumidifier that produces liquid water):

An air dehumidifier with a desiccant rotor (silica gel, sorption, adsorption) works in a completely different way. These also convert moisture into liquid water, but the way they work is much more efficient in low temperatures. Whether you use it in the living room at 20 degrees or in the garage at 2 degrees, it is almost equally effective.

A desiccant rotor dehumidifier is therefore much more suitable for a garage than a compressor-based dehumidifier. However, there are a few things you need to consider before buying this type of dehumidifier:

• Can there be frost in the garage? If the temperature never drops below freezing in the garage, this is a good option. If there is a risk of frost in the garage, you must be careful. In principle, we would then recommend using a sorption dehumidifier with wet air exhaust, but if you are careful, you can still use it.
• How do you get rid of the water? This type of dehumidifier converts moisture into liquid water. You must dispose of this in some way. We have some options:
  A) Lead the water to a drain if you have one in the garage.
  B) If you don't have a drain in the garage, you must empty the water tank. Remember that this may need to be emptied every single day. Are you in the garage every day, and do you want to do this every day?
  C) Lead the water out through the wall. This is possible, but we do not recommend it. 

Examples of good desiccant rotor dehumidifiers for use in garages:

• Arida Sandefjord
• Meaco DD8L

Sorption dehumidifier that blows moisture out of the garage

This is often the best solution. It costs more to purchase and requires some installation, but once this is done, it is a very good solution.

A sorption dehumidifier with wet air exhaust works well in all temperatures. You can also use it in freezing temperatures without problems. Very simply explained, this dehumidifier works as follows:

• The dehumidifier sucks air from the room where it is located
• Inside the dehumidifier, a desiccant rotor (sorption element) is used to separate the dry part of the air from the moist part of the air.
• The dry air is blown back into the garage
• The moisture is blown out of the garage as moist air (not liquid water)

This technology offers several advantages:

• Well suited for all temperatures (including frost)
• No water to drain. No water tank to empty
• Small physical size. Easy to place. Can be conveniently hung on the wall (or up / down from the ceiling)
• Long lifespan (higher price, but often lasts much longer)

Disadvantages:

• Price (but also longer lifespan)
• Requires some assembly (Very simple, and only done once)
• Must make a hole in the wall to get the hose that blows wet air out (Typically 40 mm or 80 mm) Feel free to use an existing vent in the wall
• Must be placed in the immediate vicinity of an outer wall (Shortest possible hose from the dehumidifier to the outside air)

Examples of good desiccant rotor dehumidifiers for use in the garage:

• Arida S12 (NB Small. Check size)
• Arida S19

How to get rid of the water?

In one way or another, you need to dispose of the water produced by the dehumidifier. If you have a sorption dehumidifier with exhaust, it's easy. If you have one of the other alternatives, you need to dispose of liquid water. You have a few options:

1- Lead the water to a drain or sewer 2- Empty the water tank
3- Water hose out of the wall (Generally, we do not recommend this, but with caution, it can be done.)

Temperature in the garage

A very important factor to consider when choosing a dehumidifier for the garage is the temperature. Remember that this varies throughout the year. The lowest temperature should be the determining factor. In summer, when it is 20 degrees, you can use anything. Even a condenser dehumidifier with a compressor will be useful then. If the temperature drops below 10 degrees in autumn and winter, you should consider a desiccant rotor dehumidifier instead. If it freezes, you must either use a dehumidifier with wet air exhaust or turn off the dehumidifier in winter. The table below schematically shows what you should choose.

What size should I choose for the right dehumidifier for my garage?

General recommendation with a table showing garage size, usage, and dehumidifier size. Remember that the amount of moisture entering is more determining than the size of the garage.

 NB: The recommendations are given on the assumption that:

• there are no special problems
• cars with snow on them are not driven in often
• wet cars are not driven in often
• the garage is sealed (you should close all ventilation, including ventilation in the eaves etc)

If in doubt, you should go up at least one size.

Lifespan and size

A larger machine means less operating time and longer lifespan. If you have a small dehumidifier, it will need to run many more operating hours than a large one. It rarely gets a break. This means that even if the stated power consumption is lower, it will over time use more electricity because it is actually too small, and therefore has to run many more hours. The internal components also get many more operating hours, and the dehumidifier will probably break down earlier. If you can afford the cost and have the space, it will ultimately be cheaper to buy a dehumidifier that is too large rather than one that is too small.

Installing a dehumidifier in the garage

It is usually easy to install a sorption-based dehumidifier. Most people install the dehumidifier themselves, but we can also put you in touch with companies that install dehumidifiers for you. Among others, we can recommend Skadedyrkontroll1.no

Table showing characteristics of different types of dehumidifiers

Power consumption

How much power does a dehumidifier use in the garage? It is absolutely impossible to answer this. It completely depends on how much moisture needs to be removed. If the car often comes in with water or snow on it, then a lot of water needs to be removed. If you have a wall that draws moisture up from the ground, then a lot of moisture needs to be removed. If you have a garage that is mostly dry, but you just want to make sure that it doesn't get too humid there at certain times, then little water needs to be removed. It is not the size of the garage that matters. Nor is it the type of dehumidifier that matters so much. What matters is how much water needs to be removed. For every liter of water that needs to be removed, you use a certain amount of power. The type of dehumidifier you use matters less. Over time, it will be more efficient and cheaper to use a large dehumidifier than a small dehumidifier.

Example: You choose a compressor-based dehumidifier because it appears to use little power (according to the specifications, it does). It uses little power per hour, but because it is so inefficient at low temperatures, it has to run for many hours to remove the same amount of water. The power consumption over a day therefore becomes high, even if the power stated in the data sheet appears to be low. If you have a cold garage, you should choose a dehumidifier with a desiccant rotor if you are concerned about power consumption. Even if a dehumidifier with a desiccant rotor uses three times as much power (on paper), it is so efficient at low temperatures that it finishes the job in an hour, while a compressor dehumidifier needs to run for 6 hours. Measured over an entire day, the sorption dehumidifier will still use less total power, even if the stated power is significantly higher.

Hygrostat (what is it and why should you use it?)

A hygrostat is a device that measures the humidity in the air. It is used to turn the dehumidifier on and off to maintain constant humidity in the garage. A hygrostat controls the dehumidifier in the same way a thermostat controls the heater.

Most dehumidifiers have a built-in hygrostat. On some dehumidifiers (especially professional ones), you can connect an external hygrostat that measures humidity elsewhere than exactly where the dehumidifier is located.

Where you do not use a hygrostat, the dehumidifier will dry constantly. This is not necessary, and you use more power than you need to. (Think of a heater. You would hardly use a heater continuously without a thermostat, even if it is technically possible).

External water tank (Possible with extra capacity, but does not stop when the tank is full)

Dehumidifiers that collect water in a tank stop when the tank is full. You then have to empty the tank to get it to start again. To avoid this, you can connect a hose and lead the water to a drain. If you don't have a drain, you can lead the water to another water tank / jug / bucket. This means you don't have to empty the water tank as often. NB: If you do this, you must be aware that the dehumidifier will NOT stop when this extra water tank is full. You must therefore keep an eye on it so that the water does not overflow and onto the floor. Normally, we do not recommend this, but we know that many do it at their own risk. See example in the video below.

Leading water out through the garage wall

If you don't have a drain to lead the water to, and you don't want the hassle of emptying the water tank, you can lead the hose out through the wall and dispose of the water outdoors. This works well, but you must be very careful in winter. Remember that the water in the hose can freeze. If the water freezes and the hose gets clogged, the water tank in the dehumidifier will still fill up. Some use a heating cable to prevent the water from freezing. Also remember that you will get an ice chunk outside the garage where the water comes out. This does not necessarily have to be a problem, but you must assess it for your specific case.

Leading water into the floor

Some also choose to drill a hole in the floor and lead the water into draining masses under the garage floor. Provided you have good drainage, this can work well for many.

Difference between condensation dehumidifier and sorption dehumidifier

In the video below you can see the difference between a condensation dehumidifier (with compressor) and a sorption dehumidifier (with desiccant rotor). This explains how they work, and why one is better than the other in a cold basement or cold garage. It is important to choose the right dehumidifier for the garage.