Do all new models have continuous fans?
by Anon
I was told by a salesperson that all new portable models in the $200-$400 range now have continuously running fans. As I do not want a continuously running fan, and this does not actually seem to be the case from my reading of reviews, I would like to know if it's true. Thanks.
Answer
You are quite right to be sceptical; there are current models both with and without continuously running fans.
This issue comes up frequently and, to avoid having to repeat myself, if you scroll down this page you will find all that you need to know in my answers to similar and related enquiries from other visitors.
Tom
Basement dehumidifiers and continuous fans
Do all basement humidifiers run with a continuous fan operation? Is there a model(s) that shuts down completely, and turns on again to begin working. It seems like a waste of energy and a fire hazard to have the machine in continuous operation. Thanks
Answer:
Dehumidifiers have a fan to move air through the unit for three purposes.
1) Dehumidifying: To pass the air over the cold coils to condense the water vapor from the air. Common to all units.
2) Defrosting: When ice forms on the coils the compressor stops running, so the coils are no longer cooled, but the fan continues. The flow of air speeds up melting of the ice. Common to all units.
3) Sensing: When operation of the dehumidifier is being controlled by the humidistat (humidity sensor) the compressor stops operating when the programmed level of relative humidity is achieved. In order to sense any increase in relative humidity, and restart the compressor accordingly, the air must be sampled. To obtain the air sample the fan must operate to draw air into the unit.
Some dehumidifiers achieve this by continuous fan operation. Others will sample the air by running the fan for a few minutes only, at intervals of an hour or so.
The argument in favor of continuous fan operation is that the dehumidifier's response to a rise in relative humidity is more prompt and more precise. The fan circulates air through the room so, by operating continuously, it mixes the air, thereby evening out variations in relative humidity within the room and detecting a general increase more quickly.
The arguments against are the one you have raised in your question, energy use, and noise, since the fan is the main contributor to dehumidifier noise levels. The question of a fire hazard is valid but the risk is only slightly greater than when the fan is not running continuously. The main causes of dehumidifier fires, which are rare, are restrictions of the air flow in and around the machine. These can be avoided by following the installation instructions, the safety advice and cleaning the air filter at the recommended intervals.
With respect to energy use. The fan consumes power at a rate similar to a standard light bulb; the main energy hog is the compressor. The additional cost of continuous fan operation is offset by the more rapid response to changes in relative humidity, which reduces the time that the compressor is in operation. The main reason for choosing a dehumidifier with a fan that runs only while the unit is dehumidifying or defrosting is to reduce the noise nuisance.
Having said that the choice is, of course, yours. If you are considering a portable home dehumidifier for use in a basement we recommend five brands. Of these The Alen and Winix models do not run the fan continuously, Danby, Frigidaire and GE models do run the fan continuously.
If your basement is cool, below 65deg F, and you are looking for a purpose built basement dehumidifier there are models, even within the same brand, that do and do not have continuous fan operation. For example, the Santa Fe Classic's fan runs only while dehumidifying whereas the Santa Fe RX's fan runs continuously.
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Basement dehumidifiers with fans that don't run continuously
by Cheryl P
(Belchertown, MA)
I currently have 3 dehumidifiers that when they come on to reduce humidity the fan runs and when the humidity level is reached the compressor shuts off and so does the fan.
I need to know who makes a 50 to 70 pint dehumidifier that has this feature? I do not want a dehumidifier that the fan continues to run when compressor is off.
Answer
Hi Cheryl, thank you for your question.
As you may have seen there are five manufacturers whose products we particularly recommend.
These brands, in alphabetical order, are Alen, Danby, Frigidaire, GE and Winix. All of these brands include dehumidifiers of 50 to 70 pints capacity.
Alen, Frigidaire and Winix all manufacture dehumidifiers in which the fan runs only when the compressor is operating. In Danby and GE dehumidifiers the fan runs continuously.
There are valid reasons for preferring either a dehumidifier with a continuously running fan or a model in which the fan only runs when the compressor is active. The main disadvantage of a continuously running fan is noise. The advantages of a continuously running fan are lower energy costs and more precise control of relative humidity.
Dehumidifier users are often surprised when I say that a continuously running fan saves energy but this option provides the dehumidifier with a continuous flow of air so that relative humidity is measured constantly rather than every hour or so. The compressor is the major energy user in a dehumidifier and a continuously running fan ensures that it operates for the least number of hours each day.
I won't go into any more detail here but if you or any other visitor wishes to see a fuller explanation I have provided the information in my answer to a similar question from another visitor which you can find here.
My purpose in drawing attention to the advantages of a continuously running dehumidifier fan is not to question your preference but simply to make it clear to any who read this that there is a "trade-off" between lower noise nuisance and lower energy costs and that a choice between continuous and intermittent fan operation must be made according to which of these two benefits is the more important to the individual making the decision.
I hope you find this information helpful and that you will understand my reasons for taking my reply a little beyond your specific question :).
Tom (Webmaster)
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Danby Dehumidifier
Does the fan run all the time?
by Robert
(Newmarket,Ontario)
Does the fan on a Danby 60011R dehumidifier ever shut off or does it run all the time?
Answer
Hi Robert, thank you for your question.
The simple answer to your question is yes, the fan runs all the time.
Continuously running fans are raised as an issue by many of our visitors and there are two reasons why many folks dislike them; additional noise and the belief that this characteristic increases the energy consumption of the dehumidifier.
The issue of noise is not in question. A dehumidifier with a continuously running fan creates more noise than a model on which the fan runs intermittently.
The question of energy use is more complex. The compressor on a dehumidifier is controlled by the humidistat. When the humidistat senses that relative humidity has risen above the programmed level it switches the compressor on. It cycles it off again when the humidity has been reduced below the programmed level.
In order to sense relative humidity the humidistat needs a flow of air from the room. There are two methods by which this flow is provided to the humidistat. On a Danby dehumidifier the fan runs continuously while on some other dehumidifier models the fan switches on for a few minutes at intervals of about an hour.
Relative humidity is not evenly distributed throughout the room. Where the air is warmer, nearer the ceiling for example, relative humidity is lower. Where the air is cooler, such as next to basement walls, the relative humidity is higher.
A continuously running fan circulates the air and creates a more even distribution of relative humidity. It also detects a rise in relative humidity as soon as it occurs. The air flow on a Danby 60 pint humidifier, for example, is sufficient to cycle an amount of air equivalent to that contained in a 1000 square foot basement roughly three times every hour. A 60 pint dehumidifier running the fan for just five minutes every hour will only cycle one quarter of the same "basement-full" of air every hour, one twelfth as much.
It will be obvious that the measurement of relative humidity in that same basement taken by a dehumidifier with a continuously running fan will be more accurate, due the air being more thoroughly "mixed". It will be equally obvious that the response time of the dehumidifier to a rise in relative humidity will be much shorter.
These two factors mean that the operation of the compressor in a dehumidifier with a continuously running fan will be more precise and this will reduce the amount of time that compressor operation is needed to maintain the level of relative humidity programmed with the humidistat.
In any dehumidifier the compressor consumes the lion's share of the energy used; the fan, while running, uses no more than a typical light bulb. The net result is that a dehumidifier with a continuously running fan uses less energy overall than a similar model with a fan which operates intermittently.
The real choice that a user has to make is either to have less noise or to have a lower energy bill. Either option is perfectly reasonable, depending on the priorities of each individual but it is important to be aware that it is not possible to have both benefits at the same time.
Tom (Webmaster)
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House Dehumidifier - Fan Runs Continuously
by Marlin Palm
(Mountain Lake MN USA)
The fan keeps running all the time. I do know the compressor is not running. Can you tell me if I've got it set wrong?
Model# is BHD-501-G
Answer
Hi Marlin, thank your for your question.
There is nothing wrong with the setting you have selected, the dehumidifier is operating normally.
There are two occasions on which the compressor will stop operating. The first is when ice forms on the evaporator coils which may happen at any temperature from 65F and below. In order to operate effectively the ice must be allowed to melt and the dehumidifier switches to "de-frost mode".
In defrost mode the compressor stops and the evaporator coils will no longer be cooled. The fan continues to operate and the flow of ambient air over the coils accelerates melting of the ice. Once the dehumidifier senses that the ice has melted the compressor restarts and the dehumidifier removes water from the air once again. An indicator on the control panel will display when the dehumidifier is in defrost mode.
The second occasion on which the compressor stops is when the level of relative humidity selected with the humidistat has been achieved. The compressor will cycle back on whenever the dehumidifier senses that relative humidity has risen above the programmed level.
In order for the humidity sensor to detect changes in relative humidity it must monitor air from the room. To obtain that air the fan must be running. In order to do this a dehumidifier may be designed so that the fan operates for a few minutes at intervals of around an hour or operates continuously to test the air.
The advantage of intermittent sampling is that it reduces noise nuisance from the fan. The advantage of a continuous flow of air is that changes in humidity are detected more promptly and the measurement taken is more accurate, due to the continuous air flow in the room and the better "mixing" of the air.
Many dehumidifier users believe that a continuously running fan increases the overall energy consumption of the dehumidifier and that an intermittently running fan is more energy efficient. This belief is mistaken.
The fan uses power at a rate equivalent to a light bulb; the "energy hog" is the compressor. By detecting changes in humidity more promptly, and by cycling the compressor on to deal with them immediately, the continuously running fan ensures that the hours during which the compressor operates are minimized. A continuously running fan is, therefore, a net energy saver.
Dehumidifier users have a choice between less noise nuisance or higher energy costs and either is a legitimate choice depending on an individual's order of priority. Unfortunately it is not possible to have both benefits simultaneously.
Tom (Webmaster)
Winix dehumidifier #:WDH851
Does the fan run continuously?
by Pedro Gonzalez
(Marietta, GA, USA)
Does the fan turn off when humidity reaches the set level?
My old one did, the GE I bought does not. Looking for one that will turn off to conserve energy.
Answer
Hi Pedro, thanks for your question.
The fan of the Winix WDH851 will turn off when relative humidity is reduced to the level programmed with the humidistat. It may run for a short time after the compressor switches off to cool the condenser coils but it will stop after this brief interval.
The main advantage of a fan which runs only while a dehumidifier is removing water from the air is that it reduces the noise nuisance of the appliance. I cannot say that I agree with the suggestion that it will save energy.
The main energy consumer in a dehumidifier is the compressor. The fan uses no more energy than a typical light bulb. A continuously running fan maintains air circulation within the room, ensuring that relative humidity is relatively even throughout that room. Meanwhile the humidistat has a continuous supply of air to sample and will quickly detect when relative humidity has risen beyond your chosen level.
By operating in this way a dehumidifier is able to respond promptly to a rise in humidity and this ensures that the compressor runs for the shortest possible time to return humidity to the programmed level.
A dehumidifier which samples the air, typically running the fan for five minutes every hour, will have a less consistent air sample to evaluate and will not detect a rise in humidity so quickly. This is likely to result in the compressor running for a longer total period each day than would be the case with a dehumidifier in which the fan runs continuously.
It is a valid choice to prefer the lower noise option with a dehumidifier in which the fan stops when the compressor shuts down but this benefit may come at the cost of slightly higher energy costs. I make this point in order that other visitors who read my answer to your question do not assume that there is an energy saving to be made by avoiding dehumidifiers with continuously running fans.
Tom (Webmaster)
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Dehumidifier - Constant Fan Feature
by Anon.
Can I run the fan even when the unit is not dehumidifying?
Answer
Hello and thank you for your question.
Most dehumidifiers do not provide a "fan only" function but a few do. An example of a dehumidifier with this facility is the DeLonghi DD45P.
Those dehumidifiers that do not have this facility operate in one of two ways. Either the fan runs all the time or the fan runs only when the unit is dehumidifying, that is when the compressor is operating. The majority of dehumidifiers operate with the fan running all the time so if you have a model of this type your particular need is provided for "by default".
If you have one of those models on which the fan runs only while the compressor is operating and there is no facility on your model for the fan to run without the unit dehumidifying the only option is to set the humidistat to its maximum level, usually around 80% relative humidity. At this setting the compressor will run only when this level is exceeded.
This "solution" runs counter to the purpose of the dehumidifier however and if your model falls into this group it may be simpler to purchase a separate fan.
Hope this helps.
Tom (Webmaster)
Dehumidifiers without continuous fan operation
by Betsy
(Southold, NY)
I see a Danby dehumidifier that I like; however, the fan runs continuously which I would think adds to the price of running it. Do they make models where the fan does not always run? We are looking for a 70 pt model for a basement. Would like auto-restart as well as auto-defrost.
Answer:
Hi Betsy
This issue is often raised by our visitors and I think you will find the detailed answers you need on this page where I have responded to previous questions about the subject.
Briefly, Alen, Frigidaire and Winix models do not have continuously running fans while GE and, of course, Danby units have fans that run all the time.
Paradoxically continuously running fans actually save energy; their main disadvantage is the additional noise.
Tom (Webmaster)
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