When should you use a timer on a dehumidifier?

Often when people are buying a dehumidifier for the first time one of the features that they look for is a timer.  They think that the timer on a dehumidifier will allow them to control when the unit turns on each day and this will be the best way to use their dehumidifier – but that is a myth.

A dehumidifier has something called a humidistat that measures the relative humidity of the air – the amount of moisture in the air that could potentially cause condensation. It is the humidistat, coupled with the setting that you have selected, that decides whether the dehumidifier needs to work or not.

If you restrict the dehumidifier by having it turned off for several hours per day then the humidistat will not be able to do its job. So the unit will not spot that you have had a bath or a shower, or cooked a meal – and as a consequence the relative humidity has increased.  This new moisture in your home will be free to do as it pleases and will move around the house until it is absorbed by organic materials such as your wardrobe, clothes, sofa and plaster.

This is exactly what you do not want to happen – and presumably  the reason why you bought the dehumidifier in the first place was to stop this sort of thing from happening.

Let the dehumidifier decide

It is much wiser to let the humidistat make the decisions about the level of moisture in the air rather than try and guess yourself.

One of the reasons why people want to use the timer on a dehumidifier to restrict the hours that the dehumidifier runs is because they are worried about the running costs.  This is unnecessary. In the UK, dehumidifiers are mostly used  as a winter product – all of the energy it uses is returned to the room as heat and heat in winter is a good thing.

By removing moisture from the air, the dehumidifier is helping to reduce your overall energy bills. That’s because there will be less moisture in the air and therefore less work for the heating system to do.

So why is there a timer on a dehumidifier unit?

Good question!  The timer is mainly useful for drying washing at minimal cost. Dehumidifiers are great at drying washing. Just pop them next to a clothes horse in a confined space and use the Laundry mode to dry the washing in a couple of hours.  The clothes will feel softer than they do when you use the tumble dryer because the dehumidifier does not use heat to dry the clothes, just dry air.

Once you get used to how long it takes to dry your washing, you can leave the timer on for say an hour or two and go off to work knowing that the dehumidifier will work at maximum capacity for a couple of hours and will then switch itself off.  Your washing will be dry when you get back in and the timer will have ensured that you have used as little energy as possible to dry that load.

That is what a timer is for!

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39 Responses

  1. I have just purchased a Meaco 12L Low Energy dehumidifier to combat mould in our bedroom window area.

    Will it work effectively under a dressing table? – as it won’t fit in the floorspace below the window.
    Also, do you recommend keeping it on 24/7 during the winter months, or can it just be left on overnight ?

    1. Rod,

      Thank you for your purchase and your message. Your best bet is to place the dehumidifier in the hallway where it has more space and leave the internal doors open as much as possible and leave the curtains/blinds open during the day.

      Chris

  2. Hi Chris,

    We have the low power 20l dehumidifier, we bought it around 8 months ago and it has only ever reach reached the target once or twice.. even now in the summer months. What rh is safe enough to presume no mould will grow I have ours set to 45.

    1. Brendan,

      Mould grows at 68%rh so you are well below that point. If the machine is collecting water then all is fine. Please check that the filter is clean because that will reduce the amount of water that you are collecting. A target of 55%rh would be sensible. Hitting low targets like 45% can be a challenge, particularly in the humid British summer.

      Chris

  3. Hi Chris,
    I’m on economy 7, and want to run the dehumidifier at night (in the same way the immersion heater is set up for example)
    Is there a version with a built in timer? Or could one use an external plug timer and have the machine re-start when it next sees power?
    I want this to work even when I’m out, so don’t want to have to press a timer button every day.

    1. Rob,

      Thank you for your message. Don’t use a plug in timer with any dehumidifier from any manufacturer as that will cause the dehumidifier to fail much sooner than it should do. Only the Meaco DD8L zambezi has a built in On/Off timer to do as you wish safely.

      Chris

  4. hi I purchased the meaco 20 L dehumidifier I am puting a 3 hour timer but it keeps turning off after 15 to 20 mins. Even if I dont put a timer it turns of after 20 mins it is collecting water but keeps turning off can u please help

    1. Rafia,

      It sounds as though the target is above the room humidity. Please press the button under the display and set it to 50%rh. If it is already on 50 then your humidity is already under control. Feel free to call us on 01483234900 if you need more help.

      Chris

  5. Hello, Mr. Chris Michael. I am looking for ideas. The first one is about finding the amount of pints I need to use for a desiccant dehumidifier if I want to have an area with 10% humidity.
    Also, I am looking for insights for the same application. I have already an area that have 10% humidity( a small room). I am having to perform two process using an apparatus that for one function it needs to be at 10% humidity and later, it needs to be above 20% humidity.The deal here is that I do not want to transport this equipment from one side to the other one because it is heavy and expensive.I have thought about isolating the machine like a greenhouse and using a desiccant-dehumidifier that will go 10% and later above 10%.However, this is still expensive and might be even unnecessary.
    I would like to know if you have any thoughts in this matter or if you could recommend me someone or a company to talk about this.

    1. Teresa,

      10%rh is very much a niche commercial application commonly seen in trades like pharmacetical or specialist museum storage for metals. Domestic dehumidifiers are not designed to reach such lows and the desiccant is programmed not to go lower than 30%h/35%rh and will therefore not work in your application.

      Sorry that we cannot help.

      regards

      Chris

  6. I’ve just purchased a ecoair Arion 26ltr dehumidifier. If I set the timer on and off, I find I have to do it again day after day. Is this right. Can’t I just set the times for on and off and that’s it for 7 days or more. Please advise.

    1. Having to reset the timer each time you want to use it is an issue with all dehumidifiers apart from the Meaco DD8L Zambezi. Only Zambezi has a Daily Run Timer.

    1. Terry,

      Thank you for your purchase. The 20L Low Energy dehumidifier has an Off Timer which can be used to forced the dehumidifier to stop after a set number of hours (5 hours for example). This can be useful for example if you want to leave the dehumidifier drying your washing when you go to work and what it to turn off after a few hours rather than run all day. To set this press the ‘clock’ button to the left of the display until you see the number of hours required and then let the dehumidifier run. It will turn off after the number of hours you have set. This is a one time only operation and you would have to set this each time you want to use the function.

      Hope this helps.

      Chris

  7. Hi Chris

    I have got the new Meacodry ABC 10l. So far so good and it has collected quite a lot of water as we have single glazed windows so we’re expericing condensation. I set the humidistat on 55 but the dehumidifer is staying on even when the humidistat is showing a level below 55, 52 for example. Is this normal? I would have thought that once it reached 55 it would automically switch off?

    Please can you advise?

    Many thanks

    1. Chantelle,#

      Thank you for your purchase. Our dehumidifiers stay on until they are 3%rh below the target to ensure that things are stable and to take into account the accuracy of the sensor. So what you are seeing is normal.

      Hope this helps.

      Chris

  8. Hi Chris I have just found your web page and wonder if you can advise me? We have a ‘holiday flat’ which we visit roughly once a month and stay for about a week. Its a basement flat with double glazed windows and powered by electricity. We don’t open the windows very often as we are always out and about. We have discovered that we are starting to get mould on the furniture and the bed, bed linen and clothes are feeling quite damp. We think it is because of lack of ventilation and will now open windows more often. Do you think a desiccant humidifier would help? We could leave it on when the flat is empty although this might send our electric bills sky high! Your advice greatly appreciated and any recommendations for humidifiers would be great! Thanks again

    1. Jeanne,

      This is a common problem with second homes that are empty for a large part of the time. When you are there make sure that you are using the extractor fans in both the kitchen and the bathroom. Ensure that any trickle vents are not blocked and that you have no leaks. You can then use a dehumidifier that uses its continuous drainage into the sink or the shower and leave all of the internal doors open so that the damp air can migrate to the dry area created by the dehumidifier.

      By using the humidistat on the dehumidifier you will control it’s performance and it will be on for as little time as possible and although you will see an increase in electricity it will be a trade off against less or no mould.

      The DD8L Junior would be the cheapest choice for a desiccant and it would use 330 watts in low fan speed. You could opt for the 12L Low Energy if the flat does not drop down below 10°C and that would just use 165 watts for a similar buy price.

      Hope this helps. You can always call us on 01483 234900 if you want to chat more.

      regards

      Chris

      1. Hi Chris,

        Re using a dehumidifier in a holiday flat when its empty during the autumn/winter – can you recommend one please for a 2 bedroom apartment with open plan kitchen lounge, around 80 sq metres in total? Also please let me know if the window trickle vents can be left open for ventilation or should they be fully closed. Ideally I want to avoid having any heating on during the empty period.

        I look forward to hearing from you

        Kind regards

        Ray

        1. Ray,

          Leave the trickle vents open and think about having heating on low to avoid burst pipes over a cold winter. With regards to the dehumidifier then the Meaco 20L Low Energy will work fine in a cool environment without costing much to run.

          Chris

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