Here at Meaco, we have great conversations with our customers all the time. We’re commonly asked questions about desiccant dehumidifiers, so we thought we’d put this handy guide together.
How Does A Desiccant Dehumidifier Work?
A desiccant based dehumidifier draws the air in from the room over a filter and passes it over a rotating wheel. This wheel is full of a material called Zeolite which absorbs the excess water out of the air. When the wheel is saturated it needs to be regenerated. A heater in the base of the dehumidifier blows warm, dry air over the Zeolite to force the moisture out of the wheel. The Zeolite is now ready to dry again and the warm, wet air from the wheel hits a metal surface which ensures the excess moisture condenses and the water drips into the internal tank. The heat used during the drying process is mixed with the dry air to ensure that the air that comes out of the dehumidifier is not just drier but 10-12°C warmer than the air that came in.
My Dehumidifier Has Stopped Collecting Water
Desiccant dehumidifiers like the Meaco DD8L and the Meaco DD8L Junior have a pre-set humidistat so in Minimum mode they dry down to 60%rh, in Normal they dry down to 50%rh and in Maximum they dry down to 40%rh. Once they reach that level they turn themselves off and then check the relative humidity once every 30 minutes to see if the relative humidity has increased.
I Have Laundry Out And No Water Is Being Collected
If the relative humidity is below 40%rh then the dehumidifier will not collect any water. The moisture from the washing will evaporate into the air and increase the moisture content of the air but this increase might not be enough to increase the relative humidity above 40%. This is a very common issue in winter when there are temperatures below freezing outside and we have our heating on in the house.
I Have Condensation On My Windows And Still No Water Is Being Collected
Condensation forms when a surface is at the appropriate cold temperature, so if you have a room temperature of say 20°C and a relative humidity of 35%rh then there is nothing more for the dehumidifier to do because the air is cold enough.
If the surface temperature of the windows drops to just under 5°C or colder overnight then you will get condensation. The dehumidifier is not to blame; it is all down to the quality of the glazing.
How Can I Be Sure If The Relative Humidity Has Dropped And The Machine Is Not Just Faulty?
After a bath or a shower, leave the window closed in the bathroom and put your desiccant dehumidifier in the bathroom in its Laundry mode. Shut the door the best you can and turn off the extractor fan, come back in two or three hours time. If water is collected then the machine is fine, if no water is collected then let us know as the dehumidifier is faulty and we need to sort it out for you.
A desiccant dehumidifier is a cost-effective way to manage condensation in your home.
How can I prolong the life of my machine and keep running costs down?
Keep the filter clean. The more dirt on the filter, the more strain on the fan and the greater the risk of the fan or the heater failing. This will also prevent the dehumidifier from become nosier than necessary.
Does running a desiccant dehumidifier cost a lot of money?
Desiccant dehumidifiers are very energy efficient – all energy that is consumed returned to the room as heat. This is a good thing as it replaces the heat generated by your central heating. Desiccant dehumidifiers also dry the air very quickly, so they are in dehumidification mode for much less time than compressor based dehumidifiers. Southampton University tests show that this is around 3.5 times faster. This means that they can actually be cheaper to run than compressor dehumidifiers.
Remember that whatever dehumidifier you use, you are reducing your heating bill by making the air dryer. Dry air is much easier to heat than damp air because there are fewer water molecules in the air. The money you save on the heating bill will outweigh the money that you spend on the dehumidifier.
In fact the best way to waste money is to not run the dehumidifier and let the level of moisture build back up in the house!
The air feels cold coming out of the desiccant dehumidifier
It might but it is not! When the desiccant dehumidifier is drying, the air coming out is 10-12C warmer than the air that came in. This is because the energy used in drying is being returned to the room. When the dehumidifier stops drying and goes into fan only mode to sample the air it does nothing to the air, the air just passes through the machine, nothing more. When it comes out it is exactly the same temperature as when it came in, nothing has happened to it. Moving air feels cooler than still air (like a fan in summer), but it is not cooler and the room temperature will not drop.
How does damp air affect my health?
We are keen to steer clear of claims here that we are not qualified to make, so we will keep it simple.
- Dust mites reproduce in damp environments
- People who suffer from asthma, eczema and other allergies find that inhaling dust mite droppings can make their condition worse.
- Mould grows in damp environments.
- Mould gives off mould spores (seeds)
- Inhaling these spores can make conditions worse.
A dehumidifier keeps conditions dry and therefore stops dust mites from reproducing and mould from growing. Therefore a dehumidifier helps people who suffer from allergies, asthma and eczema.
Find out more about dust mites here.
Does the desiccant need to be changed?
No the machine automatically regenerates the desiccant internally and you will never have to replace it.
Are there are replaceable parts?
No
What about the filter?
Just maintain the filter as per the manual and it will be good for the life of the machine.
My desiccant dehumidifier smells
When you first use the dehumidifier and periodically afterwards you might notice a smell coming from the dehumidifier. This is caused by the Zeolite desiccant material and is not a sign that the dehumidifier is faulty, nor is it harmful to humans or pets. The smell occurs because the Zeolite absorbs odours from items like cigarettes, cosmetics, hair sprays, building materials and new furniture and then when the desiccant is heated the smell is discharged into the room. This smell has been described as being like a burning smell or a sour smell. It is normal, will not last long and is not a sign of a fault. If you prefer you can put the dehumidifier in the garage and run it on Laundry mode there to get rid of the smell outside of the house.
The fan light is flashing
If one of the following events happens then the control panel will lock up and the fan light will flash.
- Temperature below freezing
- Temperature above 40°C
- Relative humidity below 40%rh
- Machine has been working hard and needs to cool down internally
If you find that this happens and you none of the buttons on the control respond then do not worry, this is normal and the dehumidifier will start to work again when the conditions allow.
What can I do about the check light on the DD8L?
The alarm light on the dehumidifier could mean that it is being used at too low a temperature (below freezing), too high a temperature (above 40°C) or that the air flow is being blocked. If the temperature is ok then make sure that the filter is clean and that it is far enough away from the wall to allow the air to flow through (at least 30/40cm).
If it becomes a regular issue then call the office on 01483 234900 for further help.
79 responses
I purchased a DD8L Junior dehumidifier in November 2016. I was very happy with the performance until it stopped working in March 2018 (no power light). Because it was under warranty, Meaco provided a very fast collection and repair service. The reported failure was the Main PCB which was replaced. Now less than a year later, the same fault has occurred again (no power light). Since the dehumidifier is out of warranty, I took the unit apart to check for any obvious causes of failure; the thermal fuses had not blown and the fuse on the Control board was good. This lead me to the sad conclusion that the main device on the Control board had failed. On examining the circumstances of this failure, I am of the opinion that the circuit was damaged by a power surge or spike from the mains. This opinion is supported by the fact that the digital Controller for my Immersion heater had also failed. We live in a remote part of the country and the mains voltage is typically high. Right now as i write this the mains voltage is 252.7 volts. The DD8L specification quotes 230 volts. Having worked with electronics most of my life, I fully support progress in digital electronics and associated technologies. However, I do wonder if our ‘clever’ devices are becoming more vulnerable. Should I be looking for a Dehumidifier without all the ‘whistles and bells’?
Julian,
Thanks for the comments. If you contact the office on 01483 234900 they will arrange a service of your machine for you and the engineer can try and work out whether the fault is voltage based and then feed that back to you.
Voltage is +/-10% so should be ok.
Chris
We got the Dd8L junior for som month now. And it works well but it doesn’t smell good, lol the smell of metal. I thought it might go away but after lots of time running it still smells. Should I have gone for the DD8L instead off the Junior? It otherwise works perfectly and it’s nice to have on a sailboat and we also have tried to let it run outside for 48 hours but still smell like metal.
Thank you for your message. the DD8L uses a desiccant material which will absorb anything the in the air, heat it up and then blow it back into the air. This will be where the smell is coming from and it will be something that is present in the air.
Running it away from the environment is the correct thing to do and it sounds like it needs to be run for longer away from the space. The problem of course comes if the VOC is still present in the space because the desiccant will continue to pick it up each time you use it.
Thank You Thank You Thank You. It works now. The part I asked for has fixed the problem. The person I spoke to was taqeer and he was very very helpful. No “you can’t do that’s”, no obstructive behaviour. I asked for a new main pcb and it was sent. It arrived the next day- I have just fitted it and it works. No need for expensive and wasteful transport back to HQ. No protracted wait for a solution. The company trusted me to fix it and indeed I did. It would have been slightly better to have received the micro that drives the thing but certainly more difficult. I repair surface mount pcb assemblies every day, but of necessity this one is covered with a conformal coating in order to exclude moisture ingress, which would make rework a tad difficult to say the least.
I cannot speak too highly of this excellent company. Well done and thank you again.
BUY WITH COMPLETE CONFIDENCE THAT IF THERE IS A PROBLEM IT WILL BE FIXED.
Hi
Well Meaco was as good as your word would have me believe. We shall see how it goes but they have done exactly as I asked and to be honest it is out of warranty-how many companies would do that?
Thanks but too late-obviously I have pulled it apart. It must be out of warranty and in so doing two of the mounting lugs broke because it is less than obvious that two of the retaining screws are located under blanking plugs beneath the handle pivots. It is just another example of modern throw away equipment which with a bit of thought and the provision of circuit diagrams etc would enable people like me to effect a perfectly satisfactory repair. I repair surface mount pcb assemblies every day as my job. I presume a new control pcb posted to me would be out of the question.
Have a word with the office, they will try and help. We always look after customers outside of warranty because we don’t want people to attempt a self repair or to thrown anything away. We are always the best first port of call.
You can call them on 01483 234900.
We have had one of these for just over 2 years. It has worked very well but last week it failed completely so not that impressed to be honest. The thermal fuses are intact and the switch mode power supply on the pcb is working-the 5V and 12V rails are present but the display and backlight are off and the controls are unresponsive.
Jeremy,
Thank you for your message and your feedback. If you are in the UK then there is no need to try and do a self repair, we would prefer you to contact us and allow us to service it free of charge. Please contact the office on 01483 234900 and we will look after you.
Chris
Hi,
I am trying to find a way to clean the filter but I can not open it. Not the filter that is removable but the deeper one.
Is there a way to clean that one? It,s full of dust and the machine has started making noise 🙁
Mnay thanks,
Deny
Safest thing is to let us do it. Just contact the office on 01483 234900 and we can arrange a repair if necessary.
I think I have the same problem as Deny. I have 2, 10 litre machines. Both are affected.
I have always kept the removable filters clean and the machines do their job very well. But a few months ago, I noticed a musty smell coming from both machines. On closer inspection I saw that (on both machines,) the metal grill behind the removable filter is largely covered with what looks very like some sort of grey/green mould (or even lichen!)
Suddenly worried about the health of everyone in the household (and we have all had repeated respiratory tract infections since using them,) I ‘phoned the ‘help desk’ to be told that I must not attempt to dismantle the machine myself but send it back to be cleaned at a cost of around £100!
Perhaps it would be more economically sensible to buy 2 new machines but then I would have to be prepared to do this every couple of years!
Margaret,
Different issue, different machine and different technology. We cannot recommend that anyone untrained opens a dehumidifier up to do some cleaning or repairs because we are talking about a 240 volt device that could kill if not handled correctly. Our maximum charge is £70 including VAT to collected, service, clean, test and deliver back to you a dehumidifier.
What you can see in the machine will mostly be dirt, there might be some mould as well. Such growth is very, very rare though.
Chris
Hi, I was wondering if you could identify a fault that my Meaco DD8L started indicating yesterday. The fan light (next to the double fan symbol on the dashboard) started flashing, but contrary to what the manual says, all the buttons are working and when I start the dehumidifier, it seems to be working.
I first thought it could just be too hot in the room as it had been running for a while, but this morning it’s flashing the same light still.
What can this mean please?
Thank you
Paulina
Paulina,
Thank you for your message. The light flashes when the relative humidity is below 40%rh or when the room is too hot or too cold. It will though continue to collect water in this state. Please call us on 01483234900 so we can talk through some of the settings (what is the humidistat set to, what fan speed do you have it on and what size is the room). If you are not able to call then feel free to email me via chris AT meaco.com.
regards
Chris
Hi my meaco dd8l has been brilliant in the year we have had it
But now it seems to not collect as much water and smells like burning dust coming from it ?
Any ideas?
I regularly take the filter plate of the back to clean it
James,
This might be because of a change in the weather resulting in less water in the air or it could be because of a blockage on the desiccant wheel. When you next remove the filter use a torch to look through the condensor tubes. Behind that you will see the honeycomb desiccant wheel, this should be more or less pure white. It it has turn grey or black then too much dirt has got into the machine and this is why you are getting less water.
Whatever you find please do contact the office on 01483 234900 and ask for help. we will always look at a machine free of charge and even if it is outside of warranty if we can fix it we will.
Hope this helps.
Chris
I purchased a MeacoDD8L in September 2011 from yourselves and I am more than happy in
fact amazed at my all double conservatory is free of condensation since I have used the machine, I should add it was the one you recommended, thank you. Its so effective I take it into the working kitchen and also the porch to remove the condensation rather than open the windows. What I am now looking for is a smaller version of the DD8L or a recommended alternative to use only in the working kitchen and porch. From my past experience I know you can help. I recently completed your on-line questionaire.
Best regards Ivan Faloon
Ivan,
Thank you for the kind words, glad to hear that you are happy. To be honest there is not a mini version of the DD8L and with the DD8L being so quiet it would make sense to buy the same again.
Please call the office on 01483 234900 and ask about our returning customers discount code to help keep the cost down.
regards
Chris