Recommendation needed for dehumidifier to remove mould in a bathroom.

[Mocame]

I have found some mould in a bathroom in my house. It is an internal bathroom, with no windows and a not very effective extractor fan. I am thinking of investing in a dehumidifier in an effort to resolve the problem. But i am a bit overwhelmed by the choice of models and brands.

I have a quite big and old house (almost 200 years old) with high ceilings. But the rooms where I plan to use the dehumaniser (bathroom and perhaps kitchen) aren't big. So should I go for a big (20 lr) one or will a 10 lr one do? I would prefer the latter because I assume it would be easier to move and store but obviously not if the smaller dehumidifier is totally ineffective.

 

[RedOnion]

The 10l vs 20l is the maximum amount of water they can extract in 24 hours. The bigger you go, the shorter you need to run it for each time you use the shower to bring humidity back down. But if it's a single room, the 10l should be adequate.

Once you've any immediate damp issues dealt with, they won't need to be run for long on a regular basis to keep things in check.

I've used both Delonghi and Dimplex brands and happy with them. Some models can be a little noisy if they're next to a bedroom - think of a fridge running constantly.

 

[DannyBoyD]

Meaco fan here, you can use a piece of hose so it drains & saves you having to empty it.

But to honest, you'd be better dealing with the extractor fan & the causes of the damp.

Theres a good youtube channel - CharlieDIYte where he does a lot on damp & humidity in old houses.

 

[NoRegretsCoyote]

Desiccant dehumidifiers are in my experience the best, I have one still on the go after ten years of constant use.

I have found some mould in a bathroom in my house. It is an internal bathroom, with no windows and a not very effective extractor fan.

From experience as landlord and tenant of same property a dehumidifier is a help against build-up of mould but priority should be ensuring low humidity in the first place.

If you haven’t it’s worth upgrading the fan and timing it to run for longer after every use. If there is a shower use of a squeegee is very effective.

Once you get the wall dry scrape off the mould, spray with chlorine to kill the spores, clean the wall and then apply a paint effective against mould.


Finally it’s best to have a dehumidifier that can target a given humidity and switches on/off automatically- you shouldn’t have problems below 55%.

 

[hazelgreen]

Definitely deal with mould first by killing it. Use squeegie after shower use and maybe a used towel to finish off with. Keep some window open in adjacent room. I use dehumidifiers in the rest of the house, one upstairs and one downstairs. You will have an issue using an electrical appliance in a bathroom.

 

[lff12]

I have the 130 euro 10l Woods dehumidifier from B&Q. It pulls a lot of moisture out of the atmosphere, its cheap to run, but it is loud when running.
If you are seeing mould in a particular room get a smart hygrometer and monitor the room over time - basically if the humidity level is consistently over 60% or more it would explain your issues.

I would try to deal with the root causes of the issue first - check all your vents are clear and not blocked, verify that there are no leaks, check for rising damp in the property and make sure any extractor fans are working properly and not obstructed. The bathroom should be adequately heated in the winter hours but also properly ventilated.

Trying to find the cause can be difficult, but there can be many causes - historical leaks, blocked vents, underheated homes and undersized vents/extraction fans (or none at all) can lead to issues with mould.

10L should be more than adequate for your needs - but would try to address the extractor fan if you own the place. Check for hidden leaks as well. I did try a very small 500ml unit but it was absolutely useless and made no difference.
Oh - make sure also your vent is properly connected to the duct - in my sisters home she discovered that a duct to an internal bathroom like yours wasn't properly secured to the duct and was just spewing moisture into the attic space. If you can, get someone to check it out.

 

[Mocame]

Thanks for all the very good advice everyone. I think the cause is my three teenage children who spend ages the shower to the extent the room is like a sauna afterwards. They also refuse to use any other shower in the house so I think no fan can realistically be expected to cope with this amount of steam. My husband has suggested installing an egg timer or alarm in the shower and I may be driven to that!

 

[Leper]

Cillit Bang + a pot scrub available in most supermarkets for around a fiver plus some elbow grease will do the job. Take care not to fall if using a small ladder or chair.

 

[elcato]

My husband has suggested installing an egg timer or alarm in the shower and I may be driven to that!

Remove the door.

 

[hazelgreen]

Do be careful of fumes when using cleaning products especially as you have no window to open and create decent airflow.

 

[Leo]

A good extractor will always work better than a dehumidifier which needs to run for longer to deal with the humidity levels in a poorly ventilated bathroom. The most common problem that causes poor operation of an extractor fan is failing to allow for a source of air to enter the room to replace what is being extracted. Think about sealing around the top of a bottle and trying to blow more air in versus blowing through a pipe.

For a long time here it seemed to be acceptable to build bathrooms with tightly fitting doors and no ventilation source expecting a small extractor fan to work miracles, There should be a source of allowing fresh air into the room, via another if direct external ventilation isn't possible, and the source and extraction should be arranged so that the airflow between them passes above the shower.

 

[Buddyboy]

Another issue is that the incorrect extractor fan is installed (quite common). The axial fans that are mounted on the wall/ceiling are normally only good for a "through wall" application and have a maximum run of 1.5 meters of pipework. In the case of internal bathrooms, there can be a lot more than that (to the outside) and the fan is insufficient. Replacing it with a stronger fan in the attic which is situated along the ductwork, and normally secured to a joist may be a better option.

Axial ceiling mounted fan example

Xpelair 100mm Axial Wall or Ceiling Extractor Fan

Xpelair 100mm Axial Wall or Ceiling Extractor Fan Available at Dwyers, a trusted retailer with over 50 years of experience in providing high-quality products with exceptional customer service, this fan is your perfect solution for efficient and effective ventilation in your home or commercial...

www.dwyers.ie

Better, duct installed fan example

Manrose MF100T 100mm Inline Extractor Fan with Timer 240V - Screwfix

Order online at Screwfix.ie. Powerful, in-duct mounted mixed flow fan designed to produce higher working pressures for applications that require high air flows with low relative noise. 3-speed setting selected via an internal dip switch. Flush-fit with double insulation. Black finish. FREE next...

www.screwfix.ie

I'd agree with Leo, solving the extraction problem is a much better solution than trying to deal with the humidity.

 

[iamaspinner]

Desiccant dehumidifiers are in my experience the best, I have one still on the go after ten years of constant use.

Which one is that? Any particular brand?

 

[Blackrock1]

Which one is that? Any particular brand?

Ecoair are good, have gotten expensive unfortunately

EcoAir DD1 Simple Blue MK3 Desiccant Dehumidifier | Rotary Dial | 7.5 L/Day | Quiet 34dBA | Anti Bacterial Filter | Laundry | 6Kg | Home Garage Basement Boat https://amzn.eu/d/edfPAwD