Cheapest = open your window wide during a shower and for a while afterwards, but tried this last night, not sure I'll do it again, -2 degrees not the best temp to step out of a warm shower. Perfect in the summer.

Next cheapest = extractor fan, simple and effective, plus without the severe freeze you get with an open window.

Then you get to dehumidifiers, that are really most effective at dealing with the aftermath of leaving the window shut/extractor off and the rest of the house is now damp. They are expensive to run, but usually quite effective. I tend to use a dehumidifier to remove any lingering moisture after a shower.

There are two types of dehumidifier, those that work with a compressor, these use a similar process to the freezer, but in reverse, so you chill the air, condense the water and extract. What they don't tell you is that the 4l per day or whatever rating is based on living in the tropics, with high temperatures and humidity, 4l becomes 2l at 20 degrees, i.e. a relatively high temperature, 1l at 15 degrees and barely anything at lower temps - the exact amount depends on the brand and generally cannot be gleaned from the literature, because they don't want you knowing this. Plenty of people will tell you their compressor dehumidifier works as intended, but as this is down to laws of Physics and not the manufacturer using clever technology, it's largely wishful thinking.

The other type is the desiccant dehumidifier, this works by using a similar material to silica gel, which absorbs moisture, this is then heated to expel the water which is collected. These do not vary so much depending on temperature, but the rub is, you're heating stuff, which costs electricity, on average it can cost twice as much to run, but you do warm the room up. These are also supposedly more likely to break down, even though they are simpler in design - I can't comment as mine works fine.

I have one of each type, cold rooms and damp (it's Manchester = wet). Both machines are rated to the same level, the desiccant variety needs emptying two or three times daily, in a 24 hour period, there was barely a cup of water in the compressor type.

mike

That's what I said in my post, without a doubt more expensive to run (at least double), I happened to put my desiccant one in a closed room at 7 degrees yesterday, after 2 hours of dehumidifying, the room was at 11 degrees and the water container nearly full, which quite simply a compressor couldn't achieve. I tend to prefer to use mine in rooms I plan to use, it's a pretty good space heater. I never use this one in the summer, when I don't need warmth.

I'd agree that you get more water in air at a higher temperature, however you've got to think where this water comes from, e.g. a shower or kitchen where you're not in an equilibrium situation, and of course atmospheric pressure affects the amount of water. The mathematics starts to get quite complicated (you have to include atmospheric pressure), before you start to introduce the desiccants own performance, which although affected by temperature and humidity, generally will remove almost as efficiently at lower temperatures and humidities, certainly the sort of humidities caused by cooking or having a shower, so even if you have less water contained in the air, the desiccant still removes almost as much water in a given time. It's important to remember the cost of running the desiccant dehumidifier is directly proportional to the amount of water extracted, so if it extracts at a lower rate, the heating of the desiccant is reduced, this is by far the most electrically expensive part of the equation (and quite the reverse of the symptoms of a compressor dehumidifier, where the expensive part is the compressor, and this runs for longer the lower the extraction).

In the absence of proper scientific experimentation (and willingness to do the maths), sticking the two different systems side by side in the same room, proves all I need to know. Desiccant types work better in lower temperatures, but the cost is much higher.

It seems rather dubious to me that all the manufacturers all quote dehumidifying capabilities at what is frankly an almost unachievable temperature in the UK, the validity of those figures is about as useful as measuring the acceleration of a Ferrari in free-fall dropped out the back of a Hercules.

mike

Go to Home Bargains, go to the cleaning isle and buy a Mould Spray called KillRock. It's £1.99 all you do is spray the Mould and it disappears after 5 minutes you don't need to scrub it or anything. Ours never came back!

My vote for 12l one

What is the best and most effective and cheapest to run solution to take damp from a bathroom? Anyone have any good advice? My bathroom is starting to get little mold patches in my bathroom and I want something to stop it before it spreads.

nice, thanks

Wish I had read this before I bought the 12l compressor one last week. Do you think it would help locating the dehumidifier next to the radiator? This is in my dining room with open conservatory.

The rub is that desiccant ones seem to cost double to run, as shown by user tests.

Cold air by its nature does not hold much water so the desiccant too removes less when cold, it also using more electricity to heat the colder and lesser amount of water.

That 275W spec is likely 200W when running, 265 the very short startup drain for the compressor. A 16l desciccant is likely to be 500W.

Bought one of these on Saturday. Absolutely brilliant. Highly recommended

Have to say, when i researched this before purchase I ended up going the dessicant route. Bought an EcoAir Classic from Aplliances Direct (cheaper than Amazon after I'd taken out the Which trial which gave a £20 discount) and would,'t be without it now. We live in a bungalow that was definitely suffering from damp (75%+ himidity in some rooms). Ran the EcoAir on full setting for a few days and now the 'base' reading is around 45% - 48% in all rooms. We only run it (on lowsetting) for 2 hours a day now and we simply cannot believe how much water this machine has literally sucked out of our air.