Dehumidifiers

[Cowsontheloose]

So talk to me about dehumidifiers for drying clothes? I have several airers. Are they really worth the hype?
Any recommendations?

Beg to differ. I've always found dehumidifiers largely useless, and a fan dries my washing perfectly.

I learned about the topic when trying to get a decent air conditioning unit and was schooled by the people that do all the power and cooling for a large company (so have good credibility). In this case, I learned why the standalone air con units spend the majority of their energy dehumidifying and not so much on cooling, and that it is largely a self defeating cycle as the air drawn back into the room just contains more moisture (assuming an exhaust hose poked out of the window). Same thing applies to dehumidifiers. One has to spend a lot of money for it to be effective.

It isn't just opening a window, it's the air movement, hence the fan. Two windows need to be open and a breeze going through. One window won't do much by itself. It will be a little worse by the sea of course. Probably also in a wetter part of the world such as the Emerald Isle (there is a reason it is green).

It is an individual choice. I'm pleased they work for you.

I don't think that average humidity is 50 - 55% in the UK. It's more like 70 - 90%.

Without a dehumidifier, the humidity in my house will stay around 80%. This has been pretty much the same in every house that I've lived in.

The trouble with humid houses is that they are difficult to heat. If you remove the humidity it takes less energy to heat the house and the house will feel warmer.

Agree cheap ones are false economy. We have one decent one that makes a huge difference when drying clothes. We have to empty it regularly.
Will buy another one when I get paid this month

I've been using one for the past few weeks and it's cut down the drying time a huge amount. I put clothes to dry about 8pm and when I checked at 6am they were dry, usually they would take around 48 hours.

I use the water from it in my steam generator iron so it's not wasted.

It's not expensive to run, much less than a tumble dryer.

I have a Meaco dehumidifier and love it. The atmosphere in the house feels so much nicer and clothes dry quicker. We haven't had the heating on yet so it stops the house getting damp.

We use a dehumidifier with a heated airer because I don't want the utility room getting damp and mouldy.

I'm about 12 miles from the sea on the south coast and my average internal humidity is 55%. It will rise a bit over winter. This is about the same for every house I've lived in (it is maybe a little higher here as I used to live much closer to London, this is the closest I've ever been to the sea).

Agree it takes more energy to heat a humid house as the air is denser, however opening a window helps here too as it aids convection, and equalises internal and external humidity. This is why most radiators are placed under windows as it assists air movement.

Some are better than others but we really wouldn't be without ours now, we have a twenty litre one with laundry mode that is brilliant and way better than the so called smart mode. When we're not drying clothes this is the mode we use and it really makes a difference to the chill in the air.

We also have a ten litre and five litre in the larger bedroom and the smaller bedroom respectively.

@HappiestSleeping

I live in the north, not sure whether that makes a difference. Even so, an average humidity of 55 would be very hard to maintain. We live in a very humid country:

www.currentresults.com/Weather/United-Kingdom/humidity-annual.php

There are lies, damn lies, and statistics. It seems the sources for relative humidity as are unreliable as government performance 🤣

This suggests lower in winter. Hmmmm.

I really love my ebac dehumidifier. Have no need for it during the summer months as I try to dry outside or open a window but extremely effective during winter.

I find a dehumidifier works really well for drying laundry. About 4 hours and it's pretty much dry.

Ebac and Meaco are both good brands. Ebac customer service is great - and after thebwaranty runs out they will repair any dehumidifier for a fixed fee if it's under 10 years old (ours - run pretty much constantly - broke after 9 years; they collected, repaired and returned it within a week).

There are 2 types of powered dehumidifier. Desiccant ones work much better than compressor types at low temperatures (like an unheated utility room or conservatory). The compressor type is better if you'll be using it in a heated room, because they use a lot less electricity.

I aim to have the house at about 65% humidity.

I tend to set the timer for either 1 or 2 hours (but I an usually at home to keep an eye on it).

Humidity is my house is around 80% all the time. I have humidity readers in every room and outside. I’m a bit obsessed. The dehumidifier reduces it to around 45%. It’s fab. Very fast for drying laundry.

I have a dehumidifier and find it really effective. I leave the laundry in a closed room with it on and it cuts down the drying time without causing damp and mould. Mine is an EcoAir desiccant type. It definitely starts to work better when combined with the heat being on though. It's not quite as good during those in-betweeny times when it's not quite cold enough to turn on the heating. If it isn't raining, I hang the washing outside for a few hours, then finish it off with the dehumidifier.

Can I jump on this post and ask what size people generally use? I've seen 10L, 12L, 20L etc. I would be looking to use one in a through lounge/diner (where we dry washing).

A few people are confusing the matter. A dehumidifier does not take water out of your clothes.

Water will leave your clothes and accumulate in the air as moisture. The dehumidifier removes this water thus allowing the clothes to release more moisture into the air. Cycle repeats.

If you are buying the thing specifically to dry washing you might be disappointed that it does not work as quickly as you hope.

I'd be absolutely lost without ours. We can only really dry our laundry indoors in one particular room (small house and no space) it holds 5 litres of water and as someone said upthread it's so satisfying emptying it every day! (yes we have a lot of laundry to get through it's the bane of my life) after almost constant use from October to April (not to mention all the wet summer days!) ours died after 5 years and we immediately replaced it. It doesn't damage your clothes like a tumble dryer can, and is a lot cheaper to run.

Meaco

I have two. Both bought preloved from Gumtree for around £50.
I have a condensing Meaco in the warm utility room to absorb water from drying laundry and a desiccant one in the cold bedrooms which I run for an hour a day to avoid condensation on the windows.

Fairy, for a large room plus washing I'd go for the 20 litre if possible.

Buying a dehumidifier last winter was an absolute game-changer for me. We had moved to a fairly large, quite old house. I had previously used a tumble dryer in winter, but wanted to be more energy-efficient.

I did a lot of reading up on the relative merits of different tumble dryer types vs heated airers vs dehumidifiers etc, and there is conflicting information out there. But the advice that seemed most logical was the following (very long) post from a Money Saving Expert forum:

"Drying clothes in colder weather is a little more challenging but nobody commenting above seems to understand the physics of it.

When your clothes are wet, they contain a specific amount of water - let's just work through an example assuming your washing contains 1 litre of water when the wash cycle has finished.

It takes 0.72kWh to evaporate 1 litre of water from room temperature. Yes, that is the amount of energy whether you hang your clothes outdoors on a sunny day, windy or not, put them in the tumble drier or on a heated clothes rack - that 1 litre of water needs 0.72kWh to evaporate. Exactly the same amount of energy (2.6MJ) whether the clothes dry in 1 hour or 12 hours.

Where you get that energy from and where it goes is what is important along with how much is wasted in the process.

1. On a summer day, clothes on a rack with no heating, will absorb 0.72kWh from the heat of the room - the room will therefore drop in temperature slightly but that isn't an issue on warm days.

1. Winter days with the heating on, thermostat set to say 20C, the clothes will absorb 0.72kWh of your room heat. So this means to maintain the exact same 20C temperature in the room, your central heating will need to supply 0.72kWh extra compared to not drying your clothes in that room.

1. Winter day, heated rack, heating on, thermostat set to 20C same as above, 0.72kWh of energy - your clothes will dry quickly due to the heated rack, but exact same energy output to that room is needed provided you keep the room at exact same temperature - this time some of the heat will come from the rack, but total energy provided to that room will be the same.

1. Winter day, heater rack, heating off. The clothes will absorb 0.72kWh to dry themselves but the rack won't transmit all the heat to the clothes, a lot will go into heating the room instead so it will use much more than 0.72kWh of electricity. Your room will be warmer than when you started which is a waste if you didn't want to heat the room.

1. Unvented heat pump tumble drier - this will "move" 0.72kWh of energy from the ambient room temperature to the water to evaporate it but then will recover most of that energy as it condenses that water again. Running this process will require energy to power the heat pump and tumbler/fan etc which is lost as heat to the room. Typically will use about 30-50% of the amount of energy they "move" but that will be released into the room. So in a heated thermostatically controlled room, it will be more efficient than 2,3, or 4 above. In an unheated room, the excess heat is lost to heating the room so again is wasted.

1. Dehumidifier - similar to 5 above but the energy consumption is harder to control because it isn't a closed loop in the tumble drier, it will dehumidify the whole room. This can be an advantage when your heating is on because it takes less energy to heat a low humidity room to the same temp as it does to heat a high humidity room.

1. Condensing tumble drier - these will still use 0.72kWh in evaporating the water but a lot more heat is lost from the loop to the room and typically use twice as much energy as a heat pump in the process. Same applied, excess energy is lost to the room, so if it is a thermostatically controlled heated room, the main heating output will drop to compensate so all energy retained, otherwise wasted in an unheated room.

1. Vented tumble drier - most wasteful. Extracts ambient air from the house causing outdoor air to come in, which if colder will cool the house. The heat used to dry the clothes is lost to the outdoors. Pure waste of energy and money - don't use.

Note: If the excess heat energy goes into a thermostatically heated room, then the main heat source will compensate by reducing heat output so nothing is wasted.

If the excess heat goes into an unheated room or is vented outdoors - this is all wasted because you don't intend to heat the room or the outdoors.

In summary:

1. Spin clothes to the max to extract as much water as possible.
2. Use ambient heat to dry the clothes - ie outdoors or unheated room temp for the cheapest cost.
3. If you must use energy to dry the clothes - close the loop and keep that energy in the house, preferably in a room you are heating anyway rather than an unheated room where the benefit isn't felt.
4. Keep in mind humidity is bad for houses. Ventilation involves allowing outdoor air into the house, which if cold requires energy to heat, so a dehumidifier or heat pump drier will work out more efficient on cold days.
5. The cost of the source of heat is important, using your gas-powered central heating will mostly be cheaper than an electric-powered rack heater."

I agree with above PPs that you need to buy a decent one. We bought the Meaco 25L ultra low energy platinum one, and use it in an upstairs room that previously always felt a bit damp and cold. The laundry mode is excellent. The unit still draws in air through the grille at the back and removes the water from the air, then it blasts the damp washing (on airers) with dry air. The fan louvre moves up and down so that all the clothes are in the firing line, so to speak.

I set it up in the evening - damp clothes over two large airers (two wash loads full) and it is completely dry by morning. That room always feels dry and warm now. We have just bought a second unit to keep downstairs, as it makes total sense to me to keep the air as dry as possible to make that air cheaper to heat! Used to wake up to loads of condensation on windows, even when using the tumble dryer for clothes, and now they remain dry. Emptying out a full tank of 5L water is extremely satisfying!

Just be aware of the capacity of the tank if you're looking to buy one. As PP says, "Emptying out a full tank of 5L water is extremely satisfying!" and it is. Mine is described as a "20L dehumidifer" the actual tank holds 5.5 litres so every morning this is what I pour down the sink. But for example, you could buy a 16L dehumidifier and the tank is only 2L capacity. You'd have to empty it more often as it will cut off once full so that could be a problem if (like me) you prefer to hang out washing in the evening and let it dry overnight. And lots have even smaller tanks. Hope I'm explaining this properly!

My high ceiling house is knocked through on the ground floor so we went for a 20l Meaco. The tank is 6 litres (just checked online). I'm pretty certain that I could add a pipe to it to drain automatically, but we move it from room to room depending on what we're up to.