Dehumidifier

[whiskeyomega]

Can you recommend a cheap dehumidifier that I can buy for my kitchen? Not too much money please ( less than £100?) and economic with the electric.

[Andrew Gabriel]

Open Window? Hob Extractor?

Seriously, what is the source of moisture, and what is the symptom you are trying to solve with a dehumidifier? There may be better solutions.

I would imagine you might get a second-hand one from eBay (local pickup only) or Freecycle, because people often find they don't actually meet the perceived after they bought one. For the compressor based ones, keep them upright during transport, and don't switch-on for 24 hours after moving. Power consumption varies from around 200W to 400W - higher power ones remove moisture at a higher rate, but also get increasingly heavy. There are versions with built-in humidistat which automatically switch on/off as humidity changes.

I bought some which were at the end of reductions in one of the DIY sheds, and they were cheaper than second-hand ones on eBay. That depends on hitting the sheds at the right time of year.

[whiskeyomega]

Open window@ This weather? Its freezing in my kitchen already and I do have one window permanently open because the wood has swelled up and it wont shut. The window sill is still sopping wet.

I was told on this board a dehumidifier would help.

General cooking, two walls which are outside , N facing and weatherside of the house, no heating.

I have seen a lot of " wanted" ads for dehumidifiers on our freecycle . No one has them to give away. I huess the problem I have might be fairly widespread in the area somehow.

I have seen a couple of these but I don't know whether they are suitable or not.

[Martin Pentreath]

All dehumidifiers work on the same principle, there's not much to choose between them (given a certain extraction rate, the specs will tell you what that is). Some may last longer than others I suppose.

But I would agree with Andrew. If the problem is being caused by steam from cooking and lack of heating, then the better solution is to address the causes not the symptoms. First priority, put an extractor over the cooker (one which actually extracts instead of just whirring and recirculating), or at least a fan in a hole in the wall (in which case I'd suggest at least a 6" one, not a 4" one). Secondly, get some heating in the kitchen.

Incidentally, if you've got a window stuck open that won't be helping in this weather. By reducing the air temperature in the kitchen you're going to increase the tendency of water vapour to condense.

Cheers!

Martin

[Martin Pentreath]

PS As money is tight how about this?

quid, well within budget, and at 30 watts you'll use a hell of a lot less lecky running that for an hour or two while you're cooking than leaving a dehumidifier on 24/7.

[Andrew Gabriel]

I'm only familiar with compressor based ones. There are other types, such as semi-conductor (pelier-effect) ones, dissicant discs, and even dissicant crystals you put on the window sill. Pelier-effect works with same principle as compressor, creating a cold area to condense out the water and a hot area to reheat the cold air and dump excess heat from the process, except they are lower power and much less efficient than compressor units (much less condensing ability).

If you go for a 400W dehumidifier, you will get some heating out of it (not 400W, as some of the energy is required to condense out the water). Often the heating is a bad side effect (e.g. they are no use for dehumidifying on a hot summer's day as it just gets hotter), but in this case the heat could be welcome. I've used them to make a drying cupboards for clothes where this works very well.

The danger with using a dehumidifier in a house is that it creates large differential humidities between areas of the building, and these can cause problems such as floor boards curling across their width where one side is dry and shrinks and the other side is moist and expands. This doesn't necessarily go away completely when you remove the dehumidifier (and takes a long time to do so in any case). Tends to be more of an issue in older houses with real planks, laths, etc than newer ones with chipboard, MDF, etc.

They are noisy too. At about 4 times the power of your fridge compressor, expect it to make 4 times the amount of noise. Probably not an issue in the kitchen - many kettles make more noise.

[whiskeyomega]

It might be very good but OH wont fit an extractor fan for me and would not allow anyone in the house to do the job. A de humidifier stands alone and only needs plugging in. Its not about money as such as about what he will allow me to spend before he has a wobbly over it.

[Andrew Gabriel]

^ Peltier

[Martin Pentreath]

Fair enough.

Plan A: kick other half up the arse.

Plan B: (Possibly in addition to plan A)

've got one of these keeping the cellar dry, and I would recommend it. It's small and quiet and you can arrange it so that it drains into a drain so you don't have to keep emptying it. The Screwfix customers seem to be happy too. Downside: it's 13 quid over budget.

[John Stumbles]

Bzzzt! As I understand it there are (at least) two different operating principles. One is compressor type - like a fridge - that cools the air to below the dew point to cause moisture to condense out then warms it again as it blows out. The other type uses some sort of rotating disk of silical gel (?) which I don't pretend to understand the principle of but has different characteristics and is more suitable for operation in very low temperatures where the incoming air is already so cold that cooling it further in a compressor-type machine produces ice rather than liquid water.

[NT]

If its an unheated kitchen in midwinter, a compressor based machine wont work. Ditto peltiers.

Desiccant boxes are a waste of time.

Ventilation wont work either, as the house is unheated

Your only effective options are: desiccant wheel machine fan extract moisture sources heat the place

NT

[Mike Lane]

Andrew Gabriel wrote on Dec 21, 2009:

On the contrary. If I remember my 'O' Level Physics correctly, water vapour releases its latent heat when it condenses (2.3 kJ/g). The energy is released as heat in the hot side of the refrigerating coil.

[Dave Starling]

I have a yellow ebac powerdri de84ye dehumidifier from Screwfix but seems they discontinued it. It was around =A3170. I would agree with comments made on this thread. You still need the heating on otherwise the electrical heater is on constantly. The ebac consumes around 250w on its highest setting and can fill the 3litre container in around 8 hours if there is a lot of condensation or you are drying a room thats been painted.

I had tried one of the smaller box units but found it didn't really work.

Dave.

[Andy Champ]

I know what you mean, but it may not be clear: You will get MORE than

400w out of it.

Andy

[Kevin Poole]

use one of these in my garage, but haven't got round to any sort of comparitive testing with a compressor-type. My excuse is that the instrumentation is too difficult.

[Andrew Gabriel]

Yes, you're right. I was thinking back-to-front.

[Roger Dewhurst]

Heating wet air reduces the relative humidity. That is all. The air is is still just as wet but now provides a better climate for fungus growth. A dehumidifier actually removed the water from the air, several litres per day. That is more than cooking will put into the air. The OP is looking for a cheap solution. Cutting holes in the wall, installing rangehoods, fans etc. may be a good idea but it is not cheap.

R

[Roger Dewhurst]

I had that in mind when I provided the original advice. However I cannot suggest any particular model as I am on the other side of the world.

R

[Roger Dewhurst]

I have a 300 watt Cascade which is virtually soundless. Had it for so long the plastic has changed colour!

R