How to pick a dehumidifier?

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kanwal13

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#196624 7-Jun-2016 09:45

Hi Everyone

I have never bought a dehumidifier so have no clue what to look for when buying one. Every morning i have a lot of water on the windows and window sill (aluminium frames). My house is generally warm even without the heater but i think that causes a lot of condensation on the windows so i am thinking of getting a dehumidifier. It is 2 bedroom unit (approx 75 sq. m). Advise please.

I am based in Wellington(Hutt Valley)

Cheers

Kanwal

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#1566898 7-Jun-2016 09:56

Dehumidifiers fix the symptom, not the cause. They cost money to run. The problem is warm moist air hits the cold windows and window frames. The solutions are:

entilation, which can make the house cold unless you do heat recovery ventilation
Removing moisture creating sources (extractor in shower / kitchen / laundry)
Double glazing, which is very effective. You can do a retrofit double glazing which just adds a plastic sheet over the window frame or individual windows, which is effective and cheapish.

But people will always create moisture, so you can't eliminate it entirely. A dehumidifer may be an acceptable solution - it's basically an air conditioner that takes moisture out of the air.

We have a ventilation system but we don't run it at night as it makes the house colder. Instead we run it on a timer during the day, and with double glazing we get no condensation.

kanwal13

34 posts

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#1566904 7-Jun-2016 10:02

Thanks makes sense. We can look at double glazing but i was looking at immediate solution. So if you can suggest some good dehumidifiers please

trig42

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#1566914 7-Jun-2016 10:21

Mitsubishi always used to make good ones.

Do you have a heat pump? Can you install a heat pump? If so, it may be a better solution (heat pumps have a dehumidifying cycle as well as the advantage that they can be a heater and cooler as well).

kanwal13

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#1566915 7-Jun-2016 10:22

Oh ok. No i dont have a heat pump. Will look into that.

rp1790

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#1566920 7-Jun-2016 10:24

The Mitsubishi ones are expensive but they have a major advantage in the swinging louvre thing where the air comes out the top. I have a very nice looking other model that was half the price but it's also not half as quick at getting rid of the moisture. With the Mitsi you can direct the warmer, dry air at the source at it just works better.

timmmay

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#1566928 7-Jun-2016 10:31

We have two heat pumps, I don't find either particularly effective at dehumidifying.

Consumer recommends:

Goldaire GD330 ($500
DeLonghi DDS30 ($700)
Suki WDH-928DBH-20R ($340)

Mitsubishi were rated as "worth considering", but their water removal "just ok", and cost $700. Evantair TWYL2120 at $300 was also rated "worth considering", but the text suggests it was a pretty good all-rounder.

Consumer also points out you get a bit more heat out than you spend in power, because of the energy released when gas turns to liquid. Not sure how much this is. Reducing water in the air makes it easier to heat as well.

Before you buy a dehumidifier try this: open windows at each end of the house, or in each room, for half an hour or an hour during the day. Cold air doesn't hold much moisture, so the house will be easier to heat afterwards. It'll be colder, of course. We had the windows replaced with double glazed last week, having no windows at all for 6 hours made the house heaps colder and it took a lot longer to heat up as well - you're not just heating the air, you're heating the walls, the floors, the furniture, etc.

rp1790

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#1566932 7-Jun-2016 10:38

The model I mentioned that was half the price and half as effective as the Mitsi's is the DeLonghi DDS30 model mentioned above. I've often wondered if it's working at all because of how little water it has in the tank compared to the Mitsi.

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richms

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#1566966 7-Jun-2016 11:08

Depends on the temperature how effective they are. I was in someones "warm" house which was probably about 16 degrees. A dehumidifier will do stuff all that cold. I know the one in my ice-box bathroom does almost nothing overnight in winter and my towel is still absurdly damp the next morning.

Richard rich.ms

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#1567031 7-Jun-2016 12:24

I live in a cold, damp Ak house. Opening windows blah blah doesnt solve the issue , at all.
So I have 2 rooms with dehumidifers (both 15+ years old)
Despite how cold it can get , they do still suck out ALOT of moisture , I can see it in the tanks. I leave them on all day, on the weekend days I turn them off & open windows.

The issue with very cold rooms is simply that very cold air wont hold as much moisture, so if the moisture isnt in the air (too cold) then a dehumidifeir cant remove it.
So some have built in heaters to heat the room first.

mdf

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#1567455 7-Jun-2016 20:30

We've got the biggest Suki (20L I think - there is a range) from Bunnings. It's flippin' loud but seems to remove a *lot* of moisture from the air.

That said, it is very much a temporary solution to deal with a very damp musty room in our new place until we fix it properly. As others have said, far better to deal with the cause rather than the symptoms.

If the house is just slightly damp because of people living in it, a far better option is a ducted ventilation system like a DVS, HRV or SmartVent (plenty of other brands too) that circulate dry air around the house - there are some differences between positive pressure and balanced systems though, so it's worthwhile doing your homework.

Other possible causes might be leaks - look around windows especially. If you're not sure, a building inspector should be able to do a quick non-invasive test with specialist tools to determine conclusively. Other causes might be damp from under the house, in which case a moisture barrier will do wonders.

richms

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#1567457 7-Jun-2016 20:35

HRVs will also help heaps with damp basements because the pressure stops the flow of air up into the house and will hopefully push it out of the basement thru the vents on the side.

But damp windows are not a problem themselves unless you just find them ugly. You need to actually know what the humidity is in the place. I am sitting on 45-50% most of the time, sometimes down to the 35's which I find uncomfortably dry and the windows are covered in water because they are single glazed crap in the bedroom. Thats where all the moisture goes, onto the window, down the window, out the little gap at the bottom, like its a dehumidifier draining to outside.

Richard rich.ms

alasta

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#1567475 7-Jun-2016 21:14

Years ago I had a cheap Goldair which worked okay but was it noisy as hell. I replaced it with a Mitsubishi Oasis which I've had for four years and it has been 100% reliable and it's reasonably quiet. I like the fact that it can be programmed to turn on or off at a preset time. Keep in mind that there is some basic maintenance required - mine needs the filter vacuumed weekly, washed every three months, and replaced every two years.

When I've been browsing in shops I've felt that the Mitsubishi and the high end Delonghis are the only ones I would buy - everything else looks quite cheap and nasty.

Run your dehumidifier in conjunction with your heating - the warmer room will make the dehumidifier more effective and the dehumidifier will make the room easier to heat.

Sideface

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#1567506 7-Jun-2016 21:29

trig42:

Mitsubishi always used to make good ones.

Do you have a heat pump? Can you install a heat pump? If so, it may be a better solution (heat pumps have a dehumidifying cycle as well as the advantage that they can be a heater and cooler as well).

Heat pumps are much more efficient and effective than dehumidifiers, but they are more expensive, and are not portable.

In my experience Mitsubishi make the best (and quietest) heat pumps. (We have two of them in our 1918-vintage villa)

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qwertee

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#1567510 7-Jun-2016 21:50

I was looking for a dehumidifier last year and ended up with a Mitsubishi Oasis MJ-E22VX.

Very quiet and efficient in removing a lot of moisture.

sparky1685

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#1567512 7-Jun-2016 21:51

We bought one of these:

http://www.goldair.co.nz/product-catalogue/heating/dehumidifiers/8l-desiccant-dehumidifer-gd330

a couple of years ago and have been very happy with it. It was "Consumer Recommended" for what that's worth. It's small enough to move around the house easily if needed.

The dessicant ones like this apparently work better at low NZ temperatures than other dehumidifiers. It also does a very good job of drying washing inside on those days when we can't use the clothes line. I see on the consumer site that a few people have complained about it leaking, but we haven't experienced that. The water tank doesn't feel like the sturdiest bit of plastic though...

Price for these was all over the place when we bought ours, so it might pay to shop around. Pretty sure it was about $280 from Moore Wilson when we bought ours.

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