Spec me a dehumidifier please?

Gammawolf said:
Half of that % drop was just from heating the air 2c :p
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Is it though?

Warmer air can hold more moisture than colder air so, in theory, the hot air will have a higher humidity which the dehumidifier takes out.

I used mine again for the first time in about 5 years. It took the bedroom from about 66% to 51% and raise the temperature from 16oC to 22oC over a 3 hour period.
 
My house is solid walls and humidity is 70% plus most of the time. Been opening windows regularly, bought a window vac to get rid of morning condensation too. It doesn't feel wet in here but gauge still reads 70% plus.

Bit confused on how to deal with humidity. For example, I put the gauge outside the other day and humidity was 70% out there too. If it's 70% outside and I have open windows how can I expect humidity to drop inside?
 
broona said:
I got mine from the link Doobedoo shared above, but I googled discount codes, and found this one gave 5% off - NMTL5
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Thanks very much for the code and I've just ordered the same thing now. :) delivery for Saturday so I paid a bit extra but easier to make sure we will be in!

Where did you find that code please? I seem to suck at finding discount codes for purchases lol.

The Zambezi looks similar to my old Delonghi Dnc65 model and those both failed right around 2 years of use! This with the 3 years warranty will keep my mind at ease at least!
 
danlightbulb said:
My house is solid walls and humidity is 70% plus most of the time. Been opening windows regularly, bought a window vac to get rid of morning condensation too. It doesn't feel wet in here but gauge still reads 70% plus.

Bit confused on how to deal with humidity. For example, I put the gauge outside the other day and humidity was 70% out there too. If it's 70% outside and I have open windows how can I expect humidity to drop inside?
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And herein lies the problem and you've hit the nail on the head! :D

People open their windows in the morning like they're told to etc but during winter, the humidity in the morning can be 90 percent! Yeah you will get nice fresh air etc but it will be high in humidity that you then lock in your house and add to during the day!

Dehumidifiers or a PIV (positive input ventilation) system is what you really need, especially for older single brick houses.

We have a PIV system that was upgraded in summer last year to one of those Mr Venty tempered heating ones and I turned it off about 7 months ago during summer to see if it helped with the house being warmer. I'm sure it did but I'll be going back into the roof to turn it back on I think soon!

The dehumidifier should help but it's the cost to run that vs the colder house of the PIV. Decisions!

Edit: For the entire day today, humidity where I live is above 90 percent all day and even goes as high as 100 percent at one point! Good luck opening your windows then.
 
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Richie said:
Is it though?

Warmer air can hold more moisture than colder air so, in theory, the hot air will have a higher humidity which the dehumidifier takes out.

I used mine again for the first time in about 5 years. It took the bedroom from about 66% to 51% and raise the temperature from 16oC to 22oC over a 3 hour period.
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Thats not how relative humidity works, your hot air can hold more water but it doesn't magically gain water (quickly) so with a relatively quick increase in temperature your RH goes down as a % because your air can hold more and the amount of water has stayed the same. From that example i quoted, if his starting temp was 19c at 70%, then that would have 9.61g of water per kg of air. Heating that by 2c still has the same amount of water but the RH has now decreased to 61.8% because the air can hold more.

In your example of starting from 16c and 66% heating up to 22c would reduce the RH to 45.4%. Obviously as you lower RH in the air objects in the room start putting moisture in the air as it balances out to the new lower % norm
 
danlightbulb said:
My house is solid walls and humidity is 70% plus most of the time. Been opening windows regularly, bought a window vac to get rid of morning condensation too. It doesn't feel wet in here but gauge still reads 70% plus.

Bit confused on how to deal with humidity. For example, I put the gauge outside the other day and humidity was 70% out there too. If it's 70% outside and I have open windows how can I expect humidity to drop inside?
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It entirely depends on the temperature outside. If its cold and humid, ie 7c and 90%, then letting that air in and heating it to say 18c will produce air thats 45% relative humidity. That is all these PIV systems are doing, taking in air from outside and making you heat it to lower RH
 
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Gammawolf said:
It entirely depends on the temperature outside. If its cold and humid, ie 7c and 90%, then letting that air in and heating it to say 18c will produce air thats 45% relative humidity. That is all these PIV systems are doing, taking in air from outside and making you heat it to lower RH
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That's true yeah, I did miss that in my opening the window in a morning statement.

So if it is 14 degrees outside and 95 percent humid, what would that be inside and at 18 degrees? That's what mtyhouse is! Or where / what calculation do I need? Google is finding some rather complex ones lol.
 
I have 2 x Meaco 2.6L. 1 upstairs, 1 downstairs. Both run quietly and I empty them every day. No more condensation on the windows in the morning or damp feeling bedsheets!
 
Richie said:
Conflicting opinions on that varying anywhere between 30% and 60%.

Mould will grow if >70% for extended periods.

I would say around the 45-50% is probably good.
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Id have to leave my dehumidifier on 24/7 at full power to keep a 50%

Within a day or two it's always back up at 70%
 
panthro said:
I have 2 x Meaco 2.6L. 1 upstairs, 1 downstairs. Both run quietly and I empty them every day. No more condensation on the windows in the morning or damp feeling bedsheets!
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Do they not cost a fortune to run my EcoAir desiccant one would.

I have been thinking about one of these.
Meaco MeacoDry ABC Dehumidifier 12L
 
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Nemiyen said:
That's true yeah, I did miss that in my opening the window in a morning statement.

So if it is 14 degrees outside and 95 percent humid, what would that be inside and at 18 degrees? That's what mtyhouse is! Or where / what calculation do I need? Google is finding some rather complex ones lol.
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This one makes it easy :D https://www.lenntech.com/calculators/humidity/relative-humidity.htm

Just drop in a starting temp and RH, choose your target temp and it'll let you know new RH%. In your example it would go down to 74%
 
Simon42 said:
Is you measurement device accurate? I bought a cheap device to measure humidity before getting a calibrated data logging device and found the cheap one was quite a way off (almost 10%)
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Dyson fan, and sensor are within 1 or 2 of each other. So guessing reasonably accurate.
 
Gammawolf said:
This one makes it easy :D https://www.lenntech.com/calculators/humidity/relative-humidity.htm

Just drop in a starting temp and RH, choose your target temp and it'll let you know new RH%. In your example it would go down to 74%
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Ah yeah that one works really well! So I'm screwed then lol. 14 degrees outside at 100 percent humidity means inside at 18 degrees it's 77.9 percent. That's definitely mouldy territory and I'd need my dehumidifier to reduce it.

I was finding calculations like this so I thought you were rainman working that out! :D

RH = 100 × {exp[17.625 × Dp/(243.04 + Dp)]/exp[17.625 × T/(243.04 + T)]}
 
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