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Electric extractor fan or dehumidifier

SD_DRACULA

Not sure if this is in the right area but here goes.

I have an insulated concrete block building in my garden and I'm looking to reduce the humidity level inside as I am storing some electronics in there and the humidity is between 60-80% as is and would want it at 50% max.

The area is about 20sqm.

I have purchased a small dehumidifier from Amazon (https://www.amazon.co.uk/gp/product/B00NFRTVY6/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1) and it is collecting water but doesn't seem to be able to drop the level to less than 60%

Would a standard bathroom extractor fan do the job? I can wire this to my wifi humidity switch and turn it on/off automatically based on the humidity value.

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2011

If you use an extractor fan of any type you are making the assumption that the replacement air has sufficiently low humidity. Is that the case?

Bruthal

If the shed heats up in the day time and has high humidity, when it cools at night, the humid air will condense its water on surfaces.

For this to happen, the cooler air from the night time has to gain moisture, from either taking in warm humid air from outside during the hot hours, or from persons being in it, respiration etc.

So if the air is replaced as the day cools, it will be replacing the air with cooler air but with less humidity as per conditions outside.

But the air would have to be continuously replaced probably, if condensation was a problem.

I have a metal shed and its well insulated. A few power tools in it, and ongoing projects worked on out in it, which includes electronics. Never any condensation problem, no active extraction, just open windows if very warm and i am in it.

SD_DRACULA

The walls are 10 inch cavity and 63mm kingspan on the inside (50+12.5mm) and attic wool in the ceiling between the plasterboard and roof.
Yes condensation is not a problem during this weather moreso when it gets cold, I can see it on the PVC windows/door/plastic bottles.
And yes I have two windows but if outside humidity is 80% (like it was today) then surely I put in the same air inside right?

Bruthal

SD_DRACULA wrote: »

Yes condensation is not a problem during this weather moreso when it gets cold, I can see it on the PVC windows/door/plastic bottles.
And yes I have two windows but if outside humidity is 80% (like it was today) then surely I put in the same air inside right?

If the air coming in from outside is at 80%, then it wont really condense unless it contacts surfaces cooler than said air.

The biggest condensation problems are when warm humid air comes in, then cools down, or contacts surfaces that have cooled down. So regular ventilation keeps the inside more at parity with the outside as the temperature reduces.

So unless the shed gets colder than the outside with trapped high RH air inside, it should`t matter too much.

So if the outside air is ventilated through the shed as it gets cooler, it should keep condensation down.

i often see it on the shed windows, but it still does not affect electronics or other items out there, all year round.

If it is a big problem, the dehumidifier will work. No need to get it to a particular percentage, just low enough to keep the dew point at a lower temp, which can be done by either warming the shed interior, or drying the air (dehumidify it a bit.

Water condensing on the glass is actually dehumidifying the air slightly.

2011

Warner air can hold more water. So if the humidity is 80% outside and the same air goes inside and the inside is cooler the humidity will increase. However humidity can’t exceed 100%. When the humidity is too high the air can no longer hold it so you get condensation.

2011

I see I crossed posts with Bruthal
A similar message.

Bruthal

2011 wrote: »

Warner air can hold more water. So if the humidity is 80% outside and the same air goes inside and the inside is cooler the humidity will increase.

Yes, so ventilating it keeps it at parity with outside, reducing the condensation inside.

Also being in the shed increases humidity, so again, good ventilation eliminates that.

Bruthal

As I said, I have a steel shed, I studded inside and insulated, wood cladding on walls. No condensation problems on anything inside.

Only ventilation is the windows. A few electronic devices, laptop, tv flush in wall, this laser cutter project, and various power tools. No problems.

SD_DRACULA

Seems like 30-50% is the sweet spot for electronics and only when it gets to 80%+ it can actually cause damage long term.
I think I'll have a hard time getting it down to 50% unless I get a big dehumidifier, the one I have probably can't cope with the change of water in the air.
Main thing is to not have any condensation in the cold season and how to keep it at bay if it starts to form.
I don't have any vents in it, just vent it via the windows.

Bruthal

SD_DRACULA wrote: »

I don't have any vents in it, just vent it via the windows.

That`s all I have. Walls well insulated, and concrete floor has good damp membrane in it. Without that i would say I would have problems.

10-10-20

That dehumidifier is peltier based. You may as well use packets of salt to absorb moisture than expect that to work anywhere the chilly side of 30 degrees C! It's completely outside of its effective zone in a shed. Plus, what's 500ml really worth? You would need a rotating desiccant system to work optimally in a shed. Look them up, they do exist in smaller formats (but are a killer on power).

I don't think that 30% to 50% RH is realistic in a shed either, too low and you encourage static, plus the energy required to maintain that level of RH is going to be pretty large.
If you are storing electronics, you can have higher temperature and RH levels than operational temps. But what I would advise is that you limit the thermal-cycling so that you reduce the accumulation of moisture while going through the dew-point. That's best achieved by using insulation, which you have already fitted.

Bruthal

Yea I didnt even look at link. A non compressor job.

autumnalcore

Compressor dehumidifier is useless in an unheated space, desiccant dehumidifier will have no difficulty getting down to 50%.

If you can keep the electronics in a cabinet / enclosure a small tube heater and a humidistat may be much cheaper to run than dehumidifying the space.

https://www.electricalworld.com/en/ie/Dimplex-Eco-White-IPX4-Thermostatic-Electric-Tubular-Space-Heater---3-Foot-120W/s-1885-4484.aspx?PartnerID=73&utm_source=google&utm_medium=shopping&utm_campaign=Ireland&gclid=CjwKCAjwqJ_1BRBZEiwAv73uwCLdFfBfbaZCGTsJ7_JmUEpE4eaP-E_cOYGEst0SLEuG8QToL0uAOBoCYA0QAvD_BwE

https://www.dx.com/p/sonoff-th10-10a-wifi-smart-switch-module-wireless-switch-with-am2301-temperature-and-humidity-sensor-white-2012261.html?tc=EUR&ta=IE&gclid=CjwKCAjwqJ_1BRBZEiwAv73uwNtCmxdM7W0x26F5qH87kVeK9zdkB6Fx0Gp4XR3cnMNWDNRTz0aKIBoC_Y8QAvD_BwE

Bruthal

autumnalcore wrote: »

Compressor dehumidifier is useless in an unheated space, .

Yes true, although was more in reference to the mention of a peltier one. Thats the usual marketing thing. No compressor.

Bruthal

What sort of electronics are being stored op?
Components or devices. I have storage of components in boxes, but also a few operating devices. Stored components would be safe enough anyway.

10-10-20

Bruthal wrote: »

What sort of electronics are being stored op?
Components or devices. I have storage of components in boxes, but also a few operating devices. Stored components would be safe enough anyway.

Plus, if these components are already soldered, they aren't as sensitive to humidity as packaged component rolls are.

SD_DRACULA

PC components, motherboards, ram sticks, HDDs, that sort of stuff and the usual power tools but not worried about them so much.
I will probably need to put them in some sealed plastic boxes.

Bruthal

SD_DRACULA wrote: »

PC components, motherboards, ram sticks, HDDs, that sort of stuff and the usual power tools but not worried about them so much.
I will probably need to put them in some sealed plastic boxes.

I store similar items, plus there is a laptop out there, powered on a lot of the time. But also off for long periods.

I think one important factor besides well insulated walls and ceiling, is a well sealed floor, to limit additional water being introduced.

2011

Bruthal wrote: »

I have a metal shed and its well insulated. A few power tools in it, and ongoing projects worked on out in it, which includes electronics. Never any condensation problem, no active extraction, just open windows if very warm and i am in it.

Ongoing projects? Anything interesting? Please share.....

SD_DRACULA

The floor has the water barrier sheet, 50mm insulation in the concrete base and ceramic tiles on top.

Bruthal

2011 wrote: »

Ongoing projects? Anything interesting? Please share.....

Mod edit: Thread split. See response here

.

SD_DRACULA

I was hoping for a small power draw dehumidifier, hence that little one (25w) but how about one of these guys: https://www.amazon.co.uk/NETTA-12L-Dehumidifier-Continuous-Dehumidification/dp/B07F6DHHB1/ref=sr_1_1_sspa?crid=8F6KTY7AYLH6&dchild=1&keywords=dessicant+dehumidifiers&qid=1588157566&sprefix=dessicant+de%2Caps%2C139&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyUFBVRjFRMVJOV1dPJmVuY3J5cHRlZElkPUEwMTgxNDAzUzI3UVpCWEpBRU5JJmVuY3J5cHRlZEFkSWQ9QTA0MDk4ODMzMUxXSFhaSFBXT0lMJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
Reckon that will be able to keep up? Might have huge power draw if it needs to be on all the time.

2011

SD_DRACULA wrote: »

The floor has the water barrier sheet, 50mm insulation in the concrete base and ceramic tiles on top.

I would think that your tiled floor would be better as a warmer wooden floor. Anything that cools the room will increase the RH I would think. Not my area really just my opinion.

Bruthal

SD_DRACULA wrote: »

I was hoping for a small power draw dehumidifier, hence that little one (25w) but how about one of these guys: https://www.amazon.co.uk/NETTA-12L-Dehumidifier-Continuous-Dehumidification/dp/B07F6DHHB1/ref=sr_1_1_sspa?crid=8F6KTY7AYLH6&dchild=1&keywords=dessicant+dehumidifiers&qid=1588157566&sprefix=dessicant+de%2Caps%2C139&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyUFBVRjFRMVJOV1dPJmVuY3J5cHRlZElkPUEwMTgxNDAzUzI3UVpCWEpBRU5JJmVuY3J5cHRlZEFkSWQ9QTA0MDk4ODMzMUxXSFhaSFBXT0lMJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
Reckon that will be able to keep up? Might have huge power draw if it needs to be on all the time.

The desiccant ones would definitely be the better one in the shed as other posters said. Nice passive method. More wattage per hour as they have a heater in them to extract the water. But will be much more efficient than other types, so the running cost might be offset by lower duty cycle.

Sonoff humidity sensor was mentioned i think, so you can monitor that with your phone and probably control the unit with it.

SD_DRACULA

Yup I have the exact sonoff temp/humidity sensor already installed and I was thinking of laminate flooring but due to washing machine relocation I don't trust it as I did see it spew out some water at times if too much detergent goes in (which I am known for)