Desiccant dehumidifier

I was about to recommend mine until you said "electronic".

Any reason?

Hygroscopic plastic strip ones just arent reliable enough. The machine wont be monitored much, so a proper sensor is wanted.

NT

How about a dumb machine (like mine) with the control jammed full on and an external humidistat of your choice?

I was knocking up a Raspberry Pi networked humidistat only this afternoon, and I did one for someone's shed a few weeks ago, which switches a heater on and off to keep humidity below a set level.

Going back to that bit in the OP about not wanting to run the fan all the time, the humidistat tends to rely on the fan pulling in air so that it can sample the room's humidity. No fan, no air circulation, no proper humidity control.

We have a Ruby Dry which has an electronic humidistat (see)

We usually set it for 60% humidity, but you have to select that each time, if you switch off power at the wall rather than on the unit.

I'm not convinced there. Air and water vapour both move about in a room, and the humidistat is next to a big outlet vent.

Sounds like a feature to avoid, ta.

NT

nd need it to switch off when not in use, dont want to waste a packet on th e fan running all the time. What I've looked at online seems to be a bit sh ort on info. Any suggestions?

I'm not finding the info I need out there anywhere, and need to get on with it. So have revised the requirement to simply having an adjustable humidis tat and the fan not running continuously. If the stat proves unsatisfactory we can look for an external controller another day.

So does anyone have knowledge of these, whether the fan runs all the time? Or do you have a desiccant type where the fan doesnt keep running?

NT

Yes - that's the one I've got...

It is "simple" - rotary humidistat that works and a high/low fan setting.

Collection in reservoir with auto cutout when full.

Comes with a hose for external continuous drainage if required.

Pretty decent unit for the money - does what it says.

Oh and just to confirm - it only runs the fan and disc and heater when the humidistat calls for it.

It is eminently suitable for external control via a timer or external humidistat.

Thank you - just what I need to know!

NT

This is the which 2014 best buy.

Ok sorry to butt in on the thread but I am trying to learn - I have never heard of desiccant dehumidifier (other than silica gel usually used in packaging) so I thought I would JFGI. This led me to this page

which explains the theory. Refrigerant - quite happy with that; I know how that works. Desiccant - OK new to me but the description seems to make sense HOWEVER in the description for desiccant it says

"..... As there is no actual water produced during the process, thes...." and "....The reactivation air leaves the rotor warm and wet. This air is normally exhausted to outside...."

The units linked to above have water tanks (and the facility for a permanent drain) but I can see nothing about exhausting waste air. I am now well confused can anyone point me to a web page explaining the technology behind the devices mentioned above ( I couldn't find anything useful about "how" they worked on the manufactures web site). Thanks

Chris.

According to meco the vapour is condensed on a metal plate.

"How does the desiccant dehumidifier work?

The desiccant dehumidifiers draw the air in from the room over a filter and into a desiccant wheel that is rotating slowly. The excess moisture in the air is absorbed by the wheel. The wheel is now saturated and as it rotates heat is blown over the wheel to force the moisture out and onto a metal plate where it condenses. Thus the wheel is regenerated so that it can collect more moisture from the air. The heat used is mixed with the dry air and blown back into the room providing dry warm air into the space. Whereas a compressor dehumidifier has to stop dehumidifying to defrost itself the desiccant is able to dry the air

Ah thanks, the metal plate seems to be the key. The web site I looked at said that the moist air was exhausted, rather than passed over a metal plate condenser.

You can probably buy ones that do that. I would expect them to be fixed units rather than mobile.

so far so good

That's not why. Compressor units just arent effective below about 10-12C

NT

I was about to jump in & ask (I know I've discussed this before, probably with you, but I've slept since then) whether it could be externally switched. Thanks for the precognition!

I don't know if I can be much of help. But yeah this website contains a lot of dehumidifiers.

Suspect the OP's already solved his problem :)