Dehumidifier Help

[Maxie]

I am building a new screen drying room that will have a air conditioner and dehumidifier.
I have never used a dehumidifier and don't know how they work.
Do you leave them on all the time?
Do they work on a timer or come on when the humidity rises?
How much water do they remove from the air?
Should I look for a self draining unit?
In Israel they are not common and I've found a industrial unit that costs US$1000.
Seems like a lot, are the cheaper ones ok for our needs?
I thought of ordering one from the UK (220V).
What is a desiccant humidifier, are they suitable for silk screen?
Thanks for whatever help I can get.

[mk162]

Do you leave them on all the time? Yes, they will shut off and on depending on how dry you want the air
Do they work on a timer or come on when the humidity rises? See above
How much water do they remove from the air? different amounts, many of them are 40 pints per day, this is plenty for screen printing
Should I look for a self draining unit? Possibly, I have found the pumps in some to fail, so I either drain it into an existing drain or pump it out with a condensate pump for an AC system
In Israel they are not common and I've found a industrial unit that costs US$1000.
Seems like a lot, are the cheaper ones ok for our needs? Yes, I think mine was less than $200 USD
I thought of ordering one from the UK (220V).
What is a desiccant humidifier, are they suitable for silk screen? I don't think so, even if it was you have to replace the desiccant regularly.

[mimosatexas]

just want to augment what mk162 said, which is pretty much dead on.

most dehumidifiers will come with options for turning on and off that include a timer, humidity level, etc. I never use the timer setting on mine though, I just set the target humidity level and it does it's thing.  Both of my 40 pint units were 110v and i bought each used for $40.

[Magick]

I run a garden hose from the unit to my sump pump in the basement

[Atownsend]

I run mine 24/7. Cuts off when it gets below 35% humidity. Cost about $250... its definitely one of the better things I've bought for the screen room. Cant live without it now, it is 100% essential. My screens dry waaaaay quicker in the screen room. I just run it to a 5 gallon water container and empty it 1x / week. Maybe eventually I'll plumb it somewhere, but for now the 5 gal works.

[mk162]

we were fortunate to have some overhead condensation lines from another suite running through our darkroom.  We just hooked into those and BAM, now it drains outside.

it's a great thing, but not something I would spend a ton of money on.

[Maxie]

What humidity level and temperature are ideal for screen drying?

[mk162]

nosebleed dry

Just kidding, I keep ours between 35-50%. Mostly because the DTS is in the room.

temp can vary, ours is about 90 in the summer and 75-80 in the winter.

[Screen Dan]

We use this one (the 70qt/day model):

https://www.grainger.com/product/DAYTON-Industrial-and-Commercial-WP5534130/_/N-nlk?searchRedirect=industrial+dehumidifiers&ssf=3&s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/2HNR5_AS01?$smthumb$webparentimage$#nav=%2Fproduct%2FDAYTON-Industrial-and-Commercial-WP5534130%2F_%2FN-nlkZ1z0nv4kZ1z0g5koZ1z0g4lr%3FR%3D5EAJ5%26_%3D1447421991880%26picUrl%3D%252F%252Fstatic.grainger.com%252Frp%252Fs%252Fis%252Fimage%252FGrainger%252F2HNR5_AS01%253F%2524smthumb%2524webparentimage%2524%26s_pp%3Dfalse%26searchRedirect%3Dindustrial%2Bdehumidifiers%26ssf%3D3

Along with a small 1500w ceramic heater.  The roughly 8x8' room measures at 5-15% RH (I don't actually believe that) with our remote temp/hygro meter, bounces between 105°-125° depending on utilization.  We process about 200 screens a day.  At times there are over 150 screens in the room in various stages of drying to coat, drying after coat and drying after washout.  It takes about 20 minutes for a rack of 16 or so 23x31s to dry after coat, using 1 and 1 on the thin side of Aquasol HV...5 or 10 more minutes if there are lots of 150-S, which are coated 1 and 2 on the thin side.  A quick-dry replacement for on-press jobs takes about 3 minutes to dry after being rag dried.  A full job of 8 ot 10 screens takes about 15 minutes to dry from completely soaked after washout...no vacuuming.  Some of those times vary 10-20 minutes under heavy utilization.

Hope that info helps give some idea of what and where you need to go.

[Evo]

If you get a cheaper humidifier, or a consumer grade one, buy it used for as cheap as you can get it. That way when it fails, not if, you won't be sad.

After that, get a real one, preferably with a condensate pump so you can pipe it directly out of the room.


These rock:

http://www.sylvane.com/ebac-cd35.html

The one we have has been 24/7 for a year with zero issues. Set and forget.

[Maxie]

This is what I bought, quite reasonable, has a water outlet and I have a drain in the drying room.
Hopefully this will work for a while, I just bought a new printer and am moving my plant.     Right now I cannot afford a professional model.     I think with a air conditioner this will do the job.
My room is 12 sq m and this is suitable for up to 90 sq m.
TROTEC TTK 90 E Dehumidifier
by TROTEC
Price:   £149.95 FREE UK delivery.
Dehumidification performance max.: 30 l/24h
Power input max.: 0.52 kW
Air flow rate: 240 m³/h
Suitable for rooms with a size of up to 90 m²/ 225 m³
Operating range: 5 °C to 35 °C / 30 % to 100 %