How to build a humidity room

[simso]

Hey guys, ive read a few articles on this forum on humidity rooms, that some of you have built.

Humidity has never been to much of an issue here in perth, but we have ventured into manufacturing bulk lots (electric) at a time to keep our costs down, and also importing larger amounts than whats needed to just do singular jobs, this means the end machined product or the raw product needs to be able to be stored away in a climatised enviroment for up to a year or two with no risk of cracking.

What devices are good for controlling a small room around the clock, ideally the unit will be all in one self contained and easily operated.

Does anyone have any good links for me.

Regards

Steve

[woodrat]

Hi Steve, I have a dry room approx 6m x 1.8 that I have a domestic dehumidifier in to regulate the RH. I have a setting on the dial that I use most of the time when it is normal weather and I usually run it continuously if it is raining. I can keep a steady 45% that way. I suppose the most important piece of kit is a good quality hygrometer. I have about 1/2 a dozen placed around the workshop and in the dry room and I always have them in pairs so I can see if one has malfunctioned as can happen. If they are not reading within a couple of % of each other I want to know why.
I think in the States they may have Humidifiers/Dehumidifiers in one unit but I have not seen these here. I would like to know if one is available because we get westerlies here that drop the RH to below 30% very quickly and can shock thin sections of timber. It is then difficult to get the RH up again even if I pour a bucket of water on the workshop floor. A couple of days of that are not very nice. I know in the West it can be even worse with lower RH again.

Cheers

John

[Bob Connor]

I use a DeLonghi dehumidifier which runs 24/7.

http://www.appliancesonline.com.au/delo ... ier-cf08e/

I have found that when it gets cold here in Victoria it will not keep the RH to 40%. Most winters it'll maintain the 3x6m room to about 50%.(which is OK)

This year however (being so wet and cold) it's been around 60%.

It's only been the last couple of weeks (since it's got a little warmer) that the humidity has returned to acceptable levels in the dry room.

So I'm happy with what it does and it has been reliable.

I did have to take the thing apart to get all of the dust out of a while back.(the drip channel to the catchment tank got blocked) It's got some weird screws and I had to modify a screwdriver to get the task done.

Regards

[Nick Payne]

On a somewhat related topic, I was looking for some potassium carbonate in order to calibrate my hygrometers at something close to the humidity I want to maintain (potassium carbonate is ideal to use for calibration as the saturated salt RH value is 44% at 20C). The smallest quantity I could find was 5kg for approximately $50 from winemakers suppliers, but it would take me 1000 years to use that quantity. Has anyone seen lesser quantities for sale anywhere?

[woodrat]

On a somewhat related topic, I was looking for some potassium carbonate in order to calibrate my hygrometers at something close to the humidity I want to maintain (potassium carbonate is ideal to use for calibration as the saturated salt RH value is 44% at 20C). The smallest quantity I could find was 5kg for approximately $50 from winemakers suppliers, but it would take me 1000 years to use that quantity. Has anyone seen lesser quantities for sale anywhere?

Nick, I have been trying to buy potassium carbonate too for that reason. Like you I want to know that my hygros are accurate in the range we are interested in. Common non iodized salt gives an RH of 76% but thats not much use because you don't really know if your instrument is reading true at the mid levels. I would love to know where to get said compound in smaller quantities too.

John

[Nick Payne]

With a bit more hunting I did find a smaller quantity available: http://biomedcafe.com.au/cartpage/viewp ... 20-%20250g.

[Tod Gilding]

Nick, I would have thought that with 5kg it could be placed into 500g-1Kg bags and placed around the dry room to assist the dehumidifier and save power ?.

I could be wrong, as I once was, and I still have the marriage certificate to prove it.

[jeffhigh]

Unfortunately the 5 kg of pottassium chloride would absorb water once then need to be dried in an oven to be able to absorb more.
No saving of power.

[Tod Gilding]

How often do you think it would need to go in the oven Jeff ? I mean if it was left in the dry room with the dehumidifier.

[jeffhigh]

I have no idea Todd, but when you see how much water a dehumidifier removes, per day, then using any sort of dessicant powder only makes sense in a very small sealed package, not in a room.

[simso]

Hi Steve, I have a dry room approx 6m x 1.8 that I have a domestic dehumidifier in to regulate the RH.

Looks good john.

So you have gauges in to measure and manually (by hand) turn on a dehumidifer. I this correct.

Ive been searching and found some electronic devices that monitor temp and humidity, they then via alarms switch independant devices on and off to maintain.

So Ive ordered the controller, Ill chase down a cheap dehumdifier, and then maybe Ill need something to create humdity, like a lamp and water to go the opposite way.

Problem Im having is the wood I have laying around (upstairs) in the shop is forming mold on the surface, Im also finding bodies that I have cnc machined out forming small hair line cracks, so my humidity is all over the place (uncontrolled).

I want to create a permanent storage area only about 8sq meters that is for storage of all shop woods we use, neck blanks / fretboard blanks / body blanks etc etc

[J.F. Custom]

Hi Steve.

John makes a good point about multiple Hygrometers. One is not enough if you want to be relatively sure about what level you are at. They all seem to read differently... I average my readings out

I had a Delonghi dehumidifier/air-con (ex China build) that I was happy enough with until it packed it in. Trying to get it fixed or serviced was beyond a joke. Delonghi would not provide parts directly or even quote on a part - despite being rural and not near a repairer. They would only point me to their nearest repair agent for this unit - about 100km. So I called that agent only to be told they did not in fact repair those at all. After a lot of circular calling around, I finally found a company that did. So I dropped it off telling them I believe the pump had packed it in - it would not expel water so would constantly read full and switch off. The error message also suggested the same. I requested they quote on repair or replacement of part as quickly as possible as I need my dry room back up.

Two weeks later I had heard nothing. I called in on them and was told they had in fact assessed it. The conversation went like this - "Yeah your pump looks to have packed it in." OK, I thought as much, as I said. So how much is it to replace? "Oh?! You want to do that?" Well yes, as soon as possible but only if it's viable financially. "OK, well, we'll give Delonghi a call for info on the part." Should I leave it here with you then and how long is that likely to take? "Nah. You can bring it back later when we get the part - we don't have the room to keep it until then. So thats $120 thanks." Erm pardon? For what exactly? We're two weeks on and you have told me precisely what I told you when I dropped it in. You have not even got a quote for the part, let alone ordered it. Was I charged for storage for the fortnight? "Well, we did inspect it for you and leave it running overnight... It's just the standard workshop charge." OK thanks. Don't worry about the replacement part...

Two weeks later I got a call from them saying they could get the part in and it would be $200-250 to fix it - am I sure I don't want it? I told them frankly I'd already paid half that for nothing and have wasted a month in the process. I said in the meantime, I have now replaced the unit with another brand so I could get my dry room back in operation as needed. They did apologise at that point.

Delonghi have a good reputation, though many of their products are Chinese made - just as other far less expensive brands are. I believe they spend a lot on their 'branding' or marketing, self promotion if you like. Their reputation is not so great when it comes to repairs - so I consequently found when I searched online. Many stories like mine...

I got a Mitsubishi (Japanese Made) unit second hand but basically new. It has performed flawlessly since, but the room I use it in is probably only 2m x 2.5m at a guess, so it does not have to work too hard. But wow does it suck a lot of water from the air! Unfortunately they do not sell these in Australia anymore as there was no market for their high cost/quality.

Both of these units were manually operated and for reasonably small spaces. They are 'home' use, not industrial, nor fully automated climate control systems - that is, beyond being able to set your desired humidity level and have them auto adjust to maintain it.

May or may not be what you are after. I'm thinking you need something larger for a start, and more fully automated for your business setup.

Hope it helps.

Jeremy.

[simso]

Thanks,

Sounds like if Im going to buy a dehumidifier, then go online and get a couple of cheapies that can be thrown away when they pack it in. Have a back up.

Ive started building the area and sealing it up, already filling it fast and I havent even set the system up yet, got to be space concious.

Small area with racks, one for fretboards, one for neck blanks, one for body blanks, and then an area for cnc'd body kits ready for sale.

Amazing what you can pack in.

[woodrat]

Hi Steve, I have a dry room approx 6m x 1.8 that I have a domestic dehumidifier in to regulate the RH.

Looks good john.

So you have gauges in to measure and manually (by hand) turn on a dehumidifer. I this correct.

Hi Steve....Sometimes I am manual and sometimes I leave it to the controller on the machine....If I am in the dry room I mostly monitor it myself. The best hygrometer I have is a very old British made vintage one that I would suggest is from around the war years or just after. The brand on it is the word "ON" overlaid on a picture of a dart of the throwing type. It just says Humidity Per Cent and Made in England but its a beauty with a beautiful mechanism that reacts quickly and is accurate. Oh...and by the way I love old instruments with dials so it doubles as a working collection.

[jeffhigh]

Check what range the dehumidifier operates in.
When I was buying, some would not go below 50
I bought a Dimplex

[kiwigeo]

I got a Mitsubishi (Japanese Made) unit second hand but basically new. It has performed flawlessly since, but the room I use it in is probably only 2m x 2.5m at a guess, so it does not have to work too hard. But wow does it suck a lot of water from the air! Unfortunately they do not sell these in Australia anymore as there was no market for their high cost/quality.

These units are fairly common in NZ and appear on trademe on a regular basis. Im looking at bringing one back with me next time I visit my family over there.

[Clancy]

Ive been searching and found some electronic devices that monitor temp and humidity, they then via alarms switch independant devices on and off to maintain.

This is what I do for a living.

Present & past clients include....

- National Archives of Australia
- National Museum of Australia
- National Gallery of Australia
- Australian Parliament House
- Canberra Deep Space Communications Centre

....but trust me, you couldn't afford the systems we install & use to do the job.

I showed this to Dom the other day. It is the absoulute minimum I would use to calibrate our field devices, and still requires annual re-calibration & certification itself.
http://www.testoaus.com.au/product_deta ... dity_meter

[tim mullin]

My wood room was formerly the supply closet in my consulting office. I haven't measured it, but I'd guess it's in the order of 3 m2, but can hold an astonishing quantity of wood and unassembled parts (like unbraced tops and backs), and is arranged to encourage airflow around the stacks.

In my area of New Zealand, I don't have to worry about things being too dry on the ground floor, but I want to keep the RH in the range of 40-45%, and that usually requires dehumidification. I started with a Delonghi dehumidifier identical to that referenced by Bob -- I nicked it from our bathroom when my wife wasn't looking. Despite its "electronic" comfort control, I found it was either much drier or much more humid than I was looking for.

I ended up building an electronic humidity controller, using parts sourced from http://www.csinz.com. For about NZ$250, they supplied me with an LAE programmable humidity controller (panel mount with LED display), a humidity sensor, and a tiny 240VAC-12VAC transformer -- pricey, but I think I got a discount on older stock, so coulda been worse! I sourced an extension cord and a project box to house the electronics. A little bit of solder and it was assembled. The device is now plugged between a power point and the dehumidifier, with the sensor mounted on the wall.

The unit can be user programmed for a set point and hysteresis value for both humidification (if I had it) and dehumidification, so I have control over what RH triggers the unit to turn on and what turns it off (so that the unit isn't constantly cycling on and off around a set point). The unit display can be calibrated to a standard, if you have one. Programming is a bit of a mission, and the instructions leave something to be desired.

I had to change my dehumidifier to a more basic Delonghi model WITHOUT the electronic comfort control. A manual control can be set to full on, and won't reset when the power is cycled. I ran a drain tube through the exterior wall, so the unit now runs automatically and doesn't require any attention at all. The LED display is obvious everytime I open the door, and usually climbs rapidly with the door open.

[simso]

Ive never had to store wood before, just bought it as I needed it. Was used up within a month or two after recieving it.

Im gathering ventilation around each piece is better than stacking the wood on top of itself

[tim mullin]

I ended up building an electronic humidity controller, using parts sourced from http://www.csinz.com. For about NZ$250, they supplied me with an LAE programmable humidity controller (panel mount with LED display), a humidity sensor, and a tiny 240VAC-12VAC transformer ... A little bit of solder and it was assembled. The device is now plugged between a power point and the dehumidifier, with the sensor mounted on the wall.

A couple of pics of my bodged programmable humidity controller:

[Mark Fogleman]

If you're on a budget or are a curmudgeon (like me) you can put together a wetbulb/drybulb thermometer and a small fan for very little outlay. This will give you excellent accuracy and precision without all the calibration drama of the electronic versions. Use a psychrometric calculator like this: http://www.uigi.com/WebPsycH.html and calibrate the humidistat on your appliance. If you don't trust the onboard humidistats, connect your dehumidifier and humidifier to a remote humidistat with a relay to take control of the appliances. The humidistats used to control exhaust fans in bathrooms work well for this application.

As an aside, Thomas Jefferson made an excellent humidity meter for his tobacco curing sheds. It was a thin piece of softwood and hardwood laminated together and sliced to a final size of ~1/8"X ~1/8" X ~4". When the humidity rises the stick bends in one direction. When it drops it bends the other way. One is still in use at Monticello with over 200 years of service.

Mark
(A slide rule guy in a Matlab world)

[tim mullin]

connect your dehumidifier and humidifier to a remote humidistat with a relay to take control of the appliances. The humidistats used to control exhaust fans in bathrooms work well for this application.

In fact, I tried exactly that, picking up a bathroom humidistat from my local electrical supply, and wiring that into the supply to my dehumidifier. No surprise that the dial was hopelessly inaccurate, but more importantly the device had huge hysteresis -- the difference between the RH when the unit would turn on and the RH when it would turn off -- it was more than 20%! This might be fine when you want to dry out a steamy bathroom with an exhaust fan, but wasn't what I was looking for to hold a relatively constant RH, with variation of around 5%. So, I took the bathroom humidistat back for a refund and began my search for parts that built the controller I described earlier.

[J.F. Custom]

These units are fairly common in NZ and appear on trademe on a regular basis. Im looking at bringing one back with me next time I visit my family over there.

They are a good buy in my opinion Martin. They are very quiet and mine has run faultlessly since purchased, which was already second hand.

Two things to consider though - parts may be harder to come by over time given their obsolete nature in Australia. Of course, if they still sell them in NZ, parts should be available there.

Second is what Jeff mentioned above - check the model literature. They have different abilities when it comes to setting the humidity (auto adjust) feature. Mine can only go down to 50% on auto level setting. I think the next model up can go to 40% instead. This is frustrating as it is likely only a pre-programmed chip setting; it should be able to be changed. In any case, I don't use this feature and run mine on the "low" setting instead, full time. This keeps my room perfect, but it would probably be cheaper to run if it were able to switch itself on and off as required. I may look into an external control for this purpose but for now, this will do.

I should also mention, with respect to the hygrometers in my workshop - this machines readout is the lowest of several at 32%. It sits on the ground and obviously senses at the source of the conditioned air. The next hygrometer is digital and at bench/working height - this reads 39%. The next is a German brass and glass unit, sitting just over head height. It reads the highest at 47%.

Between all of them, I believe it to be in the zone I want. Be nice to have a fully calibrated unit to genuinely check which unit is the closest to an accurate reading though.

Jeremy.