Thread: Winter condensation and rust

Originally Posted by Michael G

The easy way

a psychometric chart dry and wet bulb thermometer readings and plot on chart

You can actually buy a small portable electric powered air dehumidifier that you leave on all the time, if you're worried about preventing condensation and rust.

A mate of mine collects old cameras and he has one in the full sized room that has his collection in - to prevent fungal growth on the lenses (which apparently can be a major issue).

I's about as big as two beer cartons/slabs, dead quiet, only switches on when it needs to, and uses bugger all electricity.

Not sure how it works, probaly piezo refrigeration, and I think you empty it once in a while.

It maintains a set level of air moisture - from zero upwards.

Maybe you guys should invest in one of those.

Rob

Originally Posted by nearnexus

Not sure how it works, probaly piezo refrigeration,

Piezo would be inefficient when compared to the refrigerated types. Mitsubishi Electric and a few other manufacturers make them....Mitsubishi Electric Australia dont have them listed on their web , but Im sure you can still get them at the Good Guys, Radio Rentals etc etc.

Mitsubishi Dehumidifiers (domestic type) are considered to be the best of the bunch

The dehumidifier he has is dead quiet and no vibration - which makes me suspect it may be piezo. I can't say for sure as I only had a look at it once a year or so ago.

It certainly is unobtrusive.

I haven't checked what's available as I just use oil film to stop rust in my shed.

I expect that once it got the initial room moisture level down it would switch on fairly infrequently.

Rob

I do not think that a thing like a piezo dehumidifier exists (there is the opposite though, piezo humidifiers, which use an ultrasonic piezo generator to nebulize water).

Like in my previous link, there are dehumidifiers working with a Peltier element. They are cheap ($ 50-200 range) but are relatively energy inefficient compared to compressor dehumidifiers, and only have very small water removal capacity of between 0.3L and some 1L per day. Power consumption 50W to 150W, continuous when turned on.

Then there are compressor dehumidifiers, these do cost more (starting at around $300 and up to several k$) and use more power (300W to several kW). The better models have a built in hygrostat (the equivalent of a thermostat, but monitoring humidity) and run only if required. Often used in Europe to keep the laundry room dry. You find the smaller models on ebay, the Italian DeLonghi are popular in Australia. Overkill for a workshop, unless its a large workshop.

Finally, many air conditioners have a "dehumidifier" function. I have an inverter split system AC in the workshop, the problem is the lowest temperature the dehumidifier can be set to is 17C. I cannot afford to keep the garage workshop at 17C day and night, so this feature is useless to me. The temperature limitation comes about because of the need to keep the indoor heat exchanger coil ice free.

Well you guys seem to know a lot more about this subject than I do. I've never had anything to do with these units.

I assumed as it was dead quiet and no obvious compressor type setup it would be piezo along the lines of those small car fridge/chiller units you can buy.

How these units work is foreign to me. Seems like a good idea if you're paranoid about rust etc.

Rob

Originally Posted by cba_melbourne

I do not think that a thing like a piezo dehumidifier exists

Your right I think ,,,what I meant to say was Peltier and not piezo when I mentioned refrigerated dehumidifiers in post above

Originally Posted by cba_melbourne

Finally, many air conditioners have a "dehumidifier" function.

they work on a timed operation cycle for the unit to operate in cool mode ..the thermostat has no control...and the unit doesnt have RH control either

Looks like Peltier is what I was thinking about earlier re the car fridge chiller. No such thing as Piezo fridge.

Glad we sorted that one out.

Always learning - the truth is out there.

Rob

For what its worth, I saw this 'stuff' advertised in the latest Australian Shooters Mag. The suggested use (for their application) was to place a block in a gun safe to prevent rusting.
Might be useful if your lathe has a cover sheet
Zerust - Welcome to Zerust Australia

Originally Posted by Briangoldcoast

For what its worth, I saw this 'stuff' advertised in the latest Australian Shooters Mag. The suggested use (for their application) was to place a block in a gun safe to prevent rusting.
Might be useful if your lathe has a cover sheet
Zerust - Welcome to Zerust Australia

Unfortunately these VCI emitters will not work under a cover sheet that can breathe. It needs a small enclosed space with no or only little air circulation, like a plastic bag or a case or an infrequently opened tool chest. There it can replace and do a better job than simple dessicant bags. At quite a premium price though. And consider it cannot easily be regenerated in an oven like cheap dessicant bags that can be used over and over again. Once a Zerust cartridge has expired, it has to be replaced.

Chronos in the UK sells a similar VCI emitter, a small tin can costs 5 pounds and will protect a volume of 100 Liters for 2 years, presumably if not opened too often in between: Rust Prevention

Being on top of Mount Dandenong, east of Melbourne, this is a big problem in my shed.
Even though the shed is insulated, that doesn't prevent condensation. It is only a problem on my lathe, probably because it is solid steel.
Motorbikes (under cover) and pushbikes don't have this problem at all.
When I turn on my gas heater, and the air starts to heat up, I even get droplets from the roof purlins.
For now I have applied ISO32 oil generously to all exposed metal, but I will see if I can find something better.