Best humidifier for unheated garage workshop

[MichaelAD]

It seems to me that every time I look into purchasing virtually anything to do with my hobby, my search sends me spiraling into the spiders web of Internet distractions and asides. Some of these distractions are really interesting and I frequently discover many things that I knew nothing about at all. Often, after only a few days, I get back on course as I remember what it was I was originally looking for...

I've just remembered...

Some time ago my standard size garage became my workshop. It is drafty and unheated. I normally protect my tools and equipment with appropriate oils/greases/waxes to help to prevent rusting/corrosion. However, after most winters I do have to carry out some remedial clean up of some items that have have a slight covering of rust/corrosion. So my question:

Would the purchase of a desiccant style dehumidifier be a worthwhile investment for added protection? If so...any recommendations?

 

[Fitzroy]

A desiccant type is better in low temperatures than a compressor type. However if it is draughty then I doubt any dehumidifier will be very successful as you’ll be fighting a loosing battle against the incoming moist air.

 

[Ollie78]

I have a dessicant dehumidifier (a meaco one) and while it is efficient at collecting moisture and warming up the space it was not adequate to prevent condensation in our house.
In the end I installed a PIV or positive input ventilation system which works far better. The principle is that it "dilutes" the stale damp air with fresh dry air from outside, increasing its capacity to carry moisture and thus preventing the condensation. It gently pressurises the air inside and so a constant flow is created of new fresh air carrying out excess moisture.
Maybe this might work for your workshop too.
As Fitzroy says it depends on the airtightness of the building among other things.

Ollie

 

[MichaelAD]

Thanks Fitzroy...I see you're from the frozen North so I'm guessing you know a lot about chilly drafts!
Seems to be a reasonable starting point to minimise drafts (I feel another Internet search developing for me...). However, as Ollie has pointed out, assuming I get the garage 'acceptably' airtight/ventilated...would I then be better armed to fight the battle with a desiccant humidifier?
(I just know that I'm going to be spiraling soon...the Internet is drawing me...)

 

[Sideways]

I bought a brush type draught excluder to fit the bottom of an up and over garage door. Alloy extrusion with a strip of 40 to 50mm long bristles. It made a huge difference to draughts in a single brick garage. Toolstation or screwfix, whichever.

I have the same winter condensation issues as you. It gets misty some evenings and mornings in our part of the world. Working outdoors until after dark the other night condensation was soaking my ladders, workmate, toolboxes and all the tools in use. I dumped them in the garage and set my new dessicant dehumidifier off on timer for 4 hours.
In the morning, I had at least 2 litres of water to pour away, my gear was dry and the garage felt pretty good.
The plan is just to run the unit from time to time over winter to keep down the damp. I'll still use my boxes, anti rust wax, silica gel etc but I'll try using the desiccant instead of a fan heater when I work in there, plus when it starts to feel noticeably damp and see how it goes.

I bought the new model / biggest domestic type desiccant from that UK company that designs here and has their stuff made in China. Can't comment on reliability but the warranty is OK, it's easy to use and looks presentable if it needs to come in the house.

 

[MichaelAD]

Thanks for that Sideways...my garage door is also an up 'n' over, so I will do as you've done and get a brush type draft excluder (will need to apply it to the entrance door too).
So...desiccant humidifier here I come...just need to check out what's available via the Internet...
(the Internet draws me...resistance is futile...where will this spiders web take me?)

 

[Sideways]

EcoAir DD3 classic mk2 was what I ended up with. It's the newer version of one that had some decent reviews.
Interestingly, with the hike in electricity prices recently, we're trying out using a portable dehumidifier in a cupboard instead of drying clothes in the old tech tumble dryer. First impressions are that this will save us some money in the long run.

 

[NicoWilson]

Might a little background heat be better than using a dehumidifier?

 

[Ollie78]

Might a little background heat be better than using a dehumidifier?

One of the benefits of dessicant type dehumidifiers is that they do produce heat. Ours has a setting for drying clothes by sort of aiming the warm exhaust at the clothes rack. It works really well in a small space.

Ollie

 

[Argus]

Might a little background heat be better than using a dehumidifier?

Precisely.

If the objective is to prevent rust forming, then keeping the tools themselves confined to the outdoor shed and just a few degrees above the anticipated Dewpoint temperature will be all that is required.

For hand tools (and unless there is a huge amount of machinery), this can be done by insulating a box.....larger box......, large cupboard..... whichever is appropriate to hold the tools, then adding a small amount of heat. Usually a couple of hundred watts and a room stat will be enough. The target, as I said, is to keep the surface temperature of the kit just above the anticipated Dewpoint temperature.

 

[MichaelAD]

Seems to me (so far), that it's all a bit of a balancing act. Right amount of ventilation, correct warmth with humidity controlled to a comfortable range...ah...pricing comes into this combination of variables too of course...
Variables plus Internet...I may be some time...

 

[NicoWilson]

I'd be keeping tools in a ventilated cupboard and putting one of these in:

45w 1ft Energy Saving Tubular Heater - IP55

 

[Sandyn]

I keep and use some cast iron tools in a detached workshop. I don't heat it. It is well ventilated. I don't have any problems with my planer or table saw, but last winter, my anvil did get a very slight coating of fine rust. I figure it's when the temperature rises rapidly in winter, the thermal lag of the anvil keeps it at a lower temperature for a day or two. If I had problems with the saw or planer, I would just put a really small tube heater in the unit and cover it with an old curtain. I have also waxed the tables in the past, so I think that helps in my situation.

I use two dehumidifier daily in the house. Both are compressor types. I have one in the bathroom to lower humidity after showers. Saves pumping the heat outside via an extractor fan. The other dries my bike after my daily cycle ride and bike hosedown.
Dehumidifiers are also 'heaters'. Whatever the rating of the unit is, that's how much heat they create. They have fans and compressors which produce heat as a byproduct and in the process of dehumidification, the exhaust air is blown over the compressor condenser coils heating the air.
Desiccant units do perform better at lower temperatures, but use more power. I geusstimate I could get similar performance from my dehumidifiers at lower temperatures if I added the equivalent heat to the input of the dehumidifier, but don't bother. Generally they work fine and go through a defrost cycle when it's cold.

 

[Sideways]

Powertools in their cases with 50g silica gel sachets
Hand tools (metal and woodwork) in airtight "toughboxes" with 50g silica gel sachets
Spare saw blades get a wipe over with mineral oil
Cast iron machines get a blanket.
Cold is not the enemy - rust is a chemical reaction that is slower in the cold
Dew point is vital like Argus says. Drying the air or raising it's temperature so it holds more moisture both move you away from the dew point, but the big hit for me is when all the metal in the garage has become cold overnight and I open the door in the morning and let in a flood of warmer, damper air from a rainy day. Instant condensation.
With outdoor humity around 80% (pretty common) your metal only needs to be about 5 degrees colder than the incoming warm, damp air for condensation to form, so blankets on the iron help to keep the moist air off the cold metal make a big difference..

Silica gel refreshes many times over in the microwave in a few minutes and really works, it really steams so must have absorbed a useful amount of moisture.

Also, we breath out quite a lot of water. If this isn't vented or dehumidified, it has to go somewhere when the temp falls at night

 

[billgiles]

I have a 3mx4m newly built log cabin type workshop so it is largely draft free. I run a domestic dehumidifier and it removes a couple of litres of water from the air a week. More in wet weather. I don’t have any rusting issues. Your garage needs to be sealed better, but I don’t believe that a desiccant could work better than my dehumidifier.

 

[segovia]

With a humidifier, you would be fighting a losing battle and burning vast amounts of energy in the process. I good airtight cabinet with some low voltage heating elements would work. I am thinking about the type of elements used in home-brewing etc. Just enough to keep the moisture out.

 

[billgiles]

Decumidifiers work on the same principle as fridges and do not use ‘vast’ amounts of energy. Of course if they are fighting a losing battle to lower the humidity of the whole locale…. I was once in the storage business and dehumidifiers were definitely more effective than heaters.

 

[sploo]

I have a (desiccant) EcoAir DD1 Classic in my garage - but it's well sealed. The bit of heat it spits out, plus the drain going outside with a small hole in the wall, do seem to keep things reasonably dry.

If your garage isn't sealed (i.e. draughty) then I'd suspect a dehumidifier would be pointless (and just cost you money). If you can seal it up reasonably well then it's a good option.

 

[ivan]

Have a Meaco Zambesi in the garage (dessicant). Aim to keep RH below 70% to prevent rust. ~300W on low fan speed when extracting, goes into standby when set RH is attained, checking every so often to see if RH has gone up and if it should turn on again. If you have air leaks it will try to dry out the whole locality (!) and run all the time whilst doing little good for your tools.

 

[Stevekane]

Cant you rigup some heavy curtains across the door, old blankets come to mind, a steel(?) up and over door is like a large radiator so definatly worth trying to cover or insulate it I would think.
Steve.
Btw they use the Meaco type on boats where winter temps get very low and I know from experience that a regular compressor type dehumidifier will turn into a block of ice in a very cold damp room.