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Read a lot of  stuff here about car tents, dehumidifiers, sealed garages, well ventilated garages etc.

The geography of my garage and contents  (it has to double as a shed and storage area and is long and narrow) doesn't leave room for access with a tent. So I am looking at a dehumidifier. Several members have advocated this, and have set up a dehumidifier with an on off time switch. (Not suitable for all dehumidifiers). I assume on grounds of economy, which seems reasonable. The dehumidifier suppliers make a case for leaving them on 24/7 as they come on and off according to RH. So though they are "on" they are not necessarily running. Makes sense as well. So I am looking for advise please.

Mike

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Mike - make sure you get one which works at low temperatures - most don't  - I can't remember the type but someone else will - I shoiuldn't worry about whether it has a built in time switch - just plug it into a time switch which plugs into a socket.

Also make sure it has a decent sized tank and/or facility to fit a permanent drain.

Cheers   Rich

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I guess it comes down whether you value the TRs condition more than about £60 worth of electricity every year. My dehumidifiers come with an on/off timeswitch on hours basis 2/4/6/8 etc but when you've got the humidity down to a decent level (no lower than 50% or things dry out and crack) it can switch off just leaving the fan on and it takes some hours before the humidity gets back up to unreasonable levels (my humidifier rates over 65% as wet). It has a permanent drain to outside and is a desiccant type not like a fridge so minus temps doesn't freeze it and turning it on off doesn't mess it up, it gets more use now with the constant rain and up and down temps rather in winter from December onwards when 4 or 5 degree daytime temps and an overnight drop to 0 or minus doesn't encourage too much in the way of moisture.

My garage is a single width but takes two cars in length plus about 8 foot space (if only I didn't keep filling it with **** !)  so I have about 36" down each side of the TR, I can easily fit a Carcoon inside which will come to midway across the scissor ramps in the floor with the TR inside and about 8" away from the sides. The ramps have 22" each side away from the walls. I think if you discipline yourself to keep the insides clear in your garage unless you have to shuffle sideways down each side when the cars in you'll get a Carcoon in quite easily. ...Oh and the Carcoon only uses 2 x 8" computer sized fans for circulation so annual electric bill for them is about £15.

Mick Richards

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Edited by Motorsport Mickey
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For a garage where the temperature gets down to around freezing you need a desiccant type dehumidifier because those based on refrigeration cannot work down there.  I leave mine running all the time (no carcoon) and it keeps RH down to around 60% which I find is enough. I also have a small workshop area and tools etc used to go rusty over the winter. Since getting the dehumidifier that no longer happens. The dehumidifier drains outside but on occasion I bottle some of the condensate as the distilled water is a useful by product.

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MikeF, likewise mine is a desiccant type (I think that's what you meant Motorsport Mickey) for low-temperature operation, draining to outside and I leave it on 24/7 via an ELCB (RCD if you prefer). It's not a computerised type, meaning I stand a chance of fixing it if it goes wrong, and the humidistat is set to just above the middle which should correspond to about 60% or so. I did log the humidity to check this (electromechanical humidistats aren't terribly accurate!) and I also logged the cost of running for a few months but I got bored and my pride & joy is worth much more than whatever it cost.

Cheers, Richard

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Can anybody recommend a good desiccant de-humidifier which doesn't cost the earth for a good sized double garage. I have a non desiccant one which stops working when it gets cold unless I put the heater on which is expensive!

Cheers

Rich

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Am I right in thinking that you either go for ventilation 

or 

try and seal the garage and dehumidify 

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Even if the garage is ventilated it can only reflect the outside temps and humidity.

You need either to seal the garage and then dehumidify, or run a Carcoon inside it which isn’t heated or dehumidified but does control the variation in temp and humidity by circulation through carbon filters. The car comes out with bright brake discs and no condensate on bare metals, even if you put it in wet ! 

Costs about £240 secondhand ( not very ) ... looks like new on e bay, size 3 large will suit a TR or Stag with room around it 3 foot on length and a foot on width.They even have outdoor versions which are double skinned.

Mick Richards

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Hi,

I'm very pleased with my "Trotec TTK40E " (www.eBay.de) since about 5 years in my cellar and workshop because the walls have contact to soil / ground.

It puts me out about 3-4 liters of water every day, with the windows closed, at 20°C (summer) in the room.

 

Are you shure you need one at your garage?

I don't, although we have our citrus trees and other winter sensitive plants with the cars in there during the winter.

Simple rule: don't let water in: roof sealed, do not put your every day car in there when it is very wet from rain or covered with snow.

Don't heat it with a gas infrared radiator when you are working there, the exhaust gas is very damp, best you don't heat it at all.

 

To the dehumidifier: they condense the water out on a cold "radiator", this is about 15 Kelvin colder than the surrounding temperature.

With less than 15°C in the room / garage you get ice on the radiator and the unit has to defrost itself from time to time.

On the low cost dehumidifiers this works very simple: by keeping the fan running and switch off the compressor.

That works lovely and amazing fast on my simple "Trotec" down to 1-2°C, with colder air you can not melt the ice.

 

Therefore you need an expensive unit that can run reverse for a short time, valves guide the hot coolant in the unit the other way round to melt the ice on the radiator.

This cost more energy and you have to drain the water before it freezes again, but you should not need something like this when you keep water out of the garage.

Because the air carries only a minimum of water below 5°, the effort to get it out is immense.

 

As mentioned my "Trotec" takes out about 3-4 liter of water max a day at 20°C in the room, that drops to 0,1 - 0,5 liter in the garage at 2-5°C.

If you anyway see a need for a dehumidifier at your garage you could switch it off with a thermostat when temperature drops below 2-5°C.

Hope that helps.

Marco

 

Edited by Z320
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I bought mine from https://www.dry-it-out.com/dry/garage-workshop.html after reading a similar post four years ago.   The model I bought is no longer listed but it’s a decent unit and around £100

you might also find some information at https://www.meaco.com/dehumidifier 

Paul

Edited by PaulAnderson
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Mine is a Meaco DD8L.  I use it only during nov and dec as the higher humidity and lower temperatures during those months do cause some minor condensation mainly from my breath!  Outside of those months then I find the humidity and temperature are either both higher or both lower meaning that condensation isn’t a problem. 

Cheers

dave

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£60 a year to dessicate the planet?   Sounds cheap to me.     'Cos that's what you're doing, unless you enclose the car in a Carcoon or similar, or seal the room it's in.

Let's consider why you get condensation.    It occurs when air that contains water vapour  cools to lower than the dew point of that vapour.   In the atmosphere, it then rains or if the cooling is due to a cold object, dew forms, which is why we see dew in the morning after a clear night, the ground radiates heat into space, and cools down.     Introduce your nice warm car, perhaps with some rain or road moisture on it, into your garage, and the warm car will evaporate the water, the car will appear nice and dry.    But overnight it will cool down, and if the same air is in the garage, the water will condense as dew, anywhere the air can reach.    And you reach for the dehumidifier.

Now contrast that with a well ventilated garage.      The warm, wet air around the car is diplaced by ambient air, cooler and in equilibrium with water lying about.        As evening comes and night passes, the breeze continues to change the garage air, so that the water vapour in it never reaches dew point, as a building because of its mass will always stay warmer, longer than the ground.    Result?  No condensation.

Am I promoting a theoretical argument?  No.    I live in Lancashire, one of the wettest counties in the UK.    My garage doors  don't fit anywhere, top, bottom or sides, and there is a slight breeze through it,   leaves get blown in, it's that draughty.  I even have a roof light that leaks in heavy rain.   And I get no condensation, none at all.    My tools stay on the wall rack, parts on the shelf unprotected and unrusted.

I've no doubt that a carccon or similar will keep your car as dry as a biscuit, but a dehumidifyer is an expensive way to desertify the planet.     Improve your ventilation, and let the breezes do it for nothing!

John

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If you are going to run a dehumidifier then the garage needs to be reasonable well sealed or you will be dehumidifying the outside world.

Assuming it is then it needs to be controlled by a humidistat unless you really don't want it to come on at night if it can be heard from inside the house. (That would seem the only merit in using a timer)

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In the winter months I use an Ecoair dehumifier which works well. The water drain is permanently plumbed in and drains outside. I now have a pretty well sealed garage with a roller shutter garage door. But previously the old garage door was very drafty. Despite this without the dehumidifier I always had condensation problems especially when the weather turned mild after a cold snap; everything metallic had condensation all over it.

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Gosh, really?   Then where did the moisture come from, in a well-ventilated garage?   

Daft Q, but no tumble dryer/kitchen extractor fan  exiting into the garage?  Is your garage attached to the house?  Communicating door direct?  Was that well-sealed?    Lots of moisture sources in the house, kitchen, bathroom, us, but because we keep them well above the dew point we don't see condensation, except on single pane windows.  If that warm damp air gets into a cold garage it will drop out of the air onto the cold surfaces.

Such air movement may be wasting a lot of heat and cost.    Worth pursuing?

JOhn

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2 hours ago, john.r.davies said:

Gosh, really?   Then where did the moisture come from, in a well-ventilated garage?   

Daft Q, but no tumble dryer/kitchen extractor fan  exiting into the garage?  Is your garage attached to the house?  Communicating door direct?  Was that well-sealed?    Lots of moisture sources in the house, kitchen, bathroom, us, but because we keep them well above the dew point we don't see condensation, except on single pane windows.  If that warm damp air gets into a cold garage it will drop out of the air onto the cold surfaces.

Such air movement may be wasting a lot of heat and cost.    Worth pursuing?

JOhn

No its a separate garage 20m from house.

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Very debatable subject,  and a subject that is very misunderstood,  (condensation)

Air borne moisture is your problem, this comes from the floor and walls, especially from the floor junction,

Many garages are of a single skin construction, badly insulated, etc,etc 

If you are  continuously drawing moisture you have a problem,  garage needs work, floor and wall resin products,

I would go for a humidity stat fan,  this would turn on when the humidity goes up,  a small heater to make the moisture airborne , this should help and it is a cheap solution 

I do use a dehumidifier, when the car is wet,  if the garage is close to the house fit it out with radiators 

Pink 

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My TR is parked in a well ventilated garage, & I don't have any condensation problems in there, however I have a small workshop consisting of a metal "shed" 8 ft by 10 ft.

It suffered from condensation problems every time the winter weather changed from cold (& dry) to warm & wet. moisture would appear on the surface of anything metal, like my lathe, the vice, the walls, & the metal roof. I added some insulation to the roof, which helped, but last year I installed a de-humidifier - not too expensive from Argos, It is the refrigerant type, & has a humidity level control, which I set to a level (after some testing) where it only comes on occasionaly to reduce the humidity to an acceptable level, I.E. no condensation.  It transformed the atmosphere in the workshop, & I am very pleased with the result. I have not noticed any problems with icing up etc in very cold weather - I guess in very cold weather the moisture in the air is low, & so it does not need to switch on. I emptied several gallons of water out of the container in the unit over last winter, so it is definately doing it's job.

Bob.

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I have my garaga insulated (10 cm rockwool on the walls, a bit more pir on the roof. Windows are double glass, we call them HR overhere (high efficiency).

The floor is concrete, not insulated.

I have a small heater plumbed in my house system, the temperature is set to keep the temperature well above freezing. On a rare occasion, in the spring when outside ambient temperatures go up (and water content increases) I have some minor condensation on the non isolated floor, but that’s it. No rust on my tools. In fact the floor, which is colder than the rest, is my early warning and also acts as a “de-humidifier”.

Waldi

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Hi Marco,

Yes, and that’s the area where I live. As long as the sills do not get submerged I should be ok, shouldn’t I?

Gruesse,

Waldi

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