White rock salt

Thanks Dave, are you Mr memory man, you should be on stage. Noted this calcium chloride is used in motorhomes just Googled the chemical and this subject is on there forums

Bob

Edited By BOB BLACKSHAW on 02/10/2020 10:25:33

I've been running pre owned ebac dehumidifier in my home made wooden workshop for more than 25 years. I switch it on early September and leave on to next May. They are not expensive to run, create a bit of warmth and more importantly he workshop is rust free. I responded to an advert for my dehumidifier, but they are often sold at Auctions and house clearance sales John

When the temperature rises fairly quickly excess water will condense from the air onto any cold surfaces that happen to be around, which can include machine tools etc., as they are large and warm up slowly. This will happen even in hot climates, unless the climate is very dry.

But if one uses low consumption heaters on, near or under the covers of each machine then the machines will not have cold surfaces and the excess water will condense out onto something else, and the machines should not rust. The water has to condense out somewhere but better on the floor or walls than on the tools?

Better to have insulation so that the internal temperature cannot rise quickly, and best to have some background heating for comfort. Ventilation systems can also work by getting the warming moist air out of the shop as the temperature rises but these may require quite complex control systems or a lot of switching on and off by an attentive person to work effectively.

yes - all your other tools. There is no getting away from the fact that you need to remove water. Some days the air will be dry anyway but that isn't the problem day.
The compressor type removes water, provides a very little heat from running (average say 150W) recovers heat from condensing the water, circulates the air for those that think having a fan somehow magically removes water.
The heater type uses a lot energy to work but does warm th workshop too which is only ecenomic if you have also insulated the shed.
The desicant or salt type are very efficent at moving money from your bank account to that of a vendor. They have minimal moisture removal capability.

The air in a garage can hold a gallon of water, the walls etc may hold more. You don't have to remove it all, but get it well below the dew point. You may not see a visible layer of moisture on you tools, if you did they would be stuffed in a month, but an invisible few molecules every day will result in that fine brown discolouration so often seen on the top surfaces of bare metal of models and machines, even those in the house.

I run a dessicant dehumidifier in my workshop for a timed 1 hour at close of play on wet days and it definitely removes a great deal of moisture from the air, which is collected as water in a built in tank.

Previously I had a condensor type when my workshop was my garage and that also removed a lot of water but tended to freeze up and stop working if the temperature fell below zero.

I recommend a dehumidifier, both types work at removing moisture but which type is best depends on circumstances of use.

Jim

I've used a Electric Dehumidifier in my Workshop for years with no rust problems. I leave it on all winter, it has a control to set the required level of dryness.

Put it on today now that the weather has really got into its winter stride ! [ I think it came from Wickes ... years ago !]

I use to find that just breathing while working in the cold workshop would result in tools and machines damp to the touch. Now just nipping in to do a quick job is more pleasant with no rust issues

If I'm going to spend more time ...I have a wood stove that make the place cosy, but also means more moisture is held in the warm atmosphere so the dehumidifier is necessary to extract the moisture as the workshop cools down.

A bonus from the dehumidifier ...... pure water for the steam engines !

Edited By The Novice Engineer on 02/10/2020 23:03:44

A lot of information thanks. My shed is small, very small, six foot by 8 ft max and not much room to move around with all my stuff in it. Looking for a small dehumidifier are .5 lt to 1lt any good or are they just a gimmick..

Bob

Bob

I'm not familiar with the machines you refer to. Mine claims to have a capacity of 8 litres per day but the collection tank is only about 1 litre capacity.

This is mine, 350mm wide by 500mm high, branded ELU. It is a dessicant wheel device. A fan collects the moist air, drives it across a rotating dessicant packed wheel which extracts the moisture then blows the dried and slightly warmed air back in to the workshop. A second fan blows warmed air through the wheel later in its rotation to extract the water and collected it in a tank for disposal.

I have seen some so called dehumidifiers in the past which are just a container of silica gel dessicant which sit passively collecting moisture which you then have to dispose of by heating the gel in an oven; I would avoid such a device.

Hope the somewhat basic description helps.

Jim

+1 (or more) for 240v dehumidifiers left running. Not experienced any rust problems since acquiring a fairly large dehumidifier some years ago.

Common belief that "you" are the major source of water vapour is not really the case compared to the ambient, weather conditions. The amount of water vapour we exhale depends on local air temp and humidity. Lower ambient temp & humidity means more water vapour exhaled. For example in conditions we wouldn't tolerate in the workshop of -10°C and 25% RH, water loss through breathing is at maximum of around 20 ml/hr. Under more comfortable conditions, it is less than 10 ml/hr.

(Added bonus of a sizeable dehumidifier is the volume of distilled water produced during autumn & winter. This is used by SWMBO in her steam iron, by me in the loco boiler and for car 'screen washer etc etc).