I have a largish workshop most of which is heated, but the 'lean too' of perhaps 600 sq foot is not insulated or heated - it's used for welding and has some heavy machinery (radial drill, 60 ton press etc) that attract lots of condensation.
Will having a large fan running stirring the air up help or hinder the situation?
AWEM
Only if it shifts warm air from the heated section to the unheated lean-to (and VV with cold air) .
Otherwise, if the lean-to were a closed system, neither really, it would help slightly by heating the air (so raising the dew point), but you'd do the same better with an electric heater.
Could you make insulated covers for the machines with a heater (filament light bulb?) and thermostat underneath.
I think it would help.
I'd say hinder, as it would just move warm moist air into the cool bit. What might help would be a flexible strip barrier or door between the two.
Possibly, but only if there's a source of moisture in the heated workshop; I'd assumed (maybe wrongly) that it's unoccupied and so warm, but dry air.
Warm air in houses usually picks up moisture from occupants, laundry, cooking, bathing, plants, etc.. If it gets into cold spaces (typically lofts) it causes condensation problems.
If the heated area is dry, a ducted fan would be more effective than an office desk fan. You'd need a return path for the cold return ai
assumed (maybe wrongly) that it's unoccupied and so warm, but dry air.
I'd assumed it to be a workshop in regular use, with an unheated annex which is only used occasionally. We might both be wrong...
Bubblewrap?
Brian
I mount heaters onto my machines in my otherwise unheated workshop. The lathe (ML7) has about 20 watts input and just keeps it slightly warmer than the surrounding air - result no rust on a machine kept this way since 1979.
The floor does have a DPM but the walls are only single skin brick. roof is insulated and concrete tiles with a vapour barrier on the 'warm' -ish side.
I'm sure keeping most of the moisture out in the first place is important.
Bob
Solid fire doors between the two shops so negligible air or heat leakage between them.
AWEM
You're not often wrong but you're right again!
AWEM
My guess is that preventing warm moist air from your main workshop escaping into the cold space would help. Air warms up easily but the bulk metal stays cold and air against it forms dew.
Could do either depending on where the moisture is coming from.
You are stuck with the fact that large lumps of metal machinery have huge thermal inertia and are a magnet for any damp air to condense onto. Running a dehumidifier might help somewhat but figuring out why the air is quite so damp in there would be the first line of attack.
The slab has a membrane Bob, but walls are single block, roof is fibre reinforced cement, and there is a sliding door to outside that is practically impossible to seal and still use. Added to this we are at the bottom of a shallow valley, and the cold air sinks down to us often leaving a mist layer on the field. We are frequently a couple of degrees lower temp than the village a mile away further up the shallow hill.
AWEM
In message , Andrew Mawson writes
I have just this problem. In my view it is mainly caused by lumps of cast iron sitting at low temperatures for several days and then collecting condensation when things warm up.
A simple plastic cover (old table cloth I think) protects the lathe. My guess at the mechanism is that the cover traps dry air and prevents moist air reaching the cold surface by obstructing convection.
A few Watts of heat under the covers would be good, as others have said.
I think a fan might make things worse.
The real trick is finding and using the covers before the weather warms up:-)
I'd consider spray foam on the underside of the fibre cement roof - should stop any running condensation. Sliding door gap - maybe brush strip would help reduce the number of air changes. Thompsons water seal or the cheap toolstation equivalent
He's already found out that the water is comeing up through the slab. Reducing ventilation would make it _worse_!
Andy
No he's not !
The slab has a perfectly good membrane - it's probably the only place moisture ISN'T coming in
AWEM (the OP)
I must have the wrong garage :( someone put a plastic sheet over the floor and found puddles underneath.
Andy
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