Talk Morgan Forums Community The Malvern Arms dehumidifier

Can anybody tell me what is the best relative humidity level for a garage.
Just bought a dessicant dehumidifier but the manual does not give any recommendations for humidity level.

David Byrne

All I know is that you don't want to make it too dry or it will affect the leather.

Here in the mountains we have the opposite issue and use humidifiers with the recommended level being 40%.

40% is about as low as you should go to protect drying out of leather etc. I would aim for 45 to 50 and regularly check it with a hygrometer after a few days rather than rely on the setting of the dehumidifier.

I bought a dehumidifier recently after Mog got a good soaking and although it's not the same type as OP's it did come with some advice and some pre-set "smart" settings. Although it can be set to manual if required.

Smart mode classes comfortable as between 50% & 55% and below 50% is classed as dry.

In the manual mode it considers 60% is "great for personal comfort and applications where 50% is considered too dry"

I don't run mine all the time as I have a separate humidity meter in the garage and I usually turn it on if the RH gets up towards 70% and run it in the manual mode set at 60%. Also if I put Mog away wet or after washing her, I run it set at 50% to dry her out properly.

I do however have a relatively well insulated garage and the RH rarely goes much above 70% even if its thick fog (i.e. 100% RH) outside.

The only time it did go over 70% was when I had to put Mog away soaking wet hence the dehumidifier.

I've had a dehumidifier in my garage for years, Its an old Elac until that gets switched on in October and off again around May time. My Hygrometer always shows approx 60% RH.

Bought because I could see some of my tools rusting, never had a problem since.

Mine is used all year round. My thermo hygrometer records high and low values. I have it set between 45 and 60 humidity. Seems to be a good balance for me with no drying out or damp issues.

I am a total numpty on the subject of dehumidifiers please can one of you help.
I have thought of buying one but my issue is surely unless you have an airtight or close to airtight semi sealed room all you are doing is removing the moisture from the planet as any dried air must surely be exchanged with moist air in the environment.
Any help for a thicko will gratefully received

In theory, you are correct, but a dehumidifier will remove moisture far faster than normal air exchange will replace the dry air with moist air.
Another reason to keep the RH at about 60% is that if the car is put away damp it will dry out quickly, significantly reducing the possibility of corrosion.

Our garage is part of the house with a bedroom and bathroom above and with insulated cavity walls, double glazed window and insulation in the roller shutter door it is a dry space. Tools stay bright: the rate at which a sharp wood chisel tarnishes is a good indicator of humidity, if it is quicker than a month then you really need to reduce humidity.

It is a fascinating subject, as I said above I live in a very dry environment where the relative humidity is around 25-32% and your nose can get very dry which is a good indicator. In the house we use humidifiers, especially in winter, that keep the humidity at around 40%, have never had a problem with drying out of leather, wood or any natural products, rust doesn't really exist here or it is a very slow process. There are many fine car collections in the area worth millions of dollars and they have no problem with the humidity being at 25-32% during the summer and 40% in the winter. I certainly don't have any problems with my Morgans, no drying of leather or cracking of wood but I do use a humidifier to keep the air at around 40%.