How effective are dehumidifiers in unsealed trailers?

[Mark W]

My syndicate are pondering an electrical hookup and dehumidifier for our trailer that's kept over winter at a site that's humid and cold (it's probably in cloud for 50% of the winter).

The trailer is an older metal trailer with unsealed doors and a rotating air vent.

I'm wondering how effective a dehumidifier can be in these conditions? It is possible to reduce the humidity in a non-sealed trailer or do you end up trying to dehumidify the world's atmosphere what with relative humidity and equilibrium as it is?

[Bruce Hoult]

You want to have *some* air flow. Around the edges of the doors is probably about right, if the gaps are reasonably small.

Maybe block the rotating air vent temporarily?

Just how cold are you talking about? I'm guessing not below freezing, as in that case the water content of the air is near zero anyway (it can be 100% humidity, but that's very little actual water).

Dehumidifiers are happiest working above 20C, and if I recall correctly they start to get quite ineffective below 10C.

If the temperature is below 10C / 50F then you probably want something using a desiccant, not one using the traditional fridge-like compressor system. Something like this:

https://www.amazon.com/EcoSeb-DD122EA-CLASSIC-Desiccant-Dehumidifier-Ionizer/dp/B00KHJICC2

According to reviews, this unit uses four times as much electricity to remove the same amount of water as a typical small compressor-based unit. I don't know what temperature that is at -- probably 20 C or warmer. That's not going to be the case at very low temperatures -- the desiccant unit keeps working pretty much as effectively right down to 1C / 34F, while a compressor unit is going to be doing nothing at that temperature.

http://www.dehumidifierbuyersguide.com/ecoseb-dd122ea-classic-review/

A nice thing about dehumidifiers in winter is that they put out a lot of heat as well. I used one for my primary winter house heating for years in New Zealand. I found that a dehumidifier using 330W of electricity kept the house as warm as running a 1000W electric heater. That's for a compressor-based one.

[jpg...@gmail.com]

The absorption/dessicant dehumidifiers like the Ruby Dry work extremely well at lower temperatures. I and others have used them in our trailers for many years over the Scottish winter with no problems at all. With the automatic setting of the Ruby Dry set to its highest humidity setting of 60% the trailer interior and contents feel bone dry even in sub zero temperatures. Humidity measurements in my trailer generally show levels well below 60%. It helps to seal the trailer as much as possible and to fit the optional tube to allow the water to drain through a hole in the floor.

They do use more electricity than old fashioned compressor types but the difference is minor compared to the cost of gliding. They produce some heated air from the small heating element that is used to dry the absorbtion disc as it spins.

[AS]

Mark - first, I would seal off the trailer as well as you can, otherwise -
as you already said - you will try to dehumidify the world.
I am using the chemical desiccant filled tubs (Damp-Rid is one brand name)

http://www.damprid.com/

I keep a few of them in my Cobra trailer which is well sealed plus two of them in the cockpit. They all fill up with water throughout the winter season, so I know they work. I live in South Carolina where the summers are very humid and the winters are not very cold but can be damp.

A friend of mine back north experimented with a self-made heater to keep the temperature up by installing a 100W incandescent light bulb inline with a small fan inside a metal duct and placing it inside his trailer. The fan kept the air moving while keeping the inside somewhat 'warm'. Since the bulb and the fan were in series, the whole thing stopped should the bulb burn out. It did work but I can't quantify how well.

Uli
'AS'

[jamesrc...@gmail.com]

Mark

Go to West Marine website and see dehumidifier offerings. We have had good results with Damp Rids used with a low wattage heater such as Goldenrod. West Marine also has low wattage heaters with fans. Mildew inside boats is as big a problem as keeping glider trailers dry in humid climates. Yes, seal up the trailer.

Jim Callaway

[jamesrc...@gmail.com]

On Tuesday, November 28, 2017 at 4:07:30 AM UTC-6, Mark W wrote: