Diesel Heater causes condensation

[SkookumB]

Not sure of the science behind this.  After 30 minutes of blowing nice dry air, all the windows and metal surfaces are covered in condensation.

About -5C outside today.

I had a catalytic propane heater before and it was a big source of moisture.  I was really hoping that switching to diesel would be the solution.


I might have to route the fan intake outside to force an air exchange?

 

[tx2sturgis]

What kind of diesel heater?

If it is a forced air diesel bunk heater (also called parking heaters) similar to an Espar or Webasto, there is a separate intake and exhaust that MUST be routed outside the living space.

This information should be clearly illustrated in the installation instructions.

 

[Minivanmotoman]

Doubt that it's the diesel heater.
You've eliminated the heater moisture but not the others, like your breathing, cooking, damp/ wet clothes, pets, etc...
Will take a bit more work to eliminate those.
Any moisture will condense upon cold glass and metal, only way to eliminate condensation is drive to Cabo or Bermuda.
In northern climates, covering the windows with heavy curtains, clear plastic or foam overnight helps reduce this along with toweling dry during the day or as you mentioned, air to air heat exchange helps dry it out. Topic discussed on previous threads.
No simple quick answer.

 

[tx2sturgis]

Doubt that it's the diesel heater.
You've eliminated the heater moisture but not the others, like your breathing, cooking, damp/ wet clothes, pets, etc...

Good point, since a forced air diesel heater will create a VERY strong odor of burning kerosene (thru the exhaust) in the first few minutes of startup. 

So, it's likely the OP would be dead or close to it, if the heater was venting toxic combustion air into the living space.

Kinda hard to post about excess moisture if you're dead!

 

[LoupGarou]

It’s due to thermal bridging. Things are sweating like a cold class of lemonade on a hot summer day. Interior surfaces are warm on the inside and cold on the outside.

 

[SkookumB]

Yes the combustion intake/exhaust is routed outside..  I am talking about the intake for the fan.  It's a 5kw Chinese diesel heater.


I think Minivanmotoman is right.  I have been building a bed and walls out of plywood.  The wood is probably containing a lot of moisture.  That's the only answer that makes sense.  I just have to bake it out for a while.

 

[MrNoodly]

Not sure of the science behind this.

Water vapor is a byproduct of combustion.

 

[tx2sturgis]

Yes the combustion intake/exhaust is routed outside..  I am talking about the intake for the fan.  It's a 5kw Chinese diesel heater.

Ok...and no, do not route the cabin intake fan pulling outside air in.

 

[flying kurbmaster]

If your heater is vented to the outside drawing air from outside and exhausting it to the outside it is working like it should and a diesel heater should dry your inside out in no time at all even in cold climates , I used to have a dickenson vented diesel and my boat dried out very quickly with no condensation on the windows, or walls even though it was uninsulated. Your breathing is not a factor, I now have a Dickenson vented propane heater and my single glazed windows are dry as a bone in subzero temperature, My guess is you are right, the wood is drying out give it a few days and report back.

 

[maki2]

Use some paper towels, soak up the moisture then put the towels outside or inside a zip lock bag. The more moisture you can remove the sooner the issue will go away. But don't slow simmer a pot of soup

 

[JD GUMBEE]

My big truck never had the issue, but I ALWAYS had my front windows cracked open (even in -5 temps.)

The human body dumps more humidity into the air with your breath than you think.

A roof vent or one of the front windows cracked a 1/2 inch should end the problem.

That heater is so good at its job, you will not notice warmth difference.

 

[Gr8ful]

Is it a new interior build? I was in the building material buiness & every new house I furnished the customer would come in the st cold spell & say their windows were sweating. Glass doesn't sweat or make water, it was the new material that was off gassing the moisture. I always told them to get thru the winter & it wouldn't happen next year & it didn't. There are other causes, unvented showers, plants, cooking, etc. Good Luck! I 'm putting a 5kw diesel heater in the ambulance, a 2kw would do buy 5kws are cheaper & seem to use the same or less fuel at the same btu.

 

[Firebuild]

One thing I've noticed and been wondering about: when I work on my bus conversion on cold nights (15 to 35F, I don't tend to spend much time out there when it's colder than that), rather than crank up the "real" heater I use a very small electric heater (400 watts) running on an extension cord from the house. I have a thick curtain drawn between the "cockpit" and the living area where I'm working to keep that little bit of heat where I want it. Invariably after a few hours of work the windshield is covered with condensation, while there's none on the windows in the back, where I'm working. I have no windows open in the back, but there is ventilation in the front because the extension cord is running through the double doors, causing them to be open a bit. I would have expected condensation in the back because that's where all the breathing is, and the new wood.

 

[maki2]

A curtain helps with drafts but it is not thick enough to provide much in the way of insulation unless you made it with insulating materials.

The temperature of the windshield surface is lower than the dew point, the temperature of the air in the cab is above the dew point. There is moisture in the air therefore you will have condensation.

 

[LoupGarou]

Any surface that has contact with both the warm inside and the cold outside will sweat like a cold glass of lemonade on a hot summer day.