Humidity Solutions

[NCeagle]

@Ray and Susan Huff recently posted a couple interesting questions about humidity in a related "cold weather data" thread and I created this thread as I think humidity deserves a thread of it's own.  🙂

Here's what Ray and Susan posted in that thread so you don't have to go back and look:

I've been wondering about running fan/cracking a window or two, when outdoor humidity is high.  So, to maintain desirable humidity while parked in the driveway in the PNW with outdoor humidity at, let's say, 95% the fan/roof vent and windows need to remain closed?

While camping for a few days recently, we had quite a bit of condensation in the trailer.  Nighttime temps were in the mid-thirties.  We ran the furnace, during the day, set to 68 degrees, but off at night.  Daytime temps were in the upper forties and the condensation dissipated as we were outside most of the day, but returned at night. (I don't recall the humidity level registered on our sensors - my bad). 

When we returned home we ran the dehumidifier for a day.  This brought the humidity/temp to 40%/45 deg  and maintained it there through the night.  The next day we swapped the dehumidifier for the oil heater we use in storage to see what this would do humidity wise.  It is set to maintain approx 60 degrees.  The humidity has stabilized at 50%.  Outside humidity is 95%; night time temps in the low 40's.

Is it better to run the dehumidifier to achieve a lower humidity, at the expense of lower temperature (40%/45 deg) or the heater that produces humidity/temp levels (50%/60 deg)?  The dehumidifier, running on high heat, draws 3 amps; the oil heater, on med 900w setting, draws 7 amps.

What is a healthy humidity level for maintaining a healthy environment in the Oliver while sitting idle?

[NCeagle]

Just now, NCeagle said:

@Ray and Susan Huff recently posted a couple interesting questions about humidity in a related "cold weather data" thread and I created this thread as I think humidity deserves a thread of it's own.  🙂

Here's what Ray and Susan posted in that thread so you don't have to go back and look:

I've been wondering about running fan/cracking a window or two, when outdoor humidity is high.  So, to maintain desirable humidity while parked in the driveway in the PNW with outdoor humidity at, let's say, 95% the fan/roof vent and windows need to remain closed?

While camping for a few days recently, we had quite a bit of condensation in the trailer.  Nighttime temps were in the mid-thirties.  We ran the furnace, during the day, set to 68 degrees, but off at night.  Daytime temps were in the upper forties and the condensation dissipated as we were outside most of the day, but returned at night. (I don't recall the humidity level registered on our sensors - my bad). 

When we returned home we ran the dehumidifier for a day.  This brought the humidity/temp to 40%/45 deg  and maintained it there through the night.  The next day we swapped the dehumidifier for the oil heater we use in storage to see what this would do humidity wise.  It is set to maintain approx 60 degrees.  The humidity has stabilized at 50%.  Outside humidity is 95%; night time temps in the low 40's.

Is it better to run the dehumidifier to achieve a lower humidity, at the expense of lower temperature (40%/45 deg) or the heater that produces humidity/temp levels (50%/60 deg)?  The dehumidifier, running on high heat, draws 3 amps; the oil heater, on med 900w setting, draws 7 amps.

What is a healthy humidity level for maintaining a healthy environment in the Oliver while sitting idle?

Let's say there are 3 "general" buckets to consider when talking humidity - and each will have a somewhat unique solution. 

1.  The first is below freezing, cold weather camping where you get condensation / humidity buildup inside the cabin - mainly on the colder surfaces like the windows and walls.  In this situation, it is almost always lower humidity outside and cracking a window with the MaxAir fan on makes complete sense.  I'm thinking how dry my lips and nose get in the Rockies in the winter - I carry a humidifier (for hotel rooms) with me on ski trips.  I have no real data on this situation yet - just educated guesses.

2.  The second situation is PNW type humidity - cool and moist.  In this situation, the temps are above freezing but not "warm" and the humidity outside is 85%+.  Cracking a window and running a fan in this situation will result in pulling in MORE moisture and be counterproductive.  A dehumidifier or heat (furnace or electric) with the Ollie sealed up is the best way to keep the cabin humidity under control.  This is the situation @Ray and Susan Huffare questioning above.  I have some good data on this I can share below.

3.  The third situation is common in the summertime, primarily in the SE US.  This is HOT and HUMID - I'm talking 90+ degrees and 70+ dewpoints.  Heat won't work here unless you want to bake a cake in the cabin heat.  🙂  A dehumidifier almost certainly will be the best in this situation as it doesn't produce quite as much heat.  I have no data on this yet, but living in NC I'll have to get it figured out sooner rather than later.

For the PNW type humidity, we've had several cold, damp days here in NC.  Here's some data to look at and we can then have some fun interpreting...

This graph is temperatures:

And this graph is humidity:

Here are the parameters of the test:

1.  Electric space heater (oil) on medium heat (draws 6 amps at 120V) set to 60F.

2.  No windows / vents open.

3.  The temperature spikes in the late morning each day are from me turning on the gas heat to get the cabin quickly heated to 70F.  I often use the Ollie as a nice, quiet place to meditate in the late morning.  🙂  Once the cabin hits 70F, I turn off the gas furnace.  The electric space heater is running at all times during all of this. 

   a.  On 2/12 it's furnace heat only. 

   b.  On 2/13 I first turned on my bilge smart fan for about an hour and a half before turning on the gas furnace (and turning off the bilge fan). 

   c.  On 2/14 I turned shore power off and ran the heat on the batteries for 30 minutes or so to drain them to 50%.  I then charged them back up to 80%.

Some findings... 

1.  This proves that a space heater set up properly in this type of humidity/temperature situation will keep the humidity in check if the cabin is kept at 60F or so.  A healthy humidity level is anywhere between 30% and 60%.  I have tried dehumidifiers as well, but I don't think they are as effective in this situation - at least I haven't found one yet - as they don't collect much water and run constantly.  They do keep the humidity down, but I suspect mostly by warming the air.  The space heater doesn't run all the time - it's off and on as you would expect, so I don't *think* it is taking much more energy if any.

Big concern?

1.  While the humidity in the cabin is fine, look at the values for the basement.  They are VERY high.  I think if the humidity stayed this high in the basement for long periods mold and mildew would form.  Does anyone have a solution for this?  Does anyone open up the hatches in storage and run a dehumidifier to keep the basement from getting mold / mildew?  I think my bilge fan may help, but I put it in as a backup for the propane furnace to pull space heated, warm air into the basement. 

[Galway Girl]

Remind us what sensors you have for all this spaces?

Craig

 

[NCeagle]

3 minutes ago, ctshort09 said:

Remind us what sensors you have for all this spaces?

Craig

 

Hi Craig,

SensorPush Wireless Thermometer/Hygrometer for iPhone/Android - Humidity & Temperature Smart Sensor with Alerts. Developed and Supported in The USA.  I'm a "bit" overboard with them - I am using 10 of them for these graphs and I just added 2 more yesterday (one to monitor the backflow valves directly and another to monitor the refrigerator).  I also have the gateway so I can see them and they can send me alerts remotely.  What can I say - I like data.  🙂

[Jairon]

SensorPush also has some new units out with better battery life and slightly better accuracy: HT.w and HTP.xw

https://www.sensorpush.com/sensor-comparison

I'm a big fan. The data is exportable and the mobile app does what it needs to do and nothing more.

Edited February 15, 2021 by Jairon

[SeaDawg]

31 minutes ago, NCeagle said:

Hi Craig,

SensorPush Wireless Thermometer/Hygrometer for iPhone/Android - Humidity & Temperature Smart Sensor with Alerts. Developed and Supported in The USA.  I'm a "bit" overboard with them - I am using 10 of them for these graphs and I just added 2 more yesterday (one to monitor the backflow valves directly and another to monitor the refrigerator).  I also have the gateway so I can see them and they can send me alerts remotely.  What can I say - I like data.  🙂

I have to say, we appreciate all the data you send our way, as well.

[Ray and Susan Huff]

@NCeagle Thanks for the dedicated discussion.  I expect this will gather some useful information regarding humidity control.

So, you answered one of my questions: PNW conditions (above freezing/high humidity) do not crack vent/windows).  I can see where this applies during storage.  Would it also be the recommendation while the trailer is occupied (humans and cooking increase humidity) or is that a case where some ventilation is needed?  When the trailer is occupied, we generally only heat the cabin during the day, not at night, unless it is extremely cold (when inside temps dip below 45 degrees).  Honestly, we rarely camp in those conditions.

When we returned from camping (after moderate interior condensation) we ran the dehumidifier for a day or so, with no additional heat.  This removed a large amount of moisture; I didn't measure, but I'd say close to a pint.  Now we are heating with an oil heater (with no dehumidifier).  Maintaining temp around 60 degrees keeps the humidity level at near 50%, which I guess is a healthy level.  It will be interesting to see the change when outside humidity gets below 90%+ (if it ever quits raining).

I did monitor the basement humidity, with the hatches closed, and it did not get as high as the outdoor humidity.  I will do some more testing in that respect.  I'm curious to see if keeping the nightstand basement access hatch open makes an appreciable difference.

Hoping to learn more as others contribute to this discussion.

BTW: we do not have a 30amp plug at home, so when connected, we could probably run both the dehumidifier and heater, but if both kicked on at the same time, it might trip our extension cord breaker (it kicks off before the 15 amp house breaker, which unfortunately also has a freezer plugged into it).   The dehumidifier and oil heater together draw approx 10 amps so there is potential for a breaker tripping.

[NCeagle]

6 minutes ago, Ray and Susan Huff said:

So, you answered one of my questions: PNW conditions (above freezing/high humidity) do not crack vent/windows).  I can see where this applies during storage.  Would it also be the recommendation while the trailer is occupied (humans and cooking increase humidity) or is that a case where some ventilation is needed? 

Honestly, I don't know what you do to control humidity when it's 90%+ humidity outside.  All I know is that if it's more humid outside than it is in your cabin, opening windows and running fans won't help a bit.  I'd say if the humidity outside is greater than inside (regardless of whether you are cooking, showering or just watching TV), the only ways to get the humidity down would be to heat the cabin or remove the moisture from the air in the cabin.  Sounds like your dehumidifier does a good job getting some water out of the cabin air - what brand and model do you use?  I suspect if you are camping in some PNW moisture, a dehumidifier will do better than just plain dry heat.  I don't think running a dehumidifier and heater at the same time would be necessary - I know either / or work for me but I chose the space heater so far this winter because I also think it's best for me to keep the cabin around 60F rather than 50F - mainly because I have been in the Ollie tinkering with something every day and 50 is just too cold. 🙂  

[Ray and Susan Huff]

1 hour ago, NCeagle said:

Honestly, I don't know what you do to control humidity when it's 90%+ humidity outside.  All I know is that if it's more humid outside than it is in your cabin, opening windows and running fans won't help a bit.  I'd say if the humidity outside is greater than inside (regardless of whether you are cooking, showering or just watching TV), the only ways to get the humidity down would be to heat the cabin or remove the moisture from the air in the cabin.  Sounds like your dehumidifier does a good job getting some water out of the cabin air - what brand and model do you use?  I suspect if you are camping in some PNW moisture, a dehumidifier will do better than just plain dry heat.  I don't think running a dehumidifier and heater at the same time would be necessary - I know either / or work for me but I chose the space heater so far this winter because I also think it's best for me to keep the cabin around 60F rather than 50F - mainly because I have been in the Ollie tinkering with something every day and 50 is just too cold. 🙂  

This is the dehumidifier we purchased.  It doesn't have a great capacity, but has an auto shut off.  You can also hook up a drain hose (included) and drain into a larger container.  It is very quiet, if you plan to run it while you are on board.  It does have a heating element which seems to raise the temperature about 5 degrees.

[NCeagle]

16 hours ago, NCeagle said:

Honestly, I don't know what you do to control humidity when it's 90%+ humidity outside.  All I know is that if it's more humid outside than it is in your cabin, opening windows and running fans won't help a bit.  I'd say if the humidity outside is greater than inside (regardless of whether you are cooking, showering or just watching TV), the only ways to get the humidity down would be to heat the cabin or remove the moisture from the air in the cabin. 

I've been researching this topic since posting yesterday and I've got to correct something I posted (above).  Relative humidity is sort of tricky to think about because, well, it's relative to temperature.  The dew point is actually another key data point to look at as that represents the amount of water in the air (or space containing the air) independent of temperature.  Relative Humidity is important because it tells you how close you are to the dew point - where condensation occurs (also called accidental dehumidification 🙂 ).  Dew point is important because it tells you how much moisture is in the air.  

So, my statement above is not always true.  You can actually pull colder, more relatively humid air into the cabin and reduce the overall humidity if the dew point outside is lower than the dew point inside (and you have access to dry heat)!  It works because the cold air has less water content (lower dew point) even though the relative humidity is high - when you heat that fresh, cool, dryer air to your cabin temp, it actually has less relative humidity than the air it replaced.

Confusing?  I thought so.  Sorry for my misleading statement.  

 

[topgun2]

5 hours ago, NCeagle said:

Confusing?  I thought so.  Sorry for my misleading statement. 

Its all relative. 😇

[jordanv]

I noticed something over the past couple of nights here in Florida. 

We run our AC set to "ON" at night, to have a white noise in the background that helps us sleep better. It also prevents us waking up when the ac shuts on or off. I have noticed though, that this seems to actually increase the humidity level in the camper by morning. When waking up, once I shut the AC to auto, or off, we don't seem to have the damp feeling anymore.

Tonight I will try running the AC set to auto and see how that works.

I do not have any humidity level readings so I cant confirm percentages, it just feels damp when we wake up, even with our humidifier running.