Cold temperature data

[NCeagle]

NC had a cold snap over the past few days / nights and I was able to get some pretty good data that validates what other owners already know - the Ollie does quite well in cold weather and will stand up to just about anything if you run the furnace. 

Disclaimer:  I have done some minor cold weather modifications.  In addition to adding some reflectix to the outside shower housing and the battery and basement storage doors, I added a furnace duct through the basement and down the street side.  By putting 3 small holes in the duct to help heat that side of the basement, I have raised the average temp ~7F, so that gives you an idea if your Ollie is stock.  During this testing, I had the hot water heater on occasionally (I've been testing my new shower head) and had the fresh water tank full at the start and used 20% or so during the two days.

Here's the data:

Some observations...  

1.  The higher risk areas are definitely the rear storage compartment and street side basement.  They tend to get colder than the other parts of the trailer and do have a considerable amount of plumbing.

2.  The front street side near the toilet / black tank are definitely the coldest.  I'm not worried about that as I have a composting toilet and have drained the water from the line that's there for the standard toilet.

3.  Both nights were similar in temperature, and an average of 7.2 lbs of propane was burned per night.  At peak, the furnace ran 5 times per hour for 7 minutes each (so 35 minutes per hour).  During this test, I burned about .75 pounds of propane for each 60 minutes of furnace run time.  I'm going to run a separate test soon to pinpoint propane usage over furnace run time as that's going to be important for trip planning.

4.  The batteries run the furnace and each night the batteries dropped an average of 22%, so 88 Ah of battery was also required per night.

5.  As long as the Ollie has electricity and propane, nothing is going to freeze easily if at all.  Even the Lithium battery compartment stays warmer than I expected.

I need some colder temps to do more testing, but this looks very promising!

[John E Davies]

Great info, thanks for taking the time and effort to collect the data. I love your graph!

What was the thermostat temperature setting? 68? I set mine at 55 overnight and it doesn’t use so much propane, and it definitely saves the batteries, but it also doesn’t provide as much heat under the floor. But as warm as your underfloor areas are,  I think you could safely lower your stat a whole lot. Just bundle up.

Did you have any windows or vents open?

Did you have the bathroom door open?

Do you have adequate airflow to the bathroom air register?

How did you determine propane use -weigh the tank?

It is interesting to see how warm your battery compartment stayed. I am sure  your extra duct on that side of the floor was doing that. With no battery compartment vents, do you think your lithiums will be too warm in summer, on a 100 degree day in direct sunlight? Have you added any extra vents there, inside? I am working on that mod.... to warm it in winter but also to cool it in summer. Minimal cost, around $60, but you have to drill a bunch of big holes😳😳

Thanks again.

John Davies

Spokane WA

Edited December 29, 2020 by John E Davies

[mjrendon]

Thank you for sharing.  I really enjoy data like these.

What system was used to collect these data (logger and sensors)?

Any thoughts on why the temp dropped on the rear curb at 2pm-4pm on the 26th?

Are you planning any further modifications based on these results?

Mike

Edited December 29, 2020 by mjrendon

[Overland]

Great info, John - thanks for sharing.  I think the only thing that surprises me is the outdoor shower, since I'd have thought that area would be colder than the basement if anything.  

I think the one important area that you're missing is the space underneath the closet.  If you could get a sensor in there somehow, it would tell you how well the furnace ducting is working to protect the plumbing that feeds the bath.  

I'd be curious to see what the temps do without the heat going at night.

3 hours ago, mjrendon said:

Any thoughts on why the temp dropped on the rear curb at 2pm-4pm on the 26th?

It seems unintuitive that it would cool off while the other areas are warming, but the rear curb temps are going to be largely dependent on whether the furnace is running or not, so it does make sense.  I'm actually surprised that the temps there aren't higher than the cabin, but I guess that depends on exactly where the sensor was placed.  To a lesser extent, the bath vanity would be the same.  

[NCeagle]

4 hours ago, John E Davies said:

Great info, thanks for taking the time and effort to collect the data. I love your graph!

What was the thermostat temperature setting? 68? I set mine at 55 overnight and it doesn’t use so much propane, and it definitely saves the batteries, but it also doesn’t provide as much heat under the floor. But as warm as your underfloor areas are,  I think you could safely lower your stat a whole lot. Just bundle up.

Did you have any windows or vents open?

Did you have the bathroom door open?

Do you have adequate airflow to the bathroom air register?

How did you determine propane use -weigh the tank?

It is interesting to see how warm your battery compartment stayed. I am sure  your extra duct on that side of the floor was doing that. With no battery compartment vents, do you think your lithiums will be too warm in summer, on a 100 degree day in direct sunlight? Have you added any extra vents there, inside? I am working on that mod.... to warm it in winter but also to cool it in summer. Minimal cost, around $60, but you have to drill a bunch of big holes😳😳

Thanks again.

John Davies

Spokane WA

Hey John, great questions.  Here's some answers...

- I had the thermostat on 68 and that kept the inside at roughly 66 the entire time.  I have been using 52 to keep it at 50 in my garage and that has kept all the temps well above freezing so far.

- No vents or windows open.  Closed up tight.  With the furnace venting the moist air outside, I don't foresee humidity being a big concern in cold weather.

- Bathroom door was open.  If the door is closed the bathroom gets very much colder since it's pretty airtight and with the door closed the airflow through the vent is really non-existent.  With the door open, quite a bit of warm air comes through the vent.  Side note:  Interestingly, I also opened the access door in my vanity, the hatch under the dinette seat nearest the shower, and the back basement access door on the nightstand to see if that made a difference.  If anyone can see any blips in the graph where I did that let me know - it didn't seem to do anything at all.  My guess is that the cold air settles in there and with no fan mixing it around it's the same open or closed up.  

- Yes, propane usage was done by weight the tank before and after the test.

- I really don't think the battery compartment felt the effects of the furnace ducting - at least not to the extent other areas of the basement did.  I say that because the sensors collect data every minute and I used hourly averages.  I could see the up and down spikes on most of the sensors from the heat running and shutting off - but I couldn't see any of that on the battery compartment - it seems to be dependent on the outside temps.  I used foam inserts in the battery door vents and 2 layers of reflectix on the inside of the door.  I can easily remove all of that in the summer to let the batteries air/cool via the vents.  If that doesn't work well enough, I'll put a hole or two through the inner hull and battery compartment under the pantry with a small DC fan to mix cool or warm air into the compartment from the cabin.  I'm going to wait and see what you and Overland do to get conditioned air into your battery compartment and then copy the best one.  😉

John

[NCeagle]

4 hours ago, mjrendon said:

Thank you for sharing.  I really enjoy data like these.

What system was used to collect these data (logger and sensors)?

Any thoughts on why the temp dropped on the rear curb at 2pm-4pm on the 26th?

Are you planning any further modifications based on these results?

Mike

Hi Mike, I used SensorPush Wireless Thermometer/Hygrometer for iPhone/Android - Humidity & Temperature Smart Sensor with Alerts. Developed and Supported in The USA and then put the hourly averages into Excel.  I put hourly averages into a spreadsheet manually, but there is a way to download that I just looked up - what a dummy I am - I could have saved a ton of time!

The curb temp dropping - Overland nailed it - the temps in the basement curb stay really warm when the furnace is running.  It's only a few degrees of difference when the furnace is running and the difference increases as the furnace runs less.  

I'm not really planning any further cold weather modifications unless something comes up in further testing.  I'd love to have an all-electric backup plan, but that's a bunch of holes and computer fans so I'm not going there at this time.  I'll run more tests with my current config if I get substantially colder weather this winter.  I'm also planning on towing the trailer around in cold air with the furnace running to see how much I could push my luck traveling from ski resort to ski resort without winterizing.  That could result in some additional changes.

I think there will be a few modifications needed to keep that battery compartment cool in the summer - that's probably going to be tougher than keeping it warm in the winter.

Edited December 29, 2020 by NCeagle

[NCeagle]

46 minutes ago, Overland said:

Great info, John - thanks for sharing.  I think the only thing that surprises me is the outdoor shower, since I'd have thought that area would be colder than the basement if anything.  

I think the one important area that you're missing is the space underneath the closet.  If you could get a sensor in there somehow, it would tell you how well the furnace ducting is working to protect the plumbing that feeds the bath.  

I'd be curious to see what the temps do without the heat going at night.

It seems unintuitive that it would cool off while the other areas are warming, but the rear curb temps are going to be largely dependent on whether the furnace is running or not, so it does make sense.  I'm actually surprised that the temps there aren't higher than the cabin, but I guess that depends on exactly where the sensor was placed.  To a lesser extent, the bath vanity would be the same.  

Overland, for the outdoor shower area, I knew from reading the forum that area was very susceptible to freezing, so I put an extra large hole in the duct I have on that side - and it's pointed right at that plumbing.  That really helped bring that whole area up about 7 degrees from "stock".  I may try to get a sensor under the closet from the bathroom vanity access.  I'm not sure if I can - do you know of any "easy" way?  maybe a small access port in the floor?

I'm wondering what you mean by what the temps would do without heat?  Do you mean without the furnace and maybe just an electric heater running in the cabin?  Without any heat, the temps everywhere would approach the outside temps.  Some areas would be faster than others for sure depending on where you start.  Let me know what your interested in here and I'm happy to run some additional tests.  We have temps in the mid-upper 30's here for a while now so I could easily do some testing without heat or with different heat sources.

[Overland]

59 minutes ago, NCeagle said:

I'm wondering what you mean by what the temps would do without heat?  Do you mean without the furnace and maybe just an electric heater running in the cabin?  Without any heat, the temps everywhere would approach the outside temps.  Some areas would be faster than others for sure depending on where you start.  Let me know what your interested in here and I'm happy to run some additional tests.  We have temps in the mid-upper 30's here for a while now so I could easily do some testing without heat or with different heat sources.

I'm just curious how quickly the hull temps would fall.  We do sleep without heat most nights, but in freezing temps, we'll typically keep the heat on, but at a very low temp - 50° or so - perhaps that's a more useful test.  I know some other owners that do the same.  

A test with an electric space heater would also be interesting to see, since there'd be no air circulation in the hull.  Quite a few owners carry a space heater to use when plugged in.  

[NCeagle]

56 minutes ago, Overland said:

I'm just curious how quickly the hull temps would fall.  We do sleep without heat most nights, but in freezing temps, we'll typically keep the heat on, but at a very low temp - 50° or so - perhaps that's a more useful test.  I know some other owners that do the same.  

A test with an electric space heater would also be interesting to see, since there'd be no air circulation in the hull.  Quite a few owners carry a space heater to use when plugged in.  

Ah ok, those are easy tests.  It's going to be 26 tonight here, so that's a reasonable temp for the space heater test.  I'll turn on just an electric space heater (1500 watt) to keep the cabin in the low 60s or so.  If any of my sensors send me a text that it's approaching 32 somewhere in the basement during the night, I'll call off the test and turn on the furnace.  🙂

 

[Overland]

34 minutes ago, NCeagle said:

If any of my sensors send me a text that it's approaching 32 somewhere in the basement during the night, I'll call off the test and turn on the furnace.  🙂

Nah, we need data on freeze damage, too.  😛

[John E Davies]

3 hours ago, NCeagle said:

 

- No vents or windows open.  Closed up tight.  With the furnace venting the moist air outside, I don't foresee humidity being a big concern in cold weather.

Thanks for the info. I have to comment on your furnace venting...... the combustion air comes in from outside and goes back outside. The cabin air recirculates all the time, the two parts of the furnace are completely separated, unless you have a failure.... So you may need to crack a vent and or window to reduce condensation. Humans respire about 300 ml of water daily, and that doesn’t include moisture from washing and cooking. Or alternatively run an electric dehumidifer.

John Davies

Spokane WA

 

[Jim_Oker]

Yes, ditto on the thanks, and I second what  John says about  source of indoor moisture  once  you  are spending the evening/night/morning in there (along with possibly moist ski  clothes etc.). In our camper van I've found that in colder weather we need to crack a window and our Fantastic roof vent lid a bit - the amount required depends on outdoor humidity and temperature. Otherwise the condensation on the windows (and  presumably hidden surfaces w/in the walls) gets pretty out of hand. A compact dehumidifier would of course change that picture (and use more amp hours) somewhat. Our van has  a Suburban propane furnace with the intake/vent holes on the exterior so as here the furnace propane burning is  not a contributor of moisture. 

[Jim_Oker]

50 minutes ago, Overland said:

Nah, we need data on freeze damage, too.  😛

Yes, you don't know how good something is until you test  it to failure 😄

[Overland]

7 minutes ago, Jim_Oker said:

Yes, you don't know how good something is until you test  it to failure 😄

Or until you get someone else to test it to failure for you. 😄

[Jim_Oker]

Yes, that's clearly better in this case 😉

[Ray and Susan Huff]

2 hours ago, NCeagle said:

Ah ok, those are easy tests.  It's going to be 26 tonight here, so that's a reasonable temp for the space heater test.  I'll turn on just an electric space heater (1500 watt) to keep the cabin in the low 60s or so.  If any of my sensors send me a text that it's approaching 32 somewhere in the basement during the night, I'll call off the test and turn on the furnace.  🙂

 

So . . . . we too were down to 26 degrees last night; our Oliver parked outside the house, connected to power.  We ran an electric heater; the lowest temp I saw was right at daybreak, when the cabin temp reached 55.  It was 26 outside (national weather service got that right on the money!).  We did not drain our water heater, but the compartment was 36 degrees; same for the basement.  We did leave the nightstand basement access door open.  We hand pumped antifreeze into the fresh/city water inlets, also running it into the outside faucet.  This is such an easy thing to do and good insurance for the water connections.  Regarding the water heater (ours is Suburban), does anyone have an idea of the temperature where it becomes vulnerable to freezing when the cabin is heated?  We did not drain ours or turn it on; maybe we should have.

[SeaDawg]

I would drain the water heater and bypass it, for the winter. 

Small spaces freeze first. Easy enough to refill when you want to go camping .

[John E Davies]

I agree about the water heater. It has foam insulation on the inside, to keep the water warm between cycling on and off. But outside, under the ventilated cover, there is ZERO insulation. Which seems to me to be a pretty major design flaw. 

When you drain the tank, remember to turn off the electric heating element switch outside, and also flag the inside propane switch so nobody will try to turn it on when it is dry. I use a strip of blue masking tape across the rocker.....

John Davies

Spokane WA

Edited December 29, 2020 by John E Davies

[connor77]

Hey John, this is great info - thanks.  Have all of your modifications eliminated the need to consider additional heating sources down below?   Meaning do you now know that a bilge heater (or heaters) wouldn't be necessary or helpful?  I have the same question about skirting - have you determined that you won't need to use anything like this for extended cold weather camping?  

[Mcb]

14 hours ago, Jim_Oker said:

Yes, ditto on the thanks, and I second what  John says about  source of indoor moisture  once  you  are spending the evening/night/morning in there (along with possibly moist ski  clothes etc.). In our camper van I've found that in colder weather we need to crack a window and our Fantastic roof vent lid a bit - the amount required depends on outdoor humidity and temperature. Otherwise the condensation on the windows (and  presumably hidden surfaces w/in the walls) gets pretty out of hand. A compact dehumidifier would of course change that picture (and use more amp hours) somewhat. Our van has  a Suburban propane furnace with the intake/vent holes on the exterior so as here the furnace propane burning is  not a contributor of moisture. 

It would be interesting to see what happens to your experiment with the fantastic fan on, or open. We haven’t dealt with really cold temperatures yet, just a couple nights between 30-32, and the fantastic fan set on 10% with a window cracked kept the condensation away. We had the thermostat set at 66 or 68... something like that. I’ve noticed that the air being pulled into the cabin from the open bathroom vent by the fantastic fan set at 10 or 20% is significant... with the bathroom door open of course. Might be a good option to cracking a window. 

[NCeagle]

Here's the humidity from outside and inside the Ollie during the same time period.  It seems with no one inside and the furnace running (no vents or windows open), the humidity is largely stable and independent of the outside humidity.  Sort of interesting - the furnace must not be adding a lot of moisture - not sure how it works.  I have the 2020 Dometic furnace.

In the 6 weeks of ownership, I've only seen high humidity in the trailer when it is pretty warm outside (no furnace running) and raining or foggy (nearly 100%) outside.  I've had humidity levels near 70% inside then, but the only condensation I saw was on the rear windows.  I ran a dehumidifier, but the "smaller" one I have is basically useless.  A real dehumidifier (for a small basement) works but seems like overkill as it keeps the humidity down by running all the time and not collecting much if any water.  I'm still searching for a good dehumidifier to use for semi-storage and traveling.

[NCeagle]

10 hours ago, connor77 said:

Hey John, this is great info - thanks.  Have all of your modifications eliminated the need to consider additional heating sources down below?   Meaning do you now know that a bilge heater (or heaters) wouldn't be necessary or helpful?  I have the same question about skirting - have you determined that you won't need to use anything like this for extended cold weather camping?  

Hey connor77,

I haven't put a hole in my ductwork in the basement yet and that is definitely something I'm considering as the data is showing it stays the coldest right now.  It has plenty of plumbing that can freeze sitting right up against the back bumper.  Bad design there - Overland solved this by rerouting that section under the beds / floor.  I may do that instead as it looks pretty easy now that Overland has shown us the way.

Bilge heaters or any heaters that use electricity are not going to work for boondocking (imho).  They simply use too much energy (a 1500W space heater drains about 15% of my 400Ah per hour with only about a 20 - 25 degree differential).  So propane is an absolute must to boondock in the winter and the batteries are used to push the air around only (fans, furnace fan, etc.).  I'm running a test as we speak with an electric space heater (only) keeping the inside warm.  Will see what the data says in that scenario.  If shore power is available, strategically placed bilge heaters would certainly help/work. 

Skirting will help keep the basement a bit more stable since the weep holes are a good source of outside air.  This would be especially true in wind I suspect.  I haven't done any testing there.  Mcb had an interesting idea to somehow catch the hot exhaust from the furnace and reroute it back under the skirted trailer.  If that worked, it would certainly lower the resources required to keep the inside warm.

I think with the design of the Oliver (already good for semi-cold temps), I'd prefer to carry extra propane instead of skirts.

Bottom line so far - nothing can compete with propane for heat when boondocking.  

[NCeagle]

1 hour ago, Mcb said:

It would be interesting to see what happens to your experiment with the fantastic fan on, or open. We haven’t dealt with really cold temperatures yet, just a couple nights between 30-32, and the fantastic fan set on 10% with a window cracked kept the condensation away. We had the thermostat set at 66 or 68... something like that. I’ve noticed that the air being pulled into the cabin from the open bathroom vent by the fantastic fan set at 10 or 20% is significant... with the bathroom door open of course. Might be a good option to cracking a window. 

I can run some experiments with the fan cracked and on during some different conditions.  I know from some recent experience that with the fan open and running (which infers a window or two cracked), the inside humidity is going to approach the outside humidity.  If it's raining or foggy you don't want to turn on the fan and crack a window.  Been there - done that - got lots of water and condensation on the inside of the trailer in less than an hour.  🙂

[NCeagle]

On 12/29/2020 at 12:42 PM, Overland said:

I'm just curious how quickly the hull temps would fall.  We do sleep without heat most nights, but in freezing temps, we'll typically keep the heat on, but at a very low temp - 50° or so - perhaps that's a more useful test.  I know some other owners that do the same.  

A test with an electric space heater would also be interesting to see, since there'd be no air circulation in the hull.  Quite a few owners carry a space heater to use when plugged in.  

Ok, for the data geeks like me out there, here's the test results with no heat other than an electric space heater set to ~65:

This was a "real" test since I actually showered and slept in the trailer last night.  Some of the interesting things that impacted the data:

- Showered at 5:30PM yesterday and again at 9:30AM this morning.  You can see the associated spikes (about +5%) in the inside humidity from that.  The humidity also stayed in the low 40's with me in there as compared to the low 30's without anyone.  So each person may raise the humidity by 5-10% to JD's earlier point.  It starts to go down again once I turned the heat up (see next point).

- The temperature dropped to about 62 during the night and I woke up cold at 3:30 AM.  I had the space heater on low and it couldn't keep up.  I put it on high mode at the same temp and slept fairly warmly for another hour.  You can see that the temp does spike during that time and it does not drag up the basement temps at all - as expected.

- I added a sensor to the floor of the closet at 10:00 PM.  It's just as cold in the closet as it is in the storage area and front street basement.   I'm convinced I need to gain access to that area (somehow?) and poke a hole in the duct.  🙂

- At 7:30AM I pulled the plug on the test and started the furnace up.  The temps in those 3 areas mentioned were around 38.  The low overnight was 28, so maybe could have survived a few more degrees without the furnace but not much with the fresh water and city water valves probably at risk the most.  I may have to address that risk as well.  You can see everything shoots up pretty quickly once the furnace is started.  Would have been nice to see how the temps rebounded on their own and how close it tracked to the outside temp, but I'll have to do that next time.  I suspect they would not have rebounded fast at all given that when I cranked up the space heater at 3:30 AM it didn't stop the basement temps from plummeting at the same rate as the outside temp.

- I ran the space heater on the inverter for a while to see what kind of drain they put on the batteries.  I charged the batteries at 5:30PM before I started and again at 8:30 PM after I finished.  You can see the heat goes up in the street side basement from the inverter fan during charging.  The batteries drained 45% (180 amp hours) over that 3 hours and it wasn't even that cold out!  I had the heater set on low and it was drawing about 80 amps consistently when on.  That's incredibly high drain, so electric heaters aren't going to work well for boondocking.

- All in all, it looks like all the basement temps came down about 10 degrees closer to the outside temps with the space heater as compared to where they were with the furnace.  More importantly, the furnace is keeping the basement temps from falling as fast as the outside temp does.  It's also a great way to get some heat into the basement areas pretty quickly if needed.

 

[Fritz]

Kudos on collecting, compiling, and presenting these data.  It appears that the space heater resulted in a 10°F temperature differential between outside ambient and basement temperatures, and the furnace (with the ducting mods you've made) made an approximate 20°F difference.

Thank you also for recording propane use.  Your nightly use of 7.2 lbs of propane, or about 1.7 gallons (at 4.24 lbs per gallon), would cost about $7 (at $4.00/gallon).   Substantially less than the tax on a ski-area hotel room.