Actually a 3.75 Season Trailer?

[Chukarhunter]

I too have a 2020 LE II and I definitely bought mine new as a 4 season trailer and as I use it extensively through the winter in Oregon, I do not winterize it.  I am extremely pleased with the LE II overall, but OTT completely failed when they engineered the forced air heating system.  A forced air heating system does not distribute hot air throughout the living space, it has return ducts that pull hot air from the supply ducts across the living space to a one or more return ducts and back to the furnace.  Oliver only put in one return duct and they located it immediately in front of the furnace itself.  This means that there is no circulation of heated cabin air through the basement.  It is dead air space. Even more inexcusable, OTT didn't put any return vent in the bathroom so when the bathroom door is closed, the supply vent in the bathroom pressurizes the bathroom space and warm air doesn't flow into the bathroom.

Given the primary problem is a lack of properly sized and located return air vents, adding or relocating supply vents will not be very effective at warming the basement.

I too spent did lots of testing with thermostats to get a good understanding of basement temperatures at various cabin temperatures.  Like you, I found that no matter how hot I heated the cabin, the area around the outside shower would  inevitably fall to around 5 degrees above the outside temperature.  I determined the main reason was the lack of heated air circulating through the basement due to the lack of appropriately located return vents in the cabin.  I also found that the tiny vents in the bottom of the trailer designed to drain any water that finds its way to the basement are a problem in cold weather given the flaws in the heating system.  There are enough tiny air leaks in the cabin to create a slow convection effect which draws cold outside air slowly through the basement vents. Since there is no warm air circulating through the basement even when the furnace is running given the flawed design, this slow intrusion of outside air pools in the basement creating the dramatic temperature differentials between the cabin and the basement.

I have not permanently fixed the problem yet, but found a temporary workaround that I am confident is good down to 15 degrees or so.  If you have the inverter like I do, there is a large street side hole just behind the battery box (to access the inverter GFCI).  When it gets cold, I just unscrew and remove the cover and create a second temporary street side return vent.  Now more than 50% of the hot cabin air flows into the street side of the basement and across the water tanks and rear area stirring up the air.  The area by the outside shower now varies less than 10 degrees from cabin temperature and the battery box stays within 5 degrees of cabin temperature (I have lithiums and have sealed and insulated the battery door).  The furnace seems to run quieter and the cabin heat is more evenly distributed.  The walls don't get quite as cold either.  This winter if it gets real cold, I will also temporarily tape over the vents under the trailer to stop the convection currents from pulling cold outside air directly into the basement.

For me, I think the permanent fix is to add a few return vents to the trailer.  I will probably put one under the front dinette next to the CO detector and another smaller one in the bathroom.  This should ensure that the entire basement enjoys adequate circulation of warm air when the furnace is running and that the bathroom is warm even with the door closed. 

You may want to try unscrewing the cover from the street side hole in front of the inverter and see if you experience the same improvements in basement temperatures that I did.

 

 

 

[GAP]

13 hours ago, Chukarhunter said:

I too have a 2020 LE II and I definitely bought mine new as a 4 season trailer and as I use it extensively through the winter in Oregon, I do not winterize it.  I am extremely pleased with the LE II overall, but OTT completely failed when they engineered the forced air heating system.  A forced air heating system does not distribute hot air throughout the living space, it has return ducts that pull hot air from the supply ducts across the living space to a one or more return ducts and back to the furnace.  Oliver only put in one return duct and they located it immediately in front of the furnace itself.  This means that there is no circulation of heated cabin air through the basement.  It is dead air space. Even more inexcusable, OTT didn't put any return vent in the bathroom so when the bathroom door is closed, the supply vent in the bathroom pressurizes the bathroom space and warm air doesn't flow into the bathroom.

Given the primary problem is a lack of properly sized and located return air vents, adding or relocating supply vents will not be very effective at warming the basement.

I too spent did lots of testing with thermostats to get a good understanding of basement temperatures at various cabin temperatures.  Like you, I found that no matter how hot I heated the cabin, the area around the outside shower would  inevitably fall to around 5 degrees above the outside temperature.  I determined the main reason was the lack of heated air circulating through the basement due to the lack of appropriately located return vents in the cabin.  I also found that the tiny vents in the bottom of the trailer designed to drain any water that finds its way to the basement are a problem in cold weather given the flaws in the heating system.  There are enough tiny air leaks in the cabin to create a slow convection effect which draws cold outside air slowly through the basement vents. Since there is no warm air circulating through the basement even when the furnace is running given the flawed design, this slow intrusion of outside air pools in the basement creating the dramatic temperature differentials between the cabin and the basement.

I have not permanently fixed the problem yet, but found a temporary workaround that I am confident is good down to 15 degrees or so.  If you have the inverter like I do, there is a large street side hole just behind the battery box (to access the inverter GFCI).  When it gets cold, I just unscrew and remove the cover and create a second temporary street side return vent.  Now more than 50% of the hot cabin air flows into the street side of the basement and across the water tanks and rear area stirring up the air.  The area by the outside shower now varies less than 10 degrees from cabin temperature and the battery box stays within 5 degrees of cabin temperature (I have lithiums and have sealed and insulated the battery door).  The furnace seems to run quieter and the cabin heat is more evenly distributed.  The walls don't get quite as cold either.  This winter if it gets real cold, I will also temporarily tape over the vents under the trailer to stop the convection currents from pulling cold outside air directly into the basement.

For me, I think the permanent fix is to add a few return vents to the trailer.  I will probably put one under the front dinette next to the CO detector and another smaller one in the bathroom.  This should ensure that the entire basement enjoys adequate circulation of warm air when the furnace is running and that the bathroom is warm even with the door closed. 

You may want to try unscrewing the cover from the street side hole in front of the inverter and see if you experience the same improvements in basement temperatures that I did.

 

That sounds like a good solution to warming up the basement area.  As Im a bit of a techno boob, let me ask a clarification question:  Can you share an image or be more explicit about the location of the cover in front of the inverter?  I could not identify that location.  I do have a 15a duplex plug kinda where you are describing but do not otherwise see a blank or cover that opens into the main cabin.  If that opportunity does not exist in my 2021 (was incorrect about my E2 being a 2020) I have a 4" hole saw and am not afraid to use it to cut a return vent.  

My solution, so far, to the bathroom dead end was to cut an eyebrow vent (so no shower water intrusion) from the rearward side of the toilet to the area under the front dinette seat.  Capitalizing on that placement, I think your idea of adding a return vent either under that dinette seat and/or somewhere close to the inverter (either under bed or behind the battery box)  would serve to draw cabin air into the streetside basement.  I was also considering covering half the current return vent with a magnetic sheet from the backside so as not to add any ugly to the situation.  I am guessing that would increase the draw of warm csbin air to areas that need it (along the streetside) instead of where that heat is redundant on the curbside.  

That sad faced part of these tweaks is 1) that they need to be done at all and 2) they will not help with the exterior shower pex lines run behind the false wall on the rearward side of the basement.

Thanks much for the great ideas.  As it sounds like you have a better idea of what you are doing than I, please let me know what you think of my approach.

 

 

[Rivernerd]

13 minutes ago, GAP said:

If that opportunity does not exist in my 2021 (was incorrect about my E2 being a 2020) I have a 4" hole saw and am not afraid to use it to cut a return vent.  

A 4" deck plate hatch is available from Amazon for about $12.

https://smile.amazon.com/gp/product/B08VJ1S1KC/ref=ox_sc_saved_title_1?smid=A2QJ57U0XMN4Q0&psc=1

[Chukarhunter]

My trailer is stored across town so I can't post a picture today but it sounds like your 2021 doesn't have an access plate hatch where my 2020 does which is located below and slightly left of the galley.  That hatch is very close to the pex lines to the outside shower and distributes heat to that area well. 

I think you are on the right track and this is what I will probably do when I get around to doing a permanent, quality fix.  First, your idea to make the existing return vent in front of the furnace on the street side smaller when you add other vents is a very good idea.  I will probably close off that vent entirely.  I will then ensure I add sufficient  return vent area to replace it.  The manual says something like a minimum of 50 sq. inches but I will probably make sure I have at least 60 sq. inches unobstructed with at least 8 sq. inches in the bathroom and at least 50 sq. inches on the streetside of the main cabin.  I am leaning toward placing the bathroom vent immediately below the sink in the upper part of the recessed towel bar insert so that shower water can't easily enter.  This vent should keep the bathroom warmer when the door is closed and also keep the plumbing area under the closet close to cabin temperature. 

For the main cabin, I will block the existing vent in front of the furnace and add two square vents of at least 25 sq. inches each to the streetside.  I will place one of these directly across from the existing vent on the curbside to heat the garage/outside shower area and the second somewhere close to the front of the main cabin on the streetside. 

One other issue in my 2020 was that OTT shared the bathroom duct run with an adjustable duct in the main cabin.  This is another design flaw as when the adjustable vent is closed (to try to force more air to the bathroom vent?), there is insufficient supply duct capacity (a safety issue) and the furnace overheats and short cycles.  I tried  to make sure that the vent was always adjusted open but found that the vent always closed itself when traveling.  It is easy to remove the rotating closure ring from the back of the round vent cover which I did so now that vent is always fully open.  This solved my short-cycling problem and the furnace heats the main cabin of the trailer much better (but not the bathroom). 

 

[Rivernerd]

On 10/28/2022 at 6:20 PM, Chukarhunter said:

For me, I think the permanent fix is to add a few return vents to the trailer.  I will probably put one under the front dinette next to the CO detector and another smaller one in the bathroom.  This should ensure that the entire basement enjoys adequate circulation of warm air when the furnace is running and that the bathroom is warm even with the door closed. 

Attached is a photo of what I believe to be a bathroom return air vent in our new Hull #1291 Elite II.  It is on the back side of the aft bathroom wall, right above the black tank flush/check valve, and therefore accessible from underneath the front dinette seat.  

The second attached photo is shot from the bath side.   I suspect the return air is expected to make its way back to the furnace through the area under the floor.

You will note that the forced air vents are smaller than in previous models.  I believe this is because we were the third Elite II upgraded to the Truma AC/VarioHeat furnace package.  The air ducts are smaller diameter, but much more substantial than I have seen in photos previously posted on this forum.  Maybe Oliver added return air vents as part of this upgrade?

For what it's worth, a cold front moved into Tennessee last night.  It has been in the high 30's today, with lows for tonight forecast to be in the mid-20's.  We have run the furnace most of the day, with the bathroom door closed, yet it has been only a bit cooler in the bath than in the main cabin.  I suspect that small return air duct has helped balance the flow of heated air to the bathroom.

 

[CnC]

On 10/28/2022 at 5:20 PM, Chukarhunter said:

Given the primary problem is a lack of properly sized and located return air vents, adding or relocating supply vents will not be very effective at warming the basement.

As a retired forensic engineer who specialized in indoor air quality and ventilation for 40 years, I AGREE !!!  

Charlie 

[Gliddenwoods]

Chukarhunter

Thanks for the good information. I previously considered installing an air return vent in the bathroom but will do so now for sure.

Question. How did you "seal and insulate" the battery door (also on my to-do list)? Same for storage door?

Thanks.

[Rivernerd]

On 11/12/2022 at 8:22 PM, Rivernerd said:

Maybe Oliver added return air vents as part of the upgrade?

Rodney Lomax confirmed to me yesterday that the vent in the bath below the toilet is a return air vent that is included with the Truma upgrade.  

[Chukarhunter]

2 hours ago, Gliddenwoods said:

Chukarhunter

Thanks for the good information. I previously considered installing an air return vent in the bathroom but will do so now for sure.

Question. How did you "seal and insulate" the battery door (also on my to-do list)? Same for storage door?

Thanks.

The method (hack?) I chose to seal the battery door vents was quick and temporary until I get around to a more permanent solution.  I just taped over the four vents on the inside of the door with wide white tape of the kind that is used to tape insulation around metal duct work and water heaters.  You can't see the tape from the outside so it is not unsightly and does seal off the air flow.  I then cut a piece of reflectix insulation to fit the inside of the battery door 1/2 inch , smaller around than the door, cut a hole so the reflectix would fit over the lock mechanism, and then taped the reflectix insulation onto the backside of the door with Frog Tape completely around the outer edge.  It has lasted almost two years and worked well enough that I have not been motivated to do a more professional job.

There have been posts with pictures in the past on this forum by folks that did a professional job at sealing the vents and insulating the door itself.  I searched awhile and couldn't find them, but I will bet someone else on the forum remembers this and will post a link to the thread(s).  They did it right.

I have yet to insulate the storage door but it is on my to do list.

Steve

[Mike and Carol]

3 hours ago, Gliddenwoods said:

Question. How did you "seal and insulate" the battery door (also on my to-do list)? Same for storage door?

I had a fellow Oliver owner give me plugs that he cut from a piece of fiberglass he had.  They fit perfectly into the ventilation holes from the inside.  Then, I cut a section from a yoga mat and used contact cement to stick it to the inside of the battery compartment door.  You could use any moisture resistant material to cut plugs out of.  Mike

[rideandfly]

On 10/24/2022 at 11:09 AM, SteveCr said:

•  

I also carried a Caframo heater

Wanted to replace our existing heater this winter. Ordered a Caframo heater today, Thanks for the info!

[John and Debbie]

On 11/12/2022 at 7:22 PM, Rivernerd said:

Attached is a photo of what I believe to be a bathroom return air vent in our new Hull #1291 Elite II.  It is on the back side of the aft bathroom wall, right above the black tank flush/check valve, and therefore accessible from underneath the front dinette seat.  

The second attached photo is shot from the bath side.   I suspect the return air is expected to make its way back to the furnace through the area under the floor.

You will note that the forced air vents are smaller than in previous models.  I believe this is because we were the third Elite II upgraded to the Truma AC/VarioHeat furnace package.  The air ducts are smaller diameter, but much more substantial than I have seen in photos previously posted on this forum.  Maybe Oliver added return air vents as part of this upgrade?

For what it's worth, a cold front moved into Tennessee last night.  It has been in the high 30's today, with lows for tonight forecast to be in the mid-20's.  We have run the furnace most of the day, with the bathroom door closed, yet it has been only a bit cooler in the bath than in the main cabin.  I suspect that small return air duct has helped balance the flow of heated air to the bathroom.

 

We were in Salina, Kansas and we were comfortable at 21° at night.  the Truma Varioheat seems to do a good job.  We have the bathroom door closed at night and it's only a little cooler than the main cabin.  I haven't tried the nighttime mode on the furnace.  I wasn't bothered by the sound of the furnace.  I leave Denver hopefully tomorrow after getting our 2017 Ford Expedition fixed.  It misfired under load, like going up hills, from Tennessee to Denver.  It turned out to be a cracked #3 spark plug.  They replaced all of them.  I am hoping for a nicer drive to Portland.  How are you doing?

John 

[GAP]

21 hours ago, Mike and Carol said:

I had a fellow Oliver owner give me plugs that he cut from a piece of fiberglass he had.  They fit perfectly into the ventilation holes from the inside.  Then, I cut a section from a yoga mat and used contact cement to stick it to the inside of the battery compartment door.  You could use any moisture resistant material to cut plugs out of.  Mike

I was considering something similar.  I was going to contact cement a piece of pre cut foam pad to same sized piece of reflectex, both shaped to cover entire door.  As I have lithiums, there is no need in cold weather for venting.  Foam would be cut from a cheap, closed cell camp mat.  I'd attach heavy duty peel-and-stick velcro to back of reflectex and inside of the battery compartment door.  That way, it would be easy to remove the insulation and allow ventilation during the summer.

[GAP]

On 11/14/2022 at 10:46 PM, CnC said:

As a retired forensic engineer who specialized in indoor air quality and ventilation for 40 years, I AGREE !!!  

Charlie 

Just a couple of clarification questions:  Wouldn't you think that by diminishing the size (or eliminating) the existing return vent by the furnace and placing return vents further forward that feed into the basement, that when the furnace runs, it would pull warm air through the basement ?  In my case, I placed a vent by the toilet, feeding into the basement below the forward dinette.  There are exterior shower water lines run through the garage which is the most susceptible area with water to cold temps. To address those lines, was planning on adding a vent to the wall (separating basement from garage) in basement under the streetside bed and another in wall between garage and basement by the furnace under the curbside bed.  I've already rerouted a heat duct through that area feeding into the main cabin below the battery box.  This has considerably warmed up the area around the exterior shower.  By partially of fully covering the only existing vent (right by the furnace) wouldn't the furnace operating then pull warm air through basement from the bathroom and through the garage from the now warm area under the streetside bed?

[John E Davies]

1 hour ago, GAP said:

Just a couple of clarification questions:  Wouldn't you think that by diminishing the size (or eliminating) the existing return vent by the furnace and placing return vents further forward that feed into the basement, that when the furnace runs, it would pull warm air through the basement ?  In my case, I placed a vent by the toilet, feeding into the basement below the forward dinette.  There are exterior shower water lines run through the garage which is the most susceptible area with water to cold temps. To address those lines, was planning on adding a vent to the wall (separating basement from garage) in basement under the streetside bed and another in wall between garage and basement by the furnace under the curbside bed.  I've already rerouted a heat duct through that area feeding into the main cabin below the battery box.  This has considerably warmed up the area around the exterior shower.  By partially of fully covering the only existing vent (right by the furnace) wouldn't the furnace operating then pull warm air through basement from the bathroom and through the garage from the now warm area under the streetside bed?

The reason Oliver installs that huge vent right beside the furnace fan is because that is specifically required by the manufacturer’s installation instructions. You can go ahead and add return air paths far away, just be sure the total square inches is equivalent to that big grill. I plan to do this, I will be removing my Dometic fridge for maintenance and I am going to see about making a return grill at the entry door down low, forward of the fridge.

Once you have plenty of air return, from different areas of the hull, then you can block off and sound insulate the existing air return, which will dramatically quiet the furnace. This is a future How To article, assuming it works out.

John Davies

Spokane WA

[GAP]

19 hours ago, John E Davies said:

The reason Oliver installs that huge vent right beside the furnace fan is because that is specifically required by the manufacturer’s installation instructions. You can go ahead and add return air paths far away, just be sure the total square inches is equivalent to that big grill. I plan to do this, I will be removing my Dometic fridge for maintenance and I am going to see about making a return grill at the entry door down low, forward of the fridge.

Once you have plenty of air return, from different areas of the hull, then you can block off and sound insulate the existing air return, which will dramatically quiet the furnace. This is a future How To article, assuming it works out.

John Davies

Spokane WA

It's hard for me to tell which one of those last two bullet points are the one to pay attention to.  I'm thinking the last one describes our situation where the small round exterior vent is exhaust, which is not described as being exhaust venting in their description above.  If so, the size of the existing return vent is too small as it is roughly 6x10".  Either way, I was considering adding more area of return vent capacity through both the basement and garage due to the distances involved (to the bathroom and through garage via vents placed in walls under beds) and obstructions/restrictions along the path.  I am not worried about there being fresh air to feed return vents as there are so many drainage holes through the belly to outside.  There are enough holes to the outside that it makes me consider blocking some of them with plugs of closed cell foam as will be inefficient to heat the area between shells otherwise.

[Chukarhunter]

I would advise against using closed cell foam to plug the vents underneath the trailer.  The foam is semi-permanent and can't be removed from the bug screens on the inside of the vent at all if you needed to.  If you ever get water in the basement, the holes are the only way for it to escape.  I would suggest making a small ball of HVAC putty and place it in the vent opening, being careful not to push it in too far into the screen.  The putty does not harden and can be flicked out with a screwdriver when you want to open the vents for ventilation.  I personally like the vents open anytime the temperatures are not going below freezing.

[CnC]

On 11/16/2022 at 10:23 AM, GAP said:

Just a couple of clarification questions:  Wouldn't you think that by diminishing the size (or eliminating) the existing return vent by the furnace and placing return vents further forward that feed into the basement, that when the furnace runs, it would pull warm air through the basement ?  In my case, I placed a vent by the toilet, feeding into the basement below the forward dinette.  There are exterior shower water lines run through the garage which is the most susceptible area with water to cold temps. To address those lines, was planning on adding a vent to the wall (separating basement from garage) in basement under the streetside bed and another in wall between garage and basement by the furnace under the curbside bed.  I've already rerouted a heat duct through that area feeding into the main cabin below the battery box.  This has considerably warmed up the area around the exterior shower.  By partially of fully covering the only existing vent (right by the furnace) wouldn't the furnace operating then pull warm air through basement from the bathroom and through the garage from the now warm area under the streetside bed?

There are basic rules that apply in almost all mechanical air movement (think physics.)  You need more return air available than air supplied (think sizing of vents/ducts.)  The further the return from the unit, the more resistance in that returning air (think restriction similar to water/hydraulic piping.)  Supplied air that cannot return requires the unit to seek that missing air from elsewhere (shutting the bathroom door stops the bathroom circulation and if the bathroom vent/window is open it then requires the unit to suck air from around cabin windows, doors, weeps, etc.)  And then the one that everyone is complaining about...  "short cycling" refers to air that returns to the unit from a supply vent located too close to the return air - perhaps the simple solution to that is using a 12v fan on low to stir/mix the cabin air - that works.

Charlie

[GAP]

1 hour ago, CnC said:

There are basic rules that apply in almost all mechanical air movement (think physics.)  You need more return air available than air supplied (think sizing of vents/ducts.)  The further the return from the unit, the more resistance in that returning air (think restriction similar to water/hydraulic piping.)  Supplied air that cannot return requires the unit to seek that missing air from elsewhere (shutting the bathroom door stops the bathroom circulation and if the bathroom vent/window is open it then requires the unit to suck air from around cabin windows, doors, weeps, etc.)  And then the one that everyone is complaining about...  "short cycling" refers to air that returns to the unit from a supply vent located too close to the return air - perhaps the simple solution to that is using a 12v fan on low to stir/mix the cabin air - that works.

Charlie

Hey Charlie,

I do appreciate the response but truthfully, if I had a better idea of 'physics, sizing of vents/ducts and water/hydraulic piping" I'd not have to ask these questions.  Ha, ha.  My work and education background is in other fields and I just don't speak that language.  Am doing my best to figure out how to tweak the trailer so that it can operate in the cold conditions that it was supposedly built to work well in.  

I guess I'll do as planned, opening alternative return supplies further away from the furnace while incrementally closing the supply vent closest to the unit and keep an eye out for short cycling.  From my 20 plus days in below freezing conditions, the cabin temps have been spot on yet varying to an acceptable degree between the bathroom (that was a dead end before my earlier tweaks) and main cabin. it's the temps surrounding remote water lines that has been the big issue.

I really appreciate the feedback.

[GAP]

4 hours ago, Chukarhunter said:

I would advise against using closed cell foam to plug the vents underneath the trailer.  The foam is semi-permanent and can't be removed from the bug screens on the inside of the vent at all if you needed to.  If you ever get water in the basement, the holes are the only way for it to escape.  I would suggest making a small ball of HVAC putty and place it in the vent opening, being careful not to push it in too far into the screen.  The putty does not harden and can be flicked out with a screwdriver when you want to open the vents for ventilation.  I personally like the vents open anytime the temperatures are not going below freezing.

Great idea on the putty.  Sounds like a good option.  The closed cell foam I  was considering is not a spray can, construction item.  It's the same sort of stuff, but slightly firmer, that yoga matts are made of.  Would simply cut tiny half moon wedges to fit the the intake covers.  Of course this would be a winter only thing and I'd have to keep an eye on the floor of the basement and garage to confirm they are dry.  

[NCeagle]

I've been very interested in and following posts talking about modifying the vents to improve heating / airflow - including a return vent in the bathroom as Oliver now does in the new units.  Many owners have also added a return vent in the bathroom and all seem to like it.  However, if you have a composting toilet I've learned that ANY airflow in the bathroom can easily overrun the little fan in the toilet and can potentially reverse the airflow from the toilet exhaust back into the main cabin.  My greatest fear is that a return vent in the bathroom might be more than the little composting fan can handle and the toilet air would reverse and be sucked into the cabin when the heat / fan is running.  Anyone with a composting toilet and a return vent in the bathroom have any data / comments on this?  Thanks!

[GAP]

3 hours ago, NCeagle said:

I've been very interested in and following posts talking about modifying the vents to improve heating / airflow - including a return vent in the bathroom as Oliver now does in the new units.  Many owners have also added a return vent in the bathroom and all seem to like it.  However, if you have a composting toilet I've learned that ANY airflow in the bathroom can easily overrun the little fan in the toilet and can potentially reverse the airflow from the toilet exhaust back into the main cabin.  My greatest fear is that a return vent in the bathroom might be more than the little composting fan can handle and the toilet air would reverse and be sucked into the cabin when the heat / fan is running.  Anyone with a composting toilet and a return vent in the bathroom have any data / comments on this?  Thanks!

I do have a composting toilet.  Placed a 4" hole "eye brow" style (partially covered so water will not get not splash on, vent between bathroom alongside the toilet into the area below the front dinette seat.  I've noticed problems with furnace drawing air in wrong direction thorough the toilet.  Given the further mods I'll have to make to allow for wintertime water usage, I suspect there could be enough draw to cause that issue and, if so, I'll have to adjust accordingly

[Rivernerd]

On 11/17/2022 at 8:06 AM, GAP said:

You can go ahead and add return air paths far away, just be sure the total square inches is equivalent to that big grill.

When picking up our Elite II after repairs, I asked about adding a return air vent on the street side aft of the Xantrex inverter.  Jason Essary advised that Truma "okayed" the idea, but he cautioned to place such a vent far enough aft of the inverter to ensure structural integrity of the fiberglass sidewall is not compromised.

I plan to add that additional return air vent after we get back home next Tuesday, to further improve the performance of the Varioheat furnace system.  I don't need to do it before then because testing during our return trip back to Idaho has confirmed that the Varioheat furnace, with the new return air duct in the bathroom, has improved air circulation enough to protect the "bilge" area of the trailer down to single digit temps.  It got down to 11 degrees F last night in Cortez, Colorado.  With the Varioheat furnace set at 70 degrees F it ran all night, but never raised the cabin temp above 68 degrees F.  Yet, the monitors set on the "floor" near the Pex supply plumbing under the front dinette seat and the rear street-side bed never read lower than 38 degrees F.   This 27-degree F positive differential between outside temp and bilge temp is a significant improvement for cold weather camping.

[John E Davies]

38 minutes ago, Rivernerd said:

When picking up our Elite II after repairs, I asked about adding a return air vent on the street side aft of the Xantrex inverter.  Jason Essary advised that Truma "okayed" the idea, but he cautioned to place such a vent far enough aft of the inverter to ensure structural integrity of the fiberglass sidewall is not compromised.

 

I wanted ventilation for that HOT compartment in warm weather. This also functions as another furnace return air path.

https://olivertraveltrailers.com/forums/topic/5329-how-to-victron-mppt-solar-charge-controller-underneath-the-street-side-bed/

I think there are way too many dead end spaces in an Ollie, like the pantry and closet, and those electronics bays. There needs to be much better air transfer through all of them.

John Davies

Spokane WA

[GAP]

10 hours ago, John E Davies said:

 

I wanted ventilation for that HOT compartment in warm weather. This also functions as another furnace return air path.

https://olivertraveltrailers.com/forums/topic/5329-how-to-victron-mppt-solar-charge-controller-underneath-the-street-side-bed/

I think there are way too many dead end spaces in an Ollie, like the pantry and closet, and those electronics bays. There needs to be much better air transfer through all of them.

John Davies

Spokane WA

I think John has hit it on the head.  Addressing  dead ends are an opportunity to address a few problems:  1) lack of heat in the belly - especially flowing back to the water lines backside of garage, 2) to bring warm air to compartments (primarily the bathroom and closet) where little to none now flows and 3) to fix problem with furnace short cycling.  Oliver has recently addressed a piece of these issues by putting a return into the bathroom which serves to allow for air flow through bathroom and introduces warm air into the basement.  Yea.  

As to the rest, my current plans are to decrease or eliminate the existing return vent under the curbside bed.  I agree with previous statements in this chain that warm air from cabin flowing in there is the likely a cause of short cycling.  Cutting back on that return vent will have the furnace looking for other source(s) of return air.  Oliver has supplied some by adding a vent to bathroom.  I'll add another by opening a vent under the street side bed to the basement.  That wall is pretty tight but all other walls surrounding the garage are soooo leaky that the thirsty furnace should draw some air through there feeding it's need for return air and warming the rearmost water lines.  I'll also cut and place a vent just above and to the left of the speaker over the closet door.  Assuming the bottom of the bathroom cabinet is open to the basement (anyone know???), I'll add a small vent from closet into that cabinet which will open the dead end in closet.  That circulation will allow wet ski/bike/kayak clothes to dry while hung which has always been a problem for me.  

My bet is that the air introduced through the bathroom and closet will be quite cooled down by the time it reaches the furnace so will fix the short cycling of the furnace.  I'd also like to cover the drainage holes in the belly for the winter so as not to draw in a lot of frigid air.  Will use cut pieces of thick yoga matt for that job (from the outside) making my cuts such that they would allow a little water to escape = a little fresh air to still get in and feed the furnace.  If furnace still sounds like it would like more fresh air, I'll follow John's lead on adding a small vent from cabin to basement from under the street side bed.  

For what it is worth, you contributors on this forum have been an amazing resource for a techno boob such as myself.  Thanks much for all for adding to this chain.  That said, if this mad scientist experiment falls flat, I'll make sure to spread the blame.  Ha.