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Main Forum => Tips and Tricks => Topic started by: LRUCH on May 23, 2021, 05:53:38 pm

Title: Consolidated list of insulation tips, bumper to bumper
Post by: LRUCH on May 23, 2021, 05:53:38 pm
In general when shopping for an RV I wanted a well-made B+ and the PC is one of the best insulated available. Itís important for me to point out that my PC was built in 2010, so this dialog reflects a work product from 11 years ago and my work to insulate it over the past year.   Any or all of these issues could be resolved in newer coaches. But, this may give you some ideas on how to stay more comfortable.  What I have found is that Phoenix construction quality tends to falter anywhere the sandwich layers of the walls, roof and floor end or have a hole cut in them,,, especially when you include the Ford cab (which Phoenix obviously doesnít make). So, understandably this list is mostly an inventory of every hole cut in the RV. Phoenix, if youíre reading , I love your work and my RV, but this is an area to improve. 
I live in and travel in/around Texas all year, and visit relatives in the freezing Midwest around Xmas/New Years so my PC sees both extremes.  With the following improvements I can easily say I stay comfortable at 70F whether it is the occasional low of 9F or a daily high of 110F (which are my coldest and hottest temps so far).  Many of these improvements are from tips and tricks I read here in the PC forum and other forums,,, along with a few ideas of my own.

Letís start with the cab area where there are a LOT of forum discussions alreadyÖ

Engine cover aka "the dog house":  a frequent forum topic
I double insulated with ĹĒ firewall black foam roll and cleaned/dressed the black rubber seal.  There are several YouTube videos on how to do this.  Also, be extremely careful that the final result does not get too close to the engine and exhaust pipes.  Side note:  While I had this off I found old remnants of a squirrel or rat nest in here.  I keep my RV in enclosed storage, so it must have been from the previous owner.  Itís worth checking this periodically on your RV as there is a LARGE area on the top of the 6.8L engine block for a nest.
##net result = cab area cooler in summer, warmer in winter and MUCH less engine noise.

Driver and passenger doors:
>Air flow: I repaired plastic liner that covers the inner metal door face with duct tape.   The plastic liner was tore up where the PC factory needed to get into to install the mirrors. This fix, in general, stopped air leakage.
>Insulation: I added ĹĒ firewall insulation layer to all of the inner door liner except the speaker and the handle. Be sure to insulate all the way to edges.
##net result = MUCH quieter ride and less air leaks, especially on windy days. This upgrade and the dog house insulation eliminated a lot of engine and road noise.  My phone conversations on bluetooth speaker phone are now peaceful... The person on the other end canít tell I'm driving.  Iíve also noticed the doors are quieter when you close them.  No more hollow thud.

Foot wells:  IĎve not seen this one discussed yet.
>For the short outer walls below the A pillars: I covered them with 1/2" firewall insulation layer.   Leave an over-lapping flap of insulation to allow access to the relays on right side and keep an open spot for the fuel pump shutoff reset button. I was only able to put minimal insulation on left side due to so many obstacles (parking brake, hood release, wiring, etc).
>The black plastic step areas across the bottom of each door will lift out and there is a big gap between them and the metal box behind/under them. These can be insulated with a 1/2" layer of firewall insulation and more fiberglass.   Just donít clog the drain holes.
##net result = less cold drafts in winter and no hollow sound when you step up into the cab. This also blocks the sound of water spray from the front tires.

B Pillars: IĎve not seen this one discussed yet.
>Just like the doors, these have no insulation at all.  I didnít notice the heat transfer and exterior noise from them before the work listed above, but definitely noticed it after.  This requires taking off the vertical covers that rise from the foot well and continue up to the seat belt mechanisms.  Make sure whatever you add stays out of the way of the seat belts.  I also noticed that from underneath there an opening for air to enter the cab frame under the B pillar.  I closed it off with aluminum tape and poked a couple small holes in the tape with a nail in case water should get inside and need to drain out.  I just didnít see a need for a 1 inch hole.
##net result = less cold drafts in winter and a bit less wind noise.

All windows:
> I had my 3 cab windows "tinted" with BDF S2M ceramic film. It adds no color, but it blocks 99% of UV and 96% (or maybe 94%? I canít remember) of infrared (Llumar has a ceramic film that is similar, but not as clear). And this works both ways in keeping heat out in summer and heat in in winter.  You also get the benefit that nothing will fade.  Some states ban any kind of film on the windshield, but a cop would need to be inside the cab and up close to the glass to notice.  To me, itís worth the risk of a ticket. 
I donít have insulated windowsÖ my PC is too old for that, but I do have awnings over all of them except the rear window, so they are shaded when parked.  I ĒtintedĒ all of the windows and feel this is a good alternative to double glazing.  I can still see out day or night and the tint and awnings block the sunlight whether I am parked or on the road.
##net result = This was one of my first PC improvements as I have this same done my car, including the glass roof and love it.

Pedestal under passenger seat:
>This is basically a post on a large metal plate bolted to the metal cab floor. It conducts heat all year. What concerns me still is the pedestal itself is conducting heat up to the metal frame of the seat and acting like a radiator.  It's difficult to get to it from under the cab and itís close to the exhaust pipes, so the only thing I can improve needed to be done on the top. For now I created a square foam pillow slightly larger than the plate, 3" thick with a hole in the middle and a slice to the outside edge to get it around the post. It looks like a big square donut. The chair skirt hides it.   I thought about doing the same for the driverís seat, but it has a different base and is covered with carpet and seems to not transfer as much heat.  Iím considering taking up all of the carpet and insulating the entire cab floor, butÖ not Iím that ambitious yet!  If I ever replace the carpet that would be the perfect time.  Also considering if a heat shield between the exhaust and seat bolts would help (thereís another forum thread on this).
##net result = At the end of a long drive in hot Texas this pillow is VERY warm on the bottom side so I know it is doing its job.

Transition walls between the coach and cab:
>While adding a 110V outlet behind the driverís seat I discovered that this diagonal wall is barely insulated with white fiberglass  --Iíd say it was about 1/3 full. I was able to insert insulation and push it towards the top using the open hole at the bottom that the carpeted panel covers, but I know I didnít get it insulated all the way to the top. I just couldnít reach that far.  Both sides are done now.  The right side was less insulated.
##net result = I assume less heat transfer and quieter nowÖ to be honest I didnít notice it cold in winter or hot in summer before and Iíve never rode in the second row, so I donít know how much this helped.

Next, the outer shell of the PC coachÖ or specifically the holes in the shell.
Roof vents:
>Inside: take off the inner face plate and fill the gap between the vent and ceiling with insulation. The cold is more noticeable in winter.  I know it wasnít an ďair leakĒ and water doesnít leak hereÖ but everything helps and this is an easy task.
>Outside: clean and dress the rubber seal on the rim... Clean the inside of the vent door. When closed the cap/door should land flat against the seal and ensure no air leak. If it doesn't, there's not much to align or adjust. You either have a warped door or an un-level installation. That's an entire topic on its own.
##net result = warmer in winter. Some say I should fully close off the vent with one of those square pillows... But I like the light I get with the vent unblocked.

Main entry door:
>My door seals well and there is no noticeable air leak around it, but... The handle leaked air and I could tell this handle has been replaced (Iím the 2nd owner).  This should have been made waterproof when replaced.  I decided to seal the outside half to the face of the door with silicone and stop there. I didn't want to interfere with the operation of the latch and deadbolt so I was very conservative in adding insulation.
##net result = probably nothing other than peace of mind knowing I wonít have a leak.

Main door step: a frequent forum topic
This is basically a steel box covered with floor covering on the sides and it has NO insulation at all. I think this conducts more heat loss than the roof vents since it is metal and if you don't have carpet it's even worse. I covered all of this on the under side with 1Ē foam (same firewall material used everywhere else,, but double thickness). I had to leave an opening for the step light and armature so a small part is not insulated.
##net result = noticeably warmer and less draft. This also reduces road noise and gives a better impression of quality when someone steps up into the RV since the steps are very quiet now.

Storage compartments:
>covered the sides (outside left right and back, bottom, and inside front) of the big drawer with 1" foam insulation and sealed the top edge to prevent air exchange.
>covered outside left, right, back and bottom of the side compartment with ĹĒ black foam insulation. Iíve added nothing on the door yet since it folds down and insulation would be in the way.
##net result = The rear bedroom is now warmer in winter. I think this also protects the plumbing that is in the walls just above the storage drawer as well.  It also keeps the dust out of the big drawer. A side benefit is that the bottom drawer is basically a giant cooler.  I can empty the drawer, fill it with drinks and cover them in ice that will last all day. I donít need to haul a giant cooler any more.

Fuel/gasoline door:  For the door itself,,, I thought about adding a thin layer of insulation.  But after a bit if poking around I decided to insulate the fuel fill cavity from the back side and not bother with improving the door at all.  If you crawl under the RV and look up there is a large 6Ē by 8Ē by 15Ē area all around the fuel fill pipe that is exposed.  On my 2900 this is right beside the water pipes and toilet.  I filled all of this with fiberglass and sealed it off from the bottom even with the floor with a sheet of the firewall foam and aluminum tape.
##net result = The bathroom is no longer mysteriously cold in winter.  I used to think the cold was a result the lack of heat coming out of the furnace vent.  I have to think that this was an oversight by the factory on my coach,, otherwise other PC owners would have frozen pipes too.  Has anyone else found this?  I didnít find this topic in the forum at all.

Awning wiring portal:  There is a small hole for the awning motor behind a false panel in the cabinet inside the front awning bracket.  It is sealed on the outside, but the hole is quite larger on the inside.  I found this when adding a light strip under the awning.  I sealed this up with expanding foam and shaved it off flat.
##net result = I doubt if this made a temperature difference, but I know I avoided a water leak in the future.

Slides:  a frequent forum topic
>motor and gears: I caulked a lot of cracks and gaps around the motors and the water fill inside the slides.  Don't obstruct the gears.  I was amazed at how many small holes/cracks there are here. On a sunny day you can easily find where light (not to mention air and bugs!) is leaking in, especially if you are parked on bright white concrete and have the slide extended.  Maybe itís because my PC is 10 years old and the original caulk & sealers have fallen out, but I found a lot of open holes.
>inside: all outer walls of the slide compartment under the queen bed and nightstand got a 1" foam board layer.  I probably could have added more and probably will if I ever open that area up again. I didn't insulate the inner walls so that heat could transfer during the winter. (I'm considering adding 2" round vents to improve airflow between the water tank and the room.)  Behind the sofa all walls got a 1" foam board layer and I stopped low enough so not visible and kept it out of the way of the moving sofa. I toyed with the thought of taking up the carpet and insulating under it, but I didnít want to face the thought of removing the sofa and re-installing it.
>frame/border: the top, left and right edges of the slide have good rubber seals behind the woodwork. Clean and dress them and make sure they align with the opening. The bottom edge is made differently and has visible air gaps. I used white duct tape across the entire width of the wall below the slide. The tape was thin enough to not interfere, and still able to seal the cracks/gaps.  (My arms were not skinny enough to reach the same under the entire width of the bed on the rear slide-out).
>I experimented with long sections of black foam pipe insulation and pool noodles wedged into the crack under the slides. They fit in the rear storage area when not in use, but I needed to remember to insert/remove them each time... However(!) I don't think they contributed much insulation after all of my other improvements and decided they are more work than benefit.  I abandoned this idea.
##net result = in general I now have less heat/AC loss through the slides and less dust on the carpet at the bottom edge of the slide, PLUS no more insects crawling in.   After doing this improvement I distinctly noticed that if the roof vent fans were on and I opened & closed the door the vents would speed up and back down.  Iím now in control of where fresh air comes in by opening a window or vent.  This clearly eliminated most of my air leaks.  Another thing I noticed is that the generator is quieter now, which also tells me I have reduced the chance of generator exhaust from entering through the front slide out.

Outdoor shower:
>There's not a lot of flexibility or room here for improvement but it is needed. Basically I remove the hose in winter and then allow the water to back flow out of the faucet. I haven't found any good way to insulate this other than to fill it with bubble wrap in the winter.  I'm also concerned that there doesn't appear to be much insulation behind it from what little I can see in the holes around the faucet. I know my indoor shower faucet is within inches of this and the shower water is really cold in winter, so I know the cold is reaching the shower faucet and pipes.
I've considered taking a solid block of foam and cutting it to fit the rectangle opening, then carving out the impression of the faucet for a custom fit. Each winter I could re-use this foam insert.  Iíve thought about some kind of heat tape for this, but the only way to get power to it would be from the outside and that would look bad.  Any ideas out there???  I really wish this was on the other side of the RV and not behind the shower wall.  I would use it more often to wash my feet before going inside, but where it is,,, itís basically useless.

Spare tire: the spare tire cover is not insulated at all, unlike the rear storage compartment door.  I know this is the biggest heat exchange for the rear storage compartment.  I added a ĹĒ layer of firewall foam on the back of the tire cavity.  I thought about insulating the tire cover, but decided against it for 2 reasons.  Thereís not a lot of spare room in there and I didnít want to add more weight to the cover.
##net result = This past winter in Illinois (9F at night), the bedroom inside wall was no longer colder at the tire.

And finally the appliances and interiorÖ
AC unit: I have a 13.5K btu Penguin with a softstart, but this should generally apply to any brand.  Disclaimer Proceed with all power disconnected and only if you are comfortable with this type of work and at your own risk. Ėor get a professional to do it.
>inside... There are several YouTube videos on how to do this, although most seem to focus on efficiency and less on insulating.   I do both.
   Clean all surfaces. Dust build up slows down airflow. I armor-all the black plastic air flow surfaces to inhibit future dust.
   Isolate the cold side from the hot side with aluminum tape so no cold air is sucked back in too soon.
   Seal the inner parts of the unit to the ceiling so air is not lost to outside or within the ceiling.
>outsideÖ   You'll need to remove the outer cover and then the inner black cover over the front half. Clean and armor-all the interior surfaces, again to improve airflow.  Use compressed air (gently!) to blow out dirt on the coils. I found a few dead moths and mosquitos stuck in there that required the help of a soft paint brush. Take your time and be gentle with the coils.
   Segregate the cold from the hot side so no cold air is sucked back in too soon. Again, aluminum tape and silicone.
   Check the fan while you are there. It should be clean, smooth and turn easily with no wobble or noise.
   Seal around the edge of the coils so air is forced to pass through, not around. I use silicone caulk.  I also found that due to some warping of the black plastic framework the coils were not positioned correctly and basically bouncing around allowing a general free for all. Getting this in place and sealed definitely made a big improvement as well as eliminated one more vibration/rattle (my AC is really quiet now!). There should be soft grey putty around the copper tubing where it enters this cold chamber.   Reshape it as needed to protect the tubing and ensure no air leaks.
   Check for any air leaks where inside could leak out or outside leak in. Only exceptions are the 2 drain ports. I reduced these to just 1/2" tall to reduce cold air lossÖ but donít block them or you will have water dripping inside.
   Replace the inner black cover and be sure it aligns well and is totally sealed. I used silicone caulking to fill some gaps as the cover was aged/damaged a bit and generally warped.
   Insulate well the front half which contains and cools the air from the RV. Don't block air flow in the back half where the coils release heat to the outdoors. You want to keep it as unrestricted as possible to expel heat.  Fill the gap between the inner black dome and outer cover with fiberglass insulation... all the way around, but leave room for the drainage ports.  Keep in mind there's not much between the hot roof where you are standing and the "cold" air that you want to be created and kept in your RV... so this last layer of insulation is vital.  This is the thinnest ďwallĒ of your entire RV except for the windows.
##net result = greater than 28F air temp difference between in/out and I can now get the interior down to 67F on a 104F day, and I have a much quieter experience.  Again, getting the airflow fixed and adding insulation gave me a big boost in cooling.

Stove vent: this had a 1/2" gap all around it and leaked a continuous draft of air. It was sealed on the outside to the flapper door housing, but nothing inside sealing it to the inside wall.  I wonder if this was skipped on my PC or are they all like this?  I filled it with insulation and then covered it with a wide smooth bead of white silicone caulk.
##net result = one more cold draft gone. A candle on the kitchen counter no longer flickers.  - - and the vent/wall looks better!

>outside access door. On a sunny day you can see from the inside that there is nothing around the perimeter of the furnace where it is mounted in the outer wall other than a single bead of clear caulking.  Also, the outside wall was warm in the winter when the furnace was running. I know I was throwing away heat.  I insulated the outer wall with firewall insulation and stopped about 6 inches short of the furnace for fire safety reasons and then insulated the last 6 inches with fiberglass.
>Before I determined that the entry step was not insulated and the main reason for a cold living room, I added an additional furnace duct. It runs under the pantry, kitchen stove, drawers and sink cabinet and blows forward at the door.   This made the front half of the coach much warmer.
>I investigated the poor airflow through the under floor duct in the bathroom.  First inspection showed some construction trash in the channel under the floor.  But even after getting that out there was still not much air flow.  After rerouting the air hose that feeds it to have less turns and kinks it improved a bit.  In the end, I replaced the round vent covers throughout the coach with a newer version that has a small knob to adjust louvers.   Finally, this made a difference.  By closing the vent closest to the furnace to only 30% open all of the other vents were much more effective.  Cold air at the ends of the coach is now forced back towards the furnace.  I think that vent was just introducing hot air into the hallway and immediately returning it to the furnace just be heated again Ėhence the warm wall on the outside. Itís not a good place for a heat vent at all.  I might end up removing it.
##net result = The front of the RV now stays warm and cozy with the extra vent and the entire RV is more even temp. For long PCs Iím surprised a front vent is not standard equipment (mine is 29 foot).  As for the extra insulation, itís hard to tell how much that helped because the furnace is back up under a closet and behind drawers, but the outside wall no longer has a warmer area.  I think the improved airflow was the winner here.

Refrigerator: a Norcold 621.
>Remove the outer vent cover and inspect the ďwooden box" that the fridge is mounted in. I found that the corners did not align well and there were some finger sized holes around wires going through the bottom, which allowed outside air (and insects) to go down into the space under the fridge where my inverter and converter are located. You want lots of air flow behind the fridge, but you want the air to enter the bottom vent and go out through the top vent... Not in or out of the RV living area.  From the roof vent I donít see any gap above the frdge as mentioned in other forum threads.  I must be lucky here.
##net result = less draft on days the wind is hitting the fridge side of the RV.

Water heater
To be honest, this is well sealed to the outside wall and it has a Styrofoam blanket. No need to improve this.  I just added some duct tape in a few places to keep the Styrofoam blanket closed tight and eliminated a squeak.

Remaining items on my listÖ
The "PC forehead", ie the dome over the cab:
>I plan to rebuild the TV mount and add an extending swivel arm. When I do that I will be insulating this area.  I read in another forum thread that this forehead area has little to no insulation.

Cab floor:  Like everyone else,,, Iíll replace the carpet one day and insulate under it.

Batteries:  Whenever I replace the coach batteries with Lithium (or possibly the new Aluminum?) -Ion, Iíll need to insulate the battery compartment.

Sewer tanks:  Iíve noticed I have a few places on the grey and black tanks where the insulation is damaged. Itís more frequent on the grey since it is located behind the rear axle.   I need work on this one day when Iím in the mood to crawl underneath again.

Sewer valve & macerator area:  My only concern here is freezing weather and putting antifreeze in the lower pipes and macerator is a lot of undesired work.  Iíd also like to keep it all operational during cold weather instead of disabling it with antifreeze.  I may build a cover for the sewer parts and macerator one day and have it seal to the back of the sewer compartment and up to the floor.  Then, if I insulate the door it would be protected on all sides and could be heated.  I would need to have a few access ports to reach the valves should they fail and the stinky-slinky connection. TBD.  Might be more work than it is worth.  Has anyone else tackled this?

Heat strips: I know the grey and black tanks are heated, but if you look under the floor there are several exposed drain pipes that do not have heat tapes.  There are also fresh water pipes that run the perimeter of the RV just above the floor. In my 29 footer there is a run of about 6ft of hot and cold pipes across the rear in the carpeted ďbaseboardĒ that get very cold when the outside is in the single digits. I might add heat strips to them if I plan to travel frequently in zero temp weather.  On the other hand, if the tanks are not full, these pipes should be empty and not at risk to freezeÖ they just conduct heat or cold to the sink or shower above them.

This may all sound like a lot of work; in a way it was but it is worth it.  Iíve kept track of how much weight I have added.  So far, the projects listed above total up to roughly 12 pounds, most of which is the heavy black foam firewall insulation with one side foil and the other side self-adhesive. Hereís a link to the Ĺ inch product: (
I consider these 12 pounds a good investment to avoid carrying an electric heater in the winter, using less energy all year long while being more comfortable.  And before I get a bunch of replies warning me Iíll get mold and condensation for sealing everything up, Iím watching for this closely and so far I have none.  I shower with the bath vent open. I cook with the stove vent running.  Iím in and out the door several times a day.  And, I live in south Texas where the humidity is >90% most of the time.  Enough fresh air is entering naturally to avoid condensation and mold.  In the summer, my AC produces a nice trickle of condensation drainage and keeps the interior below 60% humidity.  It all seems to be paying off quite well.

My apologies for publishing a "book",,, but hope this proves helpful to someone.
Title: Re: Consolidated list of insulation tips, bumper to bumper
Post by: fandj on May 24, 2021, 06:10:33 am
Thanks for taking the time to provide a comprehensive description of the various areas for potential improvement.  This should be a good resource for anyone looking to improve their PC whether for noise, heat transfer, or air infiltration. 

Title: Re: Consolidated list of insulation tips, bumper to bumper
Post by: mikeh on May 24, 2021, 08:04:56 am

I agree--that list is pretty darned comprehensive!  Took some time to assemble it!  There have been periodic discussions on this forum of various aspects of your list as you point out--but no consolidation of the subject like you've done here.

There will be numerous users of this post over time--thank you for taking the time to put it together.

All the best,      Mike

Title: Re: Consolidated list of insulation tips, bumper to bumper
Post by: Ron Dittmer on May 25, 2021, 07:56:30 am
Wow....LRUCH, you didn't go the extra mile.  You went 2 extra miles.  Nice comprehensive write-up too.   2o2
Title: Re: Consolidated list of insulation tips, bumper to bumper
Post by: LRUCH on May 25, 2021, 11:09:53 am
Much appreciated feedback.  I feel like I owe the forum... It has helped me a lot.

Larry   ;)
Title: Re: Consolidated list of insulation tips, bumper to bumper
Post by: LRUCH on August 24, 2021, 11:04:05 pm
I have an update on how I insulated the cab floor and pedestal under the  passenger seat.

I took the PC in for a mechanical check up (oil & filter changes, etc) and mentioned the heat on the cab floor. We discussed how to insulate it and decided that fiberglass fabric wrapping around the exhaust manifold pipes on both sides of the engine might be the best way to address this. My mechanic has often  done this on large engine trucks and race cars (especially with turbo chargers). After it was done I found that not only is the floor for both sides and the passenger seat pedestal much cooler but the engine noise is reduced as well. On my latest trip I was driving through Mississippi in August and didn't have the AC on high.

Title: Re: Consolidated list of insulation tips, bumper to bumper
Post by: Ron Dittmer on September 03, 2021, 12:19:40 pm
Years ago I bought an insulation wrap for the two V10 engine manifolds but have not yet installed them in fear of some unknown consequence.