Insulating and cooling a Bus

[artvonne]

  From the flooring thread I started, several suggested starting an insulation thread. Mostly to see if any new ideas have surfaced, better ways to skin the cat, etc.

  Whats everyone else doing, done? 

  Beyond insulation, one thing of great interest to me is fresh air ventilation. Buses dont seem to offer much in that regard, so once the AC quits, even if your moving, they turn into a hot house that rapidly becomes unliveable. Nothing is nicer than to be able to park somewhere, a nice shady campground for example, and be able to enjoy having open windows and not have to listen to pumps and fans burning up energy. And moving down the highway, fresh air, if its available in large quantity, is much more enjoyable than AC.

[lostagain]

Insulation:

My old Courier 96 hardly has any: gets hot quick in the hot summer sun, and the furnace never quits on a cold night.

The MC5C is really well insulated (prof. conversion), and there is a huge difference.

Ventilation:

Both buses have windows that slide open fully. That is really nice for the breeze either parked or driving. You don't have to use the AC unless it is really hot out. The Courier had the original stock sliders. The 5C has Penensula sliders, single pane, double pane would be better yet.

Compared to the hockey team's bus I used to look after (102D3): the windows did not open, and either the heat or the AC had to be on all the time.

Paul, you really only have one chance at doing it right, so take your time.

JC

[bevans6]

If you decide to re-side the window area of the bus, you can have a great choice of stock size windows from RV conversion sources.  Most seem to have a very large glass and a very small slider for ventilation - not my choice.  I want to maintain the stock window look, so I have installed a screen in the one stock slider in the front of the bus, works OK but not the ultimate but a very large screen area, and two Peninsula sliders in the bedroom - excellent windows, well worth the price in my book, easy install and very stock looking plus very large screen and open window area.  I would like to add a Peninsula slider on the drivers side of the lounge area, and for the door and drivers window, but time will tell.  As far as open windows go, roll out sun screen awnings in the most important thing you can do, since you can't always park on the shady side of a tree.  Again on my list of things to add.

Again the stock interior height of a MC5 comes into play.  You really can't add a couple of inches to the floor and take a couple of inches off the ceiling height for insulation unless you are going to be happy with around a 6' interior or do a roof raise.

Brian

Brian

[happycamperbrat]

If you want fresh air, I have seen a great set up for that! As a bonus, it might even help on fuel mileage 

[TomC]

I took out all the transit windows and replaced them with Peninsula Motion windows.  My bus has single pane lighty tinted and all are sliders with screens.  Plus I have a Fantastic Fan in the bathroom and over the stove in the kitchen.  Running the fans with the windows cracked will make for a nice through breeze even with no mother nature breeze.  Insulation is also very important.  I suggest pulling the old fiberglass insulation out (you won't believe how dirty it will be-wear a mask and be prepared to get real dirty), inspect all metal for cracks or rust, undercoat then have sprayed insulation installed.  I used 1x2 fir strips to make the walls that much thicker and to have something to screw the 1/4" plywood walls and ceiling to (actually used 1/8" on the ceiling because of the roof curve). 
I have three Coleman 13,500btu A/C's with heat strips (and yes the heat strips work-just takes a bit to get them warmed up) that cools the bus very nicely.  Good Luck, TomC

[artvonne]

  I have 1/4 ply over the original ceiling with 1/2 foam rubber and naugahyde. There are currently two roof airs which stick down about three inches and I can walk under them just fine, so I should have no problem with 3 or 4 inch thickness in the ceiling. I'll replace the roof airs with something like fantastics.

 

 

[chart1]

I have 4" in the ceiling and 2" in the walls and 2" in the floor. I use 1 15,000 BTU coleman roof top and it keeps it cool in 100 degree weather and for those temperatures around zero ,  I use 2 kick toe  type under cabinet heaters in the winter and you will crack windows to let some cool air in. I also have double pane rv windows.

[RJ]

Paul -

Beyond insulation, one thing of great interest to me is fresh air ventilation.

Here's a solution - and it's free!  To wit:

Way back in the paleolithic, when I was putting myself thru college driving Crown skoolies, it was very common at the end of the day to use the "four-fifty broom" to sweep out the coach while headed back to the bus barn.

I'll let you ponder for awhile what that might have been. . .   

FWIW & HTH. . .

[happycamperbrat]

I have 4" in the ceiling and 2" in the walls and 2" in the floor. I use 1 15,000 BTU coleman roof top and it keeps it cool in 100 degree weather and for those temperatures around zero ,  I use 2 kick toe  type under cabinet heaters in the winter and you will crack windows to let some cool air in. I also have double pane rv windows.

Hi! Im curious what kind of insulation you use. It seems it works very well!

[Ed Hackenbruch]

 Sounds like open the windows and doors and go fifty miles an hour for four miles.

[artvonne]

Sounds like open the windows and doors and go fifty miles an hour for four miles.

  Does kinda sound that way, lol

[RJ]

Paul -

Ed came close. . .

The "four-fifty broom" was open the last four windows on each side at the back of the bus, leave the front door open, close the driver's window, and hit the freeway, 50 mph minimum for best results.  (On a Crown skoolie, the front door opens inward.)

The strong vacuum created by the bow wave off the front of the bus at speed did a wonderful job of sucking all the debris out the door, saving a good twenty minutes or so of unpaid time using a real broom.

Opening the driver's window meant instant dust in your eyes - not good!

Sadly, the "four-fifty broom" has been retired - the CHP frowns heavily at open doors on skoolies on the freeway, deadheading or not!  Not to mention, of course, the extra litter created. . .

Point here, tho, is that if you open the rear windows on each side, and crack the front windows plus the toll booth slider, you'll get nice fresh air as you roll down the interstate.

Unless it's 1630 and you're westbound into the summer sun - THEN you'll wish you'd spent the extra time/effort/cash to insulate and properly size the HVAC for your coach!

(Speaking of HVAC, FYI, there was an A/C evaporator interconnected with the front defroster core on your coach from the factory.  Used with an automotive compressor and clever placement of a condensor, you could easily have OTR driver A/C.  Freon lines are already there, too!)

FWIW & HTH. . .

[chart1]

Hi! Im curious what kind of insulation you use. It seems it works very well!


I had it spray foamed. It seals up the bus and adds extra strength.

[robertglines1]

This time Going with Mini-split ac and heat. for performance and economy reasons. 45 ft coach with 3 slides raised roof using 2 9000 btu heating&cooling units and 1ea 12000 btu heating and cooling.  Have drivers air and heat(coach). Using a fantastic vent in roof  2ea to aid in heat removal off ceiling. have 2 screened windows in front (one each side) and one in rear plus original drivers fresh air intake. creates nice draft going thru coach in warm weather and exit out rear roof vent . when it gets hot air comes on! Insulation. I use the board type screwed to the steel structure of bus with self tapping screws.Tip get the little dis shaped plastic washers they use to fasten house wrap on homes to spread out load and not putt thru insulation. or just buy box of ones that have nail in them and push nails out and put screws in. Cheap and effective.Make sure all steel is covered with non conductive material. Like insulation then plywood is best. second would be ply wood. Steel frame is just like a toaster element in the sun!. Break the flow and you won't get toasted!!  A cheap temp gun from Harbor freight will help you decide where to spend your available bus budget quickly.In the Prevost from the factory there was 2 1/2 inch foam but metal ribs were exposed on a sunny day I shot insulation was 75 degrees  metal rib was 115 degrees---I put 1 inch blue foam board over entire inside coach and 3/8 plywood over that any voids were sealed with Great Stuff(spray Foam)..   2 inches in roof of all bays. And In raised bedroom rear bath area(starting at last bay bulkhead) 6 inches under floor for sound and insulation. Almost forgot have a 20 inch ceiling hugger fan above driver to bring hot air down to mix with cooler air on floor or vice versa.  Just My way...   Bob

[artvonne]

  My Bus does not appear to have the front driver AC option, if not having the switch is any indication. But ill look around and see if there are any parts there for it.

  Some of my thoughts, open for critique....

  The Bus still has the original road air. Against much experienced and well intentioned advice, I plan to run it. But I plan to reduce it in size (tonnage capacity) considerably and modify it. I have found in reading, that there are load valves on the compressor which are adjustable. I need to do more research, but it appears I can "de-tune" the compressor to a far lower tonnage capacity so it wont draw as much power nor cool at the rate needed for 47 passengers. If not, I will work to replace it with a smaller compressor. I am looking at cutting both the evap and condensor down thinner, sizing the evap to around 3 tons, and am looking to slip in second units with them to create a dual AC system using the original HVAC system, and drive the second system with a standard 2 ton residential AC compressor. I say 2 ton, because in a parked situation the cooling loads should be lower. I say 230V, only because I am not sure I can find a 120V compressor that size.

  Next are the fans. I am looking to replace both centrifugal blower fans with axial fans, both to reduce power loads through greater efficiency, as well as better utilise space. 

  If I can pull this off I would "almost" have a redundant AC system. The only parts they would share are the evap/circulation and condensor fans. And as getting rid of that big centrifugal fan in the condensor bay opens up all that space, what do I do with it?

  Ive done measurements, and with the blower out of the condensor bay, if I relocate the AC drier, the Generator will easily fit in the condensor bay along with the condensor with a flat axial fan against it. The only question is how the Gen would effect condensor cooling, or how the hot condensor would effect generator cooling. With a temp switch controlling the condensor fan, its possible the Gen radiator fan could move enough air the condensor fan wouldnt run, reducing loads further.

  Yes, I am aware the original system is somewhat prone to leaks. But I also believe that by going through the entire system and replacing every hose, seal, and O-ring, I can greatly reduce that problem. I would also convert the system to R-134a or R-290. But while R-290 doesnt scare me in a car, the system capacity in a Bus (looks to be 24 pounds of R-12) is quite large and goes well beyond my comfort range. Even reducing evap and condensor capacity, I would likely have over 4 pounds of R-290 in the system, and having the Gen possibly sharing space with an R-290 leak is just too much. As most of the Freons being used are becoming banned and going out of production, we are going to have to look to other alternative refrigerant gases, and those will likely be either flamable (R-290/propane), toxic (ammonia), or higher pressure (CO2). Though Freon isnt exactly safe either. Burned it creates Phosgene gas, and 134 will auto detonate if the pressures goto high or its released into a high temp area (engine compartment).

  The biggest issue with CO2 is that the pressures are much higher (over 1000 psi on the high side) than any other refrigerant. To use it, I would likely have to replace all the AC lines, and doubt the stock compressor, evap, or condensor would work with it, meaning I may have to build a complete new system from scratch. But refills would sure be cheap. I am going to give this serious consideration over the next few weeks, as this is most likely the direction the industry is going to go in the very near future.