Removing HUGE interior AC and Ducting?

[TucsonAZ]

As you can see this is WAY bigger than the normal little AC unit normally in the back. I'm wondering a couple things:


1) How much do you think this has reduced engine life as I would assume it's a lot of addition power consumption.



2) Would deleting this be fairly easy reletive to all the work that already needs to be done?


3) If removed, should I convert the AC compressor to an Air Compressor or just remove it?


4) Is there any world it would make sense to keep? I'm going to have a 28kwh LifePO4 battery bank so I have plenty of power for other AC units.

[fo4imtippin]

1. My A/c compressor for my 80k btu MCC unit is rated at about 5hp load. It was running on a single v belt and had no issue. I dont think your going to see much about engine life even if it used 10hp.
I was interested as i was going to use the crankshaft pulley to run a 48v alternator that can peak at 20hp loads.


2. Deleting is fairly straight forward, but youll want to have a shop capture the refrigerent before cutting lines.


3. York compressors make pretty good engine air compressors, but do you already have air brakes? If you do, then your set and can tap into existing system. If you dont, i would just get a 12v viair or something for filling tires and things. You may want a second alternator to charge your house battery bank while running down the road.

4. I wouldnt delete the system outright, maybe just remove the ducting. No amount of rooftop A/C, Mini splits or other 120v A/C will cool the bus while driving in the south.

[TJones]

I have a very similar if not the same system.I bought my bus because of the giant AC system. If it is the same as mine it can output 130,000 btu/ hr of cooling. It would take 10-13k rooftop units to equal what you have.

Is you system a carrier/ transicold? If you were located near me I would remove your system for you so I could have spare parts.


Edit: After further review I believe yours is a thermo king. That's better because they are still in business.

Ted

[TucsonAZ]

Originally Posted by fo4imtippin

1. My A/c compressor for my 80k btu MCC unit is rated at about 5hp load. It was running on a single v belt and had no issue. I dont think your going to see much about engine life even if it used 10hp.
I was interested as i was going to use the crankshaft pulley to run a 48v alternator that can peak at 20hp loads.


2. Deleting is fairly straight forward, but youll want to have a shop capture the refrigerent before cutting lines.


3. York compressors make pretty good engine air compressors, but do you already have air brakes? If you do, then your set and can tap into existing system. If you dont, i would just get a 12v viair or something for filling tires and things. You may want a second alternator to charge your house battery bank while running down the road.

4. I wouldnt delete the system outright, maybe just remove the ducting. No amount of rooftop A/C, Mini splits or other 120v A/C will cool the bus while driving in the south.

1) I didn't know they even made a 48v alternator, that would be very helpful for me if it would be able to meet the proper charging perimeters of a LifePO4 bank.



2) Yeah, 134a is also getting costly, I'm honestly assuming it's not working but I haven't checked so I will.



3) Great point, I'm so used to the 4x4 community that was my first thought.


4) Are you saying work that system into the build and keep it functional with less ducting? I have heard people say there isn't much you can do to keep cool while driving. Is these true even with say R20 in the roof?

[cadillackid]

you keep cool while driving by keeping the factory air conditioning and tuning it up so it works right if its broken.. the ducting can come down if you want the space.. most all of those ducted units use the same evaporators as the free-blow (side hanging units).. you could even source those covers and run them that way..



asd for do you keep it or not? I have never had anyone complain to me other than aesthetics when they decided to keep their factory A/C vs yank it out.. I have had many complain to me after I helped them remove their factory A/C that they were roasting in their bus trying to keep cool with a rooftop of minisplit.. (the back of the bus was nice but the driver seat was an oven)..


I had 3 requests this late spring / easrly summer from people wanting me to help them remove their A/C (I have the tanks, pumps, recovery units, yada yada).. all of them I said wait till the first 90 degree day then go for a 2 hour bus ride with your A/C off.. then call me.. 1 never called.. 2 called and said they were keeping the A/C and could I help them check the system out and tune it up...


this was a HOT summer (still is in many areas).. I even added a 32,000 BTU dashboard A/C to a 45 year old bus so i could enjoy it all summer long...

[Crown_Guy]

Cadillackid has it right. It's MUCH better to have factory A/C, and this is a very nice sized almost a Coach level of cooling capacity, and nicely done. All factory engineered and built-in properly for the life of the bus. One thing to remember is that the A/C compressor is not taking any hp from the engine until it's turned on and that electric clutch is engaged, then it will take whatever it needs, I'd guess from 10-20hp. A typical Coach A/C will take about 20-40hp when operating. But these are truly massive systems with compressors at least twice the size of yours.

This has no effect at all on engine life whatsoever and will only possibly add additional heat due to extra throttle/fuel needed to maintain road speed and run the A/C. It will also hit fuel mileage a bit but that's the price for not frying your brains out in a non-A/C bus in summer. Dropping the windows and going 60mph for that 13/60 A/C in Summer ain't all that fun when the outside air is over 90+. Go ahead, ask me how I know....

Keeping that nice, big, A/C system is not that much of a sacrifice and it doesn't take up that much room. It's already there and any replacement will cost a ton of money and impact your build even more, and won't begin to work as well as the factory A/C will. Like was said before, you will probably be wanting to add an additional dash mounted A/C evaporator for extra cooling up front, all that windshield glass Really adds a lot of solar warming, again, ask me how I know.

My Crown happens to have an oh-so Extremely Rare, for a Crown school bus, factory A/C that I intend keeping in place plus adding a front evaporator to keep me cool while driving into the Sun. I wouldn't dream of ever getting rid of the factory A/C. I have several plans for how I'll manage an A/C for when stopped and these will become a true design and engineering challenge to make it all work together without disrupting the clean lines of the SuperCoach body. That means no rooftop units. All will be hidden away out of sight.

I've never understood the seemingly universal urge for everyone to go in and start removing all the built-in bus systems. As if the dreaded "bus" stigma will make their dream home somehow tainted. Of course the extra crap installed in buses today like no kid left behind, warning gates signs etc, even the extra interlocks on doors and such, I agree should come out, but Extremely carefully and one wire at a time as has been noted here ad-nauseum. But Factory A/C of this size and obvious high quality isn't one of them. If you remove it you will likely come to regret it, and once it's out you can't replace it's functionality.

You have a (free) gift many with school buses don't ever get. Don't blow it. Find a way to incorporate it into your build plans. You'll very quickly see how good it is to have that factory A/C.

Especially as it appears you're in Tucson. What are you thinking even considering getting rid of it. It's Tucson for heavens sake. I'll bet it isn't even good enough to keep up with the heat as it is, even with no passengers on board. Each pax body produces about 4k watts of heat. If you want to run with it turned off, and the windows down, you always have that option, but if you remove it you'll forever be without the A/C if you ever want it, or need it. American Southwest is definitely A/C Country.

[cadillackid]

Originally Posted by Crown_Guy

Cadillackid has it right. It's MUCH better to have factory A/C, and this is a very nice sized almost a Coach level of cooling capacity, and nicely done. All factory engineered and built-in properly for the life of the bus. One thing to remember is that the A/C compressor is not taking any hp from the engine until it's turned on and that electric clutch is engaged, then it will take whatever it needs, I'd guess from 10-20hp. A typical Coach A/C will take about 20-40hp when operating. But these are truly massive systems with compressors at least twice the size of yours.

This has no effect at all on engine life whatsoever and will only possibly add additional heat due to extra throttle/fuel needed to maintain road speed and run the A/C. It will also hit fuel mileage a bit but that's the price for not frying your brains out in a non-A/C bus in summer. Dropping the windows and going 60mph for that 13/60 A/C in Summer ain't all that fun when the outside air is over 90+. Go ahead, ask me how I know....

Keeping that nice, big, A/C system is not that much of a sacrifice and it doesn't take up that much room. It's already there and any replacement will cost a ton of money and impact your build even more, and won't begin to work as well as the factory A/C will. Like was said before, you will probably be wanting to add an additional dash mounted A/C evaporator for extra cooling up front, all that windshield glass Really adds a lot of solar warming, again, ask me how I know.

My Crown happens to have an oh-so Extremely Rare, for a Crown school bus, factory A/C that I intend keeping in place plus adding a front evaporator to keep me cool while driving into the Sun. I wouldn't dream of ever getting rid of the factory A/C. I have several plans for how I'll manage an A/C for when stopped and these will become a true design and engineering challenge to make it all work together without disrupting the clean lines of the SuperCoach body. That means no rooftop units. All will be hidden away out of sight.

I've never understood the seemingly universal urge for everyone to go in and start removing all the built-in bus systems. As if the dreaded "bus" stigma will make their dream home somehow tainted. Of course the extra crap installed in buses today like no kid left behind, warning gates signs etc, even the extra interlocks on doors and such, I agree should come out, but Extremely carefully and one wire at a time as has been noted here ad-nauseum. But Factory A/C of this size and obvious high quality isn't one of them. If you remove it you will likely come to regret it, and once it's out you can't replace it's functionality.

You have a (free) gift many with school buses don't ever get. Don't blow it. Find a way to incorporate it into your build plans. You'll very quickly see how good it is to have that factory A/C.

Especially as it appears you're in Tucson. What are you thinking even considering getting rid of it. It's Tucson for heavens sake. I'll bet it isn't even good enough to keep up with the heat as it is, even with no passengers on board. Each pax body produces about 4k watts of heat. If you want to run with it turned off, and the windows down, you always have that option, but if you remove it you'll forever be without the A/C if you ever want it, or need it. American Southwest is definitely A/C Country.

ive never really been a crown person... really for that fact.. rare A/C..these busses are classics and for me im more into the classic / vintage Bus versus conversion.. I like to cruise all over the place and want to do it comfortably.. so ive never bought a crown because ive never actually seen one with factory A/C.. thats the only way id ever own one is if it was air-conditioned... Love the look and the way they drive but would be a summer-only (no ohio salt) ride for me so A/C would be a must.. I added it to my superior because I found a dash unit that was high capacity and looks vintage for the late 70's.. hidden under-bus modern ACT condensor, and a vintage York 210 Compressor under the hood makes it feel right to me.


hang a cheap clear shower curtain behind the first row of seats and it keeps me and anyone riding in those seats nice N cool on humid days up into the low / mid 90s...



but for those thinking about adding A/C.. that dash unit is 32000 BTU. (pushes the york 210 to its limit(I spin the york a bit slow just because they last forever that way... spin a york fast means buy a new york faster!)..

using a car-dash A/C kit in the front of a bus with no other A/C is going to result in failure..

[HamSkoolie]

And for the opposing view (unless you're planning to be driving daily when on the road):


Engine driven (factory) AC:
is worthless when you're not driving or idling the engine.
Takes up precious space inside, underneath and in the engine bay.
Is intended to keep leaky, uninsulated buses that are constantly opening
the door to pick up and drop off students, somewhat comfortable.


The solution:
Sufficient solar panels and battery bank to run TWO mini splits
12,000 BTU mini split in the front, on the forward top bulkhead
9,000 BTU mini split on the rear top bulkhead.
Closed Cell spray foal insulation on walls and ceiling
AT LEAST 1" of closed cell foam board on the floor
Solar panels mounted on racking that provides 100% roof coverage

and at least 4" of separation between the frame and roof of the rig
to allow air flow to remove the solar heat load created by the panels.

Removal of leaky school bus windows prior to spray foam
Reflective film on any remaining windows



With proper insulation, roof top shading, glass reduction and treatments, and efficient mini splits, there should be no problems cooling the bus.



DISCLAIMER: ours is still in construction so it's all theoretical but the biggest contributors to a bus being hot are: poor insulation, single pane windows, and air infiltration. Address these and our planned build should be more than sufficient.

[TucsonAZ]

Originally Posted by HamSkoolie

And for the opposing view (unless you're planning to be driving daily when on the road):


Engine driven (factory) AC:
is worthless when you're not driving or idling the engine.
Takes up precious space inside, underneath and in the engine bay.
Is intended to keep leaky, uninsulated buses that are constantly opening
the door to pick up and drop off students, somewhat comfortable.


The solution:
Sufficient solar panels and battery bank to run TWO mini splits
12,000 BTU mini split in the front, on the forward top bulkhead
9,000 BTU mini split on the rear top bulkhead.
Closed Cell spray foal insulation on walls and ceiling
AT LEAST 1" of closed cell foam board on the floor
Solar panels mounted on racking that provides 100% roof coverage

and at least 4" of separation between the frame and roof of the rig
to allow air flow to remove the solar heat load created by the panels.

Removal of leaky school bus windows prior to spray foam
Reflective film on any remaining windows



With proper insulation, roof top shading, glass reduction and treatments, and efficient mini splits, there should be no problems cooling the bus.



DISCLAIMER: ours is still in construction so it's all theoretical but the biggest contributors to a bus being hot are: poor insulation, single pane windows, and air infiltration. Address these and our planned build should be more than sufficient.

All of the pros and cons make perfect sense and I think it comes down to travel style and needs of the person more than anything. For me, 200-300 miles of driving at most each day, I'll be full timing in it and will maybe put on 10k in a year. That works out to like 25 miles of driving per day but I'll be staying in one spot for months at a time between drives.



Another factor is R134A which has gotten SUPER expensive! Do I want to maintain that system? I can, I have a good amount of HVAC skills but do I want to, that's another story. And with a roof raise I would have to face those concerns sooner than later even on a working system.



I'm also a solar nut and will have a 28kWh LifePo4 battery bank so I'm not overly concerned about power.


Was a separate from some from you build wise is spray foam and splits. And maybe I know too much about both but I would never use either in my build. No way on earth I would use a split over a dual inverter window unit in a mobile application. I have my whole house on splits, they're AMAZING, but for a bus, no way on earth!


Spray foam as well, 2 part mixture, I don't trust anybody enough to get that so perfectly matched that there are no off gassing concerns. And if I don't trust myself that much I for sure don't trust the guy spraying it. In theory it's great, in labs it's Zero VOC but that has never been reproduced by anybody outside of a lab.



It just isn't worth my health and it isn't an issue of spraying it too thick or anything like that. It's an issue of way too many factors from temps, humidity, and dew point to equipment that means there's no way they're going to reproduce laboratory ratios in the back of a bus on a 100 degree day.



No upside and best case I'm locking in a small space inhaling flame retardants for 2-3 years if it was done as right as possible. I'd rather save those lost brain cells for something more fun ( :

[cadillackid]

I think in the instance of a bus built like ham's you have a fighting chance at cooling it up front if you either have a split right above the windshield.. or if using rooftops you have one right up there..



I call those hyper-insulated busses (and its the way to go if you have the time, skills, and $$ to do it.. it will give you the best overall experience as far as noise and hot / cold from a living-space standpoimt.. I dont agree with ham's build having almost no windows but apparently he is a cave dweller.. its not my bus...



an alternative to keeping the extra big system is to hyper insulate the bus (and sounds like you are not going splits so im assuming RV rooftop units?), if so you can downsize the current system.. keep one of the under-body condensors if thats what it uses.. put in a standard sanden SD7 enhanced compressor and bracket.. and install either a dash air .. or if the bus is flat-nose (I think yours is RE) hang a unit from the front ceiling that is smaller and more compact.. that same unit I used as under-dash in my superior is really designed to be hung from a ceiling in a bus.. i just adapted it for dash A/C.. or try and find a bulkhead unit which mounts recessed in the space above the windshield...



price of 134a is high yep.. but so is the cost of generator fuel if you are running your rooftop units and generator driving down the road.. maybe you'll have enough solar to charge your house batteries and also power a couple A/C's in that case no genny fuel required...



I also run my house on minisplits.. i essentially built my own units as ducted models werent available in 2008 when i started my home project... (and I didnt want ugly wall warts( I never wouldve thought theyd last in a bus.. however somewhereinusa has had them for years without issue.. and several others here put them in and havent come back to say there are issues with leaks or vibration damage..



one of mine got whacked by lightning so is in the process of getting replaced now with an actual ducted model...



my A/C use case is different than most here.. when my busses are out, 90% of the time im in them im driving.. the DEV bus is somewhat less since its a monile DEV lab I do park and work out of it.. and at times it gets way too hot.. I dont have good parked-A/C so I look for shade.. I just have a midea 14,000 BTU dual-hose inverter Portable that when parked in the shade doesnt do bad.. but if im parked in the sun it essentially just blows cool air on my body so parts of it dont melt..



that bus is all stock.. non tinted windows, factory walls / ceiling / doors...

[HamSkoolie]

Originally Posted by cadillackid

I dont agree with ham's build having almost no windows but apparently he is a cave dweller.. its not my bus...

Our build isn't that bad on windows. We're keeping 6 windows out of 14, possibly 7 (the large side door window). We don't have the traditional school bus windows but large coach windows. There will be four in the living area and two in the bedroom with an emergency escape window on each side in each area. Plus the driving area glass.... drivers side window, windshields, front entry door. And when we get teh layout finalized there may be a window in the kitchen and another small one added to the bathroom.
So yes, we're pulling a lot of windows out but they're mostly in areas that will be covered with things like the shower, toilet room, refrigerator, closets, etc. The area where our couch, video projector, and work station will be located has four large windows.

Originally Posted by cadillackid

...my A/C use case is different than most here.. when my busses are out, 90% of the time im in them im driving..

In such a case engine driven A/C makes more sense than our 110/120vac systems.

One of our first steps in researching the build was to sit down and put to paper what our expected main use style was (part of "the Mission") and what we needed to be able to fulfill that mission in comfort. The "better" (cough choke) half insisted on 24/7 A/C with multiple redundancies to all but eliminate the possibility of losing that A/C. Of course designing the system and providing those redundancies falls on me so that if we ever lose all A/C for whatever reason, it will be my fault. LOL

[cadillackid]

coach windows make a lot more sense than school bus windows.. at least they keep out the cold or hot a lot better!!


hey I can understand the ball N chain wanting 24/7 A/C.. my house has 3 zones for HVAC so can set 3 different temps.. there are 3 separate small ducted High SEER units providing it... this summer my number 2 unit (all the common areas of the house) got whacked by lightning.. I fixed the board.. got whacked again 3 weeks later (along with about 20 of the 400 houses in my subdivision.. it was worse than florida lightning.. had never see nanything like it).. board melted.. so i still had 2 of 3 units to cool the house (late july and august).. while supply chain stuff slowed down me getting a new unit.. switching manufacturers since the old ones from 2009 were EOL.. so make all new ductwork plenums, write new software ot integrate it.. yeah redundancy baby!!! all about it! at least my and the roomie;s bedrooms and baths have been fully A/C'd..

[HamSkoolie]

Yep redundancy.....
9,000 BTU is theoretically sufficient for the CuFt of a 40' RE bus and then some. But getting both ends to comfortable levels with only one unit would require ducting and fans to push the air around. Since the bedroom is largely blocked from the from it just wouldn't be very efficient.
So the big 12,000 in the front can cool the largely wide open floor space of the cockpit, living area, work station and kitchen during the day when the 2900 watts of solar should able to handle most of the power requirements of that unit for most of the day. When we go to bed the 9,000 unit will hardly cycle to cool the 60-70 SqFt of the bedroom.
Should the rear unit fail the front unit should be able to keep the place liveable until the rear unit is repaired. Should the rear unit fail we might find ourselves sleeping in the living area.
Heat is tripple redundant with diesel parking heaters, portable propane "Mr Buddy" on a plumbed line if needed, and a 110/120 portable electric heater. At night, we'll be using a 110/120 Sunbeam electric mattress pad.

[cadillackid]

I have one of those sunbeam electric mattress pads.. that thing gets HOT even on medium heat... if your nose wouldnt freeze you could use that and not even need heat at night!!

[Jackula]

I have similar ducts in mine, I will be removing them and making a smaller duct with a fast blower instead of having that wide duct with slow flow. It will be able to be in the back of the cabinets above the windows and not take up valuable space. I’ll also be moving my evaporators, I have one on each side in the middle of the bus. One is above the emergency door, ultimate head banger. I’ll move one closer to the back in a closet and the other farther forward to be in the pantry.

[melwade]

The engine has to be running for this AC to work. This is great for buses as the only time it is needed is when the vehicle is being driven. This is not the case with RVs.

[cadillackid]

Originally Posted by melwade

The engine has to be running for this AC to work. This is great for buses as the only time it is needed is when the vehicle is being driven. This is not the case with RVs.

if your RV is always parked.. yes.. if your RV is on the road lots.. ie travelling in hot weather across the country or even a few hour run.. that massive windshield, if its front engine you even have engine heat to contend with.. if you enjoy sweat rags you can do fine..


ive driven RVs in the summer.. and had to have the generator running weith all the RV air units that it would support and also the dashboard air built into the chassis... the exception being van-based where there is a real cab that is easily curtained off.. I stayed nice N cool without the RV unit on.



other exception was the million dollar prevost that had a full engine-driven coach A/C (centrally ducted) system as well as its RV system.. no generator required there.. a good portion of that coach A/C was ducted into the driver area of that rig.. i never once felt warm even in the deep south in july / august..



if your bus is going to make mainly short trips or only move in the fall and spring and be parked the rest pof the time mostly then you wont need that engine-driven A/C.. or if you are fat and want to sweat off some weight.. otherwise it will come in nice and handy..