Bus Conversions dot Com Bulletin Board
July 22, 2014, 08:26:38 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an E-Mag Subscription: It takes up much less space in your bus.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 3 [All]   Go Down
  Print  
Author Topic: Bus A/C Options  (Read 3827 times)
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« on: March 24, 2011, 02:28:30 PM »

  Now that I have a Bus coming home, among other issues I will have to start considering is air conditioning. As many others here feel, I absolutely can not stand anything up on the roof, it totally detracts from the Buses looks, and looks terribly crude having boxes up in the airstream. I want those two ugly turds off the roof. So im looking for innovative ideas that can be done DIY for reasonable costs.

  Currently the Bus still has the original road air. I know most everyone here rips it out, but I would like to work with it if at all possible, and am interested in any ideas that would make it more efficient and hopefully help others in the process.

  Obviously the heat load on the system will be greatly reduced, and I intend gut the inside, reinsulate, cut out two window units on each side and wall over them so that that area will be insulated equal to the walls, as will the rest, floors etc., reducing the load further

  Starting from that premise, I have been trying to estimate the heat load. Ive tried residential calculators and tried to make assumptions, but obviously these are not accurate, or you wouldnt see RV's with 4 or 5 roof top AC units and 20KW generators. However, I only have a single on the 32' Bounder, and while its uncomfortable above mid 90's, its better than opening the windows. But if two would work, it seems safe to assume 20-25K BTU would be sufficient, so maybe say 30K just to be safe. And considering the furnace in the Bounder is 25K Btu output, and can keep it warm down in the teens, thats probably a reasonable figure.

  My thoughts then, are to replace that giant 600 pound compressor with a small automotive type, cut down the size of the evaporator to match the lower maximum heat load, pull the big DC motor and blowers out of the condensor bay, leave the condensor its full size, and put in a flat radiator fan that draws less energy. I may also consider changing out the heater blower fan for something lower HP.

  Another idea I would like someone to comment on, is teeing in a residential 230 volt 2 - 3 ton compressor with check valves, that could run on shore power, gen power etc., and wonder if its possible to also construct it as a heat pump?

  My desire is to keep as many systems as possible operating on 12/24 volt DC and/or engine powered, but increase their efficiency any reasonable way. I want to stay away from ac powered air conditioners, inverters, at least large ones, as well as stay away from a large battery bank.

  Any ideas, even revolutionary ones would be welcome.

 
Logged
robertglines1
steam nut
Hero Member
*****
Offline Offline

Posts: 3969





Ignore
« Reply #1 on: March 24, 2011, 02:41:14 PM »

? what kind of bus? Using 3 mini split on new project. super efficient only about 1500$ for 30,000 btu heating and air.
Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
John316
Hero Member
*****
Offline Offline

Posts: 3212

MCI 1995 DL3, DD S60, Allison B500.




Ignore
« Reply #2 on: March 24, 2011, 02:44:11 PM »

Thanks for letting us know what you think about roof airs Roll Eyes.

You could has stated that you don't care for the looks, without saying that everyone of us that has roof airs, has a bad looking bus....
Logged

MCI 1995 DL3. DD S60 with a Allison B500.
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« Reply #3 on: March 24, 2011, 03:02:13 PM »

Thanks for letting us know what you think about roof airs Roll Eyes.

You could has stated that you don't care for the looks, without saying that everyone of us that has roof airs, has a bad looking bus....

  Uhmmmmmm. Hmmmm. Whats that saying about bein careful who's toes you step on?

  Sorry for sharing my hard feelings against them, one mans pleasure is another mans, etc... and all that. No hard feelings?
Logged
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« Reply #4 on: March 24, 2011, 03:10:06 PM »

? what kind of bus? Using 3 mini split on new project. super efficient only about 1500$ for 30,000 btu heating and air.

  MCI 5B. Then im back to runnning AC all the time in order to cool.  The engine is running going down the road, why not take advantage of it. When its not running, why not incorporate something into the existing system? Thats what I would really like to look into.
Logged
dougyes
Full Member
***
Offline Offline

Posts: 123




Ignore
« Reply #5 on: March 24, 2011, 03:35:32 PM »

My experience in the commercial bus world is the coach AC is always needing fixing. It's a constant, expensive, maintenance item. For the price of one time in the shop you could buy a few roof airs or minisplits. But then you need a generator. But a quality generator will not need alot of fixing.
Logged
luvrbus
Hero Member
*****
Online Online

Posts: 12055




Ignore
« Reply #6 on: March 24, 2011, 03:57:42 PM »

You will lose 1 to 2 mpg running the factory air then you need turn it off every time that DD see a hill lot more guts than I have trying to keep a 50 year ac unit going hope you have deep pockets
good luck
Logged

Live each day like it was your last,one day it will be
JohnEd
Hero Member
*****
Offline Offline

Posts: 4571




Ignore
« Reply #7 on: March 24, 2011, 04:12:51 PM »

  Now that I have a Bus coming home, among other issues I will have to start considering is air conditioning. As many others here feel, I absolutely can not stand anything up on the roof, it totally detracts from the Buses looks, and looks terribly crude having boxes up in the airstream. I want those two ugly turds off the roof.

Lots feel that way though dew share it with your eloquence. Huh Roll Eyes Grin Grin

 So im looking for innovative ideas that can be done DIY for reasonable costs.

The absolute cheapest and easiest way to install AC is with the roof units.  They are also the easiest to replace and cheapest to do so.  They are noisy and intrusive but if you duct them they are OK.  Duct them and they become less efficient...trade-off.

Go with the Mini Split.  Look it up c ause you don't sound like you know what that is.   You can install three zones and the only unit that comes on is the ones that need cooling.  Three separate thermostats.  Much higher efficiency than can be had with roofs.  USE A HEAT PUMP whichever way you go.  36KBtu plus.  Augment the Heat pump with a propane furnace in the 30KBtu range.

  Currently the Bus still has the original road air. I know most everyone here rips it out, but I would like to work with it if at all possible, and am interested in any ideas that would make it more efficient and hopefully help others in the process.

The OE bus air is extremely over sized for our application.  The enormity of the unit makes it a serious power drain and consumer of fuel.  It is also prohibitively expensive to repair....like in the thousands every time.  Use the front evap unit for the driver and front and just replace the huge compressor with a LARGE automotive unit.  Install a separate evap in the bedroom and maybe one amidships.  I think the stock condenser is a great idea but our resident AC guru, and I say that with sincerity, is Nick Badame and he says that the system needs "sized and matched" so a new condenser is needed.  Uhhh, I dunno but I can't contradict Yoda.




  Obviously the heat load on the system will be greatly reduced, and I intend gut the inside, reinsulate, cut out two window units on each side and wall over them so that that area will be insulated equal to the walls, as will the rest, floors etc., reducing the load further

Use spray in foam insulation for the best performing insulation and to add an enormous amt of sound deadening.  No other way.


  Starting from that premise, I have been trying to estimate the heat load. Ive tried residential calculators and tried to make assumptions, but obviously these are not accurate, or you wouldnt see RV's with 4 or 5 roof top AC units and 20KW generators. However, I only have a single on the 32' Bounder, and while its uncomfortable above mid 90's, its better than opening the windows. But if two would work, it seems safe to assume 20-25K BTU would be sufficient, so maybe say 30K just to be safe. And considering the furnace in the Bounder is 25K Btu output, and can keep it warm down in the teens, thats probably a reasonable figure.

Double paign all glass.  The roof used to have R5 or so and the bus stayed cool but then it was fed by a 50KBtu AC unit.  So you weill push the R to at least 22 and it should be about R30.  The walls will be at R 15 and the floor should be 20 with the foam spray under the floor and on the ceiling of the bays.  All of this is just blah blah blah.....45K Btu of roof air works for everybody.....do what works.  The Btu for roof airs is less than a house would be specified at so instead of 3 ton of Mini Split you might get by with 2.5 ton.  But why scrimp?  Ask the board which Mini's they used and how big.  With the condenser in the bay you will be giving up a bay and that is why I will have warts on my roof and for that reason alone.

  My thoughts then, are to replace that giant 600 pound compressor with a small automotive type, cut down the size of the evaporator to match the lower maximum heat load, pull the big DC motor and blowers out of the condenser bay, leave the condenser its full size, and put in a flat radiator fan that draws less energy. I may also consider changing out the heater blower fan for something lower HP.

Great thoughts except the heat blower in the front.....leave entire system.  Maybe add a evap unit with the blower shooting the cold air back into the living room.  The condenser will get by with auto rad fans if they can move enuf air.


  Another idea I would like someone to comment on, is teeing in a residential 230 volt 2 - 3 ton compressor with check valves, that could run on shore power, gen power etc., and wonder if its possible to also construct it as a heat pump?

If this is the deal where the OR AC has a ac powered compressor for use with shore power and you only have one system with two compressors.....my local ac dude says he can do that without problems but Yoda was not very encouraging.  I think that would be optimum and worth the engineering.  On the other had with the engine and AC powered unit you will always have a spare installed and waiting no matter what.  Parked you can run the engine or while driving you could run the genny and the AC powered units.  Decisions?Huh
?

  My desire is to keep as many systems as possible operating on 12/24 volt DC and/or engine powered, but increase their efficiency any reasonable way. I want to stay away from ac powered air conditioners, inverters, at least large ones, as well as stay away from a large battery bank.

You can't get there from here.

  Any ideas, even revolutionary ones would be welcome.

 
[/quote]
Logged

"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.
Pla
Hi yo silver
Hero Member
*****
Offline Offline

Posts: 818




Ignore
« Reply #8 on: March 24, 2011, 05:24:49 PM »

Well, I know I'm the exception, since my bus was an original 1982 factory conversion, thus, not a bunch of miles, but I'll share my experience just in case there is any value for you. When I bought it three years ago, the over-the-road air didn't cool. After much consideration, I took it to a local commercial refrigeration outfit, and asked their opinion. They pulled a vacuum on the system, deemed it worthy, and charged it with "Freeze 12". It has been working like a champ ever since. I wouldn't say it's grossly oversized, but it is highly effective. Driving into the sun doesn't overpower it. My take on it would be, as long as it can be kept without a budget breaking expenditure, it is good to have. Works for me.
Dennis 
Logged

Blue Ridge Mountains of VA   Hi Yo Silver! MC9
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« Reply #9 on: March 24, 2011, 07:32:07 PM »

After much consideration, I took it to a local commercial refrigeration outfit, and asked their opinion. They pulled a vacuum on the system, deemed it worthy, and charged it with "Freeze 12". It has been working like a champ ever since. Dennis 

   Not long ago a search for alternate refrigerants would bring up all kinds of horrific discussions, your going to blow up, kill people, burn, some claimed a building in Texas took out at an entire block when a car with a can of propane refrigerant blew, killing dozens, etc., but of course, if you dug into the story you found nothing to support it. Now with real testing being done in Europe and Australia, and with the Dupont genie out in the spot light, people are returning to natural refrigerants once again, Ammonia, CO2, Propane, etc.. They are now selling refrigerators with Propane, just about everywhere except the USA. Cars in Australia now run Propane refrigerant, and testing has shown its no more dangerous than R-134a in an accident. But im not so sure I would want Propane in the Bus system, as it has a much greater capacity.

  However, R-12/Freeze 12 may be less efficient as IIRC, Bus systems use R-22. Im no refrigeration geek, but the R-12/Freeze 12, may not be cooling as well as the proper refrigerant. I read a site on conversion to propane, and this guy said the expansion valve is the main culprit, that the capillary has to have the same gas as what you run in the system. Then he went on to explain how to convert one.

  I dont know if a automotive compressor is large enough, but definetly the original is much to large for cooling a well insulated Bus with only a handful of people. What I havnt found yet, is how you size the evaporator. Someone, I believe it was Tom C., claimed that if you used too large an evaporator it would ice up. Perhaps pinching off a circuit or so would be enough to do the trick.

  Maybe its not so much it wont work, or cant work, so much as no one really wants to take the time to try. Screwing around with R-22 at $20 pound would get real expensive real fast. And if it leaks out every year and you have to pay someone to service it, your talking $100's of dollars, and I can see that being a real obstacle people would want to avoid. I have a reciept for AC service on the Bus thats over $700, so its nothing to sneeze at. However, if a cheap or free gas can be used, it would offer the ability to experiment a little and see what might work. At least until throwing your hands up in futility.
Logged
Oonrahnjay
Hero Member
*****
Offline Offline

Posts: 1343





Ignore
« Reply #10 on: March 24, 2011, 08:12:11 PM »

I asked a similar question about "dual powered" air conditioners a few months ago.  I was told that if you want to run an A/C system off a 120V compressor part of the time and an engine-driven compressor part of the time, then the best way is to have two separate systems.  You stack the two evaporator coils one in front of the other so that your air-handling system (blower fans, ducts, etc.) are the same no matter which you're running.  Of course, it increases your cost but you're already doubling the system anyway.  (You'll need to double the condensers, pressure valves, tubing etc. as well as buying two compressors.)  But it sounds to me like a good way to make a versatile system.

Also, on the subject of a freezing up evaporator, you can run a thermostat to the evaporator.  Anytime the temperature at the coils drops to about 36 degrees, you use the thermostat to drop out the clutch on the compressor.  The air blowing over the coils stays pretty much the same temperature but it will warm the coils up pretty quickly.  Once it does that, the thermostat kicks the compressor back in and cools the coils up again.  This process gives you a fairly steady stream of cool air but stops the evaporator from freezing.  It has the advantage, too, if you have a lot of really hot air, as the air-handling system draws that air in, then it is longer before the coils cool down enough to be in danger of freezing.

Oh, also, be sure that you have a good catchpan and drain system -- anywhere but the bone-dry deserts, you'll be pulling lots of moisture out of the air.

There are a lot of factors here, but these items may help you with some of the details.
Logged

Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« Reply #11 on: March 24, 2011, 11:30:06 PM »


There are a lot of factors here, but these items may help you with some of the details.

  You know, that is actually a fascinating idea I had never thought of. The original road air looks to be about 8 tons capacity, or about 3 times larger than needed in a typical RV application. That makes the condensor and evap about 3 times larger than needed. Cutting them down would easily leave enough room to slip in second core units to share the same space, and I would still have a redundant system and without roof airs. And if I get that big electric motor and blowers out of the condensor bay I just might have room to stuff the genny in there too.

  Any ideas for building a heat pump out of it?

   

   
 
Logged
Bob Belter
Full Member
***
Offline Offline

Posts: 148


Eagle 01 //Cummins M-11 Roadranger OD RTO1110




Ignore
« Reply #12 on: March 25, 2011, 12:10:04 AM »

Ahoy, Art,
My Eagle has two automotive compressors, the old GM A-6 items from the 70s or so.  I asked a few years ago, and our A/C Guru noted that the A-6 is likely to be around for a good while.  Big and heavy, but they even have a built in lube pump.  Plenty of capacity, and I seldom need to run both.  My system is hydronic, heating or cooling secondary coolant.  Powerful and effective, but It cannot be considered acceptable because of condensation on the cold hoses which make a mess in the bays.  Id planned to insulate them, but it became too hard to do.
I run four 120vac compressors. There are two separate independent systems.  That is, one A-6 and two 120vac units for each, plus condensers and evaps.  Check valves for each 120vac unit, none for the A-6s, because the valve scheme is a check valve.  Ive never tried (or have needed to) run the engine A-6 units and the 120vacitems at the same time.  Id expect it to be too much.
I cant see how using the original large condenser would present problems.  All the condenser does is condense the gas to a liquid, and bigger would only seem to further cool the liquid.  A shortcoming would be that you would only have one system if you use the existing condenser.
Good luck  /s/   Bob

Logged
bevans6
Hero Member
*****
Offline Offline

Posts: 4528


1980 MCI MC-5C




Ignore
« Reply #13 on: March 25, 2011, 05:27:49 AM »

I had a random thought about this - MC-5B only has two bays.  All your wet tanks and such will probably fill one bay (does on mine) so you only  have one bay for carrying stuff.  If you fill it with air conditioners,  you won;t have room to carry stuff.

You have a decent generator on the engine.  if you build in a suitable inverter you can run sufficient AC from the bus engine converting to 120 or 240 VAC to cool the bus on the road.  And plug in to pedestal when parked, or have a generator.

Bus OTR AC typically needs about $1500 annual maintenance.  That solves a lot of roof wart issues for me but maybe you have deeper pockets or are smarter than me.  It draws a lot of power - maybe your engine is more powerful than mine, but my 8V71N was fairly marginal.  It's really heavy, probably adds 400 lbs.  It occupies a bay that is  very useful for a generator or house batteries.  It only works when the bus is running.  Even on a trip, my bus is running only maybe 15%  to 30% of the time.  I do tend to stop and stay a while when I get to where I am going.  My analysis said that the bus OTR was a non-starter.  It came nowhere close to solving my problems, regardless of cost. 

I like redundancy.  While I only have one roof-top now, plan is to add a second small unit of some sort for the bedroom/bath area, and have zone cooling capability.  I like the idea of being able to stop at a camping world or other RV store with a dead unit and a couple of hours later be rolling with a replacement installed and working.  Aside from the weight, they are plug and play.  I can install one by myself with what I carry on the bus in around an hour.

I completely agree the way they look sucks. 

Just some thoughts.

Brian
Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
justin25taylor
Full Member
***
Offline Offline

Posts: 101

1974 05 Eagle and 1986 10 Eagle




Ignore
« Reply #14 on: March 25, 2011, 06:24:00 AM »

I would think long and hard before pulling OTR system out. Nothing will cool as well as it does down the road.
I have had to replace a hose or two and top off the system once or twice in the last 10 years. Hoses were around $100 Ea. Not that big of a deal to me. Sure wouldn't want to have to do without it.

Learn to repair it yourself. You can save a lot of money that way.
Logged
Joe Camper
Hero Member
*****
Offline Offline

Posts: 666



WWW

Ignore
« Reply #15 on: March 25, 2011, 06:55:23 AM »

I agree with Hi yo silver.

I did spend a few thousand getting ours up in 06 when we bought the bus but haven't spent a penny on it since.

Where does the ongoing annual expense come from I haven't experienced that.

1 thing I do not like is the inability to run just the dash loop if and when I choose. Hooked a cruisair up to inverter to remedy that.

For info sake you do not need a big battery bank to run ac off inverter. I use a 2500w inverter 4 automotive sized deepcycle flooded wet cell batts and the 50dn alt. Works flawlessly all the time.

Many different ways to get there with a/c important thing for me is I have slightly more than I need. I know 2 roof air will reasonably cool a 40 ftr even on a hot day but what if 1 goes down? I think we will be keeping the 3rd one we have. If you are using calculations for a residential situation I would about double the figures for capacities.

Running the A/c off inverter or running the gen for a/c uses fuel too. No free rides
Logged

Signing off from Cook County Ill. where the dead vote, frequently.
Hi yo silver
Hero Member
*****
Offline Offline

Posts: 818




Ignore
« Reply #16 on: March 25, 2011, 07:29:24 AM »

Just as info, the work on my OTR a/c cost me around $450 about two yrs. ago. If it had been several times that amount, then I certainly would have reconsidered. One other point, I didn't rely on my own expertise, I took it to Thermo King. They knew how to evaluate the system, knew what would work in it, and I trust their advice. So far, so good.
Dennis
Logged

Blue Ridge Mountains of VA   Hi Yo Silver! MC9
luvrbus
Hero Member
*****
Online Online

Posts: 12055




Ignore
« Reply #17 on: March 25, 2011, 07:33:59 AM »

2 roof tops will cool a 40ft bus when parked but not will driving and 2 roof tops parked are a little iffy here in AZ in July I have saw H-45's and they are supposed to be easier to cool than a xll here with large basement units the people spraying the bus with water to help with cooling.
They don't install 5 or 6 units for nothing and no way can you replace 10 or 12 tons of cooling from the factory with roof tops or basement air won't happen in the real world lol that is my take on it.
On the OTR air I have a friend that owns Arrow and he says the OTR air is his most expensive maintenance item on his buses but he runs his buses every day some where on this board I posted the numbers he gave me and it is not cheap 


good luck
« Last Edit: March 25, 2011, 07:40:29 AM by luvrbus » Logged

Live each day like it was your last,one day it will be
lostagain
Hero Member
*****
Offline Offline

Posts: 1503


MC5C




Ignore
« Reply #18 on: March 25, 2011, 07:44:50 AM »

OTR air is great when it works right.

However, it can be expensive to maintain: when I looked after the hockey team's bus, it had to be recharged once a year at a cost of =-$1000. They were small leaks than nobody could ever find.

When I drove  that vintage of bus in the '70s, we always had to turn the A/C off to go up most hills so as to maintain decent speed. OTR A/C uses a lot of HP, and will knock you down one gear in a 4 speed going up a hill.

JC
Logged

JC
Invermere, BC
1977 MC5C, 6V92/HT740
TomC
Hero Member
*****
Offline Offline

Posts: 6667





Ignore
« Reply #19 on: March 25, 2011, 08:07:57 AM »

With my truck conversion-I'm teeing into the truck A/C unit to run a slave unit (like what is run in a sleeper) to keep the front of the living area cool/warm.  And since my roof line is too high (13' then 13'6" at the bedroom), I'm directed at basement air.
I just talked to Nick yesterday.  My idea is to use Duotherm Penguin roof top airs mounted in the basement section.  The Penguin is the only roof top air that has a squirrel cage blower for the condenser that can be ducted out of the basement.  Granted it will take a bit of engineering, but once in, I can also replace the units if one fails.  They run about $900.00 each-so $1,800.00 for two.  In the cab, I'm going to run a 7,000btu Duotherm truck basement air.
The other choice is to run CruiseAirs.  These are freon split A/C's.  So with the front, I'd run the full 14,000btu to the living area.  The mid A/C would be freon split with 7,000btu to the front and 7,000btu to the bedroom-like a night time A/C.  But-Cruiseairs are exactly twice the cost of the roof tops.
There are also the fore mentioned mini splits intended for home use, but very difficult to duct the hot air out of the basement.
Also is DC air that is about a 6,000btu 12v or 24v dc powered A/C aimed mostly at trucks.  This might be a good one for night A/C so not to run the generator.
You could even modify through the wall A/C's to work.
Lots of choices-just have to find one that will work for you at the cost you can bear.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
John316
Hero Member
*****
Offline Offline

Posts: 3212

MCI 1995 DL3, DD S60, Allison B500.




Ignore
« Reply #20 on: March 25, 2011, 08:47:31 AM »

Clifford,

Thanks for weighing in. I wondered if we did something really wrong on our bus, since it takes at least three airs to cool when driving (or just two up front). Four is nice, and keeps everything nice and cool when we are down south, or in the desert. We have spray foam, and everything, but two roof airs just won't cut it.

But, it looks like we are simply normal.

God bless,

John
Logged

MCI 1995 DL3. DD S60 with a Allison B500.
Len Silva
Hero Member
*****
Offline Offline

Posts: 4083


Angle Parked in a Parallel Universe


WWW

Ignore
« Reply #21 on: March 25, 2011, 08:51:33 AM »

As far as I know, the basement air from Duotherm are basically repackaged roof airs.  The main difference being that they use separate motors for the condenser fan and air blower.  I had basement air in the bus and now have roof airs on the Vogue, and I would give up the bay space in a heartbeat for basement air.

Much, much quieter and better circulation (with proper design).
Logged


Hand Made Gifts

Ignorance is only bliss to the ignorant.
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« Reply #22 on: March 25, 2011, 10:56:34 AM »

   I really hadnt thought I would run into so much opposition on the subject. I did not mean to offend anyone about roof airs, and I appologise immensely for anything I said, or how I said it. Please accept my appology.

  

    
    

  

  

  
Logged
robertglines1
steam nut
Hero Member
*****
Offline Offline

Posts: 3969





Ignore
« Reply #23 on: March 25, 2011, 11:07:02 AM »

I stepped out early in this discussion.I said I was using mini split system. I did not mention that I do have a drivers air that is driven off a small compressor on the engine:I understand it is a 2 ton unit. I have it as a back up or primary how ever it may end up. My coach is insulated to maximum capacity of space available with a minimum of glass area. Bob
Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
luvrbus
Hero Member
*****
Online Online

Posts: 12055




Ignore
« Reply #24 on: March 25, 2011, 11:18:07 AM »

The drivers ac is a lot larger than 2 tons most were 28,000 to 33,000 btu more than both of your split/units combined

good luck
Logged

Live each day like it was your last,one day it will be
robertglines1
steam nut
Hero Member
*****
Offline Offline

Posts: 3969





Ignore
« Reply #25 on: March 25, 2011, 11:24:08 AM »

Thanks for info: guess I got a good cushion. nice to have extra available if you need it. I will give truthful response after the summer months have come and gone. Guess I'm one of the test markets. Was really impressed with others results and Duwayne (a friend) results in his Mci 8.
Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
JohnEd
Hero Member
*****
Offline Offline

Posts: 4571




Ignore
« Reply #26 on: March 25, 2011, 11:26:09 AM »

  I really hadnt thought I would run into so much opposition on the subject. I did not mean to offend anyone about roof airs, and I appologise immensely for anything I said, or how I said it. Please accept my appology.


You already said your "OOOPS!" thingy.  Only a very few are really sensitive about almost anything.  My observation, anyway.  Of course with 5 peepbels ignoring me, I could be wrong but 5 out of three thousand is nothing short of a "murakul" as far as I am concerned. Though it demonstrates your concern for us and that is truly a plus.  "Now just stop being so cussed abrasive".  YAR YAR YUK... Grin Grin Grin

John
  

    
    

  

  

  
Logged

"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.
Pla
JohnEd
Hero Member
*****
Offline Offline

Posts: 4571




Ignore
« Reply #27 on: March 25, 2011, 12:16:33 PM »

I have heard many say that the roof airs don't cut it when going OTR.  More so they say that a couple are good when stopped but three aren't enuf underway.

It matters vary little how much AC capacity you might have on tap......you don't need many "leaks" to nullify their affect.  There isn't a state in the union that you can cool with any AC unit. (sarcasm).  Quit trying.  (more sarcasm)   Fix the air infiltration leaks.

There are many 40 footers that stay cool just fine almost anywhere.  If you have the same thickness of spray foam throughout it doesn't matter what model or make you might have.  Each should require the same Btu's to operate satisfactorily.  I am not gullible enuf to think that it works out that way and you don't have to dive very deep into the posts on the search to come to the same conclusion.  Why?Huh,  i dunno!

In homes we put foam pads in front of out duplex outlets under the face plate.  Conduit will act like a mini duct to bring in air.  Wire penetrations are virtually open holes.  Mating points of structural panels and braces are often gaping even though they are mechanically strong.  Fiber glass is worthless as insulation of air is being pushed through it.  Our furnace filters don't provide much insulation and they are FG, right? (sarcasm,  again).

The front of a bus can be expected to be a high pressure area and any HOLES will admit air like gang busters.  There must be many other places that have high pressure outside air.  Here is the rub and seeming contradiction.....most buses have a "LOW pressure" inside while underway.  Even without the high pressure areas the thing "sucks" as it goes down the road and that "suck" is in "series" with the "push" from outside so you get a push/pull affect and even MORE air.  Hot or cold...doesn't matter cause they are ambidextrous.  Or was it by-lingual

As you drive down the road at your normal cruise, have somebody crawl all over the interior walls and floors and cabinet interiors and any merge of a wall and floor or roof or duplex out let or pipe or duct..... all over.  Not so much for the fun of seeing them do that but arm them with a no contact heat sensor from HF,  sold for $29, and note temps.  Now it can't be one of those days when the outside is the same temp as the inside....the heating or cooling system must be trying to alter things.  These air permeations kill the temp change efforts while underway but they are also very bad when you are parked and wind exacerbates everything stopped or OTR.

Glass is a really bad culprit.  Double pane AND with that solar load rejection feature are really critical.  You can defeat the bad behaviors but it ain't cheap.  No matter the quality of the view, if you are freezing or cooking.....it ain't a pretty pic-shure.  While glass is expensive, it gets intolerable as a "Do Over" so get it right the first time and don't scrimp on the spray foam...an R here and a R there adds up and eventually you are talking a Btu or two and discomfort.

Want to see how much "suck" is going on in you bus?  Open one of those front drivers windows while at speed and note the air blasting "out" the hole.  My drapes stand out straight out the window.

I hope someone will do a survey of their bus and let us in on the conditions and maybe even get a survey for different models/makes.  I can tell you that my Winne, 30 footer, is crappy and CANNOT be corrected with any reasonable amt of work.  Sitting still, though, in 90 plus temps in the sun I can keep the interior down to 70 running only one AC unit and it cycles maybe 50%.  Roof is R50 in the center and tapers to R20...or thereabouts.  All windows sealed with film and dash area insulated to maybe R14.  I didn't do all that cause it was needed but primarily cause I could.  It worked!  OTR?  Only the drivers area is habitable.

Wellllllll!  That was fun.

Be well and happy all,

John
« Last Edit: March 25, 2011, 01:13:35 PM by JohnEd » Logged

"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.
Pla
TomC
Hero Member
*****
Offline Offline

Posts: 6667





Ignore
« Reply #28 on: March 25, 2011, 03:00:54 PM »

I have three 13,500btu Coleman roof tops with the front close enough to blow on me when driving and with a dash fan.  We normally run just two of the roof tops-108 degrees is the hottest I've been in. I have tried all three running, but then my wife has to wear a sweater.  It all depends on your insulation.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Geoff
Hero Member
*****
Offline Offline

Posts: 518





Ignore
« Reply #29 on: March 25, 2011, 05:25:53 PM »

I have three 15,000 BTU AC's on the roof and I never have to run more than the middle and front unit to keep cool.  The killer is driving into the sun--I don't care if you have 100K btu's, the sun through the windshield will cook you.  Especially on a modern bus (like the RTS) with the large windshields.
Logged

Geoff
'82 RTS AZ
JohnEd
Hero Member
*****
Offline Offline

Posts: 4571




Ignore
« Reply #30 on: March 25, 2011, 08:15:31 PM »

Geoff,

If you get by running two and that is the case while you are running down the road, well then, your bus is sealed up tighter than a jelly jar lid. Roll Eyes  Noth'n tighter than that cept (insert ethnic slur here). Grin  Don't complain to me cause it's your unPC mind that just thought that up. Angry

Good for you.

About those windows..... I have contemplated affixing a sheet of SS to the "outside' of the windshield.  Stand it proud 1/8 or 3/16 inch with the sides clear.  What it doesn't reflect convection will carry away.  There is a lot of windshield that is useless to see out of for driving or just the view.  The windshields in my Winnie are as narrow in the vert as an old Silver Sides.  I LIKE THAT.....personally.  Little sun when parked and a cool and quiet feeling while OTR.  I know I am flying in the face of modernity but it works.  I can see the view from any of my narrow old windows if I sit next to the window and if I really want that panoramic I can walk 10 feet and step outside and get the ambient temp and auditory along with the visual nirvana.  I would give a lot of thought to running a strip across the top as well as the bottom.  Don't forget to mark the window with a crayon as to what sections you can live without.....it is different from side to side.  As a min install sun blocker in those areas.  Who needs to see directly down onto the road 10 feet in front of the bus?  I can't see stuff that close from the pilots seat of my Lex.  Just my way and I am cool about it and I mean that pun.

John in the shade
Logged

"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.
Pla
Barn Owl
Roanoke, VA
Hero Member
*****
Offline Offline

Posts: 2040


PD4106-1063 "Wheezy Bus"




Ignore
« Reply #31 on: March 25, 2011, 08:26:47 PM »

 Grin $$$$$$$$$ Grin
Logged

L. Christley - W3EYE Amateur Extra
Blue Ridge Mountains, S.W. Virginia
Its the education gained, and the ability to apply, and share, what we learn.
Have fun, be great, that way you have Great Fun!
blank
Hero Member
*****
Offline Offline

Posts: 1929




Ignore
« Reply #32 on: March 26, 2011, 09:28:06 AM »

Geoff,

If you get by running two and that is the case while you are running down the road, well then, your bus is sealed up tighter than a jelly jar lid. Roll Eyes  Noth'n tighter than that cept (insert ethnic slur here). Grin  Don't complain to me cause it's your unPC mind that just thought that up. Angry

Good for you.

About those windows...  Little sun when parked and a cool and quiet feeling while OTR.  Just my way and I am cool about it and I mean that pun.

John in the shade

   What about a visor? A Visor would offer shade, keep the sun out of the interior a bit more dropping the heat load. If it had some dark windows in it you could still see up at stop lights and low overheads, depending on how far it stuck out. More visor = more wind drag = lower fuel economy. 

   You see black rock guards on many RV's, in the sun, dark colors transfer a lot of heat into the wall. White or polished metal reflects a lot of heat

   Mirror tint on the side glass would also drop the heat load.

   Ive never de-skinned an MCI, but on every GM we scrapped, which included a 4104, a 4106, and several transits, and also several AM Generals, I dont recall any insulation around the front of any of those buses. None in the front facing, sides, or upper cap, and none around the stair well.

   On this MC5, the underside of the stairwell can easily be seen bare as a newborn babies bottom through the spare wheel well. Bare metal sheet is worse than glass as an insulator.

   On several sites I have seen where they removed the front facing skin on an MCI, I do not recall seeing a smidge of insulation. Maybe I missed it?
Logged
happycamperbrat
Hero Member
*****
Offline Offline

Posts: 1813





Ignore
« Reply #33 on: March 26, 2011, 10:02:48 AM »

The factory AC cools the whole bus, even the driver's area really good in my RTS.... even here in the desert. One time I was having electrical problems in my bus and my AC wouldnt kick in because I wasnt getting enough juice to it thru the batteries....... what worked for us driving in the desert was little fans blowing on us with water soaked towels wrapped around our necks!
Logged

The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post
Pages: 1 2 3 [All]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!