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Author Topic: Cooling the coach to hang meat  (Read 3685 times)
PCC
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« on: November 29, 2009, 08:31:14 AM »

I have been stealing space on Ruthi's thread, and I think this is how I start one of my own. (If I am wrong, nobody will reply, and then I will have to read the directions)

I have been removing components of the dual A/C - heat system from my Prevost.

I have removed the front A/C - heat bay unit (evaporator, according to Nick) and one of the two condensors which were plumbed in series (one with a oil drive fan, and the other with a massive 24V fan).

When I asked about the tonnage of A/C I would need to maintain a decent temperature in the coach, both while driving, and while standing still, I began to feel like my information was amiss, and that I needed to reconsider the removal of the engine driven system, which could have as much as 15 tons of cooling capacity.

Because this coach will need to be able to be cool inside, even on the hotest day in Arizona, but not wanting to run the DD engine all day, I was looking for what I needed to keep the vehicle cool, and I mean cool 'cuz I like cool.

If I can find a system that will keep the vehicle cool, while stationary, then it should also keep the vehicle cool while moving, but am I wrong to remove the factory system for while driving? and is there a big enough system out there, that will fit in a bay that is 36" tall and 44" wide?

I can replace the equipment that has been removed, but need to mount the evaporator in a different place, because of the generator, so can it be mounted vertically, rather than horizontally (how it is normally from the factory)?

I can also remount the condensor in the front behind the front bumper, using the 24v fan, if I louvre the floor under that space. The spare tire doe not go there, it is in the read under the back bumper; engine is in the middle.

I can alternately mount the A/C evaporator above the driver, by making an enclosure and plumbing the refrigerant from the unit down under the bus, and connecting to the system.

So many options, but this was something I had presumed was handled, as I was going to do 2 - 2 ton units, but am now thinking that I need more like 10 tons.

I also need to find a small system to engine mount, to provide cooling for the driver only, when making a deadhead trip.

So many things to adjust, but I will be looking at the site "Red something", for their ideas and custom designs.

Hope this works - If not, none of you will ever know.
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« Reply #1 on: November 29, 2009, 09:05:25 AM »

You did it!
(started your own thread that is! )
Grin  BK  Grin
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« Reply #2 on: November 29, 2009, 09:16:58 AM »

If you will never need to connect to a 120 volt power pole, then you might consider a residential central split system of 3-4 tons.  Much less expensive than the RV units and done all the time on entertainer coaches which only run from the generator.  The only drawback is that they are 240 volts only.
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« Reply #3 on: November 29, 2009, 09:26:23 AM »

The biggest key to keeping the coach cool is superior insulation to what the bus originally came with.  On my transit, which has huge windows (my truck conversion will have even bigger windows-both my wife and I love big windows), I have single paned lightly tinted windows.  Also have 2.25" sprayed insulation.  This was done by screwing 1x2 fir strips lengthwise on 16" centers to the metal support beams.  After running the wiring and pipes in the wall that would be buried by the insulation, the insulation was sprayed in which covered everything on the wall-including the metal support beams (very important since the metal support beams will transmit heat/cold to the inside).  For cooling I have three Coleman 13,500 btu/hr roof top airs with the front one close enough to blow on me while driving.  In 108 degree weather, two are sufficient to keep the bus in the 75 degree range while driving.  If I run all three, my wife has to wear a sweater.  Just an example.  Good Luck, TomC
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« Reply #4 on: November 29, 2009, 09:52:18 AM »

Good title, lol. As was stated, first start with good insulation. Consider putting tc ceramics on the roof. We did a lot of research on it, and it is fantastic. We put it on our dina, which is being put together as we speak, and wow, you can really tell the difference. Look it up on the internet. I believe the address is  tcceramics.com. Or, just do a search for tc ceramics. We used it all over the coach. We put it on the roof, the interior and floor of the bus. But if yours is already built, doing just the roof will do great. We also put it in the engine compartment as well as the gen compartment. We foamed the walls and floor and ceiling also, so, hopefully that works out good. Good luck,Ruthi
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« Reply #5 on: November 29, 2009, 10:25:28 AM »

Thank you all for your support for me; I finally started a thread of my own.

Continued apologies to those whose threads I piggybacked on, so I guess I am now graduating to elementary BBS school.

For those whose advice I am reading, I must stay underneath the coach with my A/C equipment, and I have one completely empty bay left in which to do this, and few other hiding places.

I can plumb or wire anything I need, in order to make whatever system I install to work, so give me any information that pops into your minds, and I will sort through it all. Without the combined knowledge from this site, I might make a serious error.

I am still trying to figure out if evaporators are directional; can I stand my unit on its end and still get it to work? I have two possible locations to reinstall the factory evaporators (if I am to go back to the original equipment), and one location would require the unit to stand on end.

I can place one of my two condensors behind the bumper, with few modifications, so that part will work. The other is still in place.

I still have the original compressor in place. Iwas about to remove it and find a smaller one for a driver only system, but I am going to wait until I get more input from you-all.

The more I learn, the more I able to get into this project, my ninth coach. This is the most adventurous project I have ever tackled, and I have to get it right.

I have lots of onboard power, so the cooling system size is open ended. I just need to know that when this cooling system is done, the interior will stay cold enough to hang meat, no matter where I am in this great country.

So keep those cards and letters coming, and I will have a thousand of you to thank when this coach is travelling through temperatures over 100, and it is no sweat.
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« Reply #6 on: November 29, 2009, 12:51:53 PM »

My thoughts:

Going down the road all the tiny holes in the walls and roof and floor become "really big" as heat sources.  You will need much more capacity while driving.  Tom has built his from the ground up.

Pre uses spray foam in their walls.  They have superior insulation when compared to fiber glass but they aren't in the came league as a custom built and spray foamed bus with 2 1/2 inches and no metal framing touching the interior.  If you can add 1/2 furing strips to the walls and have it sprayed to the new thickness on top of the old foam I think you will benifit more than just the R value added as the metal will be covered and the "heat conduction path" will be interupted.

The floor on a Pre is composed of a layer of plywood, then a layer of lead(or heavy black stuff) followed by a layer of plywood.  Not much of an insulator.  Spray foam as much of the top of the bays as you can and use carpet and really good padding and cover as much as you can excepting the kitchen only.  Even closet interiors.

The AC capacity is speced for a bus sitting in the Az sun for most of the day withoutrunning...120 degree heat soak and in the sun maybe 160+ degrees inside.  You have to be able to run the AC for a half hour or so and thern stuff 50 people in there and have everybody happy cool.  That takes capacity you will never run up against.  Your compressor capacity is your problem,  It eats power that you don't benefit from.  Going to a smaller compressor would mean that you need less condenser so maybe deleting one of your two might be a solution for that.  The 24 volt cooling fan is also affecting power and MPG.  BUT....as it is designed it is a fully functional and proven design.  To get another .2 MPG I would leave it alone and be impressed with how well it works and how quickly it will cool down after a heat soak.  Put the stuff back and het the system properly charged by any shop that can pump it down before adding freon.  Did you know that Harbor Freight has vac pumps on sale for $30?  A 5 gallon jug of the 134 is all that much and if you can't figure out those gauges you also have trouble distinguishing between thunder and lightening. Huh Roll Eyes Grin

The driver already has an ac system for himself.  Maybe you can shut off or down the coach air and just cool the driver.  There must be occasions like driving into the sunrise/set on a cool day where everybody is comfy but the driver is alone sitting in direct sun.  Pre wouldn't have him get cool at the expense of his passengers....now would they?  BGK can shed light on this..I think.  Also anybody with a Pre.

Have you run this question past the guys on the Prevost Group over on Yahoo?  There are two groups there that Pre posesed.

Those glass beads have been debunked.  The bennifit that you get from them is attributed to the white paint they are mixed with.  They roughen the surface and that makes it dirt up quickly and a dark/dirty  roof ain't a god thing.  Search this forum and you will find a ton of discussion on the roof coatings.  Ruthi....I am so sorry to contradict you.  You are a sweetheart and i love your posts.  Those mfr.s usually quote "effective" or "equivalent" R VALUE.  You have "R" value and then you have other stuff and theories. There is no insulation R value to the paint coating itself.  The stuff uis spendy too so I can see why people that have bought into it would defend it to the death.  If they got someone to believe that it made the bus lighter in weight I have little doubt that there would be many testimonials where the "victum" testified that his bus "actually felt lighter going down the road".

You want to increase the comfy?  Dual pane IR reflective glass and awnings for the GOAL!

You sound very savy and I am sure you will find your way whatever you decide.

John
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« Reply #7 on: November 29, 2009, 02:49:18 PM »

I have been thinking for some time about a way to use the existing OTR heat/AC system. I believe this would work but I don't have the time to engineer it. Perhaps someone else would like to try.

Using the heating system while parked should be not problem. Just install a water coil in the existing duct work and use a Wabasco or something similar to heat the water. You would also have to have battery charger large enough to run the interior blower(s). Or, if you already have a Wabasco system, there should be a way to use electrically actuated valves to isolate the engine so you could heat the coach without wasting fuel to heat the engine until needed. Domestic hot water would be provided with the same system.

AC is a little more tricky.  First you would have to decide the maximum capacity needed while parked. Let's just assume we need 4 ton. The older MCIs used a Carrier 6 cylinder compressor that could be unloaded, one cylinder at a time and had a 10 or 12 ton capacity. I need the real data here (and a good engineer) but if it is 12 ton that means 2 ton per cylinder. You could unload the other 4 and reduce the amount of power needed to turn the compressor. Then you could turn the condenser fan slower using less power & the interior blower could stay on low maybe. Again, I need real data to to figure this out.

To turn the compressor while stopped, you could use the same type of system used on small Thermoking units. Replace the engine pulley with an electrical clutch pulley. That frees the compressor to turn while the engine is stopped. The 2 groove pulley on the compressor would have to be replaced with a 4 groove pulley. 2 grooves would be used for the belt to the engine. The other 2 would go the a 110V electric motor of sufficient size to turn the compressor fast enough to generate the capacity needed.

The only down side I see to this is you only have one system. If it breaks, you are going to be hot! ...or cold.

I know this is a lot of work but so is ripping out the OTR system and replacing it with rooftops that look bad and might leak or basement units that are expensive.

Now all I need is unlimited funds & time to try this out....  Grin Grin Grin

TOM
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« Reply #8 on: November 29, 2009, 05:07:35 PM »

John Ed, I have to contradict what you think also, but keeping it friendly. We were shown a test to see what this stuff will do. It was pretty amazing. It isnt the first stuff that came out with the ceramic beads that you mix in with paint. I take everything anyone tells us with a grain of salt, til shown, and we were shown. Put a piece of ice on a thick layer of paint chip, and put it in a fry pan, turn on the heat and see how long it take to melt. We did that with a piece of ceramics, and the ice didnt melt, but the pan was red hot. This stuff can be put on exhaust pipes, and you can put your hand on it. Fred Hobe showed us that also. Now that it is on our bus, you can feel what the heat would feel like without the coating, and with it, you cannot feel any warmth at all. So, if you dont have heat penetrating, then it certainly has to help. Race car drivers use the stuff to make it cool enough to be in their cars, and they use it to put on steam pipes in factories. And yes, the top is a rougher texture, but, for the trade off, we can power wash it.
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« Reply #9 on: November 29, 2009, 05:13:22 PM »

Thank you all for your support for me; I finally started a thread of my own.

Continued apologies to those whose threads I piggybacked on, so I guess I am now graduating to elementary BBS school.

For those whose advice I am reading, I must stay underneath the coach with my A/C equipment, and I have one completely empty bay left in which to do this, and few other hiding places.

I can plumb or wire anything I need, in order to make whatever system I install to work, so give me any information that pops into your minds, and I will sort through it all. Without the combined knowledge from this site, I might make a serious error.

I am still trying to figure out if evaporators are directional; can I stand my unit on its end and still get it to work? I have two possible locations to reinstall the factory evaporators (if I am to go back to the original equipment), and one location would require the unit to stand on end.

I can place one of my two condensors behind the bumper, with few modifications, so that part will work. The other is still in place.

I still have the original compressor in place. Iwas about to remove it and find a smaller one for a driver only system, but I am going to wait until I get more input from you-all.

The more I learn, the more I able to get into this project, my ninth coach. This is the most adventurous project I have ever tackled, and I have to get it right.

I have lots of onboard power, so the cooling system size is open ended. I just need to know that when this cooling system is done, the interior will stay cold enough to hang meat, no matter where I am in this great country.

So keep those cards and letters coming, and I will have a thousand of you to thank when this coach is travelling through temperatures over 100, and it is no sweat.

Hi PCC,

The trouble with laying your evaporator horrizonaly is, where is the condensation going to drip? Most are designed virtically or
in an "A" shape to dissapate condensation to a designated pan area then out a drain. Your big evap coupl put out as much as
15 gallons an hour on extremely humid days.
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« Reply #10 on: November 29, 2009, 05:21:02 PM »

PCC,

Here is a good starting place at Red Dot's site.
http://www.rdac.com/Pages/product_pages/off_the_shelf_units.html

You have many options and your best bet is to call a tech at Red Dot and they can design an OTR system to fit your needs.

Good Luck
Nick-
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« Reply #11 on: November 29, 2009, 06:16:33 PM »

I have sent an email to Red Dot for their advice. Thank you Nick.

I have been working the reinstalled factory system in my mind; installing the components I must move in different locations, and it is possible.

The factory evaporators were mounted horizontally across the bays, so what I was wondering is if they could work if I mounted them vertically? I can handle the condensate drainage.

I do have the room to remount the second condensor behind the front bumper. All I have to do is run 1" copper pipes to these locations, and then silver solder the connectors to the ends of these lines, just like the original.

I still need to have a system that will cool the coach effectively when the engine is not running. That is why I still will have to have a generator powered system with huge capacity.

Now comes the evaluation of the options, then the design, and finally the installation. It will get done.

Here we go !!

Keith
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« Reply #12 on: November 29, 2009, 09:13:48 PM »

Keith -

I'm a little confused. . . I am not familiar with any Prevost models that had the engine anywhere else other than in the rear, behind the back axle.

Some photos and more info on your actual coach model would assist in clearing up the fog!

FWIW & HTH. . .

 Wink
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« Reply #13 on: November 29, 2009, 11:35:55 PM »

Me too RJ,

I though I must be reading it wrong.  Crown?  DRAMATIC redesign of the Pre drive line?  Sounds interesting though.

John
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« Reply #14 on: November 29, 2009, 11:45:53 PM »

Ruthi,

Never unfriendly....ever Grin Grin Grin

What is the name of the "treatment/coating?  Fred is a very good name but then so is yours.  Is this the stuff that some got samples of to try?  I want to test that stuff myself but I don't want to pay through the nose for the small amt I will need.  Can you help me with any of that.  Do you have a smidge left over?  I will document what I do and make all data available for a peer review.  I can appreciate that you have little motivation to indulge me or anybody in a proof especially with what you have see and your being a true believer.  Can't blame you there.  Had I seen what you have described I would be vendor and barking the stuff everywhere I went.  Truly....it sounds too good to be true but if it is it should revolutionize the insulation industry.

John the friendly
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"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
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—Pla
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