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Old 09-30-2015, 10:20 PM   #41
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Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,286
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
Whoa, hey, back up the train (or bus?) just a little bit.

I love the chilled water idea. I've been thinking the same thing for my bus.. my heating system will comprise in-floor hydronic loop(s) plus a few water-to-air heat exchangers (ie, the heaters that came with the bus). The floor loops might not be much use for cooling because of potential condensation problems, but those water-to-air exchangers could be used for cooling too if only I could figure out how to chill the water. This is perfect. I had no idea exchangers like those you have from Duda were so readily available. I too dislike rooftop A/C, and would love to air ducts since I'll already have water loops running around anyway.

Maybe you're planning to draw a schematic of the system, but in case not... I guess you've just plumbed from the compressor to the rooftop condensers, then through a thermal expansion device, into one port on the plate exchanger, and finally returning back to the compressor? (and an accumulator too, I just don't remember whether it goes on the suction or discharge side.)

Have you done any heat load/transfer calculations, or is this kind of a "some is good, more is better" approach?

You mentioned the refrigerant loops are independent. What about the water side? Are the water side of the exchangers in parallel or series, or are there two separate water systems?
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Old 09-30-2015, 11:13 PM   #42
Skoolie
 
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Join Date: May 2015
Location: Las Vegas
Posts: 224
Year: 1998
Chassis: VanHool T945
Engine: Cummins M11
Rated Cap: 47,000
For use as an RV this amount of cooling (7tons) and distribution is a bit overkill. Being that 3-5 tons is usually used on large RVs / tour busses like presvost etc..
The water loop on plate side is parallel from both plates straight to 30gal tank. This setup mocks that of large format industrial chillers. Each compressor is independent to a plate exchanger. TXV expansion valve, evap coal, and plate exchanger as condenser.
The water tank itself has a set temp of what you want your coil temps to be on the air handlers. So basically the two compressors have 4 stages to maintain the temp.

1st stage 70% one comp
2nd stage 100% one comp
3rd stage one comp at 100% and other at 70%
4th stage both at 100%

These are controlled by a temp control for each stage as to not overshoot the desired water temp. Say about 1.5 to 2deg off per stage.

The tank is insulated like mad and can store the chilled water. This means (in Vegas) I can run compressors at night when it's cooler and easier to chill and it will help get through higher load during peak day.
If you had room temp water and turned system on all for stages would fire up and chill the 30gal as quick as possible. As the desired temp is reached and to just maintain the water - it will cycle down to just one or two stages.
Idea is based to be more efficient than just running 5 rooftop units.

Difficulty like you said is condensation. All water lines need to be insulated and the air/water handlers need condensate drains to outside bus.
Cool thing is the main roof unit already has this setup. I'm just gonna run high pressure chilled water through the rather large original (but modified) condenser coil that has the blowers. I put speed controllers on the blower mothers to run them all at lower speed and have less ducting now so it is fairly quiet (this main unit is in my kitchen though, so it's not a big deal for some amount of noise)
The front lounge is tricky as the air/water coil I will use here is the old heater coil from roof. (6' long but only 1.5 deep and 5" wide) so I can build a flat but long handler that hangs sorta where old parcel racks were above the side windows.

Each compressor is 3.5 tons. Original roof coils were 8tons combined so Split it's basically 2 4 ton evap coils.
Each plate exchanger is rated around 3 tons or more pending water and refrigerant flow rates in told from manufacturer.

Here is the chiller control box I'm building
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Old 09-30-2015, 11:24 PM   #43
Skoolie
 
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Location: Las Vegas
Posts: 224
Year: 1998
Chassis: VanHool T945
Engine: Cummins M11
Rated Cap: 47,000
Here is the blowers and where the kitchen condenser goes:



I am changing out the old 24v evap fans with modern radiator 12v Ones.. With all 5 runing you can't even hear it in bus and outside standing next to bus it's barely audible. As they shoot straight up unobstructed.

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Old 09-30-2015, 11:33 PM   #44
Skoolie
 
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Chassis: VanHool T945
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Rated Cap: 47,000
Chilled water coils I'll use for the front lounge (one per side of bus above windows in the parcel area) these will have their own fan controls / condensate drains / and flow air down windows and out vents. Water is controlled via a solenoid from the water loop. Temp controller monitors the ambient air temp in this zone and turns water flow on/off.. All Fan speed is set on iPads for all zones.

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Old 10-01-2015, 05:32 AM   #45
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Location: Katy, TX
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Year: 1989
Coachwork: Thomas
Chassis: Saf-T-Liner ER
Engine: 3208 CAT/MT643 tranny
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Review upgrade!!!!!



Well BEYOND amazing now...........

GLUED to this thread as y'all have BROKEN the bar, waaaaay beyond raised it.......

Looking forward to the movie!
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Old 10-01-2015, 06:01 AM   #46
Skoolie
 
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Location: Las Vegas
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Year: 1998
Chassis: VanHool T945
Engine: Cummins M11
Rated Cap: 47,000
Sweet!!! Thanks - I'm just getting started...

So today I just confirmed arrangements with a engineer I work with at a casino that does TIG welding for stainless. I decided to go complete industrial in my kitchen and wanted the stainless countertop with sink - pre wash faucet fixtures etc to go with the True fridge. I could not find one that fit the format - so bought the items to build it. 8' counter solid surface and a nice deep sink that will be TIG welded via undermount with finished edges. Will end up being one solid surface with no seams into the sink. BAM that's what I want. I'm so excited to get the kitchen on its way.
This is going to be the sink faucet:

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Old 10-01-2015, 06:08 AM   #47
Skoolie
 
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Join Date: May 2015
Location: Las Vegas
Posts: 224
Year: 1998
Chassis: VanHool T945
Engine: Cummins M11
Rated Cap: 47,000
I'll have pics of the finished countertop before next Thursday. I drop everything off to be welded this weekend.

In one week I drive to CA to do some more woodworking with my dad - I have till then to complete the drawer and undercounter design on sketchup.

More brazing and working on chiller this weekend. Should be pressure testing the closed compressor loops.

Until then - it's always nice to chill on top of a bus

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Old 10-01-2015, 06:59 AM   #48
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Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 11,140
Year: 1992
Coachwork: Ward/AmTran
Chassis: International
Engine: dt466
Rated Cap: 78
This is the bus I would have built if I weren't a poverty stricken hippie. For comfortable long distance travel, a coach is the superior platform.
And looks really boss, too.
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Old 10-01-2015, 07:22 AM   #49
Skoolie
 
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Join Date: May 2015
Location: Las Vegas
Posts: 224
Year: 1998
Chassis: VanHool T945
Engine: Cummins M11
Rated Cap: 47,000
I got bus chassis on an RV loan. I didn't have the best credit either, but she only cost me 300 month... Less than my car payment.
So going from 2k month housing expense to this was a drastic change.
My goal was to reduce my expenses and not be tied to one location.
Since it is my primary residence - I'm trying to make it a sweet ride and have all the goodies I love in a small space.
I think you can do anything you put your mind to.

I've also seen some vanhools as cheap as 9k. One is on ebay right now for 13k - It's a lot of bus for the money. Granted a skoolie can be had way cheaper at auctions and such, but Most people I talk to just don't realize the differences between these coach chassis and other busses. I just figured it was worth it in the long term.
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Old 10-01-2015, 07:41 AM   #50
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Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 11,140
Year: 1992
Coachwork: Ward/AmTran
Chassis: International
Engine: dt466
Rated Cap: 78
Paid 46k cash for my house on .33 acre lot.
I agree- paying stupid high rent is for the birds. I lived in a free downtown ghetto building before I finally bought my house. I plan to rent this place out once the bus is done. I wanna be on the right end of the vicious rent cycle!
I've seen some screaming deals on VanHools.
I think there are lots of people who would do better with a coach than a school bus. But school buses are more chic... They're blowing up on Pinterest!

If driving long distances is part of one's plan then something designed for such is a logical step but many don't seem to understand that. A coach is built to go a million miles or so. School buses are pretty rough by a half mil... usually.
My bus will likely see less than 15k for the rest of its life as long as I own it so I saved a ton of money going with a more easily modded school bus.
I want an MC5 next.
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