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Author Topic: New Guy - Questions about AC  (Read 3500 times)
Tikvah
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« on: May 02, 2011, 05:46:03 AM »

Good morning.  This is my first post.  After purchasing my first coach (MCI-102 A3) I was so glad to find a forum as helpful as this.
I wish I had found you before my bus purchase, but I probably wouldn't have done anything different.

Anyway, I'm looking today for an AC system.  I've considered roof-top units, they're more afforadable.  But they also seem to use more electricity.  I'm trying to keep my electrical usage low when possible.

This type of system looks appealing to me. 
http://cgi.ebay.com/LG-LMU180HE-Ductless-Heatpump-Dual-Zone-Air-Conditioner-/280638519827?pt=Air_Conditioner&hash=item41575bfa13

I figure I can put one wall unit above the bed in the back blowing forward, and the other unit in the front above the driver.  Not likely to run both at the same time, but you never know.

First, has anyone on here used this type of system?  What is your opinions? 
Second, Where do you mount the outside unit?  I expect I'll put a generator (when I find an affordable one) in the front AC bay.  Could you put the outside unit on the passanger side engine compartmet?  Or cut luvers into a luggage bay?

Open to ideas Undecided

Dave
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1989 MCI-102 A3
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Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
robertglines1
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« Reply #1 on: May 02, 2011, 06:13:07 AM »

I'm using 2 9000 and a 12000 in a 45ft coach because they are 120 volt instead of the 220 unit. Evergreen Products LLc is a supplier and you can get deals direct better than internet. and save on shipping.I'm no expert but have friends in business. Some have had condensate problems but with a little common sense they are easily solved. I am retaining drivers air for across road operation if I were not I would add another 9000 or 12000 for a back up just in case. rite now in the 89 I have a total of 37000 btu and in 97degree sunny weather the warmest it has gotten in coach was 76 as soon as sun was down it cooled rite off .note the 89 had extra insulation: The 45 has twice or more than the factory insulation and 1/2 the glass of the 89. noise levels of the mini splits are in the 35 to 40 dbl range.  power usage in the 9 amp each range and heat and cool with inverter technology.  My choice this time. right or wrong.   do it your way. check your message box:  Bob
« Last Edit: May 02, 2011, 09:26:51 AM by robertglines1 » Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #2 on: May 02, 2011, 06:14:48 AM »

Bob is looking at this type of set-up as well I have thought about the same. I think I would personally go with a dedicated A/C bay. Engine compartment and be oily and hot. I think the unit would perform better in a cleaner cooler environment.

Bob, have you thought about using a standard ducted air handler, instead of the wall mount. Would it work?



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Fred, 1986 Prevost XL, just beginning...Plans for roof raise, slide-outs, extension to 45', and maybe repower to CAT.
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« Reply #3 on: May 02, 2011, 07:17:08 AM »

My thoughts...

Bay mount the outside unit,  the engine compartment will be very hot with the engine running.  You could duct the hot air exhaust to the floor of the bay, you don't need side vents.  You'll need to be able to power this on the road, so plan for a 220 volt generator and you'll be restricted to 50 amp pedestal power.  General consensus is that you'll need closer to 40,000 BTU of cooling in a 45 ft bus (nice looking bus, btw).  I have a single 15K btu and it has bit of a struggle but can keep up with the front of a 35 ft MCI.  by keep up, I mean round 78 degrees in sunshine with the outside temp around 90 (typical of your area in summer).  A 9K BTU split won't do the front of your bus alone without serious insulation, roof raise, the whole 9 yards.  Adding a 15K rooftop would do it, in my opinion.  think about power and if you could do this with 120 volt units. 

Brian
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MikeH
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« Reply #4 on: May 02, 2011, 08:06:09 AM »

Dave: Welcome to the madness. I echo Brian's comments about the nice lookin' bus.

Bob Glines has already chimed in, he is one of the "experts" on this topic as he is using those types of units in his bus. You may be able to search the archives for mini splits, or hopefully when he has more time Bob will post some more info in this thread for you.

Keep us posted on your progress.

Mike
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5B Steve
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« Reply #5 on: May 02, 2011, 08:19:56 AM »



   Welcome, If your OTR ac is in good working condition, I would keep it.  Just my thought. Make sure you

  have real good insulation when doing your conversion and the roof airs will do a good job.


  Steve 5B......
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« Reply #6 on: May 02, 2011, 11:02:53 AM »


  Welcome, If your OTR ac is in good working condition, I would keep it.  Just my thought.

  Steve 5B...

  I'm sure keeping mine.
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robertglines1
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« Reply #7 on: May 02, 2011, 11:57:32 AM »

Definitely agree about keeping over the road if they are working. No disagreement there at all. Just when they fail time to look at alternative solution and cost. Many operators say that is a major cost of operation. And in our case we duplicate systems when parked: so why not when the over the road does fail . Why not beef up the one we have to have when parked anyway. Just thinking of the over all cost thing.  In my case I did not have over the road working air . On the 98 I do have the smaller drivers air and will retain it.   Bob
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« Reply #8 on: May 02, 2011, 12:31:36 PM »

My OTR air was not working and the estimates to fix it or even just recharge it were more than a roof top.  Plus the unknown of maintenance - I know some have been running them and not had problems, but mine was broken so proof that they stop working...  I also wanted the bay space, the space in the engine compartment, I wanted to lose the weight, and I spend roughly 10 times the time in the bus stopped as I do with the main engine running so I needed AC for that time anyway, and I saw no reason to duplicate systems.

I'm not saying those who keep and maintain the OTR air are wrong, it just didn't add up for me.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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« Reply #9 on: May 02, 2011, 02:02:08 PM »

The advantage to rooftop units is that they are reasonably priced, don't take up space, easy to replace, and are dependable.  The disadvantage is that many do not like the appearance, they add to roof height, and are noisy due to high velocity fans.  There is such a thing as ducting rooftops to reduce the noise.

If the OTR AC is working, use it.  Why dispose of a good working system?  However, if and when it fails, it may not be worth fixing.  Therefore, consider designing your house AC system to be adequate for the road also if you should need it.  Whatever unit you use for the driver area should be discharging air right in that area.  Many place the unit too far back to be efficient.  You do not want that cold air to have to cool you from an eight foot distance.

As several have noted above, there are also options to put your units in a bay and duct the air where you want it to go.  This is a bit more expensive than rooftops, may involve more maintenance, but is certainly a more refined option.

Whichever system you decide on, you will need a generator, so keep looking.  In a smaller coach, a generator adequate to run one AC may be okay.  You would be best off with one that could run everything, but running two AC's is probably a minimum.  This is not to say that you can not start with a smaller generator now and put a bigger one in later.  However, if you do that you should size and wire for the bigger unit of the future.  Picking a generator brings up a whole bunch of other options though, and although in many cases you can approach one project at a time, AC, power, and space are not things that can be treated as totally independent. 

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« Reply #10 on: May 02, 2011, 10:32:42 PM »

If you go to a ductless mini-split heat pump of at least 13 SEER, figure on running about 1 KW per ton(12,000 BTU) of capacity, heating or cooling. R410A refrigerant will get you heat down into the teens F. If you go for the more expensive units, they will run quieter and work down to 0 F.

They need a lot of room directly in front of the indoor unit in order to work right. Placing one in a coach will take some careful planning but will take less than 1/3 the electricity that resistance heating would require. There are inexpensive units that will work from 10 to 115 F, so they will cover a lot of your heating and cooling.

One of our busnuts used a step up transformer to run a 1 1/2 ton 230 volt unit in his coach running on a Trace SW inverter. Last I heard, he liked it.

Tom Caffrey
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Tikvah
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« Reply #11 on: May 03, 2011, 04:18:14 AM »

A couple more questions.....  and thanks for so much good input for each of you.
What does "SEER" mean?  Do I look for a higher number or lower?
Because of the input, I'm considering a couple options.  One hasn't been discused much yet, what about installing a central heating/cooling system with ducts?  What type of system is available?  There seems to be enough space if I ran ducts in combination of through the bays or through cabinets inside.
Also, I'm considering a Ductless system up front with heat/cool, then a couple roof top units in the center of the bus and the bedroom.  The ductless system would be quieter and more comfortable for the living area and the driver when moving.  But the roof tops might be fine in the bedroom or kitchen areas.

I didn't know it was possible to get 220 volts from an inverter.  That seems like in interesting thought.  Maybe this should be a different thread, but how far do you go with batteries and inverters?

Anyone use the existing ducts in the bus?
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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
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« Reply #12 on: May 03, 2011, 05:50:38 AM »

The SEER number has to do with efficiency, the higher number the better. The unit you linked at the beginning of this thread has a SEER rating of 13. I wouldn't want to go any lower than 13, and IIRC I haven't seen a rating above 19. Usually the higher the SEER the more you will pay for the unit.

Can't comment on the rest of your questions as I am still in the learning mode, too.

Mike
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robertglines1
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« Reply #13 on: May 03, 2011, 07:29:59 AM »

Unless your is a very rare exception those ducts will be nasty from years of use; and take up needed floor space(Stock ducts that is)running new ducts in a bus is a real challenge (I have done it) It is much simpler to just run the copper ac lines than to run large metal supply and return ducts. size and flexibility is the major factors here. Secondary is loss of efficiency by ducting air thru the bay area that would not necessarily  have to be air conditioned or heated as the living area would.  just food for thought.
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« Reply #14 on: May 03, 2011, 02:12:04 PM »

I have a 4ft transit with big windows.  I don't have dash air, so I use three 13,500btu/hr Colemans.  The front one is mounted forward enough to blow directly on me.  Usually running down the road, running the front and back is enough (hottest I've been in is 108F).  When running my 10kw while driving, it usually knocks off about a half mile to gallon.  But they do work well.  Having roof tops are the cheapest and easiest way to go.  Nearly every RV outlet carries them and they only take about an hour to swap out.  I've seen the 13,500btu's around the $600.00 mark-far lower than any split system. 

By the way-if a split system goes out on the road-how do you get it fixed.  Stick with the roof tops-much easier.  I'm using two Duotherm Penquins that I will modify to be mounted in the basement with ducted vents.  Good Luck, TomC
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« Reply #15 on: May 03, 2011, 11:34:01 PM »

  My intent is to go through the OTR system and compressor enough to know its mechanically sound, replace any needed mechanical parts, seals, gaskets, o-rings, rebuild the hoses, etc., and likely convert it to 134a. My understanding is the load valves on the heads can be adjusted to derate capacity. I should be able to make it drop out two banks once its cooled down. In any case, the compressor responds to cooling load, and as the max load will be greatly reduced, due to better insulation, less glass and less people, I should be able to cut the power consumption considerably. And with a greatly reduced capacity I could reduce condensor size a bit. I also believe I can put a magnetic clutch on the compressor, I have to look into that.

  With a thinner condensor, I hope to place a second condensor of about 2 tons capacity against it. Inside the HVAC housing, I hope to slip in a second AC evaporator. Then I can remote mount an 120V 1 1/2ton compressor and again set it up on 134a. This would give me two seperate AC systems that I can repair and service myself.

  The next obstacle is the HVAC and condensor fans. Combined they draw over 110 running amps, possibly over 5 HP at the engine feeding the alternator. I should be able to cut CFM at the condensor by at least half, and simularly in the HVAC compartment. Im hoping to use pairs of axial ducted fans in both locations, which should drop consumption considerably.

  Once operational, the roof airs can come down and be replaced with crank out roof vents and vent fans. I cant say it wont use less fuel than running a generator, and I cant say the loss of drag getting the roof clean will help fuel consumption either. But the Bus will look better, the AC will be much quieter, the cieling wont have things poking down to whack my head on, I can fix it myself, and probably some other plusses I cant think of yet.

  OT. I dont know if I can make this work, but with the centrifugal fans in the condensor bay gone, and pancake fans on the condensor, I believe ill have enough room to cram the genny into that bay and remote mount the radiator. 

 
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« Reply #16 on: May 05, 2011, 07:27:32 AM »

You might consider mounting the generator elsewhere.  To many heat producing items to mount in the A/C bay.  The generator should have its' own area-big enough so you can put a nice sound enclosure around it.  Remember-there is no such thing as a to quiet generator!  I've been to bus conversion get together where the generator is just mounted behind the A/C grill, or in the engine compartment on the right side where the OTR A/C equipment used to be without a sound enclosure.  Believe me-you can hear it-so much so, my wife and I were running my generator, my roof top A/C, and watching TV in the back and could still hear the generator of our neighbor that was about 75ft away.  The owner of that noisy generator couldn't hear it since his hearing was almost completely gone-do figure!  Good Luck, TomC
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« Reply #17 on: May 05, 2011, 07:36:14 AM »

You might consider mounting the generator elsewhere.  To many heat producing items to mount in the A/C bay.  The generator should have its' own area-big enough so you can put a nice sound enclosure around it.   I've been to bus conversion get together where the generator is just mounted behind the A/C grill, or in the engine compartment on the right side where the OTR A/C equipment used to be without a sound enclosure. 

Where do you suggest installing the generator?  If I put it in a luggage bay there wouldn't be enought air flow?  Right?  Or is there another way?
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1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
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« Reply #18 on: May 05, 2011, 08:21:52 AM »

  Its a pretty small Generator, and without the Radiator in there will take up even less space. I believe I have enough room to encapsulate the generator and still provide access.

  My first effort will be to bench test the Gen in the layout im considering, then to see how difficult it will be to place it in that Bay. We'll see.
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« Reply #19 on: May 05, 2011, 09:28:06 PM »

Art,

There are many designs floating around for home made "roll-out slides for the gen.  Dallas had a really nice one that he designed and posted.  Mount the gen on shock mounts.  Mount the shock mounts to the slide.  Mount the slide through the high density particle board to the frame.  A layer of lead sheeting inside the box or better, between two layers of the particle board.  Egg crate typw foam gets glued and stapled thru the lead to the wood box.  You still need air flow so both ends of the box are a plenum with a 180 degree air flow reversal built in.  Use a squirrel cage to move the air cause the duct with the 180 will resist air flow and reduce the efficiency of a bladed fan lots.  I would suggest mounting the exhaust muffler inside the box and operating/controlling the fan with a thermostat so it would run till the box cooled after use.  CO, CO2, heat and smoke sensors that will turn of fuel and elect when alarmed.  Sprinklers?  See RVSAFTYMAN for fire suppression and alarms.  You may not be able to afford or even want all of this but it makes interesting ,........!  Mount your exhaust so the pipe exits the under-coach area where you can run a 2 inch pipe up the side to deflect ex noise and gasses over your and your neighbors heads.  Insulate the bay door heavily.  I would put a small rad fan in there to keep all the air properly stirred although the circulating air fan should keep it stirred.  I am anal about this stuff. 

Terribly interesting....thanks,


John

See other posts for the name of that high density wood sheeting and it sure as heck is not "Particle Board".
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