Wiring bus for 50amp 240 for mini split

[chessie4905]

Since all three are 15 k, how does the regular model compare to the heat pump version. Which do you like better? I plan on replacing my front one with a 15 k and can't decide which one to get.

[buswarrior]

Today, the heat pump version, provided it is a new, modern refrigerant model, and not some hold-over to older tech...

More heat/cooling often with less power consumed, important for those living on the edge of power management.

The dehumidify feature found on some saves the busnut turning on both AC and furnace on one of those damp days that the coach won't dry out, too cool for AC, too warm for the furnace.

Those old stories about "heat pump" models do not apply to the new ones.

happy coaching!
buswarrior

[Geoff]

Since all three are 15 k, how does the regular model compare to the heat pump version. Which do you like better? I plan on replacing my front one with a 15 k and can't decide which one to get.

My Coleman's are 15 years old, so the new ones may not have the few issues I have.  First of all, the heat pump units do not put out as cold of air as the one unit without the heat pump.  While this is a fact, the heat pump units still put out adequate cold air when in A/C mode.
The only issue I have with the heat pumps, is that they don't produce heat right away-- I have to turn them on and off several times to get the reverse flow moving to produce heat.  But when working they put out great heat.  I should add I seem to be the only one who has this problem.
--Geoff

[bevans6]

When shopping for a Mini-split heat pump, look for the higher end inverter motor units.  They use inverter technology to drive the compressor and evaporator motors with variable frequency three phase 240 volts so they are extremely efficient, run the fan motors and compressor at as low a speed as required for the load at hand.  I have a 12K btu model in my bedroom that I have to look at the light to see if it's on it's so quiet, and it runs between 1 and 2 amps most of the time.  They do take a minute or so to stabilize pressures to produce heat after they turn on, but no more-so than when in cooling mode.  In selecting a unit for home use you look for the heat load required for heating, since the temp delta is usually far larger when heating than when cooling - 25 degrees F to 70 degrees F for a 45 degree delta, compared to 95 degrees to 75 degrees when cooling for a 20 degree delta.  There is more to it than that, but the heating BTu's are usually a lot more than the cooling BTU's, so I have far more cooling capacity in my house than I need, and just enough heating.  I think that would be far more equal or even reversed for a bus.

Brian

[sledhead]

I have 2 old style roof a/c with the heat strip . on heat it is warm and fast but the first time you turn it on you smell the crap burning off the heat strips . the newer a/c we have in the bed room has the heat pump and DW hates the on off cycle of the compressor . so if needed we use the front 2 units for heat .

the new a/c heat pump split unit in the house is amazing for a/c we use the dehumidification system most of the time as it is so quite inside and outside you can't tell it is on . I have not tried the heat pump yet   

dave

[Jcparmley]

Today I purchased a brand new semi air deflector for only 150 dollars.  It's in perfect shape.  My plan build a shelf on the back of the bus out of steel and steel mesh and mount two mini split units.  I will use the wind deflector over the shelf.  The shelf will allow airflow from the bottom and perhaps I will cut vents out of the wind deflector to make sure there is enough air flow.  I could even put a air scoop on the top and will raise above the roof a few inches such as a ram air hood would do.  I posted a pic of an old bus with a air scoop like the one I envision.  For only 150 dollars I thought it was worth a shot to try.  What are your thoughts?

Is it possible to mount the outdoor unit inside the rear cap or even on the outside like this guy?

[Jcparmley]

This is just a rough example but it might look something like this.

[buswarrior]

You will have to pay close attention to build-up of debris/oil in the unit's fins.

Everything that goes under the bus, curls up and coats the back of the bus, dist, and anything that drips from the coach.

You've seen the oily backs of crappy charter coaches and some conversions?

Happy coaching!
Buswarrior

[Jcparmley]

That's a good point. I didn't think of that. I wonder if I place louvers on bottom if that would help.  Any suggestions on how you all would do this would be great.

[richard5933]

Any reason to not stick the thing in a bay? Seems awfully exposed to potential damage hung on the rear of the bus like that.

Inside the rear cap would make more sense to me.

[Jcparmley]

I am planing on using three mini splits.  Each one will be 12k.  The first unit will be above the windshield with the outdoor unit in ac bay.  The second unit will be in the middle of the coach where the bunk beds and bathroom is with the outdoor unit on the back.  The third unit will be in the bedroom with the outdoor unit on the back.  I thought about putting the two units inside the rear cap but I believe I read on this forum that there wouldn't be enough air flow.  Do you think two units can be placed under the rear cap?  That would be ideal if it would work. 

Any reason to not stick the thing in a bay? Seems awfully exposed to potential damage hung on the rear of the bus like that.

Inside the rear cap would make more sense to me.

[Lee Bradley]

I have a 18,000 btu unit over the driver and on a warm day (80 to 90 degrees) driving into the sun it is just keeping up. However my bus is a Neoplan Cityliner and the whole front is glass. Like these

https://www.google.com/search?q=neoplan+cityliner&hl=en&tbm=isch&source=iu&ictx=1&fir=hn5YVKscHF9oaM%253A%252CQrgO_CohKaxOyM%252C_&usg=AI4_-kQcvWbkaQc_qAqTpieviAkJQSgXLQ&sa=X&ved=2ahUKEwjomcj83oveAhXcFjQIHZs9BvQQ9QEwBXoECAUQDA#imgdii=VQRyy3YegzzT7M:&imgrc=hn5YVKscHF9oaM:

[richard5933]

If you're using a 240v mini split, then why do you need three separate outside units? These are designed to run multiple inside units from one compressor outside - we recently put a unit in my in-laws house (over 2500 sq ft) and ran four inside units from a single outside unit.

I'm not an a/c expert, but something doesn't sound right about the plan to put three separate outside units on one bus if you're running a 240v a/c system.

[luvrbus]

The draw back to multi zones from 1 outside unit if 1 zone is on and the others call for cool air or heat it greatly reduces the out put of the unit,they had that problem with the multi zones unit in Needles housing and needed to add another outside unit,in a bus it would probably be worse than a house   

[Jcparmley]

At first I was thinking about using a 240 unit and run three different zones but then reading this forum made me think twice.  I don't have any other appliances using 240 and I wasn't quite sure how to power it while on the road.  I only have a 3000 watt inverter 24 volt and it can't do 240.  Also, someone suggested using the Costco 12k units that only use 120 and use three of them.  The cost of three is still under the cost of one 240 that powers three zones.  The positive of that would be redundancy.  If one fails we don't loose all of our ac.  So then I began to think about where to put the outside unit and I saw a pic of someone who mounted theirs on the back of their MCI bus.  I hope that makes sense.

If you're using a 240v mini split, then why do you need three separate outside units? These are designed to run multiple inside units from one compressor outside - we recently put a unit in my in-laws house (over 2500 sq ft) and ran four inside units from a single outside unit.

I'm not an a/c expert, but something doesn't sound right about the plan to put three separate outside units on one bus if you're running a 240v a/c system.