Air Conditioning - Inexpensive, effective, but time consuming

[edroelle]

After reading some air conditioning posts, I thought I would share my experience.

Most individuals would not want to take this approach.  But, I am continually amazed at the creativity, perseverence, and hard work of bus nuts.

Since Nick is the expert, he may want to weigh-in on this. 

I preferred not to have roof top A/Cs.  But, I desired an effective, but inexpensive, system.   I had more time than money.   I had heard that RV air conditioners were overrated, but household unit capacities were not exaggerated.

After reading some A/C books, and actually discussing with the author who was a bus nut, I was confident to give it a try.

Although my solution operated excellent, it did take considerable time to install.

I obtained two 14,000 btu, and one 12,000 btu, 110 volt, household window air conditioning units.   I split the units and installed two compressors and condensers in the old condenser area of my MCI 8.  The third compressor and condenser went on the curb side of the engine compartment.  I built an insulated box to prevent engine heat from effecting the performance.  I then installed the evaporators in cabinets, under a dinette seat (air ducted to ceiling), and in an end table.   I silver soldered the now separated A/C components, with new A/C line sets that were one size larger than was used when distances were short.  110 volt and thermostat wiring was completed.

I then purged and checked the lines for leaks with a rented bottle ($20.) of nitrogen.  I borrowed a vacuum pump and evacuated the system.  This minimized the time the an air conditioning service man was here.  A local household A/C company finished the evacuation and filled the A/C lines for $100.

In all, the systems cost about $600. total, and met my objectives.  We used it in 107 degree, high humidity, a couple of times and the A/Cs cycled!  I know the system in my new bus could not do that.

Ed Roelle
Flint, MI

[Sojourner]

That what I call a true RV A/C system without wasted space to highest efficiency at most if you wrap small line (high-side) to keep it hot.
Of course it took time but well worth it to "have it your way".

Thanks Ed for letting your ways be known. Again this is a Split-Air/Cond. system only in custom made arrangement to compact it.

PS...that what I am going to do mine when that time come.

Good to hear you again.

FWIW

Sojourn for Christ, Jerry

[TomC]

As far as wrapping the freon lines, I thought that wrapping the high side would keep the pressure higher since your trying to get rid of as much heat as possible (higher pressure is not good-puts more strain on the compressor).  By not wrapping the high side, you'll further allow radiating heat to escape (like an extension of the condenser) thus decreasing system pressure making the A/C more effective in higher temperatures.
If you wrap the cold return line, it insulates it from the outside heat helping to retain residual cold to send back to the compressor (that's how the compressor keeps from overheating) and also lowering the pressure in the system.  I did that on a home made A/C system in my truck and could really feel the difference-especially in hot weather.
Nick-comment?  Good Luck, TomC

[HighTechRedneck]

As far as wrapping the freon lines, I thought that wrapping the high side would keep the pressure higher since your trying to get rid of as much heat as possible (higher pressure is not good-puts more strain on the compressor).  By not wrapping the high side, you'll further allow radiating heat to escape (like an extension of the condenser) thus decreasing system pressure making the A/C more effective in higher temperatures.
If you wrap the cold return line, it insulates it from the outside heat helping to retain residual cold to send back to the compressor (that's how the compressor keeps from overheating) and also lowering the pressure in the system.  I did that on a home made A/C system in my truck and could really feel the difference-especially in hot weather.
Nick-comment?  Good Luck, TomC

Tom's is the way I've always understood it (or think I understand it).  I look forward to reading Nick's response.

[jjrbus]

I must have read the same article. I bought a new unit 6000 btu's and tried to do the same thing. I ran into a problem with the tubing between the units. The size I needed was not available. I was told by 2 people at refrigeration places, if it is too big or too small it will not work. The size I needed was not available. So I scrapped the whole thing!
If memory serves me right at refrigeration places they have calculators that can tell you the size tubing you need between units. Maybe Nick can pitch in on this.

[Nick Badame Refrig/ACC]

Hi Ed, and all,

I love this thread..... I'm on a ferry and with real bad connection. I posted my answer twice allready and lost it.

When I get home I'll do it again guy's..

Nick-

[Nick Badame Refrig/ACC]

Hi Guy's, I'll try this again.

Splitting window/wall units is something my father did back in the 70's in his 4104. It worked very well but,

the price to pay is that theese units are not designed to operate in a moving enviroment. The units with the scroll compressors

will hold up better then the harmetic's. Another draw back is the drain pans are not engineered to drain in 2 places like the

RV styles are. It's possible you can ruin some interior finishes by water damage.

The issue of insulating the refrig. lines is also a sticky subject. Liquid lines are only insulated when you have a installation where

the liquid would super cool too much before it reaches the orfice. This usually only happens when your liquid line is longer then 50 ft.

Under normal conditions, you want super cooling, [thus the purpose of the condencer]. Insulating the Suction line is mandatory

because you want that cool vapor to reach the compressor to help cool it.

For a bus installiotion, just use the size copper that the unit was built with unless you might be more then 25 ft. which I doubt...

Good Luck Guy's
Nick-

[H3Jim]

Kind an alternative route.

I think one of the main percieved drawbacks for the roof airs is that they are ugly, and visible. Other than that there is a lot going for them.  I got the low profiles - not as bad looking, and I put lateral arm awnings on the roof line, front to back, both sides.  When you you standing anywhere near the bus, you can't see the vents, the solar panels or the air conditioners at all.  Nice clean roof line. 

So if any of my units go out, it would take less than an hour to replace them.

[jjrbus]

The problem I ran into was the copper line between the units was some oddball Chinese size. Unavailable in the US.

[Nick Badame Refrig/ACC]

The problem I ran into was the copper line between the units was some oddball Chinese size. Unavailable in the US.

Hi Jim,
Thats ok, just get the closest size in sae, as long as you are not near the "orfice/tx valve" you will be ok.
If you have swageing tools you can change that chinees end to a 3/8 ot simular then silver solder.
Nick-

[Melbo]

I just finished installing a window "split system" in my bus this friday. What I did is buy two window units and then plumbed between them and wired between them and put the condenser half in the engine compartment on the street side and the other unit will be under the bed when I build the frame. I did it so I could use the ac from the inverter when I am parked just to cool the bedroom. I only just finished the installation today -sunday- so I have not had a chance to fire it up and check the amp draw. I am hoping it will be less than 5.2 amp which would make it possible to run it all night from my battery bank and not have to run the generator at all for the evening. I don't plan to use this unit at all going down the road in fact I am making a cover for the back so any misc dirt and oil etc will not get on the coils. I am glad to hear that others have done the same thing makes me feel like I am not the only " NUT " out there.

Melbo

[Kristinsgrandpa]

   I'm not sure how much you have invested in an efficient system like that (I really like the way you did it without wasting bay space) but I only paid $300 each for my 2-15,000 btu mini-split heat pumps that heat and cool.

At that price they should last at least 20 yrs.

Ed

[Don4107]

Ed, where did you find mini splits for that price? 

[captain ron]

Cough it up Ed

[TomC]

What do you do about the fan motor?  Typically those inexpensive window units (for that matter most window units) only have one fan motor that has two shafts-one for the condenser and the other going to the evaporator.  Which do you keep intact (my instinct would be the condenser fan and rig up a squirrel cage blower for the evaporator inside)?  Good Luck, TomC