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Author Topic: Need A/C advice  (Read 2140 times)
Uglydog56
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« on: October 09, 2011, 08:28:01 PM »

My crown currently doesn't have A/C, perse'.  Right now it has an air handler installed with ventilation to the berthing and galley, which I have determined to be a Rheem RCAS-A018S.  It is an R-22 unit with a 120v blower fan, which is all hooked up and installed and working.  The freon lines, however, are not plumbed.  Under the passenger floorboard is the compressor unit (my door was moved to behind the front tire).  It is not wired, nor plumbed as mentioned previously.  It is a Heat Controller, Inc. unit, for R-22, model MTR-153-S.  It is a 240v unit that requires a 20-25 amp breaker according to the name plate.

The front room is currently being converted from a work room to a living room.  It doesn't have any heat or A/C.  I was planning on the Soleus 12000 mini-split ductless.  Before I pulled the trigger on this, I decided to look at what I had, and see if it was still usable.

I am concerned about using a 240V compressor unit.  Although I am currently in the midst on changing the bus over to 50A service and adding an inverter/charger with battery bank, I don't know that I want the rear a/c to basically require constant generator runtime anytime I'm in a state park or anyplace that doesn't have 50A service - which is a lot of places.  Also, I read on here that R-22 has gone the way of the dodo, although the replacement gasses seem to be working okay.  But, I just don't want to spend 3 grand unless it's really necessary.  I'm just not an aquahot type of guy.

So, if you were in my shoes, and on a self-imposed budget, what would you keep, and what would you toss?  Is there a 120v version of the compressor unit I could change to?  I'm hoping to use your experience to prevent making an expensive mistake here.   I can't put roof airs on the rear two rooms - I'm out of height.  Additionally I would like to keep the roof clean if possible so I can put more solar panels up there.  I was thinking maybe I ought to change to an 18000/12000 or something?  Didn't want to buy the minisplit for the front, then find out I needed something different for the rear that I should have bought all at the same time. 

Thanks for your help.
« Last Edit: October 09, 2011, 08:33:17 PM by Uglydog56 » Logged

Rick A. Cone
Silverdale, WA
66 Crowny Crown "The Ark"
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« Reply #1 on: October 10, 2011, 02:29:30 AM »

I have been toying with the idea of using AC parts from a salvaged automobile. I could configure the oarts anyway I wanted because of the longish AC hoses. Everything is basically the same, with the exception of having a engine/motor to run the compressor.
My initial thoughts are this...pick up a system from a van with front and rear air. This gets you a condensor, compressor, two evap cores, two blowers, hoses, switches, drier. Use this system with an electric motor to run the compressor. The condensor I think is the only part that should be outside. Everything else I believe could be inside. This nets a "clean" appearance. Fashion some boxes to put the evap cores in, and a little ductwork, voila!
Boyce
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Boyce Rampey
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« Reply #2 on: October 10, 2011, 05:09:51 AM »

R-22 is gone, but there are sources for replacement parts & compressors for the foreseeable future, including enough R-22. R-12 has been banned for over 10 years but there is still a plenty of that around still.

That Rheem unit is 18K btu. Any condensing unit that produces 18K btu can be mated up to it. If you find something that is NOT R-22, you CAN change the metering device in the Rheem unit to something that matches the the new refrigerant.

The drawbacks to all of this is the unit you  have really isn't made for transport service. That said, neither are the mini-splits and there are people who are using them successfully.

The final decision is yours. How much work do you want to do? How much engineering can you do or have done at a reasonable rate? How reliable do you want your system to be?

Only you can answer these questions and weigh the tradeoffs involved.

TOM
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'82 BlueBird WanderLodge PT40 being rebuilt
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« Reply #3 on: October 10, 2011, 05:27:17 AM »

Tom: you bring up a good point about mini-split ac. They have been successfully used in air bag suspension coaches. Most if not all the guys I talked to before I jumped had soft riding coaches. I'm comfortable with my choice and my friend and fellow busnut MCI 8 tin tent has been running set up for over 5 years.   Bob
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #4 on: October 10, 2011, 10:20:39 PM »

Uglydog56, a 120 VAC  12,000 BTU mini-split heat pump will not require more than a KW of power, and it will give good heating down into the teens if it is R410A refrigerant. An inverter design will tolerate room size variations pretty well.

If you want specs, try the search term "ductless heat pump" on eBay. You should be able to track down one for $1,000 to $1,500, precharged, including lineset and shipping.

Good luck!

Tom Caffrey
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Tom Caffrey PD4106-2576
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Ketchikan, Alaska
Uglydog56
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« Reply #5 on: October 11, 2011, 11:07:14 AM »

Tom, I did just that. 

I took my outside unit to a shop here locally and sent some emails to the company and both agreed that it was obsolete and not really supported any longer, so i should pass on trying to use it. 

I looked at soleus mini-splits on ebay because someone else had used them successfully, and I think they will work for me too.  I have decided to rip out the existing air handler and vent ducting, along with the smaller of my two lpg furnaces.  I am going to install a 120v 12000btu ductless heat pump in the front room due to the extra glass of the windshield, and the minimal floor insulation in the front.  The rear two areas each have 3.5" of blown in insulation in the roof, 2.5" in the walls, and 3" of polyiscyrunate? on the floor.  So I'm putting a 9000 in the bedroom and kitchen areas.  I had looked into an 18000 dual zone for the rear, or a tri zone for the whole bus, but I still want to attempt sometime in the future to run the front one off the engine alternator/battery bank via inverter.  So that nixed the tri zone.  You can't get an 18000 btu dual zone without going to 240v, which I was still trying to avoid.  So I decided on 2 120v 9000 btu units for the rear two areas.  That way I could concievably run one or both when hooked up to 30A service, and run one or the other when on the genny to cut down my loading somewhat (I only have a 5k generator).  I think I have a plan for placement of the outside units underneath - we'll see once they get here.
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Rick A. Cone
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« Reply #6 on: October 11, 2011, 10:28:52 PM »

Hi, Rick.

I avoided the Soleus because the specs seemed to be a little shy of what I wanted. There are many available, so you can save some money on them. In a number of cases, they seemed to require an electric heater to make them work in cold weather. I wanted to avoid that.

I was looking to get good low temperature coverage, so the specs on the inverter models were a little more attractive. Some models carry ratings down to -4 F. Quite a few go down to 5 F. Some do not go below 14 F.

The ductless mini-splits were easy to find specs for; I didn't have much luck with larger units.

For what it's worth.

Tom Caffrey
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Tom Caffrey PD4106-2576
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Ketchikan, Alaska
Fred Mc
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« Reply #7 on: October 12, 2011, 07:49:57 AM »

What is the significance of it being an "inverter" type? How does that differ from non-inverter?

Regards

Fred Mc.
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« Reply #8 on: October 12, 2011, 11:43:50 PM »

Hi, Fred.

There are quite a few differences, but the main thing is that the inverter type has continuously varying compressor and fan speeds. Some have a speed range of around 3:1 and some have a speed range of around 6:1. The non-inverter type has a stepped indoor fan speed but the outdoor fan has a single speed.

In an 18,000 BTU unit, there is about 50 pounds less machine and the sellers claim that they are more efficient. I have not been able to support the greater efficiency by reading their specs, so I haven't bought any of them, yet. I had the feeling that the manufacturer may have kept for itself most of the benefit of the inverter design, so I have been unwilling to pay the extra money they want for them.

On checking with some of the makers, they have suggested that non-inverter faults are very rare; they report more failures with the inverter type.

We have 13 units operating in apartments so far, and they are saving us a lot of money in fuel.

For what it's worth.

Tom Caffrey
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Tom Caffrey PD4106-2576
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Ketchikan, Alaska
robertglines1
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« Reply #9 on: October 13, 2011, 05:28:06 AM »

Tom, I have both the only thing I have noticed is the start up load/surge in operation. and of course the ramp up in operation.  The 12 I have is non inverter and a light on the same extension cord(temp hook up) dimmed on start up.   The inverter type did not.   Just a observation.   Bob
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #10 on: October 13, 2011, 09:49:18 PM »

Hi, Bob. I have noticed a pretty good blink in the lights when one of ours starts. So far, we have never had any trouble on account of that, but I can see that a soft start like you describe would make it easier on a shore power hookup that might be running close to its maximum power.

I did see one reference to the ramping up that you describe, but I didn't know if it was typical of most inverter units. Thanks for the information.

Tom Caffrey
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Tom Caffrey PD4106-2576
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« Reply #11 on: October 14, 2011, 05:23:28 AM »

Spooky at first!! thought if was broke/no good...    MCI8 tin tent was there  hvac guy--explained it to me.
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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