AC Hacking a Figidaire 5000 BTU

[Shadow Catcher]

I just completed the adaptation of a 5,000 BTU Frigidaire to work with Compass Rose. This was actually a very inexpensive process as I used a close out Frigidaire 5000 BTU that I picked up end of season at Lowes for $50. I had an adapter made to handle a 4 inch ducts by one of the local heating and air conditioning contractors. I had originally thought of using a rather fancy digital thermostat but found that making it play well with the air conditioner was not going well, plus every time it was unplugged I would lose all the settings. What I ended up doing was pulling the thermostat out of the AC unit and mounting it and on off switch in a RadioShack project box. Wiring is very simple because with a thermostat all I'm doing is hooking into the existing wires that control the AC unit, and the power switch basically interrupts the off, cool, fan speed switch. I figured that the unit would be on high cool all the time, or off as I am pushing air through 4 inch flex duct. Control wires are connected using Anderson power poles and run through the air intake duct. The ducts run through four-inch Marine deck plates in the side of the trailer.

One of the things I did not cover was how I came to the conclusion I needed a 5,000 BTU AC, I can not find the original website I used for the calculations but have tried this one http://www.calculator.net/btu-calcu...e=50&temperatureunit=f&calctype=heat&x=67&y=9 and came up with the same result more of less. One thing to remember is that you have six exterior exposed surfaces, more or less, cabinets...

I ended up having a serious problem with the initial set up and that was icing and the discussion of that is much later in the responses on page 3. The solution however was quite simple, I added in a 4" marine bilge blower rated a 240 CFM and this has taken care of the problem. The pictures are at what is currently the bottom of this first posting. I do need to refine how this goes together and I will edit the final solution. my feeling is that I can reduce the speed of the blower and the noise produced and now that I know that it works shorten hose and route wires neatly and efficiently.

This is the electrical guts, VERY simple, Note the absence of the thermostat.

Here are the housing and adapter prepped for paint.

This is the inside of the adapter. Note the felt strip to seal the opening to the AC

The duct is the same one I used for the diesel heater good up to 450 degrees and you can see the plastic reducer wrapped up with closed cell neoprene to achieve a watertight fit.

Here is the finished adapted unit plugged into a GFI outlet. Note that the AC unit can sit entirely underneath the trailer.

On the anterior I used standard RV type duct outlets that have a wide enough spacing to allow me to run the control cables through. And yes I need to box in the outlet.

This the version II of the computer case fans. There is enough room between the fans and the event that they can be left on and help circulate the air within the trailer so that you don't get stratification with the cold air sinking to the bottom.

Here is the AC control on off and temperature, where it will end up is still open to debate and it will probably be attached using Velcro.

Deck plates

AC unit with handle

Bilge Blower

Blower in line.

Crossroads of America Gathering was the real life test of the system with temperatures in the upper 80's high humidity and no breeze. Saturday night it did not cool off much and we left it running all night. Come morning it was covered with condensation and you can see that.
The bilge blower is three speed, full, and with the use of resistors in the negative line, medium and slow. I found that the slow was sufficient to overcome the restrictions in the air movement enough to prevent freezing. My next step will be trying a PMW to regulate speed. The resistors get HOT and while I sandwiched them between a couple of pieces of aluminum to help dissipate that I hate wasting that much energy.

The latest is that I wanted to see how it withstood weather so left it attached and running and exposed during a thunderstorm with no ill effects. The PMW works great for regulating the blower speed, until you cross wire it, I will be getting another one this week.

 

[caseydog]

Like Petcool, only a lot less expensive -- and probably better performance.

CD

 

[eamarquardt]

Verrrrrrry cool. I frequently have sheet metal things fabricated at a local shop. I'm impressed as to how little they charge for my custom projects. I agree with CD probabaly better than a pet cool and for far less.

You have raised the bar on "cost effective" air conditioning.

Cheers,

Gus

 

[Synthesis]

Awesome job!

I have been looking for "port holes" for my tongue box mounted AC unit that I am in the process of building. The marine deck plates will fit the bill perfectly and still allow me to remove my tongue box any time I see fit.

Great job, and TY for the ideas.

 

[Shadow Catcher]

caseydog MUCH less expensive than a Pet Cool and it actually works. The weather had cooled down so have not been able to really test it out but for the time it did run I noted a good bit of condensate which our PC never did.

Gus I was surprised how little it was to have it fabed up less than $60 as I remember and there is no reason you could not make one using wood or plastic. I figure I have about $150 or less minus the AC unit into this.

Synthesis the deck plates are an awesome design but what was scary was drilling 4 1/4 inch holes in the side of the tear. The vents were 4 inches so there was a bit of a gap which I caulked.

 

[eamarquardt]

I picked up an a/c unit at Costco a while back. Currently it's in the attic awaiting mods. I had in mind to do exactly what you have done. Now I can follow your excellent example.

Due to my ongoing issues with the "suicide disease" (I love saying that, but it's true), the fact that my friends are "dropping like flies", my son graduating from college tomorrow (thus increasing our discressionary funds by approximately $2k/month, YEA!!), many projects at home, etc, etc, etc, I purchased a Little Guy used this week. Suzy, to her credit, got over it in record time. I've ordered brakes, have removed the stove and sink in the galley in prep for adding shelving, and will be on the road to Seattle in July (with my brother as co-pilot).

Cheers,

Gus

 

[Shadow Catcher]

Gus
I tried to make this as complete a "How To" with out going into excruciating detail as I could. Most of you can figure out what I did but I know I suffer from a good case of "I know what I did" that there may be essential details missing.
I still have not figured out what I am going to do for a handle. The sheet metal is too thin to just slap one on so I have to come up with something made hopefully from some of the scrap I have lying about.
I love being able to use some of the accumulated bits and pieces of this and that. The handle is now on and consists of one 4' piece of all thread with two cuts and threaded through a channel on the bottom of the AC and a section of old aluminum tent pole and a couple of pieces of ~1 1/2' wide aluminum tread plate. The assembly is angled to hit roughly the balance point for the AC.
Tom

 

[CliffinGA]

Tom I like it alot! This may save me a headache with havbing to decide to cut my bulk head to install the a/c. I will probably ask more questions tonight when I get back home.

Cliff

 

[Shadow Catcher]

I have just added two additional shots one showing the deck plates and the other showing the handle. Balance point is on the side (the compressor is there) so it is an easy carry.

 

[bdosborn-SMB]

Tom.

Did you separate the supply and return air in the adapter on the front of the A/C? You should add a picture of the inside of the adapter if you did. That's a great alternative to the just-too-darn-expensive Petcool with more cooling capacity to boot.

Bruce

 

[Shadow Catcher]

Bruce, yes they are separated and I will take it apart a get a picture. I also want to add an extra layer of insulation inside as there is a cold spot that is sweating on top. One of the beauties of this set up is that fixing or replacing the cooling unit is simple and relatively inexpensive. I may look for a close out next fall, I got this one for $50 dollars a year and a half ago.
I am also thinking you can regulate the level of cooling by using longer or shorter ducts and insulating or not to keep the unit from short cycling and not adequately dehumidifying.
Because there is no hard attachment and what sound there is, is broken up inside the hose it is super quiet.

 

[bdosborn-SMB]

I am also thinking you can regulate the level of cooling by using longer or shorter ducts and insulating or not to keep the unit from short cycling and not adequately dehumidifying.

Why bother with that, I like your thermostat rig better.

Bruce

P.S. I bet you could put a hair dryer element in the cover and make it heat as well as cool.

 

[CliffinGA]

Tom where did you get the ducting your using? Are you using styrofoam to direct the air in the box into the outlet? Where did you get the deck plates at?

Cliff

 

[Shadow Catcher]

The ducting was a left over piece that I got from a supply house in Toledo that specializes in hoses. However finding 4" duct is easy, as an example Lowse's has IMPERIAL "Flexible Transition Duct" and a more rigid dryer vent hose.
The box is galvanized sheet metal made up by a local HVAC shop and the internal baffle is also metal. Watching the gentleman who built it you appreciate the level of skill involved.
The deck plates came from Jamestown distributors who I also bought lights and hinges from. They are the twist and lock http://www.jamestowndistributors.com/us ... Deck+Plate

 

[Shadow Catcher]

I have added a picture of the inside of the adapter.

 

[Harold Butler]

Justin, Thank you, this is just what I need to do to adapt mine. many thanks and also I had a great time at CCG, sorry I did not get to look at your Teardrop closer. However I do know it is a Beautiful Teardrop that you and Mike put many hours of Hard Work into!!! [/b]

 

[humbird-SKO]

Shadow Catcher, thanks for posting this. I just picked one of these up today and I was not looking forward to searching for the old posts where I saw similar setups.

Do the hoses stay in the holes? I have vents in my doors already (see my album if interested). But they have screens in them so they're not as deep, I couldn't fit a longer hose/reducer like you have.

I'm wondering how this would work if I rolled the a/c unit under the trailer and hooked one hose to the port in each door. Getting in and out might be problematic

 

[Shadow Catcher]

If you look at the fourth picture down you will see that one end has a PVC pipe reducer and around that is closed cell neoprene insulation that I found at the place where I obtained the reducer. The inside RV vent has a slightly small ID than the deck plate and the neoprene means a water/air tight fit.
All I have to do to switch to the Diesel heater is change to the 3" sewer pipe adapter.

There is a lot of flexibility in the hose and I can see how you could have the AC under the trailer (ours will be in bad weather). One of my concerns was restricting flow of air to the point where the unit ices up and the plan is that if this happens I will put a 4" bilge blower in the air return line.

The deck plates are not expensive, I am looking at my spare and it was $7, the inside vent can direct the air with a turntable louver.

 

[humbird-SKO]

Have you had it hooked up under windy conditions? We were recently in Texas and experienced what they called a "breeze", lol, something easterners would call a gale. I would be afraid my hoses would blow loose if I didn't attach them firmly.

Those deck plates are a great idea, and you did a very nice job on installation. I reaally wanted to use the deck plates with the clear lens in my door vents so they would double as little windows but I went with redundant flaps so they could be closed/opened from the inside. Also because it would take all of two days before I lost the covers that weren't attached.

 

[Shadow Catcher]

Not yet.
The ends are a tight fit. It has been cool enough that I have not really tried it out yet. The trailer is in getting its frame reinforced, the first Mega-Mini failed according to the owner at the tongue, and with our maiden voyage I felt there was way too much flex.
Oh and those winds, around here we average a 15 MPH and then there are the tornado and straight line at 60 MPH.