AC Hacking a Figidaire 5000 BTU

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Re: AC Hacking a Figidaire 5000 BTU

Postby Socal Tom » Fri May 12, 2017 12:21 pm

2manytoyz wrote:My question on thise fans would be at what static pressure are they producing that airflow. A 5" flex duct only carries about 50 cfm at .5 in/wc if the static rating for those fans is near that then you will potentially shorten the life of the fan considerably. I do residental and commercial hvac for anliving and a 5000 btu unit (.417 ton unit) by industry norms needs about 167 cfm. Am i missing something that is radically different with using this type of unit as I am planning a similar design for my camper.

Brian

How long a run are your numbers based on? my guess is 100ft. Mine are only 5ft long, so a much higher CFM would be expected. The A/C units cost about $100 and they last for years under the short term conditions like these. If static pressure is shortening their life expectancy its not enough to show up under these conditions. According to the manufacture of mine the fan puts out between 111 and 136 cfm. I suspect that fans in these units are designed to push pretty hard, given that they have to suck across a pretty tight coil and then blow the air across the room.
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Re: AC Hacking a Figidaire 5000 BTU

Postby 2manytoyz » Fri May 12, 2017 1:21 pm

Good to know they are holding up. I really didnt want to spend the coin on the coleman mach 8. Static and air flows are based off a 25' flex duct.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Fri May 12, 2017 8:27 pm

The Atwood 4000 bilge blower is rated at 230 CFM 125 CFM in system. I have ours hooked up to a PWM to adjust speed and have it running at about half power which is enough to keep the coils from icing. My bet is that it is making up for resistance in the hosing and keeping the air flow at 125 CFM give or take.
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Re: AC Hacking a Figidaire 5000 BTU

Postby 2manytoyz » Sat May 13, 2017 7:25 am

Good info I was thinking I was going to have to use a freeze stat to keep it from icing. I realy like the adjustable speed idea. Being able to slow the air down to just above freezup would help with dehumidification.

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Re: AC Hacking a Figidaire 5000 BTU

Postby Socal Tom » Sat May 13, 2017 12:08 pm

2manytoyz wrote:Good info I was thinking I was going to have to use a freeze stat to keep it from icing. I realy like the adjustable speed idea. Being able to slow the air down to just above freezup would help with dehumidification.

Brian

I still believe that setting up the return in a "cross flow" configuration is less likely to ice up. Unfortunately it doesn't get humid enough here in socal for me to prove it. I'm still using a cardboard plenum, so clearly water isn't an issue for me.
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Re: AC Hacking a Figidaire 5000 BTU

Postby 2manytoyz » Fri May 19, 2017 11:50 am

Has anyone tried using either a transmission cooler or electric radiator fan? I was actually thinking about taking the condensong coil off so that i could mount it on the sidewall through a hatch wile mounting the evaporator coil under a cabinet. Should be pretty easy to design and build a shroud and new drain pan. Then add a grill for estetics a relay a transformer and a thermostat.

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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Fri May 19, 2017 6:54 pm

Brian
Part of my thinking was that there are many times when I do not want or need AC and an integrated AC unit goes with you. I have an identical 'head unit' should the current one fail.
I do not see that there would be a real problem with a split system and actually investigated a small engine powered unit using an automotive AC compressor.
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Re: AC Hacking a Figidaire 5000 BTU

Postby working on it » Fri May 19, 2017 7:35 pm

2manytoyz wrote:Has anyone tried using either a transmission cooler or electric radiator fan? I was actually thinking about taking the condensong coil off so that i could mount it on the sidewall through a hatch wile mounting the evaporator coil under a cabinet. Should be pretty easy to design and build a shroud and new drain pan. Then add a grill for estetics a relay a transformer and a thermostat.

Brian
  • I tried a 10" automotive cooling fan as a cabin mounted main fan, since I am car-centric, and I wanted an automotive/industrial/farm & ranch kind of overall appearance to the trailer. There were three problems using it: 1) since I wanted it suspended from an overhead shelf, it needed a protective cage around it (the blades are quite sharp, and dangerous), 2) the amperage draw was too high (at full power, it would consume 6-7 amps from a 12vdc battery, running it down to nothing, quickly), and 3) the noise level was too much (intended for use underhood, a radiator fan was never meant to be used in a quieter locale, like a trailer cabin). I just tested with a fan I had as a spare in the race car shop (of my friend), where I was building the frame and exterior. I only entertained the thought until I connected it, and quickly disconnected it, as the roar was too much for me, inside the 4x8 cabin. I bought a 120vac 10" fan, which used a fraction of the power, was much quieter, and had a protective casing all around the blades. Much better.
  • If you used a cooling fan remotely mounted, away from the cabin, then it would work, and also have the advantage of being waterproof. But, you'd still have a power problem. A transformer would be needed for converting park power to 12vdc to run it, without depleting your on board battery.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Tue May 30, 2017 7:21 pm

Don't try this at home :roll:
One of the problems with the AC on the ground is the fins on the AC take beating. I purchased a set of fin straighteners at my local HVAC supplier and did my best. A guard to prevent this occurring seemed like a good idea. There are four holes on the back of the unit which had screws, very short screws (this is significant). I stuck in a wire to check for depth, (also significant). Attaching the screen to the back of the AC two of the screws went in fine the third, the sudden release of potential coolth in a
hissing stream. :cry:

Note I do have a screen which is attached to aluminum angle which is attached using 3M VHB tape to the sides of the AC
148535
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Re: AC Hacking a Figidaire 5000 BTU

Postby sodatrain » Thu Jan 25, 2018 7:00 pm

This is really awesome stuff. :applause: I'm working on designing a Cargo Trailer Camper (CTC) that is 7x14.

I like the window AC because it's inexpensive and can be a smaller size (5000BTU) for lower power consumption. I don't really want to cut a huge AC sized hole in the trailer so I love the hose designs. I'm thinking about trying to build something like this but mount it on the trailer tongue and maybe even just have a straight shot for the ducts into the trailer. Assuming I can mount the AC unit, protect it, etc, that seems to me like a simple way to not have to worry about duct size/length/bends hardly at all right? 5" still seems like a good idea. Right?
--
My 7x7x14 Tandem Axel build thread: viewtopic.php?f=42&t=69731
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Re: AC Hacking a Figidaire 5000 BTU

Postby Socal Tom » Fri Jan 26, 2018 3:21 pm

sodatrain wrote:This is really awesome stuff. :applause: I'm working on designing a Cargo Trailer Camper (CTC) that is 7x14.

I like the window AC because it's inexpensive and can be a smaller size (5000BTU) for lower power consumption. I don't really want to cut a huge AC sized hole in the trailer so I love the hose designs. I'm thinking about trying to build something like this but mount it on the trailer tongue and maybe even just have a straight shot for the ducts into the trailer. Assuming I can mount the AC unit, protect it, etc, that seems to me like a simple way to not have to worry about duct size/length/bends hardly at all right? 5" still seems like a good idea. Right?

If I were to do it again, I would do 4 inchs for supply and 5 inch return, but I truly believe that if you do the sidewinder design, then you can probably do 4 inches both ways.
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Re: AC Hacking a Figidaire 5000 BTU

Postby rebar » Mon Jul 16, 2018 5:23 am

Shadow Catcher wrote:Don't try this at home :roll:
One of the problems with the AC on the ground is the fins on the AC take beating. I purchased a set of fin straighteners at my local HVAC supplier and did my best. A guard to prevent this occurring seemed like a good idea. There are four holes on the back of the unit which had screws, very short screws (this is significant). I stuck in a wire to check for depth, (also significant). Attaching the screen to the back of the AC two of the screws went in fine the third, the sudden release of potential coolth in a
hissing stream. :cry:

Note I do have a screen which is attached to aluminum angle which is attached using 3M VHB tape to the sides of the AC
148535


Ouch! Well at least it was only a $50 window air.. Did you report the refrigerant release to the epa? lol

Seriously, this is a great thread that should be sticky.

What a few of you are missing is that if you physically mount any of the window shaker components to or in the trailer, it will be allot louder feeling the compressor vibrations.

I feel the plenum adapter boxes shown on this thread are restricting air flow to much. If you built a square to round transition fitting from the rectangular supply air opening to the round duct, you wont have your supply air tumbling around in the plenum before its pushed around a sharp corner into the round duct. Attaching this transition to a hole in the top of the window shaker and blanking off the supply opening to the front removes one 90 degree internal elbow as well. The return plenum could also benefit from a transition fitting to keep air flow uniform over the evaporator coil instead of directing most of the warm return air to the center of the coil. The flex duct most of you are using also restricts the air flow because of the added friction especially in the bends. But Id bet if you used square to round transitions, freeze ups might not occur.

Time to sharpen up your triangulation skills or challenge you local tinner.
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Re: AC Hacking a Figidaire 5000 BTU

Postby working on it » Mon Jul 16, 2018 7:28 pm

rebar wrote:...What a few of you are missing is that if you physically mount any of the window shaker components to or in the trailer, it will be allot louder feeling the compressor vibrations.

I feel the plenum adapter boxes shown on this thread are restricting air flow to much. If you built a square to round transition fitting from the rectangular supply air opening to the round duct, you wont have your supply air tumbling around in the plenum before its pushed around a sharp corner into the round duct. Attaching this transition to a hole in the top of the window shaker and blanking off the supply opening to the front removes one 90 degree internal elbow as well. The return plenum could also benefit from a transition fitting to keep air flow uniform over the evaporator coil instead of directing most of the warm return air to the center of the coil. The flex duct most of you are using also restricts the air flow because of the added friction especially in the bends....
  • As I've stated before, I installed my 5k unit totally inside my TTT, not exposed to the elements, or subject to creepy-crawlies, or any debris found outside the trailer. It is firmly mounted inside a cut-out in the 3/4" plywood bulkhead, insulated and sealed-in with OSI Quad flexible sealant, taped over with multiple plies of foil tape. Everything is firmly supported with extra oak framework and struts, so there is no window (or woodwork) shaking going on. Though I added a high flow axial fan into the exhaust ducting, the entire exhaust system has fiberglass insulation covered with more layers of foil tape, so no vibratory sounds are transmitted from it. Ever been in a new motel/hotel room with a thru-wall A/C unit installed? It emits a (to me) quite pleasant hum while operating... as does my 5k "window" unit. Besides, I require a source of white noise to be able to sleep (due to tinnitus), and the A/C sounds also bring back memories of my early years, when all my relatives' homes had "window" units.
  • Concerning regulating the 4 types of air flow using A/C (output air, intake air, chassis ventilation air, and exhaust), the various areas are handled in these ways. The first two are inside my cabin, and require no separation, since the output air is directed upwards along the ceiling, then it returns via the floor area (reverse-convection, aided by the shape of my trailer's front sloped wall).There has been no icing-up, or interior condensation, when using the A/C, due to high flow rates (I use an opened vent w/computer case fan, and a small air circulator fan with up to 350 cfm). The chassis cooling is handled by ambient air (in the galley, supplied by external vent) drawn thru it by a quiet 120vac computer case fan, and the exhaust is totally sealed-off in a highly insulated 6" diameter flex hose, straightened out to extract the exhaust without much interference from the internal hose ribbing (aided by the 266 cfm axial fan inside), from a rectangular, right-angle "vent register boot" (modified to transition smoothly to the flex duct). I had problems while trying to make it flow out a sidewall-mounted, rainproof vent, but ended up just by using the vent as a cover, lifting up and away for full exhaust flow.
  • If I ever "hacked" a 5k window unit, I would use a large rectangular shroud covering the entire front of the unit (with a divider separating the intake from exhaust), connected to the trailer via a short rubber accordion boot/truck camper pass-thru gasket. The A/C unit would sit above ground level on a side-table secured as usual, so it wouldn't fall, and the exhaust and chassis cooling would be left to nature, not having to flow thru too small flex hoses. Just an easier solution to hoses. I wish I hadn't done my complicated exhaust duct, but instead, just use a short accordion boot to vent out mu closed hatch...I've thought about this easy-out method for awhile, now.
  • accordion boot seal.jpg
    accordion boot seal.jpg (153.03 KiB) Viewed 355 times
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  • *3500 lb Dexter EZ-Lube axle, w/brakes *27x8.5-14LT all-terrain tires (x 3)
  • *LED lighting, triple fans, Pioneer stereo *A/C & heat, Optima AGM, inverter & charger(s)
  • *extended-run, on-board, 2500w generator *Coleman dual-fuel stove & lantern, Ikea grill
  • *zinc/stainless steel front racks *more features to come!
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Re: AC Hacking a Figidaire 5000 BTU

Postby rebar » Fri Jul 20, 2018 5:40 pm

working on it wrote:If I ever "hacked" a 5k window unit, I would use a large rectangular shroud covering the entire front of the unit (with a divider separating the intake from exhaust), connected to the trailer via a short rubber accordion boot/truck camper pass-thru gasket. The A/C unit would sit above ground level on a side-table secured as usual, so it wouldn't fall, and the exhaust and chassis cooling would be left to nature, not having to flow thru too small flex hoses. Just an easier solution to hoses. I wish I hadn't done my complicated exhaust duct, but instead, just use a short accordion boot to vent out mu closed hatch...I've thought about this easy-out method for awhile, now.[*]
accordion boot seal.jpg
[/list]


Thanks. Here's another idea for your accordion boot seal.

The evaporator squirrel cage moves the cooled air upward, and then forces it around a tight 90 degree internal elbow to the front grill. In order to allow even more cfm to be moved, why not blank off the internal elbow, and cut a rectangular hole in the top of the window shaker? This would allow more cfm because we have omitted a inefficient short sweet elbow .. Then use your accordion boot rectangular "duct" to connect the new cold air supply hole on top, through the trailer floor to a plenum inside the trailer? Or a rectangle to round "boot" if you dont have enough room under the trailer.
Regular flexible Return duct is fine. Its the supply air that needs a easy slippery path, and with the above design, if you looked down the trailer supply plenum you would see the squirrel cage blower. Cant get much better than that and not have to worry about any other support booster fans.

Window shakers were never designed to be mounted inside anything other than a window, and will run hotter with shorter lifespan if not supplied enough fresh condenser air. From what I remember, the beauty of a window shaker design is that it uses one motor to move evaporator air and condenser air.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Sat Jul 21, 2018 5:16 am

My goal was to make this easily portable and while you can make this more efficient I have two four inch holes and left it home this last week while we were north of Lake Superior (ran the heater one night).
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