10-20-12, 03:15 PM | #1 |
Supreme EcoRenovator
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cheap window reverse cycle ac build
Hello all, this will be my first thread on the site. I've been lurking for awhile, gleaning information and experimenting in the shadows. I've noticed that lots of people are asking the same questions I am regarding details in building simple, cheap units that actually work. So I'll be asking for input from you more experienced builders to try and sort out answers while building something that works like it should. Mind you, I'm not rich... in fact, I'm usually broke. So custom data acquisition loggers / computerized controllers / postage stamp solid state phasers are pretty much beyond the scope of this build. Not that this unit won't have controls, just not complicated expensive controls.
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10-20-12, 03:58 PM | #2 |
Supreme EcoRenovator
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The unit I have chosen to modify is a vintage GE window air conditioner. It was donated to me by my wife's grandma when she upgraded to something newer. Beige box with a brown grille, 110v, 12k btu. I'll post pics of it when I have enough posts, but I bet you've all seen one. Made in USA, built to last a long time, cheap and commonly available. Not much to look at, perfect for a hot rod project.
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10-21-12, 07:49 AM | #3 |
Helper EcoRenovator
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im sure i wont be much of help, but you have my attention.
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10-21-12, 08:11 AM | #4 |
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Sounds very interesting Jeff. I can't wait to see more.
What major modifications do you have planned in order to make this thing work efficiently as a heater?
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10-21-12, 09:07 AM | #5 | |
Lex Parsimoniae
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Quote:
It was able to heat up a small bedroom. But it wasn't really very cold outdoors.. I took the rig down to my basement and setup to heat a very small laundry room. http://i46.photobucket.com/albums/f1...heatOutput.jpg Sat the unit in the doorway and blocked the top with a blanket. It was cool in the basement (60-62F) and it heated the 8'x8' room up, over 10deg F.. My guess is, a good 12,000 BTUh window AC plugged in backwards, will give you around 12,000 BTUh of heat, when outdoor temps are in the 60s (or higher). But, as the outdoor temp drops, so will the BTUhs of heating.. It will stay on longer, so it will use more power to 'pump' the same amount of BTUhs indoors. Window type ASHP heater/coolers are selling now, but 40F outdoors is their limit. (On all of the ones I've inquired about). I think you will still get some heat pumped in, but when it gets really chilly outdoors, you might do better with a $20 1500w ceramic space heater or two.. In order to make this experiment work, I had to insulate the thermostat sensor that's normally found mounted in the center outside of the indoor HX coil (Evap). If I wanted to build a control for this hack, I would place a heater resistor on the AC thermostat sensor tube (wrapped with insulating tape) and apply heat to the thermostat tube, so the cold outdoors wouldn't keep turning off the compressor.
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My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 10-21-12 at 09:18 AM.. |
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10-21-12, 12:46 PM | #6 |
Supreme EcoRenovator
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xringer,
I did the same thing with my other vintage window rattler! It's a 9000 btu kenmore, pretty much a clone of the one in this project. It's proving its right to live in the sunroom window as we speak. I basically just reversed the connections to the compressor (the pipes fit inside each other when spliced), brazed a service valve to the factory crimp jobbie (bullet piercing valves are ok to suck out the cfc refrigerant but that's about it), and left the rest alone. Vacuum, purge, vacuum, purge, vacuum, refill w/ propane, run. As for the control, it has a bulb thermostat which has both no/nc contacts. So now the factory thermostat heats! Thanks Sears... they must have made 25 models out of this one frame... I did have to move the sensor bulb off the coil so it cycled less often. I imagine the original model had a strip heater someplace when equipped |
10-21-12, 01:08 PM | #7 |
Supreme EcoRenovator
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well... that pic didn't post. Lemme try another way.
When I had this one running backwards, err, like it was built, the evap coil froze up pretty fast when it got down around 45-50*f outdoors. Now that it has been reversed, it goes pretty strong until it actually frosts outside. Last night, it got down to 39 at like 95%rh. The unit was weeping but didn't freeze up. |
10-21-12, 04:50 PM | #8 |
Lex Parsimoniae
Join Date: Feb 2009
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Kenmores Rule!
I have an old 18,000 BTUh Kenmore (got used for $200) and it worked pretty well.
Might be a good candidate for the old SwitcheRoo on the compressor lines. But, since we already have some good performing Sanyo mini-splits, that brazing fun isn't going to happen. http://i46.photobucket.com/albums/f1...10breakman.jpg http://i46.photobucket.com/albums/f1.../10goofing.jpg
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10-21-12, 11:15 PM | #9 |
Supreme EcoRenovator
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Wow, I wish I had a nice shiny new unit like that to dissect! The warranty police would be pissed! I'd have that baby heating and cooling my house, making me hot water, and putting money in the bank every month! I'd have to build a cage around it so it wouldn't get kidnapped! Nice.
Ok, so I went to the barn today and dismantled the patient. It seems it has had prior surgery.Take a look: |
10-22-12, 12:00 AM | #10 |
Supreme EcoRenovator
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Here we have a way too big start capacitor PLUS a hard start kit.
The previous HVAC Dr. has done some hacking... one cap tube blocked off, the other merged into this... and on the other side... an expansion valve and monster-size compressor! With insulator hat missing on top! I googled the model number of the compressor and found it is rated at 15k btu! Running off 110VAC!! Is this possible? It used to go in a (pre-2003) Dometic RV rooftop a/c unit rated at 1530 running watts and 15K btu cooling... the manual says use at least a 3500 watt generator (so it can start) and 12 AWG power wires! WOW. It says use a 20 Amp breaker. The txv in this unit was rated at a whopping .75 ton! Now I think I know why the 1 cap tube was spliced in and the other one crimped off. Follow me here... .75 ton = 9000 btu. 1/2 of 12000 btu worth of cap tubes = 6000 btu. SO.... 3/4 ton worth of txv plus a 1/2 ton worth of cap tube = 1 1/4 ton = 15000 BTU??? Bobby Joe's Appliance Repair done gave grandma her money's worth, didn't he? I never would have guessed this would work! Ima gonna hafta ask granny about that. Wow. |
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