EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 01-25-15, 07:43 AM   #1
Semipro
Andy
 
Join Date: Jun 2014
Location: SW VA
Posts: 45
Thanks: 6
Thanked 13 Times in 10 Posts
Default DIY refrigerant recovery system

A follow-up on this post: http://ecorenovator.org/forum/38475-post4.html

A friend, a sort of alter ego, wanted to do the same thing as me. He needed to rearrange some of the mechanical systems in his house including the GSHPs. On the split system that serves his 2nd floor this would require that he break the R-22 lines. He called around to see what it would cost to have an HVAC tech come out and recovery the R-22. He got either total disinterest or absurdly high quotes.

He went to our local trash drop-off site and found an R-22 AC window unit that was being trashed. He fixed its relatively minor electrical problems and modified it to enable its use for freon recovery.

The mods:
- Installed quick taps one on either side of the capillary tube that is used for freon expansion
- Crimped the capillary tube with vise grips to create a near total blockage.
- Connected one refrigeration gauge set to the window unit suction port and the center hose to a port on the house's GSHP to monitor inlet pressure.
- Connected another gauge set to the window unit high side port and the center hose to a nearly empty R-22 tank set in a water bath.
- Started the window unit
- Open the valves on both gauge sets, watching both for excessively high or low pressures. Used the low side gauge set valve to meter how fast freon was pulled from the GSHP into the window unit.
- The WU outlet pressure never went very high, probably because the recovery tank was empty and the WU condenser fan was cooling the freon before it was pumped out.
- No freon was released.
- When the vise grips were removed the window unit started working almost normally again. Apparently, the copper capillary tube was elastic enough to open back up.
- I'm wondering now whether he really needed to clamp off the capillary.

Semipro is offline   Reply With Quote
The Following 2 Users Say Thank You to Semipro For This Useful Post:
AC_Hacker (03-10-15), Ron342 (03-06-15)
Old 03-06-15, 11:59 AM   #2
Ron342
Apprentice EcoRenovator
 
Join Date: Feb 2010
Location: Maryland
Posts: 120
Thanks: 26
Thanked 12 Times in 8 Posts
Default

What a slick way to put together a recovery system! With the quick taps you don't need to vacuum the window unit and don't have to mess with the iffy clamp on taps either. If you didn't crimp it though - wouldn't you have problems getting the low side low enough to get all out of the bled system?
Ron342 is offline   Reply With Quote
Old 03-07-15, 09:55 AM   #3
Semipro
Andy
 
Join Date: Jun 2014
Location: SW VA
Posts: 45
Thanks: 6
Thanked 13 Times in 10 Posts
Default

Quote:
Originally Posted by Ron342 View Post
If you didn't crimp it though - wouldn't you have problems getting the low side low enough to get all out of the bled system?
I wondered this too. If I was to do it myself I would give it a try without crimping the expansion line. This would effectively render the window unit unmodified other than the service ports.
Semipro is offline   Reply With Quote
Old 03-10-15, 08:00 AM   #4
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,394
Thanks: 410
Thanked 604 Times in 506 Posts
Send a message via Yahoo to jeff5may
Default

Quote:
Originally Posted by Ron342 View Post
What a slick way to put together a recovery system! With the quick taps you don't need to vacuum the window unit and don't have to mess with the iffy clamp on taps either. If you didn't crimp it though - wouldn't you have problems getting the low side low enough to get all out of the bled system?
There is a big difference between recovering the refrigerant and evacuating the system. This method will work well for recovery but evacuation should be done with a system that can pull a deep vacuum.

A working system will contain lots of liquid refrigerant. A rig like this should be able to remove all of it, then pull gaseous refrigerant out down to a very low pressure. There will be a very small amount of refrigerant remaining. No big deal. Just remember a couple of things:

1. Use a large enough recovery tank
2. Do not mix refrigerants (unless experimenting/hacking)
3. Be safe

Last edited by jeff5may; 03-10-15 at 04:48 PM..
jeff5may is offline   Reply With Quote
Old 03-12-15, 09:03 AM   #5
Ron342
Apprentice EcoRenovator
 
Join Date: Feb 2010
Location: Maryland
Posts: 120
Thanks: 26
Thanked 12 Times in 8 Posts
Default

My concern wasn't trying to evacuate the system but only whether the window unit, without a crimp on its cap tube, would ever be able to pull down near zero on its low side when hooked to the larger system it was bleeding. If it didn't you'd still have some freon release when you opened the larger system to work on it. Did you ever try it w/o the crimp Semipro?
Ron342 is offline   Reply With Quote
Old 03-13-15, 07:40 PM   #6
Semipro
Andy
 
Join Date: Jun 2014
Location: SW VA
Posts: 45
Thanks: 6
Thanked 13 Times in 10 Posts
Default

Quote:
Originally Posted by Ron342 View Post
Did you ever try it w/o the crimp Semipro?
See post 3.
The setup described was used for recovery only.
A vacuum pump was subsequently used for evacuation.
Semipro is offline   Reply With Quote
Old 03-14-15, 04:27 PM   #7
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,394
Thanks: 410
Thanked 604 Times in 506 Posts
Send a message via Yahoo to jeff5may
Default

If a large enough recovery tank is connected, a dehumidifier or air conditioner unit will pull down its low side below atmospheric pressure pretty quickly. A capillary tube doesn't care whether it is fed liquid or gas. As long as you keep the recovery cylinder cool and empty enough, it will literally suck the juice out of the high side.

The big thing not to do in this operation is flood the compressor with liquid refrigerant. If one were to draw from the donor system too quickly, the compressor could not keep up. Liquid would be ingested and all bets are off at that point.
jeff5may is offline   Reply With Quote
The Following User Says Thank You to jeff5may For This Useful Post:
Ron342 (03-18-15)
Old 03-18-15, 01:36 AM   #8
Ron342
Apprentice EcoRenovator
 
Join Date: Feb 2010
Location: Maryland
Posts: 120
Thanks: 26
Thanked 12 Times in 8 Posts
Default

Thanks Jeff !
So a safe way to start would be to tap both sides of the cap tube on the window unit without crimping the tube, hooking up the tank and system to be bled as suggested (does it matter where you tap the bled system and if its running?) Then run the wu til you see what hi and low pressures it stabilizes at, Then, before bleeding in from the bled system, bleed the wu down a little into the tank, then slowly open the low line to the bled unit while watching to keep the high and low pressures under what you started with til you're finally under atmospheric on the bled system???
I know this is basic stuff but some of us still have to go pee before opening .a refrigerant valve!!
Ron342 is offline   Reply With Quote
Old 03-29-15, 09:50 AM   #9
WyrTwister
Master EcoRenovator
 
Join Date: Jun 2013
Location: USA
Posts: 543
Thanks: 6
Thanked 44 Times in 38 Posts
Default

The R22 tank was put in a water bath ? Was ice added to the water ? Ice and salt ( like a home ice cream maker ) ?

I was thinking , the lower the temp of the R22 Tank , the better / faster it would receive refrigerant ?

Thanks ,
Wyr
God bless
WyrTwister is offline   Reply With Quote
Old 03-30-15, 09:20 PM   #10
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,394
Thanks: 410
Thanked 604 Times in 506 Posts
Send a message via Yahoo to jeff5may
Default

Actually, there is not a high need to overly cool the recovery tank if it is large enough. A slow trickle of cool water from a garden hose is good enough. If you don't have running water nearby, an ice water bath will help. The only time cold temperatures are really needed is when you are trying to recover without a suction source. Given enough time, a cold, empty tank will literally suck all the liquid out of a sealed system. The refrigerant remaining in the system will be at whatever pt the tank is in equilibrium with. If the tank temp is below condensing temp,and the tank is not full, then all the liquid will be in the tank. The gas remaining in the rest of the system is a trivial fraction of the total mass.

The taps for low and high pressure can and should be placed close to the cap tube/metering device in the recovery a/c unit. This allows the incoming refrigerant the maximum distance to expand or "burp" on its way into the compressor. On the discharge side, having the extraction valve at the other end of the condenser coil allows it to condense and subcool. As long as your recovery tank is below the condensing temperature of the high-pressure refrigerant, it has no choice but to stay a liquid once it goes in the tank. Once the recovery tank fills up sufficiently (2/3 to 3/4 of the way full), swap it out for an empty tank and slowly fill the tank until the pressures equalize.

The donor unit should not be running during the recovery process. The window shaker doesn't need to be force-fed, nor the donor compressor starved. That being said, if you feel confident about it, the donor unit can probably pump down its own a-coil and have its service valves closed before recovery is done.

jeff5may is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:39 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design