09-20-14, 08:55 PM | #11 |
Helper EcoRenovator
Join Date: Sep 2014
Location: Oregon
Posts: 30
Thanks: 0
Thanked 1 Time in 1 Post
|
One more question...
How do you know exactly when to stop pumping propane in? |
09-20-14, 09:28 PM | #12 |
Supreme EcoRenovator
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,154
Thanks: 14
Thanked 257 Times in 241 Posts
|
Check the superheat to determine when there's the correct amount.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her... |
09-21-14, 03:26 AM | #13 |
Helper EcoRenovator
Join Date: Sep 2014
Location: Oregon
Posts: 30
Thanks: 0
Thanked 1 Time in 1 Post
|
I think I might just end up using the compressor on this unit as a vacuum pump, and make a recovery machine for the next unit. Being at the end of summer they are just giving away air conditioners on craigslist! I've wanted to try propane for A/C for a while now, but I didn't realize the smell would be filtered out. That could be a problem. If I got set up to use and reuse R22, I have a lot of projects in mind.
|
09-21-14, 08:50 AM | #14 | |
Supreme EcoRenovator
|
Quote:
Actual running pressures will vary upon conditions the unit is exposed to. On an 80 degree day, in cooling mode, mine runs around 65-80/170-180. Tune for superheat, not absolute chart pressure. |
|
09-21-14, 09:23 AM | #15 | |
Supreme EcoRenovator
|
Quote:
On the same idea, just because you can find used window units cheap doesn't mean your modded machine is worth little. Used heat pump stuff and recovery devices are not cheap at all unless you are very lucky. If you are considering building a recovery machine, use a compressor from a freezer that will pull a deep vacuum and not overheat. These also tend to not die if they ingest some liquid. The a/c pots aren't made to survive long when starved of gas to circulate. For your first project or two, just go to the zone and pony up the deposit for a loaner vacuum pump. After you learn how a real one acts, building one that works correctly will be easier. Welcome to the dark side. If this was easy, everything would be trying to do it. READ THIS FIRST Last edited by jeff5may; 09-25-14 at 07:22 PM.. |
|
09-21-14, 03:05 PM | #16 | |
Supreme EcoRenovator
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 724 Times in 534 Posts
|
Quote:
-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker... |
|
09-21-14, 11:39 PM | #17 | ||
Helper EcoRenovator
Join Date: Sep 2014
Location: Oregon
Posts: 30
Thanks: 0
Thanked 1 Time in 1 Post
|
Quote:
Quote:
I still want to hack it up and let the charge out, but hopefully I can reuse the R22 this time. Back to my original question: If I get another window unit, around 12k BTU, can I install some manual ball valves to reverse the cycle? That seems relatively easy, just flip the valves every season. |
||
09-22-14, 12:13 AM | #18 |
Supreme EcoRenovator
|
You use purge gas while brazing to avoid oxidizing the inside of the pipes. Copper likes to tarnish when it gets hot. If there's no oxygen, it can't tarnish and stays clean. The copper smut on the inside of the tube will flake off and clog up your system if you try to take a shortcut. I use propane as a purge gas, and it works well, as long as you discharge it away from where you are brazing. As always, proper active ventilation is essential when dealing with anything flammable.
As to your question about mechanical fittings, I like flare fittings second to brazed. They also take a little practice to do right the first time. The thing I like about flare fittings is they are not expensive, and they are readily available at hardware and plumbing stores. I have seen compression fittings used in automotive applications, but they crimp the ferrule to the tube with a nut behind it, just like flare fittings. The fittings used are specialty fittings made just for auto a/c and are much more heavy duty than standard plumbing compression fittings. They aren't cheap, either. Yes, you can manually reverse the flow with hand valves, but once you source the valves that will handle high pressure refrigerant and the tees and such to connect them all, you've spent more than the price of an ebay reversing valve. Also, in heating mode, the evaporator has a tendency to freeze up while noone is watching. A defrost control is a lifesaver during chilly weather. |
09-22-14, 03:55 PM | #19 |
Helper EcoRenovator
Join Date: Sep 2014
Location: Oregon
Posts: 30
Thanks: 0
Thanked 1 Time in 1 Post
|
|
09-22-14, 07:06 PM | #20 |
Supreme EcoRenovator
|
Oversized heat exchangers help everything work more efficiently. The question is more dependent on your environment. If your outdoor temperatures stay above 40 degF, you shouldn't have problems with the unit freezing up. However, as outdoor temps approach freezing, it becomes impossible to extract heat without forming frost. Once the evaporator freezes up enough to impede airflow, the unit is done pumping heat until airflow is restored.
|
|
|