The Homemade Heat Pump Manifesto

[AC_Hacker]

This is the $35 Refrigeration Recovery machine I bought.



This is a recovery machine a friend of mine bought that I have borrowed.

Originally Posted by Drake

Yes, the refrigerant collector. Can you use it to collect refrig from multiple discarded units to meet needs of new(DIY) system if needed?

If I understand you correctly, you are asking if the refrigerant recovery unit can be used to extract refrigerant from some system and then reuse that same refrigerant in another system... correct?

The answer is yes, if both systems are designed to use he same kind of refrigerant. The refrigerant doesn't wear out. And as far as I know, the lubricant which is mixed in with the refrigerant, is not exposed to air and does not wear out either. However, if the first system failed because the motor or bearings failed, and it overheated and died, there could be problems with re-using the old refrigerant.

There are also compatibility issues that were previously discussed that should be understood.

So, if you plan to re-use refrigerant, make sure you don't mix refrigerants, and make sure that you are using compatible families of refrigerants.

Originally Posted by Drake

On the HX direct to tank, your thoughts on trying a radiator coil at bottom of tank. I know it designed for air xchg but as water is better conductor it should work at least as well I would think and thermo cycling in tank should provide water movement. Coil from AC or maybe dehumdfr?

[* This is a question that comes up repeatedly. I think it springs from a fear of confronting the technology. Once this fear is overcome, a new world of possibilities will be open to you. *]

I think that trying to use a refrigeration-to-air heat exchanger as a refrigerant-to-water heat exchanger might be useful to prove a concept, but beyond that it is a waste of time. It is true that heat will be exchanged, but the aluminum fins will eventually become fouled. Also the galvanic difference between copper and aluminum would invite corrosion. For the price of taking someone out for dinner at a moderate restaurant (not burger king) you can buy a beautifully engineered and perfectly made heat exchanger that will last for many years.

But in-tank heat exchangers are being made and will most certainly work as outlined in Piwoslaw's most excellent thread.

Originally Posted by Drake

If compr and cap tb are matched and sized for heat demand length of refridg line is not also determined(set length) is it? I'm making this assumption from split AC installs where distance between units varies.

I think you are asking me if the length of the 'line set' will have an impact on how the cap tube needs to be configured (sized).

If I have understood your question correctly, the answer is that within normal boundaries, the length of the line set will have a minimum impact on cap tube sizing. The size of the thermal loads, and the operating temperatures, and refrigerant pressure, and the size of the compressor, and the type of refrigerant will have the greatest impact on the cap tube configuration. A long line set can require that more refrigerant be introduced into the system to make up for the extra system volume created by the extra line set length.

In an extreme situation, the line set could be so long that it would itself, become a significant part of the thermal load. Then, the cap tube configuration would be affected.

Best Regards,

-AC_Hacker

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