HVAC questions...

frankp

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It's been a while since I posted, lots going on here on the home front. Some of that is relocation of our HVAC compressor for our house. I'm running electrical and plumbing in preps for the actual move of the unit and come up with a question.

The coolant lines are 3/4 copper and I was running a straight shot from the new location but want to know if I can put any elbows/bends in it. The existing line doesn't have any joints, just curves and I wasn't sure whether the HVAC system would have issues maintaining consistent performance if the lines had bends (45s or 90s) rather than just curved lines.

Any HVAC experts care to weigh in with suggestions?
 

Bick

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Not an expert, but yes you can, however each one adds resistance to the flow, so may lose a little efficiency. They make long radius fittings for this purpose to match sizes. Note: always use the outside diameter when buying fittings or tubing. Keep all clean or buy cleaned fittings.
 

Bick

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Agree, good points. I assumed the move would require only adding a few feet of probably two sizes of tubing.
 

Brink

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I would use either K or L flexible tubing.
For 3/4” it takes a big tubing bender. Ends would be swaged to fit over previous tube. Joints would be silver soldered.
I’d go with as few joints and sharp bends as possible. The new R134a refrigerant loves to leak, far more than the R22 we used to use
 

CWS

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I would explore the cost of premade lines of the length you need. May be less cost in the long run. Just my 2 cents.
 

frankp

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  • Thread Starter Thread Starter
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I already have the line, it just occurred to me that it might not be good to have the bends in them. I have enough material to do a curve, just not a bender bar.
 

sprucegum

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I already have the line, it just occurred to me that it might not be good to have the bends in them. I have enough material to do a curve, just not a bender bar.

You can bend hard copper slightly by heating it with a propane torch. It will turn a dull red when it is ready for tweaking. I have done it many times to tweak a miss aligned piece of copper. I doubt that you could make a very sharp bend without kinking. Experiment with some scrap first if you decide to try it. If you heat soft copper you will harden it.
 
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robert flynt

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I would use either K or L flexible tubing.
For 3/4” it takes a big tubing bender. Ends would be swaged to fit over previous tube. Joints would be silver soldered.
I’d go with as few joints and sharp bends as possible. The new R134a refrigerant loves to leak, far more than the R22 we used to use
Actually you should use refrigerant tubing because it is dehydrated and made for that purpose. Type K and L are for water and gas. You can use long radius 90 deg. elbows but as you say it has to be silver soldiered. A leak will cause you to have to replace all the refrigerant because most of the commonly used refrigerants are blends. If I'm not mistaken 134a is a replacement for R12.
 

rocky1

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robert flynt

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Agree on the silver solder, but... Either brazing or silver solder are probably going to require acetylene. MAPP gas might get there silver soldering, dependent upon silver content of the solder, but you aren't going to do either with the typical Bernzomatic Propane torch.

https://www.hvacschool.org/2017/06/...er-lines-a-look-at-the-pros-and-cons-of-each/
Oxy/Act would be best as would 15% silver soldier for copper to copper. A turbo torch with map gas might work but I wouldn't recommend it for 15%.
 
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