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Question:

Do I really need new copper pipes for a new AC?

I am getting a new AC (Lennox XC13) and of course it is built for R410A . I have existing copper line but it‘s size left the sales guy stating that I need to replace the copper and make it bigger. Evidently 3/4 is too small and would make the new Lennox work less efficient. Does anyone know if I am being hosed?

Answer:

Yes you absolutly need new lines. The oils in the diffrent refridgerents are not compatable with each other. Even though you can buy products to try and clean the linesets this is left only for a very last resort. Lastly your new AC system is probably a TXV metered system where as your old system was a fixed orfice system. Lineset sizing is very importent in making sure your unit works properly and stays working properly. Its not just for efficency, it maintains the balance in the system. For example. The refridgenent will exit the outdoor system compressed and in liquid state. It will then enter the coil and all that coldness gets absorbed by the heat in the house. It then leaves the coil in a vapor state which is safe for the compressor to recive. If the balance, pressure, or efficency of the system is set wrong, you could end up with liquid getting back the compressor causing a hydrolock (damaging) or a frozen coil causing damage to the furnace or handler below it. This is why a Hvac tech has so many gauges and tools to properly set up Ac systems. Im in the feild and to not change the line set would be a foolish practice. Just one peice of forign matter left over from the old ac system could cause damage to your new system. Its not worth it.
Hi you old a/c was a R22 system which operate at 250 psi to 300psi on 70 to 95 f day your new a/c with R410A operate between 470psi to 570psi on the high side of the system which your old copper pipe would not handle
this sounds right, and if it's a different refrigerant, it needs a different oil, so no contamination takes place. replacing all the lines is a good idea. keep the pipe and get the money yourself, it's like 2.80 a pound!

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