FLUSHING LINES FOR 410a CHANGEOUT

[jayray]

Hi guys, I keep hearing bad reviews about improper flushing of old r-22 lines for a 410a changeout. The house I recently moved into has all the basement ceilings finished (not drop ceiling) which makes my a.c. lines roughly a 20 ft span from coil to outside unit. Since tearing the ceiling apart would be costly, should I use an r-22 unit (someone has these units in warehouse) Will r-22 be hard to get in the future? or will the flushing process be ok? how can you really know?

                                          thanks for your time and help

                                                                                         JAYRAY

[JJDH]

If the existing lines match the size needed for the new unit they can be purged with nitrogen and triple evacuated if the old system didnt burn out. r11 flush isnt always needed. R22 will be obselete soon

[jayray]

Thanks. JJDH, GREATLY APPRECIATED.

[ACtechGUY]

I agree with making sure the line sizes are right for the new system. But , a proper solvent flush should be done to the lines.

If you Blow the lines with nitrogen, You will certainly get some pockets of trapped oil out, but not close too ALL the oil. When you blow thru a pipe , the oil tends to smear all around the inside of the pipe. In reality very little of the oil will come out with this method.

Triple evacuating and a new filter dryer will get out the rest of the oil right? HELL NO!! OIL WILL NOT be removed by any vacume process. Vacume evacuating will remove moisture and gases from the piping Not oil, not EVER.

Filter dryers will also not trap mineral oils, they are designed to allow oils to pass through them.

A proper r-22 (mineral oil) to 410-a (POE oil) piping retrofit should ALWAYS involve a solvent flush (following the manufacturers directions of whatever product you use of course) .

[JJDH]

 I youst to beleive that. After some time I have learned this at training courses...........Some manufacturers frown on the flush because of the solvent and say it is more harmfull than the trace amounts of oil mixing. Trane particlarly says not to use the solvents

here is a copy past from their advanced troubleshooting. i dont know how to post the pdf...

[align=left]Flush Kits Are Not Required or Recommended.[/align]

[align=left]There are multiple HVAC flush agents available to our industry. Flush kits contain “solvents”.[/align]

[align=left]Solvents that are not completely removed can generate strong acids in the system—leading to premature[/align]

[align=left]compressor failures.[/align]

[align=left]If you opt to use a flush kit on line sets after a compressor burn out; follow the flush with a strong flow of[/align]

[align=left]nitrogen and a deep vacuum -- 300 microns for 15 minutes. Please read and understand all directions[/align]

[align=left]printed by the manufacturer as there may be differences from one product to another.[/align]

[align=left]Small amounts of mineral oil will not harm your new Trane R-410A system—moisture, acids & solvents[/align]

[align=left]are more of a concern.[/align]

For Additional Information & Advanced Troubleshooting Techniques

[ACtechGUY]

You know why they say that right? Because some of us just do and don't bother to read. Knowing some of the a/c guys out there I can easily see someone dumping the flush into a system, then pulling a halfass vacume.

But if they had bothered to read the instructions on the can they would have blown the lines with nitrogen , crimped the copper lines where the flush exits the system (to allow the solvent more time to contact the oil)and followed the solvent with high pressure nitrogen(to force as much out as possible) . He would then pull a good deep vacume , because that is what he is supposed to do(and it evaporates the remianing solvent).

Trane has likely seen one too many failed compressors traced down to improper flush proceedures, so they choose the less of the two evils. They would rather see some mineral oil in the system (that does not really harm the system) vs a solvent that truly is incapatible with POE oil and R410a. It comes down to the fact that they can't trust the dumbass contractors to do an install the correct way, so they say just don't do it.

[JJDH]

I just try to do it right the first time and rpelace all linesets when possible.

[jayray]

Thanks again guys for your valuable experience and insight. Crimping the lines to let the solvent do its work properly really makes sense to me.  I just hope this valuable info doesn't fall on deaf ears when I proceed with this project, most problems with furnace and a.c. units are created by installer ineptitude.

 

                                                                           thanks again, jayray

[Bobice]

Why not just an R-22 unit. If needed R-407 is a direct drop-in replacement.

No hassle.

[ACtechGUY]

Just find a good a/c contractor. Things to look for....Do They Advertise alot??? Maybe not someone you want to consider.

Is it a one or two guy operation? Not so good either(unless he has glowing referals. If so , That is the Guy!)

So who to choose??? Ya GOTTTA do some leg work. Call the 1-800 number for CARRIER , TRANE and LENNOX or search their web sites. Find a dealer that does all those brands. You have found someone that has successfully installed 3 different major manufactuer's equipment, Many Times.

No matter Who you find, NEVER choose the guy with the biggest ad. The right guy will have all (or mostly)positive refferals , and that is what you need. That is the guy that JUST MIGHT do a good job.

Good Luck!!!

[jayray]

Thanks again guys, greatly appreciated.