Problems with a 410a new unit

______________________________________________________________________ I recently got a new American standard a/c-heating system for my house. Is a townhouse, 1150 sqft. Very well insulated. Furnace and coil are in the attic. I live in Houston TX, very hot in here. This unit is a 410a 2.5 ton system. The problem is that I can’t get it to cool lower than 79 without being running all the time non-stop. That’s when outside is around 90, it hasn’t got very hot yet. The temp coming out of the duct is around 66 (and it gets this “low” after running it for at least an hour non-stop)when the inside temp (thermostat) is like 79. The guy who installed has come, check things, and he can’t figure it out. I’m getting concerned here and my question is: This guy changed everything,new duct work, new furnace, new everything, everything but the copper lines… can that be the reason why I can’t get this ac to cool better. The current copper lines that I have are the home originals, good for an r-22, 2.5 ton system (3/4 if I’m not mistaken). He cleaned up those lines with nitrogen I think, I’m certain he clean them. Please let me know what do you think and if you think that the copper lines are the issue… Thank you so much in advance Mario Rangel Replies: smythers1968 “Re(1):Problems with a 410a new unit” , posted Sat 30 Jun 23:02 ______________________________________________________________________ First of all nitrogen does not clean the lines. Nitrogen is primarly used to pressure upthe system and check for leaks. I under no circumstance install a 410a system without changing the lines. The oils of other refigerants do not mix. I have not experianced cross contamination of R-410a system yet. But I would not rule it out. First I would want to know what your sub-cooling is? What static pressure and CFM is? And what the blower setting is. WOW That Can Hurt!! Houston204 “Re(2):Problems with a 410a new unit” , posted Sat 30 Jun 23:15 ______________________________________________________________________ This is information beyond the capabilities of the average homeowner. It would be very useful though. It does state in the many manuals not to use a liquid line larger than 3/8 inch, so a new line may be needed. We’ve used the existing refrigerant lines hundreds of times and never have had a problem. Houston204 “Re(1):Problems with a 410a new unit” , posted Sat 30 Jun 23:00: ______________________________________________________________________ Probably a return air leak. A digital thermometer from Walmart might help you verify this. Measure the temp at the return air intake (air filter), then measure it in the duct before the evaporator coil in the heat of the day. if you see more than 3 or 4 degrees increase, you probably have a return air leak. Measure the temp after the coil as well. You should see an 18 degree drop in temp across the evaporator coil in your attic. [this message was edited by Houston204 on Sat 30 Jun 23:01] mariorangel73 “Re(2):Problems with a 410a new unit” , posted Sat 30 Jun 23:04 ______________________________________________________________________ The whole return duct was done too. And It’s pretty well sealed. The ac guy has checked all these temps and he just doesn’t understand why it’s not getting any cooler. I still think that it may have to do with the copper lines… shouldn’t they be 5/8 instead of 3/4??? Mario Rangel smythers1968 “Re(3):Problems with a 410a new unit” , posted Sat 30 Jun 23:11 ______________________________________________________________________ 3/4 is not the problem. I would call another company to come out and check the system. WOW That Can Hurt!! Schock Therapy “Re(4):Problems with a 410a new unit” , posted Sun 1 Jul 01:05: ______________________________________________________________________ It is very hard to diagnose such a problem without a full aray of pressure and temperature measurements. I will say that there is a good possibility that the problem is relating to the old line set. R-22 systems are often installed using less than ideal piping practices. Often the pipes are brazed without running a nitrogen purge. This causes the copper to become blackened with a kind of soot. R-22 systems are quite forgiving of this practice. R-410a is not so forgiving. It is an extremely good solvent, and it will very quickly scrub all of the contaminants off the piping walls and flush them through the entire system. Deposits might form in the metering device, and it is very likely that the filter/drier will become restricted. A restriction in either place would cause the type of problem you describe. Combine that with the incompatibility of any residual oil from the old system and you can see why recycled lines are a bad idea. You will be able to tell if the filter/drier is getting restricted by measuring the temperature of the pipe before and after the drier. There should be no significant temperature drop. If you can detect a temperature drop just by touching it, them you definitely have a problem! It’s only a shock if your not expecting it! [this message was edited by Schock Therapy on Sun 1 Jul 01:07] mgussler614 “Re(5):Problems with a 410a new unit” , posted Mon 2 Jul 20:35 ______________________________________________________________________ instead of blow out the lines with nitrogen he should have used ro7 flush to flush out the line if he couldn’t changed out the linset.the refridgerant is cotamined he needs to recover the refridgerant cut out the filter drier and flush out the lineset with the ro7 then reinstall a new filter drier add nitrogen then pull a vacum to 500 migrons then add new refriderant into the system then the system will work right in a town house the lineset should have been replaced my company that i work for if the can’t get the linset out they use ro7 flush to get the r-22 oil out of the lines never nitrogen to blow out the lines the system is cotaminted guz 1 actech4u “Re(6):Problems with a 410a new unit” , posted Wed 4 Jul 09:01 ______________________________________________________________________ How is your air flow compared to the old unit? There is a Ylo terminal as well as a y terminal in the Airhandler sometimes people miswire the unit and only have low speed for the blower. Have the tech check that. ACTECH4U