View Full Version : No additional refridgerant needed ?
04-18-2008, 02:16 PM
Finally had the new AC (Amana) installed. Some things are strange...
They didn't add any R410a to the system (3 ton). I was reading the literature
the installers left. It mentioned adding to the system based on a long lineset.
So, if the lineset is 45 ft. is this a great loss to be missing this extra R410a ?
[Book said ft * 0.6 oz. = 27 oz.] I would expect that they would do the book, but ...
04-18-2008, 02:43 PM
We typically add charge per line set length for R-22 but with R410-a we found that it's better to let the charge go and then set it by sub-cooling/superheat. Back in 97',98' we found we were overcharging the units when we added charge before start up.
04-18-2008, 03:29 PM
Okay, one thing off the list. They checked the charge via superheat/subcool. They
said it was fine.
04-18-2008, 04:29 PM
I don't trust the factory charge. We use the charging chart and check it ourselves in warm weather. I've seen units like yours with long line runs not need juice and others with short runs need it.
04-19-2008, 03:10 AM
I have some installers that only knew how to charge a unit by weight and had problems with over charging the unit so I told them to leave the charging up to me went and found units we over charged or under charged from factory. Every thing is done by sub cool with a nice toy digi cool.
04-19-2008, 08:11 AM
Good choice on the 410a. As long as charge was set by superheat/subcooling, you should be good for a long time. Keep it well maintained!
04-19-2008, 10:22 AM
i also don't tust the factory charge. sometimes units with 10ft. lineset need charge and sometimes longer ones don't need any additional charge. if the checked the sub/super you should be perfectly fine.
04-19-2008, 05:53 PM
i also don't tust the factory charge. sometimes units with 10ft. lineset need charge and sometimes longer ones don't need any additional charge. if the checked the sub/super you should be perfectly fine.I wouldnt trust the factory charge either. Sometimes a unit can come from the factory undercharged. So it is best to check the system out to see if you need to add or subtract by subcooling/superheat.
04-19-2008, 07:03 PM
Yeah, we never trust the factory charge (unit plus 15 feet of lineset) I put a system in last week that had a 12 foot lineset and I ended up having to add 12 ounces of 22 to get it balanced! Subcool and superheat are the only way to go!
04-19-2008, 07:38 PM
Manufacturer's charge is set for the condenser size, a 15-foot lineset and the SMALLEST matched coil you can use with the unit. So even the 'add for feet' doesn't actually address a proper charge if the coil is bigger than the smallest one, which these days it very frequently is. Furthermore, the US Government DOE has determined that less than 30% of all the system in operation are properly charged. Those companies that use proper techiniques, as you're appears to have done, charging with super heat/sub-cooling are the only one even coming close to proper charge. Now don't fall into the customer trap of thinking you don't get anything out of a tune-up on the new system. Have it serviced regularly and frequently to keep it at peak performance. :)
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