Correct charging techniques

[theapprentice]

Im currently working on a daikin split sytem with a leak in the evap coil. As the unit is in a area that is pretty hot its not really possible to take it out to fix the leak so my boss wants me to just top up the charge till christmas time when they are shut down and we can pull it out to repair. My question is what is the correct way to top up that charge. I was thinking of measuring the temp of the liquid and suction line pipes and charging till i get approx 7 degree td. If anyone else has a better way would be appreciated,
chris.

[chris96]

You boss sound's like he runs a rough company. You should never top up on a leak unless it's fixed. what if it's a major leaks and you lose the charge in less then a week?
Moaning aside because i know that being an apprentice you just need to prove yourself to your boss, charge by superheat. Put the thermometer on the suction side pipe and your suction gauge on the port then charge to you get a full evap, ie R22 runs 0 oC at about 58pis, so on your gauge you look for around say 6oC, that means you have a superheat of 6oC. the lower you take the suction temp the closer you get to liquid return.
When charging by superheat make sure your condenser fans are at full speed and your evap filters are clean.

Chris.

[paul_h]

It's illegal to top up a system with a known leak that can be repaired.
It's also difficult to charge a system with this type of low outdoor ambients we have right now using subcooling and outdoor pressure/temps. The only way to correctly charge splits is a weighed in charge.

That being said, go by discharge and suction temps, charging so DT is under 90C (splits undercharged always have high discharge temps, that's why most of them have thermistors on the discharge to protect them), and suction temp is 3-5K higher at the service valve than evap saturated temp.
Keep an eye on FLA too.

edit: But I doubt it will keep running for long with a leak anyway, so it's a waste of time and refrigerant.
Also leaves your boss open to being fined and losing your companies arctick licence now you've posted about it on a well known forum.

[JEREMIAH]

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[nike123]

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It use mechanical work done by electrical motor (compressor) to move heat from air in one space to air in other space (atmosphere), and it could do that in reverse.

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