Refrigerent Charging for new installations

[nevinjohn]

Hi,

I recently bought a split unit, as as per the specification the outdoor unit was shipped with the refrigerent (if the pipe length doesnt exceed some 5-7m). Mine is around 2 m so that was sufficient. While installing the unit I noticed that the technicians dint perfom the vaccumizaation, instead they just "leaked" the refrigerent gas (opened the valve at the discharge side) through the pipe lenth till it reached the suction tie in point. Once the refreigent reached the suction tie in they fixed it and bolted the pipe connections. When asked, the technicinas told for new installations there is no need of vaccuming! Is this okay? They did the leak test though!

Secondly, when charging the refrigerent (after a leak) why is it preffered to charge always from the suction side? Isnt there a chance the refrigerent from the cylinders might go to the compressor in liquid state? Can someone explain subcooling and associated pressure gauges reading values so as to determine whether the charging was proper?

N.B
The system use R22

[Rob White]

Hi,

I recently bought a split unit, as as per the specification the outdoor unit was shipped with the refrigerent (if the pipe length doesnt exceed some 5-7m). Mine is around 2 m so that was sufficient. While installing the unit I noticed that the technicians dint perfom the vaccumizaation, instead they just "leaked" the refrigerent gas (opened the valve at the discharge side) through the pipe lenth till it reached the suction tie in point. Once the refreigent reached the suction tie in they fixed it and bolted the pipe connections. When asked, the technicinas told for new installations there is no need of vaccuming! Is this okay? They did the leak test though!

Secondly, when charging the refrigerent (after a leak) why is it preffered to charge always from the suction side? Isnt there a chance the refrigerent from the cylinders might go to the compressor in liquid state? Can someone explain subcooling and associated pressure gauges reading values so as to determine whether the charging was proper?

N.B
The system use R22


Your first point of purging or venting the system is a way
of clearing air out of the pipes and traditionally was always
done by AC installers because it is quick, cheap and easy.

But it is the wrong way and if it is being done that way it
demonstrates poor training and poor understanding of the
problems it causes.

A pressure test and evacuation needs to be carried out first
to prove the system is gas tight and free from moisture and
none considerables.

AC installation is still done to the lowest common denominator
and the lowest common denominator is the installer. That is
why AC systems still come with flare nuts and not brazed joints.
You need to be reasonably good to braze pipes together and brazing
equipment is quite expensive, but most people think they can flare
and the tools are cheap enough.

As for charging the refrigerant into the system, with AC systems
on R410a the manufacturers tend to put one fitting on the low side
only because of the pressures involved on the high side.

If the system is off and if you have the option, always charge liquid
into a system on the liquid side, but with good designed AC systems
they come fitted with suction accumulators fitted to prevent liquid
flooding back to the comp and this then means if you charge it into
the suction side the risk of liquid damaging the compressor is reduced.

But because of the pressures involved if the system is running
(dependent on type) you will not get the refrigerant into the high
side so you have to charge liquid into the low side.

Regards

Rob

.

[GPD]

Things may become weaker in the future as the new F-gas seems will ban the pre-charge of such equipment

[nevinjohn]

yeah, ***** free gas is still expensive, and most of the companies which produce domestic units still manufacture units for R22 (at least in hot countries like in the Middle East and India)!

[rsk11584]

hi nevijohn even i bought new lg ac 8 days ago its not at all cooling, have written consumer complaint to LG, the technician did not even purge air for me , and neither used vacuum pump directly opened gas into closed system.

that is the problem in india there is lack of qualified technicians. Even companies dont educate their ASC. Which AC you purchased, is the cooling good?