Problem: AC Split With Cold Liquid Line

[AC noob]

Hi guys, so i've got a R410A split system that has a very cold liquid line when in cooling. The suction pressure is 110 psi (750 kpa) which seems about right. I can't put a hose connection onto the liquid as it doesn't have a port.

Does anyone have any ideas as to why my liquid line is so cold? It even sweats at times. What causes this and does it effect the system?

The air coming out of the indoor seems cool enough. But the owners believe at times the indoor ices up and they have to switch it off.

Thanks in advance.

[monkey spanners]

If its a Jap style system and not a USA style one the small interconnection pipe is an expansion line, its after the expansion device which is in the indoor unit and is in effect part of the evaporator, thats why its cold.

If system not short of charge/filters clean etc, then being undersized for the load is a farourite for freezing up evaps, especially in high sensible heat applications like server rooms.

[AC noob]

If its a Jap style system and not a USA style one the small interconnection pipe is an expansion line, its after the expansion device which is in the indoor unit and is in effect part of the evaporator, thats why its cold.

If system not short of charge/filters clean etc, then being undersized for the load is a farourite for freezing up evaps, especially in high sensible heat applications like server rooms.

The brand of the unit is LG if that helps.

So the liquid line pipe should be cold then? Nothing wrong with it?

[martinw58]

the exspasion devise is in the out door unit so it is exspansion line not a liquid line so this is normal

[The Viking]

And don't forget...

Both interconnecting pipes should be lagged. Therefore it shouldn't be sweating.

Depending on your pipe run and system design, an unlagged expansion line might cause you problems like freezing indoor units. If the total heat gain get outside the design envelope the EEV might start hunting and then it's anybody's guess what will happen in the evaporator.
Just a thought.



.

[BradC]

If system not short of charge/filters clean etc, then being undersized for the load is a farourite for freezing up evaps, especially in high sensible heat applications like server rooms.

Please excuse the thread-jack, but I don't understand this. I thought an undersized unit would respond the same as a unit with an excessive load, like pulling down a freezer full or hot produce, and cause excessive superheat. To freeze the evap on an AC, don't you have to restrict the refrigerant flow enough to cause the SST to drop below the freezing point of water?

[monkey spanners]

Please excuse the thread-jack, but I don't understand this. I thought an undersized unit would respond the same as a unit with an excessive load, like pulling down a freezer full or hot produce, and cause excessive superheat. To freeze the evap on an AC, don't you have to restrict the refrigerant flow enough to cause the SST to drop below the freezing point of water?

Just an observation on things that never cycle off that the can freeze up, the actual room temp and humidity would play a role too like in a server room.

All mini split style systems are desinged for both latent and sensible cooling. Latent is taking water out of the air and sensible is cooling the air down. They are desinged for x amount of latent and y amount of sensible.
If there is not a lot of humidity in the air (low latent load) the coil will freeze up (which seems counter intuitive). Without the heat load from condensing water the coil is effectivly undersized, the evaporating temp drops and ice begins to form. This is my understanding of it anyway!

This is one reason why propper server room air cons have humidifiers fitted.

http://www.daikin.eu/faq/items/sensible-latent-heat.jsp

I expect how these thing run and the problems we see would be different in our respective parts of the world due to the local weather conditions etc.

Jon