A/C Techs - Step in - Mini Split ?

[bigmoose]

So i installed my own 3 head LG brand mini split about 4 years ago. I ran and flared my own line sets. I pressure tested and ran a vacuum to evacuate the line sets prior opening the condenser service valves (condenser came pre-charged). System has been operating great so i think its safe to say i don't have any leaks and my flares were pretty good.

My outdoor unit supports 4 heads and i want to add this 4th head to a specific bedroom. The line length and elevation change is all within the manufacturer specs.

The question I have is in regards to evacuating the new line set. I assume I'll need to have a pro come out and do a full evacuation of the system to capture the existing R410A and recharge? I don't believe i can just close the service valves (isolating line sets from condenser) and evacuate the line sets myself. I'm assuming R410A is a gas at ambient temp so some portion of the charge stays in the line set?

 

[oldstv]

Don't mean to hijack your new thread but I am glad you posted this, in doing so you have answered a question for me about that system. I didn't know if I could run multiple heads on one outside system. Do you loose any effectiveness when adding multiple heads?

 

[gimmie11s]

Great questions.. in for answers.

Im intrigued by split unit AC systems and have been told i can upgrade the house for pretty cheap.

OP do you like your system?

 

[bigmoose]

Don't mean to hijack your new thread but I am glad you posted this, in doing so you have answered a question for me about that system. I didn't know if I could run multiple heads on one outside system. Do you loose any effectiveness when adding multiple heads?

You can run multiple heads on an outdoor unit if it's designed to do so. It's very common. Mine supports 4 heads. It's a 30k btu outdoor unit and it can add a total of 40k btu worth of heads. If all are running they will operate at a slightly lower capacity. The manufacturer engineering documents on the system will tell you the exact values.

Great questions.. in for answers.

Im intrigued by split unit AC systems and have been told i can upgrade the house for pretty cheap.

OP do you like your system?

I love my system. I went this route since i don't have ducts and cannot retrofit them. I am very impressed with the quality of the system. I specifically went with LG because they made a dry contact adapter for the head units. This way I can have my units operated by my Nest thermostat (cool, heat, and fan).

After helping my brother install an off brand system in his house (disaster!) I'd only stick with Mitsubishi, Fujitsu, or LG. There might be other quality brands I'm not aware of.

I'm not sure what you consider cheap. Mine cost me about $4k in parts. From talking to other people with similar systems they go for about $8-12k installed by a pro in my area.

 

[RDJ]

After helping my brother install an off brand system in his house (disaster!) I'd only stick with Mitsubishi, Fujitsu, or LG. There might be other quality brands I'm not aware of

I had one installed in my garage in 2012 .. I love it. The HVAC guy that put it in said he would not install anything other than Mitsubishi. and a top tier one at that.

LG and Mitsubishi's are what they run in Iraq and Afghanistan as well when I was out there.

I'm not sure what you consider cheap. Mine cost me about $4k in parts. From talking to other people with similar systems they go for about $8-12k installed by a pro in my area.

Mine was 5k installed here in texas .. no complaints about the price, performance, or the install

 

[slow306stang]

Depending on the manufacturer you can close the liquid/discharge valve and pump all of the gas into the condenser. Once the suction pressure drops to 0psi, close the suction port.

Add the 4th line and pressure test. Then pump it down to under 500 microns. Break the vacuum with the gas thats needed for the extra line set and then open the valves on the condenser.

 

[03cobra#694]

New straight cool going in my house Friday. 20 Seer, but we have ducts.

 

[bigmoose]

Depending on the manufacturer you can close the liquid/discharge valve and pump all of the gas into the condenser. Once the suction pressure drops to 0psi, close the suction port.

Add the 4th line and pressure test. Then pump it down to under 500 microns. Break the vacuum with the gas thats needed for the extra line set and then open the valves on the condenser.

Interesting. Never thought of that but makes sense.

I looked into this more and another method is to have your outdoor unit running, shut your liquid valve, watch your suction go to zero on the gauge, then close the gas value and disconnect power at the box. Seems legit, just not sure if it could damage the outdoor unit. This let's the outdoor unit pump do the work in place of an external pump it seems.

I realized the industry term is pump down. That makes it easier to read up on.