Introduction to VRV/F Systems with Roman Baugh

Roman Baugh gives the Kalos techs an introduction to VRV/F systems. Variable refrigerant flow (VRF) or volume (VRV, Daikin) systems are a specific type of HVAC equipment invented by Daikin. The same superheat and subcooling principles apply, though there are a few more moving parts.

VRF systems are more like VFDs that take AC voltage, convert it to DC voltage, charge capacitor banks with the DC voltage, and use pulse-width modulation to run the compressor at different hertz (at 168 different speeds). The variable-speed nature moves varying amounts of refrigerant to meet the exact demand of indoor units and run efficiently. These systems supply a specific amount of refrigerant to a given indoor unit to meet its required capacity. The indoor and outdoor units constantly communicate (via a PID loop) to make this possible.

VRF systems may use either 2-pipe or 3-pipe heat recovery. Those pipes represent refrigerant lines moving into and out of the heat recovery box, which generates the liquid needed for the indoor units. It has a branch collector box that skims refrigerant. Hot gas goes to the unit(s) calling for heating, and it condenses to a liquid in the indoor heat exchanger, which then goes to the unit(s) calling for cooling.

Capacity varies widely among VRF systems. In some cases, two outdoor units can handle a combined 40 tons of capacity. Higher-capacity systems have higher compressor and fan speeds, usually with larger compressors. Compressors and inverter boards may be refrigerant-cooled (using liquid refrigerant). VRF indoor units vary quite a bit in shape and size, coming in wide and slim, ducted and ductless varieties. Roman covers the features, advantages, and disadvantages of existing models as well as the unit nomenclature and clearances.

Roman also covers copper tubing, including REFNET kits and Y joints, as well as proper installation of those and some general brazing tips to reduce turbulence. He also discusses oil management, especially as it relates to piping consideration and refrigerant turbulence in the copper tubing, as well as oil return mode and traps. On the installation end, it is critical to remove the shipping bracket from the compressor and eliminate cross piping. Flaring, pipe lengths, pipe diameter, and proper piping support are other considerations for VRF piping and installation.

Flowing nitrogen while brazing is important in all systems to prevent the buildup of oxides and clogged screens, but the copper oxides can damage electronic expansion valve needles, which can lead to oil loss in the compressor and catastrophic failure.

Roman goes through the process of installation, including the pre-construction phase and jobsite considerations when installing VRF systems. He also explains the difference between communicating systems (including VRF/V systems) and 24v systems, and he covers control circuit terminal designations on VRF systems.

This video also covers very basic elements of service and troubleshooting, including how to think about using the correct tools for the job. The basic starting points for VRF troubleshooting include temperature in and temperature out. Temperature sensors are common fail parts, and it's important to stay on top of those, as failed temperature sensors can cause catastrophic failure in the long run. Roman also ends on a note about the importance of reading the manual to assist with troubleshooting. He also explains the importance of pulling and weighing out the refrigerant charge before adding charge to a VRF system.

[deanwalker]

Roman, You are incredible. We need videos of you going through checker data of good systems and bad systems

[alnonymous]

I originally trained on the seven lights. I still speak binary. I fixed a lot of botched installs back when reflok was still the preferred method for Daikin, (glad that went away). I spent more than half my life on earth with a system in mode 21. Read the fantastic manual!

[dylb]

Please up load the rest of this lesson with roman ASAP. The man is the GOAT

[americanpatriot]

Roman is amazing I love the way he explains things!..Please post the service and troubleshoot from him!

[jasonkeys]

Australia here i appreciate these ..Much love .

[charlespleydell]

He's a very good communicator and breaks things down into simple concepts!

[jasonjohnsonHVAC]

Being in heavy commercial and industrial...its nice to see some content thats directly related to my day to day experiences. All information is valuable information...its even more nuce when its right up alley. I know you especially have extensive experience with Daikin. I just purchased the LGMV wifi module to interface with them. Thanks for putting this video out there Roman

*** MITSUBISHI HEAT WILL SEE A DRAIN LINE COMING OFF THE BRANCH BOX ***

[RobertoCarlos-reuw]

THANKS HVAC school team
Im a HVAC technician i learnt a lot from this channel.this is what I was expecting from you desperately.eventually its there thanks a lot fr that.i hope n wish u upload more videos on VRF commissioning and maintenance

[YaakovNYC]

Daikin high static MQ and OA units are braze and bolt/gasket type. Not flared. Great video as usual Roman

[frankminisplitking]

Super awesome skim through the VRF/VRV world. Also really cool how Daikin does auto-addressing I mostly work with Mitsubishi, addressing is a pain… especially how they sometimes switch the dial… first digit/second digit left/right but sometimes right/left… haha!

[brianmcdermott]

Good day Bryan, Roman Baugh gave a super great class👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍. We need mor of these. Thank you Bryan.

[alexandergorelov]

Mr Baugh, thanks a lot for your video!

[jstiles]

This is Gold! Thanks for posting it. Learning every day😊

[OrlandoPerez-vyoy]

Just started my journey in HVAC. I been doing Industrial Automation for 8 years now. Hopefully this goes well, looking forward to learning this.

[MrWaynesea]

Great presentation. You brought out so many useful points.

[keithglynn]

Sorry, but im not a fan...as soon as we set foot on two new accounts we found a large multi unit vrf system that has a refrigerant leak within a massive bundle of refrigerant lines all grouped together in a large tube type enclosure, and none of the circuits are marked as to which units they connect. They are also completely covered with insulation. The other account has a twin compressor system in the condenser, one compressor being a variable speed unit. We learned that multiple compressors have been replaced along with the speed control boards. We were told they should be replaced as a set.We have yet to investigate what the cause of failure is. We also learned that the 2nd stage compressor will not run at all if the 1st stage seizes up or becomes inoperable for any reason. We also had a system that was acting up from the communication wire picking up electrical noise. These units seem to work well for a few years, but when they misbehave, they are the worst. Some of our older acounts have these units that blow up power supply boards and refuse to start if the condenser fan motor fails but shows no fault. I found out by coincidence by giving the fan a spin and the unit started right up. The last thing I will mention is that many customers run these at low speed for long periods so the evaps load up with mildew, even with pan tabs, and then they need to be nearly completely disassembled because the long plastic blower wheel fills up with dirt and mold and goes out of balance. Imagine trying to take one of these apart in someones beautifully decorated office with fancy carpet.

[treefrogs]

Put our oil separator in the system for security purpose. It will reduce the warranty expense long-term for the manufacturer

[salv]

I have really enjoyed this video very very good information here I am going to continue watching them I learned a lot but just taking this video a few times and writing stuff down questions that I've had thank you again

[Haggard]

Why are liquid line dryers not required with these types of systems? Mini splits, etc. If the line sets have been open to atmosphere, despite being vacuumed, there’s zero concern with moisture?

[TAGUPNBLUE]

On flaring I use a double flare just like they use in hydraulic lines with nylog and a torque wrench because of the high pressures they use those in brake lines