Oil Return and Refrigerant Charge in VRV w/ Roman Baugh

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 31 August 2023

⏱️ 40 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

Roman Baugh joins the podcast to talk about oil return and the refrigerant charge in VRV systems.

VRV systems—also known as variable refrigerant volume (or variable refrigerant flow/VRF) systems—have one outdoor unit, one or multiple compressors, and multiple indoor units. The outdoor unit modulates to meet the indoor units’ fluctuating demands. They are versatile and flexible systems.

Like parallel racks, VRV systems have long lines and a lot of piping, so oil return and refrigerant charge are especially critical. VRVs have specific control protocols, as they need refrigerant volume and velocity to move oil and keep it lubricating the compressor for its entire lifespan; oil return mode, the refrigerant charge, and the piping protocols are supposed to support that function.

When it comes to piping protocols, line sizing is critical. Whenever there is a need to relocate the outdoor unit and change the piping configuration, the charge needs to be adjusted, and the piping may even need to be upsized to prevent restrictions from happening. Daikin has VRV WebXpress (and SplitXpress) software for equipment selection; the goal is to help installers out with the line length and charging whenever it needs to be changed.

When trying to get the oil return and line sizing right, you ultimately need to look at the manufacturer’s literature and resources. It also helps service technicians if the installer makes the charge and line information readily available to anyone who works on their VRV install in the future.

Roman and Bryan also discuss:

Where and how oil can settle in VRVs
Consequences of improper charge in VRVs
Liquid lines in VRVs
Violating piping rules and safety protocols
Vertical separation in liquid line sizing
Suction line sizing
POE and PVE oil miscibility
Daikin’s resources

Check out daikincity.com to find Daikin’s literature and software programs.

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Transcript

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0:00.0	The HVAC School Podcast is made possible by these great partners.
0:08.0	Carrier and carrier.com.
0:11.0	Carrier has been a long-term sponsor of the podcast. They've made it possible very early
0:14.9	on for us to do what we do and they are the products that we sell day in a day out.
0:19.3	Everything from single-stage equipment all the way up to the green speed extreme, one of the most efficient
0:25.8	products on the market today. Find out more about what carrier has to offer and about becoming
0:30.8	a carrier dealer by going to carrier.com.
0:34.0	All right guys, Emerson's trusted filter dryers are now part of the Copeland brand,
0:40.0	continuing a century old legacy of HVACR innovation and industry leadership.
0:44.5	We all know filter dryers are crucial.
0:46.4	They're there to protect your system's compressor and expansion valves and screens and we
0:50.9	should replace them every time the refrigerant circuit is opened for service or
0:54.7	repair and with Copeland you'll find a range of options that suit your needs.
0:58.6	Remember, replace the filter dryer when there's a 4 PSI pressure drop in the liquid line or a 2 PSI pressure
1:06.8	drop in the suction line. Now keep in mind that sometimes you're going to measure
1:11.5	this in the liquid line with a temperature difference, and generally speaking, any significant temperature difference that you measure across a filter dryer is indication that it's time to replace it.
1:21.0	To learn more about the Copeland filter dryer family and benefit from their expertise,
1:25.7	visit HVECR School.com slash Copeland-Dash dryers today.
1:30.9	Copeland, continuing the legacy of innovation and trust.
1:36.2	Refrigeration technologies at refriggedech.com. Here's your host, the man who wants to be just like Jim Bergman when he grows up.
1:50.0	Brian Orr.
1:52.0	He-he-ho-ho, this is the HVAC school podcast. I am Brian. You are always humble host. I'm so humble and I know it and this is the podcast that helps you remember some things
	...

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