Manufactures VRF Piping Layout Drawings

The VRF Piping Layout is highly engineered by the VRF manufactures software to design the pipe sizes to meet the capacities and conditions required, including ASHRAE 15. The pipe sizes are affected by capacity, pipe lengths and the quantity of fittings. When any of those factors change than the design engineer needs to enter the new parameters into the piping design software to recalculate the new requirements. The changes could affect the sizes of the pipes required and the refrigerant charge.

When Should You Recalculate

When doing a VRF project the installing contractor is most likely working off of either a designed floor plan without sizes shown, in which case the piping schematics provided by the VRF manufactures software program are used for the correct pipe size. The VRF manufactures piping schematic is based on the capacity, design piping lengths and quantity of fittings. If any of these factors change then the calculation for pipe size must be recalculated using the VRF Manufactures software program.

If you have a VRF piping layout (schematic) showing that you have a 1-ton indoor unit that requires a 1/4” (6.35mm) liquid line and a 1/2” (12.7mm) gas line based on the pipe length being 20 feet (6 meters) from the branch selector box with 2 elbows, but due to field conditions you actually have 40 feet (12.19 m) of pipe and 6 elbows, then you will need to give this information to the design engineer to put into the VRF manufactures software to recalculate the required pipe size. It’s possible that no increase in size will be required, but if it is required, and you don’t make the change, you will reduce the capacity of the indoor unit.

The installing piping crew must follow the VRF manufactures piping schematic and provide any changes to the design engineer before installation begins. Not only do additional lengths of pipe impact the pipe size, but the total refrigerant charge required. The amount of refrigerant in a VRF system is critical to a successful system, so any changes to lengths is very important. The actual length to be installed is the only accurate method of getting the proper refrigerant charging amount.

Of course, you need to make these changes before installing any of the piping in case changes are warranted.

You might have noticed that we have mention multiple times the need to recalculate if there are any changes, that’s due to the importance of this in VRF System Design and installation.

Full Port Refrigerant Ball Valves

Using full port refrigerant ball valves with Schrader ports allows for isolation of any indoor unit without having to shut down and drain the complete refrigerant from the system. Make sure to check with the design engineer for the approved location of the ball valves in accordance with the VRF manufactures design guidelines.

Refrigerant Piping Supports & Seismic

Consideration must be made for how you will support long runs of piping inside the building or outside on the roof or up a shaft, etc. Will you use a B-Line Dura-Blok for piping supported on the roof as shown below? Will you use single point hangers or a trapeze?

Do you live in an area known for earthquakes? Do you need to comply with seismic restraint requirements? If so, you might need something similar to this detail. SMACNA provides guidelines on the installation of seismic restraints. The piping below is shown supported on unistrut rack, with vibration isolation springs and seismic cables.

Expansion Loops

Review our article on the use of expansion loops for long piping runs to avoid pipe ruptures due to expansion. Check with the design engineer for this requirement on your project.

VRF Startup & Commissioning

The VRF system price often includes a Factory representative to assist with the startup and commissioning of the system. This individual will want to ensure that the system has the appropriate refrigerant charge.

It’s important not to energize the power to any of the equipment before the piping is installed if you are using a nitrogen purge with brazing. Energizing the equipment could cause the EEV’s to close, preventing the nitrogen purge from doing its job.

VRF Piping Fitting Types

There are many ways to make a piping connection, including Brazing, flaring and pressfit. Checkout our article on the ZoomLock fitting versus Brazing and our ZoomLock Cost Analyses,, Reftekk Piping Solution, and LokRing Fittings

Special VRF Piping Requirements

1. Use dedicated R410A refrigerant hoses
2. Dedicated R410A flaring tool. Flares are deeper due to increased operating pressure.
3. All pipes get insulated.
4. Y-Branch when installed horizontally. LG allows a +/- 10 degree rotation from the horizontal plane, Daikin allows up to +/- 30 degrees.
5. Confirm minimum distances between fittings. LG is 20” (508mm)
6. Avoid creating oil traps. If required use inverted trap within VRF manufactures guidelines.
7. Headers have to have homeruns to Indoor Units, without other Y-Branches or Headers in-between.
8. Use a torque wrench for proper tightening of flared fittings to prevent leaks.
9. Use dry nitrogen purge when brazing.
10. Use expansion loops for long runs of piping.
11. Minimize piping lengths and fittings.
12. Report back to the Design Engineer any changes in the system installation.

Checkout Job Walk Basics 101 – What you need to know when attending a job walk on a retrofit project.

VRF / VRV manufactures require that you use their proprietary software to design the refrigeration piping for the installation of their VRF systems. You or your engineer will need to have a cooling and heating load to import or use with the VRF piping design software. Using energy modeling software is great for Heat Recovery Systems and optimizing zoning layout. Below you will find a list of links to each of the Manufactures free VRF Piping Design Software. Here is what you can expect to receive.

VRF Piping Diagram

The VRF manufactures software will provide a schematic piping diagram showing all the outdoor & indoor units along with any accessories. The schematic piping diagram will also show the pipe sizes and lengths that were used in the calculation. There will also be model numbers for the equipment and accessories with the schematic. All fittings and valves are converted to an equivalent length of pipe when calculating piping and system size.

Of course you will be asked to enter the lengths of piping unless your VRF sales representative has agreed to do it for you based on a set of plans and specifications. The software will automatically indicate whether the design has exceeded the allowable lengths as dictated by the VRF manufacture.

The VRF Piping Design Software should give you the following as shown in the Piping Diagram above;

1. Model # and Size of the Outdoor Unit
2. Pipe Sizing from outdoor Unit to Branch Selector or Indoor Unit
3. Pipe Lengths for each section
4. Model numbers of all “Y”-Branch Fittings and where they are located.
5. Model # of all Branch Selector Boxes
6. Pipe Sizing from Branch Selector Boxes to Indoor unit
7. Pipe Lengths for each section
8. Model # of all Indoor Units and its Cooling & Heating Capacity
9. Thermostat or controller Model #

Looking at the above VRF piping diagram you can see everything is drawn with a single line, but that there are three dimension (3-Pipe System) for the pipes leaving the Outdoor Unit, and two dimensions (2-Pipes) leaving the branch Selector Box going to the Indoor unit. This makes the drawing is easier to read.

VRF Electrical & Control Wiring Diagram

The VRF manufactures will provide a schematic of the electrical and control wiring diagrams showing how all of the components of the system are powered and controlled. The schematic will indicate the power and control wiring size and type.

The VRV Design Software should give you the following as shown in the Wiring Diagram above;

1. Power Wiring for Outdoor units
2. Power Wiring for Branch Selector Boxes
3. Power Wiring for Indoor Units
4. Control Wiring from Controller to Indoor Units
5. Control Wiring between Indoor Units
6. Control Wiring from Indoor Units to Branch Selector Box
7. Control Wiring between Branch Selector Boxes
8. Control Wiring between Branch Selector Boxes and Outdoor Units
9. Control Wiring between Outdoor Units
10. Control Wiring to Main Controller if used.

Bill of Materials

The VRF Piping Design Software will provide a bill of materials for the project which should include the following at a minimum;

• Equipment Model Numbers & Capacity
• Accessories: Branch Selector Boxes, Y-Branches, Headers, etc.
• Piping sizes and lengths
• Controls, thermostats
• Factory refrigerant charge & additional refrigerant charge required

Equipment Schedules

The VRF/VRV Design software will generate equipment schedules that can be used on your CAD design drawings. This will save you time and money from not having to make this yourself.

Refrigerant Charge

The software will generate an estimated quantity of refrigerant that you will be required to supply to meet the required capacity of the system. The outdoor unit should come pre-charged with an amount for the system excluding the piping. The amount of refrigerant charge should be indicated in the report.

VRF System Sizing Diversity Factor

This is known by the various names that each VRF manufacture uses to describe the ratio of Indoor Unit Capacity to Outdoor Unit Capacity. There are two formulas often used to express system/load diversity. The first involves the total peak load of all the indoor units divided by the total capacity of the outdoor units that they’re connected to.

Indoor Unit Capacity (Btuh) Total of Peak Loads / Outdoor Unit Capacity (Btuh) = Diversity Ratio.

Cooling Load diversity occurs when the engineer provides zoning of the indoor units with different peak load times. Outdoor units serving a block load contains zones that peak on different days at different times, allowing for the outdoor unit to be smaller than the sum of the peak loads of each indoor unit. This is often achieved by combining zones with different solar exposures onto the same outdoor unit. The second formula involves the total Block Load divided by the Total Capacity of the Outdoor units.

Block Load Capacity / Total Outdoor Unit Capacity = Building Load Diversity

VRF Piping Design Software Links

Unfortunately some of the VRF manufactures have several divisions throughout the globe with differing links and names for their software. Here are a few.

LG – LATS Multi V
Daikin – VRV Web Xpress
Mitsubishi – Diamond System Builder
Samsung – DVM Pro
Carrier – VRF Software
Toshiba (UK) – DesignAirs
Hitachi – HI-Tool Kit 

What you will need to get started

1. Heating & Cooling Loads with zoning requirements.
2. General layout of equipment components in building.
3. Lengths of piping between pieces of equipment
4. Type of Ventilation system
5. Type of Indoor Units for each space.

The VRF Manufactures representative will often provide the above information free of charge with the hopes that they will be able to sell you the equipment and accessories. Contact your local VRF/VRV supplier for information on the above VRF Piping Design Software.

VRF Advantages

1. 1. 1. Heat Recovery units can utilize heat removed from zones providing cooling to heating zones requiring heat.
      2. VRF systems take up less room than other system types, freeing up valuable mechanical room space for other purposes.
      3. Reduced usage of ductwork and the space required for moving air around the building.
      4. Historical buildings with limited space for air ducts and to minimize disruption of architectural features.
      5. In commercial retrofit projects, it’s possible that all the VRF equipment can be brought into the building with use of the elevators, avoiding costly cranes or rigging.
      6. Increase in energy efficiency with the elimination of large supply air fans. Requirement for DOAS may negate some of this advantage, but OSA ventilation will require smaller ducts and fans.
      7. Smaller and lighter equipment on the roof can mean less structural requirements than other system types.
      8. Using VRF in new construction reduces the need for large air ducts allowing for the possible reduction in building height.
      9. Quiet operation of the VRF indoor units and Outdoor units.
      10. Possible LEED® points for energy efficiency.
      11. Variable speed compressors for increased efficiency at part load.
      12. If using more than one outdoor unit twinned together, one can be down for maintenance while the other is still running.
      13. Modular design allows for easier expansion.
      14. Lighter roof mounted equipment than conventional HVAC equipment requires a smaller crane, thereby reducing rigging cost.
      15. Using a VRF Heat Recovery System avoids having to have two separate system and pieces of equipment to maintain, a Chiller for chilled water and a Boiler for heating hot water.

   Please email us other VRF advantages of using this technology on projects that can be added to this list.

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