The Two-pipe Takeover

For any commercial application, two-pipe Variable Refrigerant Flow (VRF) zoning systems – like that from Mitsubishi Electric Cooling & Heating (Mitsubishi Electric) – provide a solution that leaves three-pipe systems struggling to keep up. Proven in the field, two-pipe technology is not only more economical to install but reliable, energy-efficient and able to provide superior levels of control and comfort for occupants.

If you’re still designing and/or installing three-pipe systems, here are a few reasons why we here at the Advanced Products Group (APG), a division of Aireco Supply, Inc., have chosen to move toward two-pipe, and why you should consider making the move to two-pipe.

Pipe Connections
Simple: Far fewer joints. In a two-pipe VRF system with four indoor units, for example, there are 20 connections; in a three-pipe system, there are 58 connections. Each additional connection requires more materials, labor and time.

None of these resources come cheap. Consider materials: Over the past few years, copper has become much more expensive, driving the need for new technologies that don’t rely as heavily on the material. A two-pipe system’s reduced number of pipes means less copper to purchase, offering more room in the project budget and cost savings for installation.

Having fewer pipes means more than just reduced materials costs, though. With fewer connections to make, there’s a smaller chance of incorrect pipe attachments and leaks. Removing a pipe also introduces flexibility in design and installation. Smiley El-Abd, commercial area manager, Mitsubishi Electric, said, “Two-pipe is less restrictive on how copper is run from the BC controller to the indoor units. You can fish the small copper piping through to the branch controller without damaging the building. The piping is more flexible.” And unlike three-pipe systems, two-pipe systems don’t require expensive proprietary branch fittings. 

Electrical Connections
Two-pipe VRF has significantly fewer electrical termination points than three-pipe systems. Having fewer electrical connection sites reduces the complexity of the wiring process will reduce any potential connectivity issues. Ultimately, fewer components in the system means less chance of the system failing in the future.
Control 2_pipe
Two-pipe architecture allows the indoor units to change temperature quickly from cooling to heating, or heating to cooling. The cooler/hotter refrigerant from one indoor unit moves to the branch controller and gets redistributed right there to another indoor unit. In a three-pipe system, the redistribution happens out in the condenser, not locally in the branch controller. Since a three-pipe system’s refrigerant has to be moved farther to undergo the same redistribution process, the system responds more slowly, loses energy along the way and costs more money to operate. 

Future Servicing, Alteration Ease
A VRF system with a two-pipe design makes future servicing simpler, increasing lifetime cost savings. Plus if additions are needed in the future, the new components can be engineered and added while the system remains in operation.

In comparison to the complexity of a three-pipe system, the streamlined two-pipe offers more design capabilities, an easier installation and project cost savings. As El-Abd said, “For any commercial project, you can reduce significantly the amount of damage to a building with a two-pipe system. A two-pipe system will also save money because you don’t have to spend on a third pipe or extra branch controller boxes.”