A two-pipe system uses half the hydronic piping required by a four-pipe system, which results in a lower cost and a shorter installation time. The systems are also more compact that reduce the space requirements of mechanical rooms. Maintenance is also simpler in a two-pipe system, thanks to the reduced number of piping fixtures and valves.
Two-Pipe Pros
- Great for Condos, Apartments and Hotels.
- Less Expensive to Install Than a Four-Pipe System.
- Reasonably Energy Efficient.
- Simple Design.
Two-Pipe Cons
- Cannot Simultaneously Heat and Cool.
- Must Be Manually Switched from Heating to Cooling and Vice-Versa.
- Seasonal Temperature Fluctuations May Leave the Building Uncomfortable.
Four-Pipe HVAC System
This system configuration uses twice as much piping as a two-pipe HVAC system, and thus it is more expensive and takes longer to install. In addition, a four-pipe system requires more space to accommodate two hydronic piping circuits that run through the building. The increased number of fixtures, valves and connection points also results in a more demanding system in terms of maintenance.
Four-Pipe Pros
- Can Heat and Cool at the Same Time.
- Can Be Customized to the Building.
- No Need to Manually Switch the System.
Four-Pipe Cons
- More Expensive to Install than a Two Pipe System.
- Can Be More Expensive to Maintain.
- Proper Calibration is Essential to Maintain Energy Efficiency.
Three-Pipe HVAC System (VRF System)
- The 3 pipe Heat Recovery system is the equivalent of a 4-pipe chilled water system.
- A Heat Recovery system has the ability to provide simultaneous heating AND cooling.
- When both heating and cooling occur simultaneously, system and building energy can be better utilized.
- When demand is met by an indoor unit the unit will work on fan only or the fan will cycle on/off until demand returns.
Rohan Kuldhar is a Project Sales Engineer at Fusion HVAC Solutions Pvt Ltd. He possesses a BE Mechanical degree.
