Chilled water fan coil system vs refrigerant based system

1 Introduction
2 Related articles on Designing Buildings Wiki

[edit] Introduction

When choosing between a chilled water fan coil solution or a refrigerant based system, there are a couple of key factors which will ultimately affect your specification choice. These include restrictions around refrigerants in buildings, safety, sustainability and building size.

[edit] Building restrictions

Within new developments, there can be a restriction on how much refrigerant a building contains. In these cases, chilled water fan coils are a viable specification option. They are able to provide a comfortable environment using a water-based system.

[edit] Safety

F-Gas regulations require either regular inspection of joints or a leakage detection system, both of which can be quite costly. In comparison, chilled water systems use an inert liquid, eliminating the need for these additional requirements.

[edit] Sustainability

Refrigerants have a high Global Warming Potential (GWP). As we drive for more sustainable buildings within the construction industry, using systems that help reduce this are important. Chilled water systems only utilise refrigerant in the main plant and therefore use much smaller quantities.

[edit] Building size

Refrigerant based systems require a plant room once they meet their maximum distance for a single pipe run. Medium to large systems may require multiple condensers which can require additional internal space and roof space. A hydronic system, however, can operate from a single chiller unit piped centrally to the roof, which can be a consideration where space is a commodity and maximising each square metre is essential.

[edit] Chilled water fan coil systems

Although a refrigerant-based system may be suitable for some projects, where they are not chilled water systems can offer a viable alternative.

With a chilled water fan coil system everything is connected to a centrally located hydronic chiller and heat pump or boiler – often situated on the roof to increase the amount of usable space. This type of system requires a two-pipe model for cooling only, or a four-pipe model for a heating and cooling systems. This allows for smaller riser space and fewer if slightly larger pipes.

As indoor air quality and occupant comfort becomes a wider topic within the construction sector, cooling is becoming increasingly necessary, especially within new and existing commercial developments. When specifying a system, it is increasingly important to select solutions which are futureproof, carry reduced risks and support the drive toward more sustainable buildings.

For more information on chilled water fan coils or to discuss a specific project in more detail, please contact our team of industry experts. GDHV also offer a range of CIBSE accredited CPDs relevant to commercial developments on products such as fan coils and heat pumps, contact us to make a booking.

This article originally appeared under the headline, 'Why pick a chilled water fan coil system over a refrigerant based system?' It was published on 20 March 2020.

--Glen Dimplex Heating & Ventilation 13:05, 31 Mar 2021 (BST)