The Importance of Hot Water Cylinder Coils

The specification of the coil is one of the most important factors in determining the overall performance of your hot water cylinder and therefore it is vital that it’s specified correctly and rigorously tested to ensure quality.

In a recent research project carried out by the University of Ulster, where they compared the performance of a stainless steel cylinder and coil with a copper unvented cylinder and coil, the results showed the copper system reduced the heat up time of the water by 28.8% over stainless steel.

The coil is the tube which heats the water in the cylinder and the challenge is for the coil to heat the contents of the tank in the most energy efficient way. Depending on the number and type of fuel sources, there could be several coils in a cylinder.

The key factors in determining coil performance – are in the thermal transfer properties of the material and the total surface area.

The surface area can be maximised in 3 ways

  • the length
  • the diameter
  • using finned sections along the coil

The performance enhancements offered by copper go much further than simply the superior heat transfer properties.

The flexibility of the copper enables the coil to be wound tightly and therefore increases the amount of coil which can be fitted into the cylinder – offering even further savings.

Copper’s flexibility also means that multiple coils can be manifolded together to a single connection to increase the surface area further whilst continuing to deliver the required flow rate. This technique is critical with heat pump cylinders where the coil should be specified to optimise the kW output of the heat pump.

So how can you compare the performance of cylinder coils?

  1. Heat transfer properties of material
  2. Length of coil in the cylinder
  3. Diameter of coil
  4. Finned or smooth coils

At McDonald Water Storage, we offer the unrivalled benefits of copper coils and a manufacturing flexibility second to none. This allows you to achieve what you need from your heating coils – be they boiler, biomass, solar or heatpump.

No matter which fuel is being used – tell us what is required and we will ensure it is delivered.

And when it comes to quality, we go above and beyond.  Every coil is tested twice – once externally and then again when the coil is fitted in the cylinder.