Angelery / Water Wizard – Principle of Operation

The Angelery Heat Exchanger is a vertical-cross flow unit whereby modular helical coils are mounted between vertical inlet and outlet risers.

The primary enters the coil from the inlet risers, flows through all coils in parallel, and discharges from the outlet risers.

Secondary fluid flows through the shell from the bottom to top, passing over the coil in series.

The unique Compensator maintains accurate and stable temperature control under widely varying load conditions.

The thermal element located in the compensator unit senses a temperature, which are a function of both the secondary fluid final outlet temperature and the rate of secondary fluid through the heater. A change in flow rate causes the unit immediately to anticipate the need for more or less primary fluid to meet load demand without having to wait for a change in final outlet temperature.

By design, the Angelery provides a storage volume of hot water maintained at the required temperature.

Immediately any draw-off takes place with a low velocity flow of secondary fluid over the coils, the sensitivity of the Compensator unit and the resultant instant operation of the control valve, to allow primary fluid to enter the coils, reduce surge draws on the energy source.


The helical coil design permits flexing under constantly varying pressures and temperatures without damaging the coils or over-stressing the material. This flexing action tends to provide automatic descaling of solids precipitated from the secondary fluid and deposited on the coils in the form of hard scale. On steam applications, the liquid passes over each coil in series and the vapour flows through each coil in parallel creating a ratio of condensing surface to sub-cooling surface in each individual coil. This ratio varies in accordance with load and increase in accordance with the location of the coil from bottom to top of the heater. Thus, at maximum rated capacity, all coils accept the uppermost act to sub-cool the condensate.