Calorifiers to Plate Heat Exchangers (PHXs)

Site overview

A large university in the West Midlands.

The Problem

On review of this site’s domestic hot water (DHW) system, we identified that the current set up consisted of a number of inefficient, un-lagged calorifiers requiring high maintenance, a regular legionella prevention regime, as well as annual pressure testing.

The Solution

In order to reduce maintenance costs and increase DHW system efficiency, a project was initiated whereby a number of DHW calorifiers were replaced with PHXs.

The decision to undertake this work was supported by prior research (through the use of heat meters), whereby it was established that the heat-transfer efficiency of PHXs is typically 90%, compared to similar tests carried out on calorifiers which consumed substantially more energy, typically operating at about 60% efficiency, primarily due to storage losses and system pasteurisation requirements.

A 30% improvement in efficiency can therefore be realised on hot water generation through the use of PHXs.

Other benefits of using PHXs over calorifiers are:

1. Increasing the capacity is easy (simply by adding more plates).

2. Low water content reduces the risk of legionella  breeding.

3. Compact for installing in tight spaces.

4. Easy to install and maintain (the plates simply unbolt and can be removed).