UK Boiler manufacturer: Developing a better approach for Reliability Testing

A UK Boiler Company was suffering from significant early life failures. They needed to improve their understanding of Reliability and drive improved performance with upgrading in-house Reliability testing. Unfortunately testing the final product was not going to be effective as it was too large – the testing approach necessitated stressing the individual electromechanical, mechanical and electronic sub-assemblies.

This technical project resulted in a significant change for the client as they increased focus on Sub-System stress testing – improving defect stimulation during new product reliability testing.

Development of a testing approach

A programme of individual sub-system Early Life stress testing was set up with focus on the major sub-systems within the product (Main Control PCBA, Fan, Gas Valve, Pump).

A ‘design of experiments’ approach was used to develop a series of tests for each sub-system that would apply stresses in different combinations and hence maximise defect detection capability. For example, the Main Control PCBA accelerated stress testing included a range of sequential stresses such as Random Vibration, Thermal Cycling, Temp / Humidity to achieve the highest test confidence possible.

Unique Early Life Stress Test plans were also developed for other key sub-systems to define a new programme which had the ability to detect issues that had previously evaded in-house detection and were not seen until the product was in the field.

The next stage was to drive these effective techniques back into the supply chain where stronger Ongoing Reliability Testing (ORT) is seen as the key factor in making sure ongoing mass production does not suffer from sudden ‘outliers’ that impact overall return rates.

The client also wanted to be able to increase the warranty period of its products and recognised the importance of supplier ORT. We worked with key suppliers to educate them and build testing approaches into their products.


Over a 2 year period, the client committed to a strong sub-system and full system stress test programme which has driven field return levels down to world class levels.

The Production Director / Head of Quality commented;

I’d like to thank you for the work you’ve put in. All suppliers were complimentary and mentioned whilst they do some of the things you covered they could all do a more. They can see our growth contributes to their success.