Gas Boilers as Domestic Heating & Hot Water System: Speaking of Gas Boiler Efficiency Comparison

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gas boiler efficiency comparison
Looking for a convenient, cost-effective and at the same time very efficient domestic heating and hot water system able to keep your home at comfortable temperature levels even in cold environments? Demand a high quality heating system that proves to be environmentally-friendly, energy-saving and easily-serviced? In this case, gas boilers should undoubtedly be considered the best market available option.

Gas Boilers & Their Principles of Operation

Gas boiler heating system’s high reliability, high efficiency and smooth operation made it a very popular market available option. The gas boiler operation principles are simple: gas gets burnt in order to boil the water, which is later can be utilized for different domestic heating or hot water purposes. The heating system’s benefits are obvious: it’s both easily-serviced (regular maintenances prevent unwanted major repairs) and energy-saving (uses very little electricity). But when it comes to choosing a gas boiler, a customer has three available options: regular, system or combination boiler. According to recent observations, the gas boiler type stands only for 50% of the customer’s choice, efficiency rating standing for the rest. And that’s true, because many customers, while choosing gas boiler as a main domestic heating and hot water system, pay most of their attention to the boiler’s efficiency, which stipulates the need to conduct a gas boiler efficiency comparison test.

Choosing a Gas Boiler Heating System: Gas Boiler Efficiency Comparison

The boiler efficiency can be calculated or measured in u a number of ways and for different purposes. Generally, gas boiler efficiency tests are subject to uncertainties of measurement, which means that calculated efficiency values’ small differences carry no significance and should never be relied on when comparing different gas boilers. Here is an annual and seasonal efficiency comparison list of top 15 A/B efficiency band rated gas boilers (from best to worst):

  1. Keston Qudos 28h (annual – 90.3%, seasonal – 91.1%);
  2. Keston Qudos 28s (annual – 90.3%, seasonal – 91.1%);
  3. Fonderie Sime SpA Dewy 30/130 HE FS (annual – 90.3%, seasonal – 90.7%);
  4. Fonderie Sime SpA Dewy 30/80 HE FS (annual – 90.3%, seasonal – 90.7%);
  5. Gledhill GulfStream A-Class 12/OV (annual – 90.2%, seasonal – 90.1%);
  6. Gledhill GulfStream A-Class 12/SS (annual – 90.2%, seasonal – 90.1%);
  7. Ravenheat CSI System AT (annual – 90.1%, seasonal – 90.7%);
  8. Ravenheat HE System A (annual – 90.1%, seasonal – 90.7%);
  9. Worcester Greenstar CDi 25 Cdi (annual – 90.0%, seasonal – 90.3%);
  10. Keston C 36 Combi (annual – 89.8%, seasonal – 90.7%);
  11. Worcester Greenstar 36 CDi Compact (annual – 89.8%, seasonal – 90.5%);
  12. Worcester Greenstar 28 CDi Compact (annual – 89.8%, seasonal – 90.5%);
  13. Radiant RKA 34/100 (annual – 89.8%, seasonal – 91.4%);
  14. Viessmann Vitodens 111-W B1LA 35kW (annual – 89.7%, seasonal – 90.6%);
  15. ACV HeatMaster 35TC (annual – 89.7%, seasonal – 90.9%).


Gas boiler efficiency comparison test shows that efficiencies of different boilers present a slight variation due to climate, occupancy patterns, exposure, housing conditions, insulating, heating controls and other factors. What really matters is that, according to statistical analysis, if two boilers have 3% values apart, then there is 95% confidence that the boiler with a lower value is less efficient than its higher value counterpart. Choose wisely!