New test method for gas boosters with domestic solar water heaters

► A new test for in-line gas boosters used with domestic solar water heaters. ► Performance change is measured as incoming water temperature and flow-rate varies. ► Standard and condensing boosters are modeled with a variety of solar pre-heaters. ► Annual energy use is significantly greater than calculated using a current standard. ► The condensing gas booster showed a significant advantage over the non-condensing.