In the UK, approximately 16% of the energy use can be attributed to domestic wet central heating systems. Government financial support and advances in technology have led to boilers becoming more efficient and a range of technologies are now available that claim to be able to improve the efficiency of domestic wet central heating systems. One such low cost technology is a passive deaerator. This paper presents the results obtained from installing a passive deaerator on the closed loop of a gas-fired wet central heating system, under controlled conditions in the Salford Energy House. The results indicate that although marginally less heat output was required from the boiler when the passive deaerator was operating, these savings are more or less out weighted by the boiler short cycling more frequently. Consequently, the overall reduction is gas consumption achieved by utilising the passive deaerator device is only of the order of 0.5%; this scale of savings may just be a consequence of measurement noise. The implications are that although a marginal benefit may be attributed to these products, if short cycling takes place, then these savings may become insignificant
