Removal device for removing gas bubbles and/or dirt particles from a liquid in a liquid conduit system or for removing particles of a heavier or lighter liquid from the liquid in the liquid conduit system, the removal device comprising: - an entry, - at least one exit, - a housing which defines an inner space, - a main flow channel extending from the entry to the exit at least in part through the inner space, the main flow channel being defined by one tube or by a first and second tube (220A, 220B), - at least one branch flow passage formed by a series of holes in the single tube or formed between an end of the first tube 220A and an end of the second tube, the branch flow passage allowing fluid communication between the main flow channel and a quiet zone outside the tube and within the inner space which is defined by the housing, - at least one return flow passage the return flow passage allowing a return flow from the quiet zone outside the tube back into the main flow channel, wherein the return flow passage is located in the housing at an upstream side of the housing and upstream of a plate, when viewed along the direction of flow in the main channel, wherein the return flow passage is formed by a transverse tube extending from an area which is surrounded by a housing wall, the plate and by the single tube or by the first tube, the transverse tube extending into the main flow channel, wherein - when viewed in the direction of the main channel - the transverse tube extends transverse to the main flow channel and - when viewed in side view - the transverse tube extends in a downstream direction of the main flow channel, and wherein the quiet zone has a greater cross-sectional area than the main channel and wherein the removal device is constructed to branch off only a relatively small portion of the main flow, with the result that in use the liquid in the at least one quiet zone has a smaller velocity than the liquid in the main flow channel, allowing dirt or particles of a heavier liquid to settle and/or allowing gas bubbles or particles of a lighter liquid to rise in the quiet zone. - an entry, - at least one exit, - a housing which defines an inner space, - a main flow channel extending from the entry to the exit at least in part through the inner space, the main flow channel being defined by one tube or by a first and second tube (220A, 220B), - at least one branch flow passage formed by a series of holes in the single tube or formed between an end of the first tube 220A and an end of the second tube, the branch flow passage allowing fluid communication between the main flow channel and a quiet zone outside the tube and within the inner space which is defined by the housing, - at least one return flow passage the return flow passage allowing a return flow from the quiet zone outside the tube back into the main flow channel, wherein the return flow passage is located in the housing at an upstream side of the housing and upstream of a plate, when viewed along the direction of flow in the main channel, wherein the return flow passage is formed by a transverse tube extending from an area which is surrounded by a housing wall, the plate and by the single tube or by the first tube, the transverse tube extending into the main flow channel, wherein - when viewed in the direction of the main channel - the transverse tube extends transverse to the main flow channel and - when viewed in side view - the transverse tube extends in a downstream direction of the main flow channel, and