Abstract: A spacer device for incorporation into a bent-tube heat exchanger that includes a spine and a plurality of fingers that protrude from one side of the spine. The number of fingers in the spacer device is less than the number of tubes that are folded in a region to form the bent-tube heat exchanger. The plurality of fingers are configured to exert a force against the tubes and to provide and maintain a separation between the tubes in the folded region. A heat exchanger that includes the spacer device may also include a coating on the tubes in the folded region in order to reduce corrosion and increase the life-time of the heat exchanger. The method of forming the heat exchanger includes placing the spacer device between the tubes, such that the fingers lay on the tubes in the region to be folded and assist in the folding process.