Double - channel heat exchanger with wall - mounted furnace tube

Five - tube single - channel heat exchanger on opposite side of wall - mounted furnace

Wall - mounted five - tube double - channel heat exchanger

Wall - mounted five - tube single - channel fast - plug heat exchanger

Wall - mounted six - tube double - channel heat exchanger

Wall - mounted six - tube double - channel fast - plug heat exchanger

Double-channel wall-mounted furnace heat exchanger

Single-channel wall-mounted furnace heat exchanger