Copyright Goodheart-Willcox Co., Inc. 262 Hydronic Heating: Systems and Applications Flowmeters: Flowmeters provide monitoring of the flow rates of water through individual heating loops or through the entire hydronic heating system. Monitoring the flow rate can determine the proper amount of Btu delivered to the space and can also be an indicator of circulating pump performance. These devices can be incorporated into the system along with temperature gauges and can also be used for system analysis and troubleshooting, Figure 12-45. Temperature gauges: Temperature gauges are located at various points in the hydronic heating circuit, including at the inlet and outlet of the manifold sta- tion. They provide a monitoring point for determining proper water temperature at a glance. Temperature gauges can be used to regulate the temperature drop across a circuit and can be instrumental as a troubleshooting tool to decide if the system is operating at peak efficiency, Figure 12-46. Floor or slab sensors: Floor and slab sensors are used not only to assist in controlling the space temperature but also as a limit switch when incorporating radiant heat with hardwood floors. These sensors can be connected to a micro- processor control to reset the space temperature, or they can be used to shut off the zone valve in the event that the water temperature within the heating loop exceeds the desired set point. Outdoor reset controllers: These controllers should be considered standard equipment on any hydronic heating system. The outdoor reset controller is used to regulate the hot water temperature set point based on the outdoor air temperature. It functions by lowering the supply water temperature set point as the outdoor air temperature rises. Conversely, it raises the hot water tempera- ture set point proportionally as the outdoor air temperature falls. The outdoor reset controller provides maximum fuel efficiency for any hydronic heating sys- tem and can be used to control the entire system or individual heating loops, Figure 12-47. Microprocessor controllers: The solid-state microprocessor controllers found in many of today’s radiant heating systems provide a logic-based con- trol panel for multiple heating loops. Most of these controllers can command multiple zone valves to open and close by either two-position control or full modulation, Figure 12-48. They provide inputs for solid-state room sensors and Goodheart-Willcox Publisher Figure 12-45. Flowmeters are used to monitor proper fluid flow rates through heating loops. Goodheart-Willcox Publisher Figure 12-46. Temperature gauges provide a monitoring point for determining proper water temperature and can be used to regulate the temperature drop across a circuit. Goodheart-Willcox Publisher Figure 12-47. Outdoor reset controllers provide maximum efficiency in a radiant heating system by adjusting the hot water set point based on the outdoor air temperature.