Pressure gauges, safety valves and thermometers should be installed at the inlet, and safety valves, thermometers and air valves should be installed at the outlet. The economizer should be equipped with a bypass flue. The purpose is to prevent the economizer from being burned out when the boiler is started, and secondly, when the boiler is damaged and can be stopped immediately, the flue gas can pass through the bypass flue. When there is no bypass flue, a recirculation pipeline should be installed to make the water from the economizer pass to the return water tank or open the boiler drain pipe for drainage, but the latter wastes a lot of heat.
The steel tube economizer is suitable for boilers with large capacity where the feed water is thermally deoxidized or the feed water temperature is high. The cast iron economizer piping system is composed of parallel serpentine pipes, which can not only heat the water entering the drum to the saturation temperature, but also generate some steam (about 10%-20% of the total water supply). The advantage of the steel pipe economizer is that it can withstand high pressure, is not afraid of water hammer, and is not easy to accumulate dust, but it has high water quality requirements and is not resistant to corrosion. The steel pipe economizer does not need to bypass the flue, and does not need to install valves and accessories. It only needs to install a recirculation pipe at the inlet of the economizer to connect with the lower drum (or drum). When the fire is started, the water circulates in the economizer, and when the steam is supplied, the valve of the recirculation pipeline is closed to let the feed water enter the economizer.