In the heating boiler code, where should an additional stop valve be placed when one is used in the supply pipe connection?

An additional stop valve in the heating boiler code should be placed in the return pipe connection. This is critical for several reasons.

First, placing the stop valve in the return pipe allows for better control of the water flow back to the boiler. This can help isolate the boiler from the system during maintenance or repairs. If there is a need to service the boiler, shutting off the flow from the return line assists in safely emptying or servicing the heating elements without unnecessarily draining the entire system.

Second, having a stop valve in the return line aligns with safety practices. It ensures that if there were a malfunction or need for maintenance, the boiler can still remain safely contained. Isolation of the return line offers a safety protocol to avoid hot water exposure while repairs are underway.

In contrast, the placement of the stop valve in the feed water line, main steam line, or next to the safety valve would generally not provide the same level of isolation or control needed in the return side, potentially creating more risks or complications during maintenance activities. This emphasizes the importance of positioning shut-off valves appropriately within a piping system to enhance operational safety and efficiency.