Re: Hello from Massachusetts!
Posted: Fri Mar 01, 2019 3:51 am
That circuit is largely the basic setup. You can add things in the line like feed water heaters and superheater and such.
The only thing that I always press for is this. At the output of the feed water pump, have the line split into two routes. One goes direct to the boiler, perhaps through a feed water heater and certainly though a shutoff valve. The other route is through a valve which spends most of it's life closed and then to a float valve in the hot well. The feed water pump sucks from the hot well. This regulates the boiler water level. The valve before the float valve is just in case the float valve sticks open. You can manually regulate the level until you clear the float valve blockage. I've never needed mine.
This has been written up elsewhere and probably better but here's my way of explaining it. On the face of it, we are just regulating the water level in the hot well. So what? But from a larger point of view, consider that, except for leaks, safety valve events and whistle action, the total amount of water in the system is fixed. So if the hot well level goes down, the boiler level has to go up. And if the hot well level goes up, the boiler level has to go down. Now it's a royal pain in the rear to have any sort of float type thing inside the boiler. Forget that. So we regulate the hot well level and thus, inescapably, we are regulating the boiler level.
If we toot the whistle a lot or there are leaks or, like me, you let the safety valve pop a lot, the boiler level will creep down even though the hot well level is constant. So we add water to the hot well. The float tries to rise and shuts off any flow from the feed water pump into the hot well. All of the pump output goes into the boiler until the hot well level drops a bit and then we are back regulating again.
This works so well that it's dangerous for me. I forget to pay attention to the water glass because it never changes. I have steamed for hours at a time without seeing the level change. It may be fun to fuss with a pump bypass valve when you are fooling around with your power plant in the shop but you will have about a zillion other things to do when you are on the water. Like not hitting things and passengers trying to fall overboard and adjusting the fire, and, and, and . . .
The float valves are commonly found at farm supply houses. They use then keep water in livestock watering tanks.
The only thing that I always press for is this. At the output of the feed water pump, have the line split into two routes. One goes direct to the boiler, perhaps through a feed water heater and certainly though a shutoff valve. The other route is through a valve which spends most of it's life closed and then to a float valve in the hot well. The feed water pump sucks from the hot well. This regulates the boiler water level. The valve before the float valve is just in case the float valve sticks open. You can manually regulate the level until you clear the float valve blockage. I've never needed mine.
This has been written up elsewhere and probably better but here's my way of explaining it. On the face of it, we are just regulating the water level in the hot well. So what? But from a larger point of view, consider that, except for leaks, safety valve events and whistle action, the total amount of water in the system is fixed. So if the hot well level goes down, the boiler level has to go up. And if the hot well level goes up, the boiler level has to go down. Now it's a royal pain in the rear to have any sort of float type thing inside the boiler. Forget that. So we regulate the hot well level and thus, inescapably, we are regulating the boiler level.
If we toot the whistle a lot or there are leaks or, like me, you let the safety valve pop a lot, the boiler level will creep down even though the hot well level is constant. So we add water to the hot well. The float tries to rise and shuts off any flow from the feed water pump into the hot well. All of the pump output goes into the boiler until the hot well level drops a bit and then we are back regulating again.
This works so well that it's dangerous for me. I forget to pay attention to the water glass because it never changes. I have steamed for hours at a time without seeing the level change. It may be fun to fuss with a pump bypass valve when you are fooling around with your power plant in the shop but you will have about a zillion other things to do when you are on the water. Like not hitting things and passengers trying to fall overboard and adjusting the fire, and, and, and . . .
The float valves are commonly found at farm supply houses. They use then keep water in livestock watering tanks.