e.alleg wrote:with the addition of 6 valves, another pump, and expansion tank you now have the option of running oil only, coal only, or coal and oil together. This setup will pretty much eliminate any kind of no heat "emergency" and adds flexibility. My drawing could be better but I just did it quick and I like extra pipes. Note the bypass loop for the coal boiler, that is critical for summer DHW use.
OK, let me see if I understand this.
1. When the coal pump is one and the oil pump is off, the water takes the path of least resistance and goes through the by-pass for the oil boiler.
2. When the oil boiler pump is on and the coal pump is off the water takes the path of least resistance and goes through the by-pass for the coal boiler.
3. If both the coal and oil are running, then neither bypass loop is used and the boilers appear to be in series.
Here's where I need some more clarification. When you get a call for heat, how does the coal or oil boiler know when to fire up.
i.e. If my house calls for heat and the coal boiler is up and running how does the oil boiler know enough to stay off?