How does water get into a boiler if the pressure inside is greater than the water supply pressure?
1] Feedwater pumps, or 2] Jet ejectors can do the job, though it gets into some thermodynamics to explain why. Also, boilers do NOT all run at 12 - 14 psi !!! Power boilers run more like 1,000 psi, and home heating 'boilers' run at an inch of water column or so.
Hi Jon, you need a high pressure pump as a boiler feed pump.
If the boiler pressure is greater than the water press water will not flow into the boiler. The water must be higher than the boiler pressure for water to flow into the boiler. House hold water pressure can be 35 to 70 psi and a home boiler can operate near 15 psi. Water would then be able to enter the boiler. A higher pressure boiler say 100psi or more, would need a feedwater pump to boost water pressure above that of the boiler.
A boiler typically maintains a level of pressure around 12-15 psi. This level is maintained by the pressure release valve. In contrast, the water pressure in your home will most likely be somewhere around the range of 50psi. Depending on numerous variables, that number will more than likely be somewhere in the range of 40-70psi. Either way, the water pressure in your house's piping(which feeds into the boiler) will be greater than that of the water boiler. STILL... I am not sure if your question was due to you not being aware of the typical pressures you find in homes and water boilers these days. If all you really wanted to know was how water would get into a boiler, when the pressure inside that boiler is greater than the supply pressure.... Well it should be common sense that such a thing is not possible. The water supply pressure would need to exceed that of the boiler. In such cases, there are pumps specifically made for these types of applications.
