I replaced my old noisy mechanical unit with a 3250. This saved me a lot of money. I smile when my neighbors with the same houses get twice as much oil as I use in winter. The only problem I have is the low water warning. There was a lot of water in the boiler. The problem was that over the years, 10 years, the sensor has not made good contact with the well it slides into. Sliding the sensor out, cleaning the metal spring on the end of the device with a contact cleaner, and sliding it back into the recess fixes the problem.