Welcome! Here are the website rules, as well as some tips for using this forum.
We don't see many boilers with the tankless bundle heater around here, so I am not well aquainted with the high low aquastat that comes with them. I met one today and got confused. Can somone give me a simple sequence of operations to explain how it should work and the why's and wherefores. What does the differential do? Make it as simple as possible please. Break out the sock puppets if you have to. Thanks