According to the boiler manual
E37 Water pressure error – You must top up the water pressure for your system
When opening the fill loop valve to add water pressure, water flows out the exhaust pipe.
The boiler menu isn't interactive. Nothing happens when clicking the buttons, so I can't check the pressure via the display as suggested in several online videos.
We've contacted a boiler technician but we'd like to further troubleshoot until they arrive.
Attached images for visual reference:
Boiler display and menu
Piping below the boiler
Filling loop in hallway cabinet
Best Answer
Knowing nothing about your particular boiler, if you are adding water to the loop and water flows out the exhaust pipe, it sounds like your heat exchanger is leaking, as that's where a connection between the loop water and exhaust would be.
Whether that's a simple part replacement or "new boiler time" will depend on the design of the boiler and price of replacement parts.
When it's fixed, I would personally want to have a pressure or pressure/temperature gauge (analog/non-electric) installed on the loop for my own information/peace of mind/ability to quickly check. Rarely used, but nice to have when there are problems.