Help me determine the type of modulating boiler I have
Help me determine if I have an OpenTherm boiler
There are different ways to find out whether you have a modulating boiler with OpenTherm protocol or a modulating boiler that only works brand-specifically. Below we'll explain per option how to find this information.
Based on the serial number of your boiler
The most reliable way to find out what type of boiler you have is by reading the boiler's booklets. It states exactly what the boiler's serial number is and perhaps also what type of boiler you have. With a new boiler, you can almost assume that it's modulating. An OpenTherm protocol is the most common variant for modulating boilers. Whether your modulating boiler works via an OpenTherm protocol or only brand-specifically can be found in the booklet of the boiler.
Based on your current thermostat
Based on your current thermostat you can find out what type of boiler you have. It's often stated on the thermostat if it's modulating. Is that not the case? Then you can easily find out what kind of thermostat it is via the internet using the serial number (usually on the back of the thermostat). Are you, after a little research, certain that you have a modulating thermostat hanging on the wall? And have you been able to determine that it works with OpenTherm? Then you can assume that your boiler is also equipped with an OpenTherm protocol. Unfortunately, this method of research is not the most reliable method. It could be that you've been operating the modulating boiler with an on/off thermostat for years.