A house with radiators needs to see in one glance that you touch boilers
Owners of hydronic systems have been turned away enough times that they scan for the word before they read anything else.
Brick two-flats and four-families across the City of St. Louis were built for boilers and radiators. The people who own them know that many contractors will not touch that equipment, so they look for confirmation immediately.
Put it in the navigation and in the first screen, not buried on an inside page. Boiler service, radiator systems, steam. Naming the equipment does more work than any headline about comfort.
If you do not service boilers, say that too. An honest exclusion saves you a call that would have wasted twenty minutes and annoyed somebody.
The same logic applies to older gravity furnaces, converted systems and any equipment class where availability is the real question. Availability beats persuasion for that reader.