Limit an alert rule to printers.
Alerts › rules. Type sits at the top of a new rule. Printer is one tick. A company with no enrolled printer covers zero machines.
Tick printer
Open Alerts › rules and press + rule. Under type, tick printer. Leave the others clear. The chip says every printer in Example Co · 0, and the line says it covers 0 of 6. None of the six machines has type printer. The front-desk Brother at 10.1.1.50 is on Accounts server's LAN snapshot, and it is not enrolled, so it is not in this count. Other would read the same way on this company. None ticked still means every type. The address is typed and not added yet.
Add who is told, then read the sentence
Press add contact. The grey sentence reads: tell email ops@example.com when a warning or worse (any kind) opens on 0 machines printer, and again when it resolves. Press add rule when that sentence is the one you want. This shot stops before that. A printer you enrol, with its type set to printer, is what makes the count move. Check that a printer is installed is a check on a Windows machine, which is a different question from this type tick.
Checking that a named printer is installed on a Windows PC is Check that a printer is installed. A device seen on the LAN is Read devices found on the LAN. The same tick on a report is Limit a report to printers. Type other is Limit an alert rule to type other. Servers are Limit an alert rule to servers. The rest of the rule — kinds, severity, who is told — is Tell someone when a machine needs attention. The type on the machine is Change what kind of machine this is.