boiler solid flat color icons with quadrant frames

boiler heater water tank home system appliance hot temperature control energy efficiency pipe valve radiator steam pressure insulation thermostat electric gas burner safety maintenance installation plumbing utility homeheating centralheating heatingsystem waterheater energysaving heatingelement thermal thermostatic boilerroom heatingappliance solid silhouette icons frames outlines strokes square rectangular flat symbols isolated logotype glyph