it sounds like a flaky time delay relay. no, it is not essential. however, if you have pressure cutout safety switches, you should pick up a time delay relay made by icm. it does not use a common and will have two terminals. wire it in series with the coil and the pressure switches. make sure it says 'delay on break' and set the time for the full 10 minutes. that way, if a safety opens, the control will force a 10 minute delay before retrying. this will prevent short cycling of the circuit when the pressure switch automatically resets. you should be able to pick this up in most ac supply houses.