*PLUMBERSSTOCK EXPERT* responded:
Hi, there! Thank you for your interest in our Lennox 40L81 LB-94701A flame sensor kit. The flame sensor must be installed on the left side of the burner support. You'll have to mount the sensor on a bracket in the burner support and let the tip protrude into the flame envelope. Make sure to connect the sense wire of the flame sensor. For more information, you can take a look at this data> sheet and refer to page 15. Here is also a list of parts in case you need more reference about the product. If you need more information, contact our customer support representatives @ 435-868-4020 or E-mail them @ support.plumbersstock.com. Thank you and have a great day!