PRO Question: Flame Sense rod
I am an electrical engineer (new here, but not an idiot) that is adding a smart ignition/control/flame monitoring to a previously primitive (manual) burner type application. It involves adding a valve and controller with ignitor and flame sense rod. A few things came up with this.
#1. As far as the controller goes, I am using the Honeywell S87 series, they make 2 different units: one is a single rod such as S87J1034 (one high voltage output terminal for combination flame sensing rod and ignitor), and the other type is a dual rod such as S87C/D series (separate connections for ignitor and flame sense rod). They make 2 "different" compatible ignitors for these, one is an Q347A series (which is just an ignitor electrode, designed to be used with a separate flame sensing rod), and the other is a Q347B series (this is a combo ignitor electrode and flame sensing rod in the same electrode, 1 wire connection).
These controllers use a FLAME RECTIFIED type flame sensor rod, with approx 1.5uA threshold.
1a. They say the Q347A is ONLY compatible with a dual rod system and controller, and the Q347B is a single rod COMBINATION ignitor/flame sensor in one rod unit.
1b. The Q347B is discontinued, and honeywell has NO IDEA why they are still selling a single rod controller with no ignitor available for it (as per their tech dept).
I would probably prefer to go single rod as the application is space constrained, and I may not have room for separate ignitor electrodes and flame sense rods in the burner. I have both controllers, the single rod one has no connection for a flame sense rod, just a single high voltage terminal for ignitor+sense. The dual rod controller has connections for ignition (hv) and sense (low voltage).
#2. Now from what I gather, there is NOTHING special about a flame sense rod (other than the fact it is made of metal and can withstand immersion in flame), but so can any ignitor [I have heard of people using a screwdriver with a clip lead as a temporary flame sensor], so WHY can I not use their standard Q347A type ignitor, as a combo unit, and just leave out the flame sensing rod, I dont understand the difference.
#3 Can flame sensor rods be bent/cut without functional ill effects (assuming I can do it without damaging the insulator)?? I have read lots of documentation that says don't bend the rods (but as far as I know they are just a solid piece of metal, no junction, no internals).