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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7577
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a nx burner and I had to change out the primary

Customer Question

Hey, I have a nx burner and I had to change out the primary controller, I put 7284 controller, what is the highest cad cell reading on these controls befor they lock out? Because the nx burners have a much higher cad reading than the usual burners
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Summary: 1600 ohm range is lock out

The cad cells increase resistance with no flame and no light...to the 10,000 to 20,000 ohm range with no light as you probably already know.

resistance drops when there is light or flame detected by the CAD cell... trip range, for flame detection is resistance *below 750 down to 300 ohms on most burners. So you have a very very wide range between 20,000 ohms in complete darkness and 1,000 ohms or lower On your burner lock out will occur in that 1,400 to 1600 ohm or higher range.

http://www.edragonfire.com/pdf/Beckett_NX_Manual.pdf

see page 12. 1600 ohm range is lock out

http://screencast.com/t/vPq9mZd7

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Thanks for letting me work with you. When we are finished, if my answer has been polite, professional,and thorough, please click one of the ratings . If you still need help let me know!. Expert is not paid for assisting you until you rate answer. Feel free to follow up for30 days at no additional cost.