Does anybody know how you adjust the low fire on this valve? There is an adjustment screw under the cap I have been able to set high fire but don’t see where you adjust low at. Just replaced a sooted up heat exchanger on this unit I imagine was caused by the high gas pressure settings in low and high fire. It’s a model 36c76 type 486. The black cap on the side is the vent. It’s on a Trane ysc092a3rma29a![]()
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