My R85 is running rich. According to Rinnai tech support, the unit is factory calibrated to 7.5" of WC. My regulator is set to 10.5" which is max spec'd for the unit. Would the right course of action be
1. Decrease pressure at the regulator to 7.5"
2. Recalibrate high/low fire
3. Replace the unit with an electric (j/k, folks)
Whats the right way to do it and why?
Do you have a problem? Is it working right? If you don't have a problem, leave it alone.
If there is a problem, call Rinnai and Have them give you some names of Authorised Service Providers. Choose one and have them come out. If you try to reset the manifold gas pressures without the proper equipment and training, you will mess it up worse and posible void the warranty.
What makes you think it's running rich? I get the gas pressure thing, but have seen many like that never need anything done.