What is the correct way to set the bypass on a FDO thermostat?guest created 4 years, 5 months ago 1 Member · 2 Posts
MemberMay 14, 2015 at 12:00 am
What is the correct way to set the bypass on a FDO thermostat
MemberMay 15, 2015 at 5:00 am
That’s a good question to ask. I’ve often encountered temperature-related service calls on those thermostats where I found they weren’t set up properly during installation (i.e., replaced by someone not knowing how).
MOST manufacturers of ovens & griddles employing those thermostats provide a step-by-step procedure in their service manuals. You might want to check that out. Otherwise, here’s MY step-by-step procedure:
Assuming the thermostat is GOOD:
- Set it to an appropriately high set-point. 350° sounds good. Let it get happy there. Monitor the temperature with a quality digital thermometer to be sure. If the thermostat is off by more than 50°, manufacturers will tell you to replace it.
-NOTE: If you’re working on an existing thermostat and was told it’s getting too hot, don’t assume it’s a bad thermostat yet. Try adjusting the bypass DOWN first. Somebody may have set it up wrong during replacement.
- Once the thermostat has satisfied and throttled down, Turn its setting DOWN to something like 250°…WELL below set-point. At this point, thermostat should only be passing gas through its bypass flame internal port.
- Inspect the flame. It should around1/8″ high. All burner ports should be participants throughout the perimeter of the of the burner and should show established but small flames each. No flame fluttering or “walking” allowed.
- If the flame is ABOVE 1/8″, take a slot screwdriver and adjust the “B” screw (bypass) on the thermostat body IN – slowly and incrementally clockwise to gradually reduce gas flow to the burner.
- If the flame is BELOW 1/8″ or trying to go out, adjust it OUT – slowly and incrementally counter-clockwise.
- If you think you got it, check your work. Briefly throttle the thermostat way above actual oven temperature to gain a full flame again, then crank it back down below actual oven temperature.
Did the bypass flame maintain your setting? Very likely. If not, then make further adjustments accordingly.
- Let the thermostat ride at a set-point lower than actual oven temp. The temp you’re reading on the digital thermometer should drop. It will do so s-l-o-w-l-y, but it should drop.
- Obviously when the thermostat is at bypass flame,the oven temperature should NEVER continue to rise.
- After all this is done, THEN check and adjust calibration of the thermostat.
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