Despatch S Type - Manual (Page 90)

I-235 (9/03) −
87
−
SWING DOOR TROUBLESHOOTING INFORMATION
Please Note: There can be a number of reasons or combination of reasons for swing door and
oven front problems. They include: door alignment, door not sealing, door or oven front
warpage, and possibly oven uniformity problems. One thing to keep in mind while you are
investigating these potential adjustments/fixes is to make sure that you only make one change at
a time; both marking and logging each change in case you have to go back to your original
settings. If you make too many changes at one time, you may find yourself not really knowing
what fixed the problem, or worse yet, only shifting or complicating the problem.
Following is a list of items to check out:
The first thing to check is the oven pressure. Many times you will find this is where the problem
originates, especially if you are having uniformity problems. It is easy to help your uniformity by
opening the fresh air in order to overcome outside air leakage, but this also pressurizes the oven
and in some extreme cases causes excessive outside oven skin temperatures and door leakage
which can create door and oven front problems. To address this condition:
1.
Make sure the fresh air inlet(s) on the heating units/box(es) include a damper blade(s).
2. Fresh air damper should initially be closed. (Note: damper blade may be cutaway for
process requirements and/or safety requirements.)
3. Exhaust air damper should also initially be closed. (Note: damper blade may be cutaway for
process requirements and/or safety requirements.) Depending on the pressure drop in the
exhaust stack run, you may need to open the exhaust damper somewhat in order to create
a slight negative pressure in the oven. Positive/negative pressure can be realized/noted by
excessive outside oven skin temperatures, or air moving in or out around panel joints,
flashing joints or areas around the door perimeter. The simplest way to test oven pressure
is with a smoke test checking areas where leakage would be most evident. This can be
viewed on the outside of the oven watching the smoke being either pulled in or blown out
away from the areas tested.
Note: Oven should normally be set neutral to slightly negative for best door sealing
results.
·
Review door and front adjustment instructions, which are found in the "S" Oven Manual,
provided with the equipment. These instructions should have been followed prior to the
initial heating of the oven. Please review these Instructions before preceding any further in
order to familiarize yourself with the door adjustment procedures.
·
Make sure that the inside perimeter oven seal, center door seal and the drag seals have
been installed properly on the doors and front. Misadjusted door seals will cause the doors
to bind up prior to closing. Inside perimeter seals should be gapped approximately 3/8” away
from inside door frame so the seals do not get pinched between the door and framed
opening on the hinged side of the doors. Refer to illustration #8 in the ”S” Oven Manual.
·
Check doorframe with a straight edge to make sure doorframe is plumb and square and not
crowned (full height and width.) Check both the right and left side and the top and bottom.
Check the oven doors in the same fashion. Check when the oven is cold and also when
oven is hot for comparison.