Power Flame Incorporated

Transcription

1 Power Flame Incorporated VARICAM ADJUSTMENT INSTRUCTIONS THE POWER TO MANAGE ENERGY 2001 South 21 st Street, Parsons, Kansas Telephone , Fax Web Site: Copyright 2009 Power Flame Incorporated VA-0909

2 The unit being fired must be connected to a load large enough to allow the burner to be fired at full rate for an extended period of time without overheating the system. The burner firing rates must be controlled by manual means to prevent shifting in firing rate while adjustments are being made. The change in level between adjacent cam screws should not exceed 3/8. Greater level changes require excessive operating forces which may cause erratic movement of the linkage, excessive wear or jamming of the mechanism. The thread binding set screws are nylon tipped. Their function is to hold any adjustment point to which the cam screw is set. They are factory set and normally require no adjustment. However, they may be loosened if excessive torque is required to adjust a cam screw or tightened, when adjustment is completed, if the cam screw appears loose. The recommended fuel-air ratio range for the high fire rate will yield % Oxygen in a flue gas analysis. At this adjustment, when firing natural gas, Carbon Dioxide in the flue gas should be % and Carbon Monoxide must be less than 0.04%. When firing #2 fuel oil, Carbon Dioxide should be % and smoke must be #2 Bacharach or lower. When firing #4 or heavier fuel oil, Carbon Dioxide should be % and smoke must be #4 or lower. It may be necessary to operate at higher excess air levels at low fire to prevent excessive formation of carbon monoxide with gas fuel or smoke on fuel oil. Therefore, the recommended fuel-air ratio range at low fire may provide % Oxygen, % Carbon Dioxide on natural gas with less than 0.04% Carbon Monoxide, % Carbon Dioxide on #2 fuel oil with less than #2 smoke and % Carbon Dioxide on #4 or heavier fuel oil with less than a #4 smoke. 1. Begin the adjustment procedure with the cam screws set at mid-point. At midpoint cam screw adjustment, an equal number of cam screw threads will be visible above and below the cam arm and the screw tips will form a surface parallel to the cam arm. 2. Commencing with either gas fuel or oil fuel, fire the burner and, without cam screw adjustment, set the fuel-air linkage to provide the desired fuel-air ratio at both low fire and at high fire rates. Record the oxygen (O 2 ) or Carbon Dioxide (CO 2 ) levels obtained at these points for future use. For purposes of this discussion, the low fire rate will be considered to be 33 1/3% of the high fire rate. a) In addition to the desired fuel-air ratio, the fuel-air linkage adjustment must additionally be such that the last or 14 th cam screw (farthest from the jack shaft) is centered on the crown of the cam follower roller when the burner is at low fire adjustment point

3 b) Similarly, when adjusted to the desired fuel-air ratio at the high fire operating point, the fuel-air linkage adjustment must center the first cam screw (closest to the jack shaft) on the crown of the cam follower roller. 3. For the initial coarse adjustment, operate the burner at the firing rate that will position the middle two cam screws (Nos. 7 and 8) on the crown of the cam follower. This rate should be the approximate mid-point of the firing rate range of the burner or 67% of the full firing rate. a) Adjust these two cam screws to obtain the desired fuel-air ratio. This would normally be the same ratio as adjusted to at high fire. NOTE: When the cam screws are rotated counter-clockwise, the adjacent cam screws on either side of those being adjusted may begin to engage the cam follower surface as well. All cam screws engaging the cam follower surface must be adjusted to obtain the desired change. b) If insufficient cam screw adjustment is available, determine whether additional clockwise or counter-clockwise cam screw turns were required and the additional length required. Record this CW or CCW length for future use. 4. For the next coarse adjustment, operate the burner at the firing rate that will position cam screws Nos. 10 and 11 on the crown of the cam follower. This rate should be approximately 50% of the full firing rate of the burner. a) Adjust cam screws 10 and 11 to obtain the desired fuel-air ratio. This would normally be the same ratio as adjusted to at high fire or a ratio falling between the high fire fuel-air ratio and the low fire fuel-air ratio. b) If insufficient cam screw adjustment is available, determine whether additional clockwise or counter-clockwise cam screw turns were required and the additional length required. Record this CW or CCW length for future use. 5. For the last coarse adjustment, operate the burner at the firing rate that will position cam screws Nos. 3 and 4 on the crown of the cam follower. This rate should be approximately 83% of the full firing rate of the burner. a) Adjust cam screws Nos. 3 and 4 to obtain the desired fuel-air ratio. This would normally be the same fuel-air ratio achieved for the high fire rate. b) If insufficient cam screw adjustment is available, determine whether additional clockwise or counter-clockwise cam screw turns were required and the additional length required. Record this CW and CCW length for future use

4 6. If sufficient cam screw adjustment range was available in steps 3, 4, & 5 to achieve the necessary fuel-air ratio adjustments, proceed with the fine adjustment procedure described in par. 9 following. If insufficient range was available at any point, proceed with step With reference to previous steps 3, 4 & 5: a) If all of the additional adjustment lengths needed would have required additional clockwise cam screw rotations, select the largest amount required and add 1/8 inch to obtain the total offset dimension. 1) Re-adjust all cam screws on this arm by counter clockwise rotation to decrease the amount of cam screw projection beneath the cam arms by the amount of offset dimension arrived at in step 7.a). b) If all of the additional adjustment lengths needed would have required additional counter clockwise cam screw rotation, select the largest amount required and add 1/8 inch to obtain the total offset dimension. 1) Re-adjust all cam screws on this arm by clockwise rotation to increase the amount of cam screw projection beneath the cam arms by the amount of the offset dimension arrived at in step 7.b). c) By adjusting only the linkage between the jack shaft and the modulating motor and the combustion air damper, reset the burner fuel-air ratio for low fire and high fire back to the same values recorded as part of step 1. Do not change or re-adjust the linkage between the modulating fuel valve and the Varicam fuel driving shaft or the cam screws during this part of readjustment. 1) Repeat steps 3, 4, 5 & Occasionally, it will be found that the required offset on one end of the arm is in the opposite direction from that required on the other end or offset may be required on only one end of the arm. In either case, offset in the appropriate direction may be obtained in the specific area required by applying the procedures explained in steps 7.a), b), & c). 9. The fine adjustment procedure should only be attempted after all coarse adjustment points of fuel-air ratio have been correctly completed. Begin with the burner operating at the low fire point. Re-affirm that the low fire fuel-air ratio is correct, that cam screw No. 14 is centered on the crown of the cam follower and re-adjust if required

5 a) Adjust the burner firing rate so that cam screw No. 13 is centered on the crown of the cam follower. Adjust cam screw No. 13 for the desired fuel-air ratio. b) Repeat steps 8. a) for each cam screw in numerical progression down from cam screw No. 12 through No Repeat all the above procedures for the other fuel

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