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| 1 | Loosennut(A)(topandbottom). | |
3 | Neverloosennuts(C)fromeachother. | ||
heat exchanger. | 2Adjustthe | byturningbolt(B). | |
| 4.Usebelttensioncheckertoapplyaperpendicularforcetoonebeltatthe | ||
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| midpointofthespanasshown.Thedeflectionforceshouldbeapplied | |
Reverse the above procedure to replace the assemblies. |
| untilspecificdeflectiondistanceof4mm(5/32")isobtained.Todetermine | |
Procedureforadjustingbelttension: | |||
|
| thedeflection | fromnormalposition,useastraightedgefrom |
Make sure that burners are level and seat at the rear of the |
| sheavetosheavedistanceasreferenceline.Therecommendeddeflectionforce | |
BURNER AIR SHUTTER ADJUSTMENT |
| isasfollows: | DEFLFORCE |
Adjust burner shutters so no yellow flame is observed in the |
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heat exchanger tubes. Refer to Figure 17. |
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CHECKING SUPPLY AIR CFM |
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The RPM of the supply air blower will depend on the required CFM, the unit accessories or options and the static resis- tances of both the supply and the return air duct systems. With this information, the RPM for the supply air blower and the motor pulley adjustment (turns open) can be determined from the blower performance data in Tables 11 and 12.
High speed drive accessories (containing a smaller blower pulley and a shorter belt) are available for applications requir- ing the supply air blower to produce higher CFM's and/or higher static pressures. Use Model 1LD0416 for 15 ton units and Model 1LD0417 for 20 ton units. Refer to Table 15 for
blower motor and drive data.
Tnsionnewbelts | *Never(B)Loosen | ||
| the(A)max.deflectionforce(C)*rcommendedforthebelt | |||
s | .Checkthebelttensionatleasttwotimsduringthefirst24hoursof | ||
operati | .Anyreatnsioningshouldfallbetwenthee | min.andmax. | |
deflectionforcevalues. |
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| 5.Afteradjusting,retightennuts(A). |
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FIGURE 19 : BELT ADJUSTMENT
FIGURE 18 : TYPICAL FLAME APPEARANCE
Note the following:
1.The supply air CFM must be within the limitations shown in Table 2.
2.Pulleys can be adjusted in half turn increments.
3.The tension on the belt should be adjusted as shown in Figure 19.
Start the supply air blower motor. Adjust the resistances in both the supply and the return air duct systems to balance the air distribution throughout the conditioned space. The job specifications may require that this balancing be done by someone other than the equipment installer.
To check the supply air CFM after the initial balancing has been completed:
1.Remove the two 5/16" dot plugs from the blower motor and the filter access panels shown in Figure 10.
2.Insert at least 8" of 1/4 inch tubing into each of these holes for sufficient penetration into the air flow on both sides of the indoor coil.
NOTE: The tubes must be inserted and held in a position per- pendicular to the air flow so that velocity pressure will not affect the static pressure readings.
3.Using an inclined manometer, determine the pressure drop across a dry evaporator coil. Since the moisture on an evaporator coil may vary greatly, measuring the pres- sure drop across a wet coil under field conditions would be inaccurate. To assure a dry coil, the compressors should be deactivated while the test is being run.
4.Knowing the pressure drop across a dry coil, the actual CFM through the unit and clean 2" filters, can be deter- mined from the curve in Figure 20.
After readings have been obtained, remove the tubes and
reinstall the two 5/16" dot plugs that were removed in Step 1.
Failure to properly adjust the total system air quan- tity can result in extensive blower damage.
NOTE:
Unitary Products | 23 |
