York ZF150 Installation Manual

Also see for Predator ZF078: Technical guide

518674-YIM-C-0610Johnson Controls Unitary Products 57Operating InstructionsLighting The Main Burners1. Turn “OFF” electric power to unit.2. Turn room thermostat to lowest setting.3. Turn gas valve counter-clockwise to “ON” position (SeeFigure 33).4. Turn “ON” electric power to unit.5. If thermostat set temperature is above room temperature,the main burners will ignite. If a second stage of heat iscalled for, the main burners for second stage heat willignite for the second stage heat.Post Start ChecklistAfter the entire control circuit has been energized and theheating section is operating, make the following checks:1. Check for gas leaks in the unit piping as well as the supplypiping.2. Check for correct manifold gas pressures. (See CHECKINGGAS INPUT.)3. Check the supply gas pressure. It must be within the limitsshown on the rating nameplate. Supply pressure should bechecked with all gas appliances in the building at full fire. Atno time should the standby gas pressure exceed 10.5 in. orthe operating pressure drop below 4.5 in for natural gasunits. If gas pressure is outside these limits, contact thelocal gas utility or propane supplier for corrective action.Shut Down1. Set the thermostat to the lowest temperature setting.2. Turn “OFF” all electric power to unit.3. Open gas heat access panel.4. Turn gas valve clockwise to “OFF” position (See Figure 33).Checking Gas Heat InputThis unit has two stages of gas heat. The first stage is 60% ofthe full fire input and is considered the minimum input for thefurnace. The intended input for each furnace is shown inTable 28. The table applies to units operating on 60 Hz poweronly.To determine the rate of gas flow (Second Stage).1. Turn off all other gas appliances connected to the gasmeter.2. Turn on the furnace and make sure the thermostat iscalling for Second stage (100% input) heat.3. Measure the time needed for one revolution of the hand onthe smallest dial on the meter. A typical gas meter has a 1/2 or a 1 cubic foot test dial.4. Using the number of seconds it takes for one revolution ofthe dial, calculate the cubic feet of gas consumed per hour.(See example below).5. If necessary, adjust the high pressure regulator asdiscussed in the section “Manifold Gas PressureAdjustment”. Be sure not to over-fire the furnace onSecond stage. If in doubt, it is better to leave the Secondstage of the furnace slightly under-fired. Repeat Steps 1-5.To determine the rate of gas flow (First Stage)1. Turn off all other gas appliances connected to the gasmeter.2. Turn on the furnace and make sure the thermostat iscalling for first stage (60% input) heat.3. Even when the thermostat is calling for first stage heat, theunit will light on second stage and will run on Second stagefor 1 minute. Allow this one-minute time period to expireand be certain the unit is running on first stage.4. Measure the time needed for one revolution of the hand onthe smallest dial on the meter. A typical gas meter has a 1/2 or a 1 cubic foot test dial.5. Using the number of seconds it takes for one revolution ofthe dial, calculate the cubic feet of gas consumed per hour(See example below).6. If necessary, adjust the low pressure regulator asdiscussed in the section “Manifold Gas PressureAdjustment”. Be sure not to under-fire the furnace on firststage. If in doubt, it is better to leave the first stage of thefurnace slightly over-fired (greater than 60% input). RepeatSteps 1-6.This furnace is equipped with an automatic re-ignitionsystem. DO NOT attempt to manually light the pilot.FIRE OR EXPLOSION HAZARDFailure to follow the safety warning exactly could resultin serious injury, death or property damage.Never test for gas leaks with an open flame. use acommercially available soap solution made specificallyfor the detection of leaks to check all connections. A fireor explosion may result causing property damage,personal injury or loss of life.