Daikin MPS015 F Installation And Maintenance Manual

Contents

Sequence of Operation (Modulating Burner)Low Heat Option with ModulationThe following details the sequence of operation for the lowheat option.1 Unit DDC controller calls for heat.2 Furnace DDC control module receives a call for heat.3 Furnace safety switches and DDC control are checkedfor safe conditions.4 45 second prepurge cycle starts. Proof of airflow switchis checked for combustion airflows.5 Spark ignitor is activated.6 Gas valve receives a signal to open fully.7 Burner is ignited and runs for 20 seconds in high fire.NOTE: If call for heat is interrupted during this timing, thefurnace will be locked in for the 20 seconds cycle.8 Gas valve and induction blower motor receives a signalto modulate burner output to match the unit discharge airtemperature setting.High Heat Option with ModulationThe following details the sequence of operation for the highheat option. This option includes dual burners with one beingmodulating and the other being 2 stage control.1 Unit DDC controller calls for heat.2 Top Furnace DDC control module receives a call for heat.3 High limit switch is checked for safe condition.4 Proof of airflow switch is checked for combustion airflow.5 45 second prepurge cycle starts.6 Spark ignitor is activated.7 Gas valve receives a signal to open fully.8 Burner is ignited and runs for 30 seconds in high fire9 Modulating burner gas valve and induction blower motorreceives a signal to modulate burner output to match theunit discharge air temperature setting.10 If modulating burner is unable to meet dischargetemperature set point, furnace DDC control calls forthird stage of heating. The top furnace is reduced tolow (50%) fire. The bottom furnace is sequenced on perstage furnaces sequence of operation (steps 2 - 8).11 Staged burner gas valve receives a signal to open to 50%.12 Modulating burner gas valve and induction blower motorreceives a signal to modulate burner output to match theunit discharge air temperature setting.13 If stage 3 and modulating furnace is unable to meetdischarge temperature setpoint, furnace DDC controllercalls for stage 4 heat. The bottom furnace will stage up tohigh fire and the modulating furnace will reduce to 50%operation14 Staged burner gas valve receives a signal to open fully.15 Modulating furnace's gas valve and induction blowermotor receives a signal to modulate burner output tomatch the unit discharge air temperature setting.oPTIonal Gas heaTwww.DaikinApplied.com 31 IM 1058-8 • MAVERICK II ROOFTOP SYSTEMS