AAON MODGAS-XWR2 User Manual

24
MODGAS-XWR2 Technical Guide
Heating Mode
Ignition Sequence for each Valve Conguration
After heat is enabled, the modulating valve(s) will move into the
ignition sequence. As long as there is a call for heat, at least one
stage will be on. Despite the Supply Air Temperature relation
to the Supply Air Temperature Setpoint, the MODGAS-XWR2
will continue heating as long as Heat is enabled (through either
binary enable or Modbus enable).
Here is what the ignition sequence looks like for each valve
conguration:
1V1IGN1S/ 2V2IGN2S: Valve 1 moves to the valve start position
(set in the hidden screen conguration and defaulted to 70%
modulation) and Heat 1 (RLY3) is on. The valve will remain at
this position until the proof of ignition time is satised. In order
to establish proof of ignition, the binary input used for the proof
of ignition must remain high for 20 seconds.
2V1IGN1S: Valve 1 and 2 move to the valve start position
(set in the hidden screen conguration and defaulted to 70%
modulation) and Heat 1 (RLY3) is on. Both valves are connected
to the same relay. The valve will remain at this position until
the proof of ignition time is satised. In order to establish proof
of ignition, the binary input used for the proof of ignition must
remain high (24 VAC signal) for 20 seconds.
2V2IGN1S: Valve 1 and 2 move to the valve start position
(set in the hidden screen conguration and defaulted to 70%
modulation) and Heat 1 (RLY3) and Heat 2 (RLY4) are on. The
valve will remain at this position until the proof of ignition time
is satised. In order to establish proof of ignition, the binary
input used for the proof of ignition must remain high (24 VAC
signal) for 20 seconds.
Modulating Modes for each Valve Conguration
After a conguration has completed its ignition sequence, then
it moves into a modulating mode. Here’s what the modulating
modes look like for each valve conguration:
1V1IGN1S: The PID loop runs every 10 seconds and determines
the modulation percentage for the one variable valve. Then the
valve moves to the correct position. During the modulation
sequence, if the valve position is below 55%, the low speed fan
relay will energize. Once it goes above 55%, the relay will de-
energize and move the fan back into high speed.
2V2IGN2S: The PID loop runs every 10 seconds and determines
the modulation percentage for the one variable valve. Then, the
valve moves to the correct position. Only after the stage up delay
requirement has been met will the board stage up and open the
second variable valve. Then both valves will move to the same
position. During the modulation sequence, if the valve position
is below 55%, the low speed fan relay will energize. Once it
goes above 55%, the relay will de-energize and move the fan
back into high speed.
2V1IGN1S/2V2IGN1S: The PID loop runs every 10 seconds
and determines the modulation percentage for both variable
valves. Then, the valves move to the correct position. During
the modulation sequence, if the valve position is below 55%, the
Low Speed Fan Relay will energize. Once it goes above 55%,
the relay will de-energize and move the fan back into high speed.
Additional Staging Information for each Valve
Conguration
During the heating sequence, if it is determined that there is
currently not enough/too many stages, then a stage up/down
will occur, respectively. For a stage up to occur, the valves that
are currently in modulating mode must be fully open (100%
modulation) for the stage up time, and the current Supply
Air Temperature must be at least 2ºF below the Supply Air
Temperature Setpoint. For a stage down to occur, the valves
must be closed as much as possible (35% modulation) and the
current Supply Air Temperature must be at least 6ºF above the
Supply Air Temperature Setpoint. Additionally, all stages must
stage down in the reverse order they staged up (i.e. the rst one
to stage down is the last one to stage up). Below is additional
staging information for each of the congurations:
1V1IGN1S/2V1IGN1S: The rst stage up will turn on the xed
stage attached to Heat 2 (RLY4). Stage 3 would be congured
on Heat 3 (RLY5) and Stage 4 on Heat 4 (RLY6). Additional
stages must be o board.
2V2IGN2S: Both on-board heat relays are used for modulating
valves, so the rst stage up (i.e. turning on Stage 2) turns on the
second modulating valve. Stage 3 would be congured on Heat
3 (RLY5) and Stage 4 on Heat 4 (RLY6). Additional stages must
be o board.
2V2IGN1S: Both on-board heat relays are used for modulating
valves (Stage 1), Stage 2 would be congured on Heat 3 (RLY5)
and Stage 3 on Heat 4 (RLY6). Additional stages must be o
board.
SEQUENCE OF OPERATION
Heating Mode

AAON MODGAS-XWR2 Specifications

General

Brand	AAON
Model	MODGAS-XWR2
Category	Controller
Language	English