Starting order of heating/cooling

Access 4.x

Heating/Cooling sequences > Starting order of heating/cooling

The order of sequence activation is set by assigning an order number for heating and cooling.

Configuration > Functions > Function activation > Heating/Cooling sequences >

As can be seen in the configuration example below:

In case of heating demand, the Exchanger (SEQ-B) will start first and Heating (SEQ-A) will follow second.
In case of cooling demand, the Exchanger (SEQ-B) will start first and the Cooling (SEQ-C) will follow second.

Position	Heating	Cooling	Start Heating	Start Cooling	Name
SEQ-A	2	Off	0%	0%	Heating
SEQ-B	1	1	0%	0%	Exchanger
SEQ-C	Off	2	0%	0%	Cooling
SEQ-D	Off	Off	0%	0%	Recirculation 1
SEQ-E	Off	Off	0%	0%	Recirculation 2
SEQ-F	Off	Off	0%	0%	Fan heating/cooling
SEQ-G	Off	Off	0%	0%	Heating 2
SEQ-H	Off	Off	0%	0%	Cooling 2
SEQ-I	Off	Off	0%	0%	Exchanger extract
SEQ-J	Off	Off	0%	0%	Extra heating/cooling capacity

Sequence overlapping or dead band can be set by adjusting “Start Heating” and “Start Cooling” sequence parameters.

The adjustable range is -100% .. +100%.

A negative starting point will create sequence overlap while a positive starting point will delay the start of the selected sequence.

Position	Heating	Cooling	Start Heating	Start Cooling	Name
SEQ-A	2	Off	50% 0%	0%	Heating
SEQ-B	1	1	0%	0%	Exchanger
SEQ-C	Off	2	0%	-25% 0%	Cooling
SEQ-D	Off	Off	0%	0%	Recirculation 1
SEQ-E	Off	Off	0%	0%	Recirculation 2
SEQ-F	Off	Off	0%	0%	Fan heating/cooling
SEQ-G	Off	Off	0%	0%	Heating 2
SEQ-H	Off	Off	0%	0%	Cooling 2
SEQ-I	Off	Off	0%	0%	Exchanger extract
SEQ-J	Off	Off	0%	0%	Extra heating/cooling capacity

In the initiation phase of the air handling unit, a specialized temperature control regimen is applied, deviating from the standard sequence order:

During default startup, the exchanger sequence initiates regulation from 100% to 0%, contrary to other sequences. This approach expedites the attainment of the setpoint temperature and minimizes the risk of thermal shock to internal components. If necessary, the operation of the selected sequence can be modified to the conventional 0% to 100% range or any other specified sequence.

A similar inversion of the control signal during startup can be configured for an additional sequence. By default, this configuration is applied to the Heating sequence when the outdoor temperature falls below 3°C. This adjustment facilitates the achievement of a comfortable temperature and safeguards components against potentially hazardous low air temperatures.

Start up related settings of the heating sequences

Configuration > Functions > Function activation > Heating/Cooling sequence setup

Position

Heating

Cooling

Start heating

Start cooling

Name

Note

SEQ-A

Off

Heating >

2nd Heating sequence

SEQ-B

Exchanger >

1st Heating sequence

SEQ-C

Off

Cooling >

SEQ-D

Off

Recirculation 1 >

Can be configured by assigning the sequence start number

SEQ-E

Off

Recirculation 2 >

SEQ-F

Off

Fan setpoint comp >

SEQ-G

Off

Heating 2 >

SEQ-H

Off

Cooling 2 >

SEQ-I

Off

Exchanger extract >

SEQ-J

Off

External h/c capacity >

3rd Heating sequence

Variable

Available options & Selection

Note

At start up begin temperature control at 100% in

| Heating 1 | Heating 2 |… |

Heating 1 = the 1st heating sequence

Warm start up if outdoor temperature <

[3] oC

Heating 2 = the 2nd heating sequence will activate at startup if outdoor temperature is bellow limit

If warm start up begin temperature control at 100% in

| Heating 1 | Heating 2 |… |

Chapter info

Last reviewed: 2/5/2025

Access version: 4.7-1-00 build 64