What does a thermostat do when it reads high CO2 levels?

This thermostat will initiate a Demand Ventilation cycle.

The Pelican thermostat controls the HVAC unit without any other Pelican accessories:

The thermostat will start the supply fan to bring more outdoor air into the room.

The Pelican thermostat has a Pelican PEARL economizer controller wired to it:

The thermostat will tell the PEARL to enable the supply fan and open the outside damper to increase the ventilation rate. This increased ventilation rate is a ratio of starting at the Minimum Damper Position at the thermostat’s CO2 Ventilation configuration and being at  100% open if the room’s CO2 levels reach 1500 PPM. But, the PEARL will never increase the ventilation rate beyond its configured Maximum Ventilation Position.

Any time the CO2 levels are below the configured CO2 Ventilation setting, the thermostat will tell the PEARL to set the outside damper at the Minimum Damper Position anytime a heating, cooling, or fan cycle is running.

The Pelican thermostat controls a zone damper and communicates to a Z8 or Z24 air handler controller:

The Z8 or Z24 are automatically sent all Pelican zone thermostat’s CO2 readings. The Z8 or Z24 uses the highest level reported to control the outside damper to assure proper outside ventilation levels are being delivered into the building.

How do I add a CO2 sensor to my thermostat?

If your thermostat did not come with a CO2 sensor, then you will not see a CO2 Ventilation configuration and the thermostat will be unable to initiate a demand ventilation cycle. To add this sequence and configuration, you will need to purchase a Pelican plus50 and add it to your thermostat.