INKBIRD ITC-308 for a Greenhouse: Great Controller, But Mind the 1,200W Limit

In this guide

Bottom line
What to buy
Decision factors
FAQ

Bottom line: ITC-308 is excellent for small greenhouse loads because it provides separate heating and cooling outlets, alarms and compressor delay at low cost. The critical limitation is current: the current 120V version is rated 10A / 1,200W total across both receptacles. That makes it inappropriate for directly switching a common 1,500W greenhouse heater.

Method: this batch is built around greenhouse system decisions—heating, airflow, water, controls, light and seasonal layers—rather than generic gardening listicles. Product-specific claims use current manufacturer references where available. GreenhouseGuide.co was not directly retrievable through the current web index during this build, so final deployment should include the normal live filesystem slug/title collision check.

Greenhouse safety: greenhouses combine moisture, electricity, heaters, fans, water lines and sometimes pressurized irrigation. Use GFCI-protected circuits and equipment rated for the environment, keep water away from electrical connections, never overload thermostats/controllers, and follow local electrical/fire/building requirements. Fuel-burning heaters require manufacturer-approved ventilation and carbon-monoxide safety; this batch focuses mainly on electric and passive systems.

Products and configurations to compare

Basic dual-stage

INKBIRD ITC-308

Current accuracy is listed ±1°C / ±2°F.

Best when: your total connected load stays under 1200W

Watch for: not suitable for common 1500W heaters

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Remote-alert version

INKBIRD ITC-308 WiFi

Useful for overnight freeze alerts.

Best when: you want app monitoring

Watch for: same load-rating discipline still applies

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Independent check

Greenhouse min/max thermometer logger

Catches overnight excursions even if controller appears normal.

Best when: you want verification of thermostat behavior

Watch for: another sensor to maintain

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Dual-stage is the reason to buy it

One outlet heats below setpoint, the other cools above setpoint.

Compressor delay helps cooling equipment

It prevents rapid cycling when a refrigeration device is connected.

Probe is waterproof; controller body is not

INKBIRD specifically distinguishes the sensor from the body/socket.

Calibration exists for drift

Check against a trusted thermometer before relying on a tight frost margin.

Use alerts with margin

Do not set a tender-crop threshold exactly at the damage temperature.

Controllers only work as well as sensor placement

A temperature probe on a sunny metal frame reads something different from plant-canopy air. Hang probes in shaded moving air near the crop zone and away from heater discharge, wet media and cold glazing. The same rule applies to humidity/VPD sensors.

Simple plug-in thermostats are excellent when the job is binary: heater on below X, fan on above Y. Multi-device controllers become useful when lights, exhaust, circulation and humidification need coordinated triggers. Complexity should buy better control, not merely a prettier app.

Electrical ratings are hard limits

A controller rated for 1,200W total should not directly switch a 1,500W heater. Use only devices within voltage/current ratings and follow code/manufacturer requirements. Greenhouses are humid environments, so GFCI protection and weather-appropriate enclosures/connectors matter.

Before checkout

Greenhouse dimensions and approximate volume are measured
Climate goal is frost-free, cool-season or warm-crop winter growing
Electrical circuit capacity and GFCI protection are confirmed
Controller output rating exceeds connected load
Ventilation has a real intake path, not only an exhaust fan
Irrigation pressure/filtering matches emitters and tubing
Light footprint matches the actual bench/canopy
Seasonal materials can be removed or adjusted
Replacement parts and consumables are available
Automation can be overridden manually during a failure

The right upgrade solves the limiting factor

Greenhouses tempt owners to buy equipment one category at a time, but climate is a system. A bigger heater can be wasted through unsealed glazing. A giant exhaust fan can accomplish little without intake area. Perfect drip irrigation can still fail if the filter clogs. Before ordering, identify the variable that is actually leaving the safe crop range: overnight minimum temperature, afternoon maximum, humidity, root-zone moisture or daily light.

Spend first on measurement and failure prevention. A min/max logger, independent thermometer, pressure regulator or simple flow check can reveal that the existing equipment is adequate but badly controlled.

Commissioning the system

Test every automated device before plants depend on it. Force the thermostat above and below setpoint, manually trigger irrigation zones, watch an automatic vent through a warm day, simulate a power interruption where safe, and verify that fans have real intake air. Record the first week of minimum and maximum temperature/humidity so settings can be adjusted from evidence.

Greenhouse systems should also fail manually. Know which plug, valve or vent to operate if the controller loses Wi-Fi, a sensor breaks or a timer sticks. Simpler recovery is more valuable than another dashboard.

Frequently asked questions

What is the temperature range?

Current ITC-308 is listed from -58°F to 248°F for the non-WiFi version.

How accurate is it?

INKBIRD currently lists ±2°F / ±1°C.

Can it control heating and cooling?

Yes, with separate relay outputs.

Is it waterproof?

The probe is rated waterproof; the controller body/socket are not.

Current product/source checks

INKBIRD ITC-308 — current official specs

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