diff --git a/src/thermostat/thermostat.rs b/src/thermostat/thermostat.rs
index e4fbe13..d6d6440 100644
--- a/src/thermostat/thermostat.rs
+++ b/src/thermostat/thermostat.rs
@@ -302,12 +302,12 @@ impl Thermostat{
     /// VREF measurement can introduce significant noise at the current output, degrading the stabilily performance of the
     /// thermostat. 
     pub fn calibrate_dac_value(&mut self) {
-        const STEPS: i32 = 18;
-        let target_voltage = self.max1968.adc_read(AdcReadTarget::VREF, 64);
+        const DAC_BIT: u32 = 18;
+        const ADC_BIT: u32 = 12;
+        let target_voltage = self.max1968.adc_read(AdcReadTarget::VREF, 512);
         let mut start_value = 1;
         let mut best_error = ElectricPotential::new::<volt>(100.0);
-        for step in (0..STEPS).rev() {
-            debug!("TEC VREF Calibrating: Step {}/{}", step, STEPS);
+        for step in (DAC_BIT-ADC_BIT-1..DAC_BIT).rev() {
             let mut prev_value = start_value;
             for value in (start_value..=ad5680::MAX_VALUE).step_by(1 << step) {
                 self.max1968.phy.dac.set(value).unwrap();