Sub Ohm vs High Ohm: Fixing Wrong Hits

Technical guide · Puff Club Vape Leduc

Part of Power, airflow and resistance

Why it happens

An ohm is the unit that measures electrical resistance. Resistance is how much a coil slows down the electricity flowing through it. A coil marked below 1.0 ohm is called sub ohm. A coil marked 1.0 ohm or higher is called high ohm. These two coil types are built for different purposes, and mixing up their settings causes most of the problems vapers report.

Sub ohm coils have lower resistance, so more electricity passes through them at the same voltage. This produces more vapour and uses more liquid and battery power in a shorter time. These coils run at higher wattage. Wattage is the amount of electrical power sent to the coil, and most devices let you set it. If a sub ohm coil gets too little wattage, it does not heat fully. The liquid does not turn to vapour cleanly, the device gurgles, and liquid can leak or spit back. If it gets too much wattage, the coil overheats and burns the wicking material, which is the absorbent material inside the coil that holds the liquid.

High ohm coils have higher resistance, so less electricity flows through them. They are designed for lower wattage and a tighter draw, which is how much air you pull through when you inhale. If a high ohm coil gets too much wattage, it burns almost immediately because there is less material and airflow to handle the heat. If it gets too little, the vapour is thin and weak.

The second common cause is liquid thickness. Liquid is made from two base components: propylene glycol (PG), which is thin and carries the throat hit (the sensation felt at the back of the throat), and vegetable glycerin (VG), which is thick and produces vapour. Sub ohm coils have larger liquid openings and wick thick, high-VG liquid well. High ohm coils have smaller openings and can struggle with thick liquid, which leads to dry hits. A dry hit happens when the wick runs out of liquid mid-puff and you taste burnt material instead of vapour.

Step-by-step fix

1. Identify the coil. Look at the coil or its packaging for a resistance rating printed in ohms, such as 0.6 ohm or 1.2 ohm. This number tells you which type you are using.
2. Set the wattage to the printed range. Most coils have a recommended wattage range printed on the side, for example 40 to 60 watts or 10 to 15 watts. Start at the lowest number in that range. Increase in small steps of 5 watts until the vapour feels right. Stop immediately and lower the wattage if you taste anything burnt.
3. Match the liquid thickness. Check the VG and PG ratio on the liquid bottle. For sub ohm coils, a higher VG ratio works well. For high ohm coils, use a liquid with more PG so it wicks fast enough.
4. Adjust the airflow. Airflow is the opening that lets air pass over the coil. Open it wide for sub ohm coils so the extra heat and vapour have room to move. Keep it more closed for high ohm coils to get a tighter, cooler draw. If the device does not have adjustable airflow, skip this step.
5. Confirm the device supports the coil. Not every coil fits every device or battery. Some high ohm coils need a device with a low-wattage mode. If the device cannot be set low enough or high enough for the coil in your hand, the two are mismatched, and no setting change will fix it.
6. Test one variable at a time. Change only wattage, then only airflow, then only liquid. Changing everything at once makes it hard to tell what actually fixed the problem.

Prevention

Keep one coil type per device so the settings stay consistent. If you switch between sub ohm and high ohm coils, write down the wattage that worked for each and reset the device when you change coils.

Prime every new coil before use. Priming means putting a few drops of liquid directly on the exposed wicking material, filling the tank (the liquid chamber), and waiting several minutes before firing. This stops the first puff from burning a dry wick.

Check the coil rating and the liquid's VG/PG ratio before you buy or install either, so they are matched from the start. Replace coils on a schedule instead of waiting for a burnt taste, since a burnt coil cannot be fixed and must be swapped.

Keep the battery charged and use the charger that came with the device. A weak battery cannot deliver the wattage a sub ohm coil needs, and the device will underpower the coil even when the setting looks correct.

This guide is general technical information and is not medical or legal advice.