Water volume

Calculating Antifreeze Volume

Calculating water volume is usually done to add antifreeze to the system sizing an expansion tank. If adding antifreeze, you need to add only the amount required. Do not add more than needed. Do not use antifreeze used in automobiles. When adding antifreeze there is a possibility you may need to increase the pump size and/or expansion tank size. After adding antifreeze, you will find leaks that did not exist with just water in the system. Do not exceed 50% antifreeze water mix without contacting the manufacturer for their OK.

In most systems you can use polypropylene glycol in cast iron, steel, and stainless-steel boilers. If you have a cast aluminum boiler, you will use antifreeze that is suitable for aluminum. Do not use automobile antifreeze in any boiler system.

When you decide to use antifreeze you will have to calculate the water volume in the entire system including the boiler.
Pipes of different sizes will hold different amounts of water. Use the charts below to figure out system water volume and add the boiler water volume from the manufacturers manual. The charts are for piping and cast-iron radiation. For finned tube radiation, just count it as pipe using the proper size and type of pipe used in the radiation. If you have radiation with 3/4" pipe as most standard baseboard, just measure the radiation as plain pipe.

Radiation Water Volume

Copper Pipe

Steel Pipe

Disclaimer: The information found on this website is for informational purposes only. All preventive maintenance, service, installations should be reviewed on a per job situation. Any work performed on your heating system should be performed by qualified and experienced personnel only. Comfort-Calc or its personnel accepts no responsibility for improper information, application, damage to property or bodily injury from applied information found on this website as it should be reviewed by a professional.