Do I Need An Expansion Tank For My Tankless Water Heater

The ipc does not specifically require a thermal expansion tank or other device be installed with a tankless water heater.

Do i need an expansion tank for my tankless water heater. However there are a few exceptions. To avoid such situations you must opt for a proper expansion tank that will be saving you from accidents. You do need a releif valve so that if the heating does not stop and the water expands it can expand through the releif valve letting you know that the unit is malfunctioning. If you have a tankless water heater you don t have to worry about an expansion tank because you don t have a primary tank to begin with.

It is because tankless units do not have a primary tank for expansion. One 50 gallon water heater for instance can be served by a 2 gallon expansion tank. As a result of this there will be no further leaks present from the expansion tanks. You need a thermal expansion solution that is adequately sized for your plumbing system.

Their is case were you need an expansion tank with a tankless system. The water heater expansion tank serves as an overflow receptacle by absorbing excess water volume that occurs when water is heated as well as absorbing fluctuations in the incoming water supply pressure. For a thankless water heater itself you generally don t need one unless recommended by the manufacturer. If you own a tankless water heater at your home you do not have to worry about thermal expansion.

The water expands as it heats and on a tank you are raising the temp of water trapped in the tank because the water continues to heat after the tap is closed but on a tankless the heating stops as the tap is closed or its suppoesd too so you do not need an expansion tank on a tankless. If their is backflow prevention device check valve or other similar device installed on the cold water input. Since water expands when it is heated due to thermal expansion the water heater creates extra water volume every time it heats water. However if you have a traditional tank style water heater you will most definitely need to consider if an expansion tank is needed.

According to the 2018 international plumbing code ipc section 608 3 tankless water heaters do not require a thermal expansion tank when no water storage device is used. If you have more than one heater on the same or connected system you can either have an expansion tank for each heater or a single larger expansion tank. However if a storage tank is used in conjunction with a tankless water heater in a closed system which is sometimes the case with recirculation then a means of controlling thermal expansion must be provided. With the help of such a water expansion tank the overloaded water will start to get stored in it and thus it will not flow out of the heater.