Water Expansion Tanks

Why install an expansion tank?

Well the answer depends if it's installed on either the cold or water circuit.

• Cold circuit.

On the cold circuit, an expansion tank is not really indispensable however I installed it because it will reduce the number of times the water pressure pump switches on. The pump will not switch on every time the water tap is opened. Once it's on, it will fill up the expansion tank (depending on the size of the installed expansion tank) and any subsequent water usage is supplied from the tank until the pressure falls enough that the pump will need to switch on. 

The installation of this expansion tank is a huge benefit especially at night because the pump will not switch on as soon as the water tap is opened. The pump although enclosed is not very silent and at night it just wakes everyone up when it switches on!

• Hot circuit

In this case, personally I think that an expansion tank is indispensable. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excessive water pressure. If water pressure gets to high it can damage valves in plumbing fixtures, joints in supply pipes and the water heater itself.

I installed both expansion tanks at the bow of the boat (the location of the tanks is irrelevant) specifically in the master forward cabin, next to the bow thruster.

As seen below, the small hot water expansion tank is connected through a red pipe, through a Tee in the how water circuit.  

The cold water expansion tank is also installed at the bow in the bow thruster compartment. 

The expansion tank is the left most white tank. it's connected using a blue pipe through a Tee in the cold water system. On the right you can notice the RO system.