Do I need to install a check valve when two wall-hung boilers are installed in parallel?

The parallel installation of two wall-hung boilers requires a check valve. Prepare backwater devices, tees, wrenches and other tools and materials.

1. Screw the water flow sensing switch to the end, fix the backwater device at the water inlet, and then connect the cold water valve and the water flow sensing switch.

2. Install the check valve below the washbasin, and the installation direction must not be wrong. The hot water points to the cold water, and then the tee is connected.

3. Connect the faucet to install the return water system. Finally, plug it in and see if it can be used normally.