What is the difference between the Onsen 6L and Onsen 10L?

The simple answer is that the 10L has twice the heating power of the 6L, meaning that it is much more capable of heating freezing water at a decent flow rate for a comfortable shower compared to the 6L.

Orders and Payment

What are my options when it comes to supplying water pressure to the water heater?

The water heater requires a minimum water pressure of 10 PSI for the flame to ignite. Generally, three options are available: city water pressure, water pump and gravity fed system. Note that the water heater may not work properly on a gravity fed system if the water pressure does not meet the minimum requirement of 10 PSI. In that case you will need to install a water pump.