The "P" in the product name indicates that the Bosch 1600PS has a pilot light for its ignition system. The "S" stands for solar.
The Bosch 1600PS has the same specifications as the Bosch 1600P, except for the fact that it can take preheated solar water.
One common question is whether the Bosch 1600PS tankless water heater can be used WITHOUT preheated solar water. The answer is Yes! So, if you do not currently have a solar system in place but are planning to get one, you can definately install the Bosch 1600PS now in advance of your solar system purchase.
Just like the Bosch 1600P, the 1600PS provides 4.3GPM at a 45 degree F temperature rise and has a low minimum activation rate of just 0.5GPM. Both heaters take a BTU input from 23,400 - 117,000 BTU input. Also, both the 1600PS and the 1600P take 5" double-wall, Type B galvanized venting.
Steve
