Bosch Therm 660EF/660EFO Remote Controller

The Bosch Therm 660EF/660EFO Wired Remote Controller, part number BRC01US is specifically designed for the Bosch Therm 660EF/660EFO units.  The wired remote gets wired to the Bosch 660EF/660EFO unit using 18 ga wire and can be installed up to 300' maximum away from the heater.

The wired remote should be installed in a location that is accessed easy from the main point of hot water use such as on the bathroom wall.  The default setting for the 660EF/660EFO is 120° F.  For most residential applications, the recommended setting is 120° F. 125° water is scalding and is very dangerous.

The Bosch Therm 660EF/660EFO gas tankless water heaters come with wired, marked connectors in the unit by the main control board.  The wired connectors are marked, 120°, 130°, 140° and 160°.  You must have the remote controller to achieve the 160° temperature. 

The remote control comes with many special options.  The remote control will give error codes on the display in the event of a problem (refer to the service manual or contact Bosch Technical Support for error codes and troubleshooting).  The upper limit of the hot water supply temperature can be changed to 100°F, 105°F, 110°F, 115°F, 120°F, 125°F, 130°F, 135°F, 140°F and up to 160 with the remote control.  There is also a unique flow meter alarm setting on the remote control.

The flow meter alarm setting can be used to set a desired amount of gallons of water maximum that is normally used.  As an example:  say your bath tub holds 50 gallons of hot water.  You can press and hold the flow meter alarm until it starts flashing and then set the remote to a maximum of 42 gallons of water.  So when you go and fill the bathtub with hot water and once the remote senses it has flowed 42 gallons of water an alarm will sound and then you would have to physically go and shut the water off at the source.  The alarm will stop after 10 seconds.

Flow & Temperature Adjustment for Bosch Therm 520PN

The new Bosch Therm 520PN comes in either natural gas or liquid propane and has a control knob for adjusting the water flow and a slide adjustment for adjusting the heat on the front of the heater.

The Bosch Therm 520PN is a 117,000 BTU Gas Tankless Water Heater. The control knob on the right is the Temperature Adjustment knob and is for adjusting the flow of water through the heater which has the ability to speed the flow of water up making it cooler or slowing it down and making it hotter. The slide control in the middle is for adjusting the temperature of of the water by adjusting the height of the flame. When the slide is positioned on the small flame symbol the burners will be low and when the slide is on the high flame symbol the burners will get higher and the temperature hotter.

Below is how turning the Temperature Adjustment knob effects the heater:

Knob Position		Clockwise		Counter-clockwise
Degree Rise		90° F		45° F
Activation Rate		0.5 GPM		1.1 GPM
Max Flow Rate		2.0 GPM		3 .7 GPM

As the temperature adjustment knob is turned counter-clockwise, the output temperature will lower and the activation rate of the heater will be raised. Turning the knob clockwise will raise the temperature and lower the activation rate.

When sliding the slide adjustment to the left, (small flame symbol) the heater will give lower flame and cooler temperatures and sliding the slide to the right will give hotter tenmperatures and a higher flame.

The Bosch Therm 520PN has a gas control slide that modulates burner input in response to flow. Its purpose is to ensure that the hot water temperature will remain steady, although the water flow demand might vary.

Bosch 520HN Power & Temperature Control knobs

The new Bosch Therm 520HN that comes in either natural gas or liquid propane has 2 new control knobs for adjusting temperature and flow on the front of the heater as the older Bosch AquaStar 125 series heaters only had 1 control knob to adjust flow.

The Bosch 520HN has 2 control knobs on the front of the heater. The control knob on the left is the Power control knob and allows you to set the height of the burners for hotter temperatures or cooler temperatures. The control knob on the right is the Temperature Adjustment knob and is for adjusting the flow of water through the heater which has the ability to speed the flow of water up making it cooler or slowing it down and making it hotter.

Below is how turning the Temperature Adjustment knob effects the heater:

Knob Position		Clockwise		Counter-clockwise
Degree Rise		90° F		45° F
Activation Rate		0.5 GPM		1.1 GPM
Max Flow Rate		2.0 GPM		3 .7 GPM

As the temperature adjustment knob is turned counter-clockwise, the output temperature will lower and the activation rate of the heater will be raised. Turning the knob clockwise will raise the temperature and lower the activation rate.

When turning the left Power Control knob to the left will give more power and higher water temperatures. Turning the knob clockwise will give less power and cooler water temperatures.

The Bosch Pro 520 HN has a gas control that modulates burner input in response to flow. Its purpose is to ensure that the hot water temperature will remain steady, although the water flow demand might vary.