No flame ionization detected with

Problem solving

Display	Cause	Solution
	No flame ionization detected with	1.	Verify that all manual gas shut off valves are open.
	water flow.	2.	Check gas type, see Fig. 2, page 5.

3.Reset error code and open a water tap to cycle the heater in an effort to purge air on new installations. Cycling hot water tap on and off multiple times may be necessary. If heater still faults with EA error code, have a licensed gas technician properly purge air out of the gas line leading to the water heater.

4.Check three wire connections to ignition group on the lower front of the heat exchanger are secure.

5.Check gas pressure, see chapter 3.12, page 22.

6.Check venting specifications are met. Improper venting may cause premature failure of the flame sensor rod.

7.Check that the minimum power fan speed has been adjusted to the proper value. See page 34.

8.Observe inside the viewing window of the heat exchanger when a hot water tap is opened. Sparking should be followed by a steady blue flame. If flame is unstable or yellow with proper gas pressure, confirm CO2 readings per section 6.4.

Ionization failure during operation.	1. Check gas type, see Fig. 2, page 5.
	2.	Check three wire connections to ignition group on the lower
	front of the heat exchanger are secure.
	3.	Check venting specifications are met. Improper venting may
	cause unstable burner flames and loss of flame ionization.
	4. Check that the minimum power fan speed has been adjusted to
	the proper value. See page 34.
	5.	Check gas pressure, see section 3.12, page 22.
	6.	Check and adjust CO2 readings, see section 6.4, page 28.

Ionization error at standby.	1.	Loose connection to the flame ionization rod. Verify that the
	thinner wire leading from the control unit is securely connected to
	the flame sensor located on the lower front of the heat exchanger.
	See Fig. 63, page 46.
	2.	Flame ionization rod or control unit may be damaged. Contact
	Bosch Water Heating for further instruction.

Gas leakage error, gas valve circuit	1. Disconnect power supply cord and check wire connections on
not closing properly.	gas valve and the two connectors on the control board.
	2. Flow water out of a hot water tap above the minimum activation
	point of 0.65 GPM. Measure voltage at the gas valve wire plug
	connection. The voltage should measure 24VDC between the left
	pair of wires and 24VDC between the right pair of wires when the
	unit is operating. If voltage is not proper, contact Bosch Water
	Heating for further instruction.
	3. Gas valve may be defective, contact Bosch Water Heating for
	further instrucation.

Table 20

* By installer or service technician only.

6 720 608 782

GWH 2400 ES NG, GWH 2400 ES LP specifications

Bosch Appliances has established a reputation for delivering high-quality and innovative home solutions, and the Bosch GWH 2400 ES LP and GWH 2400 ES NG are no exceptions. These high-efficiency water heaters are designed to provide on-demand hot water, ensuring comfort and convenience for your home.

One of the standout features of the Bosch GWH 2400 ES LP (Liquid Propane) and GWH 2400 ES NG (Natural Gas) models is their compact, space-saving design. These tankless water heaters are engineered to fit in smaller spaces, making them an ideal choice for homes with limited installation areas. Despite their compact size, both models provides a powerful performance that meets the hot water needs for multiple fixtures simultaneously, such as showers, faucets, and washing machines.

These water heaters are equipped with advanced technology that enables precise temperature control. The Bosch GWH 2400 ES series utilizes a microprocessor-based control system that allows for consistent water heating, ensuring the water temperature remains stable even during high demand. The modulating gas valve further optimizes energy consumption, adjusting the flame intensity to meet the exact heating needs, thus enhancing efficiency.

In terms of safety, both the GWH 2400 ES LP and NG come with multiple safety features. These include a flame failure safeguard, overheating protection, and a built-in freeze protection system. Such features ensure both peace of mind and the longevity of the unit.

Installation is straightforward with these models, as they can be vented using standard venting materials, saving time and costs. Additionally, the units boast a low NOx emissions rating, making them environmentally friendly choices that help homeowners reduce their carbon footprint.

Maintenance is minimal, thanks to the corrosion-resistant heat exchanger which ensures durability and long service life under normal operating conditions. This factor, combined with Bosch’s renowned commitment to quality, makes these models a reliable investment for any household.

Whether you opt for the GWH 2400 ES LP or the GWH 2400 ES NG, you will experience the benefits of a powerful, efficient, and safe water heating solution tailored to your specific household needs. Bosch has truly combined technology, sustainability, and user comfort in these innovative models, solidifying their place as leaders in the home appliance market.

Problem solving

water flow.

Check gas type, see Fig. 2, page 5.

Bosch Water Heating for further instruction.

GWH 2400 ES NG, GWH 2400 ES LP specifications