Bosch tankless water heater error code ea

SOURCE: A2 error on Bosch tankless water heater

1. Check continuity of the flue gas limiter (see Fig. 63, page 46 of manual). Go to steps two and three to determine air box temperature sensor fault and replace it.
2. Check for flue gas leakage around the top and bottom seals of heat exchanger as well as the viewing window.
3. Check that venting is within specifications (see Section 3.3 of manual). Long vent lengths, venting with more than three elbows, blocked vent or combination venting may cause this failure.
4. Check that flue gas limiter connector and spade connections are secure.
5. Unplug heater and check the two main plug connections inside the control board.

SOURCE: Bosch SX 250 tankless water heater will attempt to

This is also known as a flame rectification sensor. It basically is what the computer board uses to detect if the pilot flame is lit. When it makes an attempt to fire is there any evidence of flame ignition? This error does not mean that the sensor is bad for sure. The error could be caused because the water heater is only making three attempts to fire and then shutting down. These water heaters are very complex and have many sensors,valves, ect that are all controlled by a computer board. Some of the basic things to check for are... Make sure that you have plenty of gas pressure. These units have a built-in pressure switch and will have issues if they are starved of gas. Most of these tankless water heaters are up to 400,000 btus and a half inch gas line or undersized connector won't work well. You can also check and make sure there is no pipe dope are debris stuck in the screen inside the gas line where it enters unit. Inspect the pilot assembly for debris or obstructions and try to blow out with compressed air. Also look for any loose electrical connectors on the board or to the sensors...one may have come loose.

SOURCE: BOSCH AQUASTAR 2400ES NATURAL GAS TANKLESS HOT WATER HEATER

Q. FA - Gas leakage error, gas valve circuit not closing properly
A.

1. Disconnect power supply cord and check wire connections on 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 .8GPM. Measure voltage at the gas valve wire connector. The connector 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 correct, contact Bosch Water Heating for further instruction.
   
3. Gas valve may be defective, contact Bosch Water Heating for further instruction.

SOURCE: Keep getting error codes and have to reset too often

This paticular problem your having is specific to the jumper in the heater. The jumper is for condensing heaters. Your heater does not have the specific wiring or computer for condensing. So they added a jumper in the wiring. It is failed or failing. It should ohm out at about 120ohms. sometimes its just a loose connection. Check this out, and called 1-800-642-3111, they have been very busy, but leave them a message and they will call you back.

Ned C Cook

• 3433 Answers
• Posted on May 06, 2009

SOURCE: no hot water, pilot light lights but no burner ignition

Thermo coupler may be defective. it controls the main gas valve by closing main if pilot is out. make sure thermo coupler bulb is positioned over and near tip of pilot flame, but not in the flame. Thermo couplers are inexpensive and easy to change out.