Bosch AquaStar 2400ES-NG - Page 7 - Answered Questions & Fixed issues

I believe they are under the unit by the pump.

refill the gas bottles and then if that doesn't fix it, get a technician out as it may be the pressure switch not opening the gas so that the pilot light ignites the burner

They recommend you have a service guy do it but if you use care manuals are here Discontinued product literature or here https://www.worcester-bosch.co.uk/installer/literature/oil-fired-boiler-literature

As cold water enters the heater. its heated by the pilot flame, and takes a while before u have total hot water? what do u mean by cuts off? perhaps u have a pilot heating problem due to it going or coming off and on? are there any air drafts around the heater?

Pilot will not light? at all? or does it light as long as you are holding it in then goes out when you let it go? If you know it has gas to it, I would say bad thermal couple

In that case get it repaired under warranty. Do not attempt to repair it yourself for two reasons:

1. it could invalidate your warranty
2. unless you are GasSafe (or equivalent) registered, it's against the law to repair gas appliances, even your own, for obvious reasons, both explosion and carbon monoxide.

gas valve sticking

Just unplug any electrical supply for at least 30 seconds.

search for worcester bosch 35 cdi manual choose Greenstar CDI & download the pdf instructions

I believe this is a hydro-sparker pilot ignition then burner on when T-Couple/Flame Sensor acknowledges pilot lit. W/O the signal feedback the Gas Valve will not open and light burner. This is a Technician Service Job as you have insufficient knowledge to DIY this potentially dangerous LP/NG Control Valve/Sparker Assembly I assume that lack of knowledge by your lack of a Manual for the Unit You cannot force ignition on a hydro-sparker manually.

Depends how far away the tankless is located. Tankless are not instant hot water heaters Also check for cross connection http://waterheatertimer.org/Crossover.html http://waterheatertimer.org/Water-heater-recirculation-system.html http://waterheatertimer.org/How-to-install-under-counter-water-heater.html Gene If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

check the thermostat

Your primary fan has a circuit board on it. If the leak splashed on the fan, the fan probably needs to be replaced.

Try descaling the heat exchanger, and also clearing the fins of any soot that has formed

Clean your orfice...it sits at the bottom of your pilot burner, where the brass pilot tube screws in to. Its a small stamped piece of stainless, about the size of a pencil eraser. You can also buy new ones online for only a couple bucks

E2 is a cold water inlet temp sensor. Has your unit experienced any freezing conditions? If it senses below 36 degrees or above 90 degrees it will show this error. If its normal temp, and you still get this error...check your sensor. Its an 8(kohm) sensor. Make sure its not open. If it reads ok and your temp is not an issue, then you probably have a bad control board

Watervalve needs to be replaced....part number is 87070063440, and can be found online. Its only held in by the water connections and 2 Phillips head set screws(about 1 inch apart) directly underneath the junction of the plastic watervalve and the grey metal gas valve

Triac devices are not restive. They are like back to back SCRs. Once gated they will not turn off until the power crosses zero. It will do that 50 or 60 times a second then needed to be re-gated.

It may not be possible, you are at 122C which is just above the recommended max. In 1988, the Consumer Product Safety Commission recommended that water heater manufacturers preset the maximum temperature at 120 degrees Fahrenheit to prevent burns. Since several states have mandated this maximum temperature.

Does the unit have a flame sensor? Check manual. Flame sensors get corroded and need cleaned or replaced. I have had success cleaning them but when you can buy a new flame sensor