Why does the spark igniter keep sparking after the burner is lit. I adjusted the microswitch because it was not lighting but now it will light but keep sparking every 5 sec, even though the burner is

Check pilot is clean and strong Also check sensor is clean and connections are clean and tight .

A lot of pilot lights have a thermal coupler... the pilot light must be lit for several min to open the coupler so the pilot light will not go out.... the newer systems use an electronic ignition and no pilot light and need power to autostart but the coupler may be gone if you are holding that pilot start button down for several min and the pilot light is still going out..ps.. leave it in pilot mode for several min after initial start up before turning turning full burner operation operation operation operation operation operation operation it will snuff out the pilot light.

If you can't hear clicks, then very likely it is the "microswitch" that is a rectangular white plastic box that can be seen at the bottom of the unit from underneath. It's purpose is this: when there is gas pressure, a pushrod turns the switch on, thereby allowing electrical current to flow from the "hydrogenerator" to the igniter unit. The hydrogenerator generators from about 1 to 2.5 volts AC (not DC) when water is flowing, powering the generator which powers the igniter unit....assuming the microswitch is allowing electrical current (the voltage) to pass through. It is a "self-adjusting" switch because the pushrod can come out at different pressures. So if your gas fluctuates, the microswitch will be fixed to a higher pressure level, but not be able to turn on if the pressure drops. This is because the pushrod is not pushing as far. It's simple to unscrew the plastic box and push the teethed switch setting back to the initial default position, and then carefully replace the plastic cover. Then do it again next time it stops working, a year or two it seems for many people. You can take out the switch and connect it's two wires directly, but if there is no gas pressure and you let water flow through, the igniter unit will constantly be sparking and thereby might fail early. If there is no gas pressure, then maybe it is because of a local leak and thereby bypassing the switch is a built-in explosion hazard, but that would require the sparking to no longer be internal to the ignition unit.

I know from you info that you don't want to work on it any more but this will help if you decide to try again.

Troubleshoot
Q. No Spark At Pilot? Q. Spark Appears When Hot Water Is Turned On, But Pilot And Burners Will Not Ignite? Q. Pilot Sparks Continuously With No Water Running? Q. Pilot Lights But Burners Will Not Come On? Q. Main Burners Go Out During Hot Water Use? Q. Hot Water Temperature Fluctuates At Tap? Q. Water Is Too Hot? Q. Water Is Not Hot Enough? Q. Burners Do Not Burn Cleanly; Yellow Flames When Operating? Q. Burners ignite without water flow? Q. Low hot water pressure? Q. Noise when the heater is running?

Hi, Please do massive / longer bleed on/off for several time and get it retry. If problem still persist, I worry you have problem on your controller and need repairing at dealer.

Regards, Jay

if you need a service call on wrong site either your gas company or company who services your heating

On most water heaters there is no adjustment to pilot light. About the best you can do is clean pilot and burner. If you are having trouble keeping pilot light lit then I would replace the termocouple.

Check and adjust igniter probe(s) so that they are in front of the flame good. When you say it goes to re-ignite, can you hear, or see spark happening at igniter, but burner just won't catch?

some times the wire for the ignitor will get burned inside the chamber, if this happens you will not get a spark and will need a tech, but turn the gas valve to the piliot position hold down the button on the gas valve while clicking the electric ignitor button, look thru the site glass towards the left side of the burner assembly while doing this, if there is no spark it will have to be taken apart and replace the spark ignitor, not a big job you just have to make sure the seal on the burner cover doesn't tear or get damaged

The clicking is a good sign. What are you trying that not working? How is the water flow-is it strong? 1) Turn the flow control button all the way to your left - this will increase the flow.
2) Pull the relief valve to simulate water flow and listen for clicking sound, and hopefully, main burner ignition. ( if installed in basement or kindly use bucket to catch water) The 1600 H NG will automatically shut off firing after 5sec of clicking.
3) How is the venting-use a household digital carbon monoxoide detector to measure any backspill from chimney.
4) Was the gas line disconnected in anyway after heater was installed? Air in the gas line will cause the igniter to click but no gas to fired the main burner.

Todate i have installed 11 Bosch Tankless Heaters -- 9(125 NG) Which is the same as 1600 Series
1(1600H NG) and 1(1600P NG)
Guess which one I having problem with- You guess it, however, the problem is their electrical wiring.

BE CAREFUL IN CALLNG BOSCH TECH. FOR SUPPORT. THE ARE GRILLING YOU TO FIND A LOOPHOLE WITH YOUR INSTALLATION TO RELIEF THEMSELF OF THEIR WARRANTY.