Gas heater shuts off after about 3minutes and have clean filter rinnai rce-329h gas heater

The owner's manual at http://rinnai.co.nz/tradesmart/upload/files/productfile/portable_convector_rce417_operation_and_installation.pdf on page 10 says to vacuum both filters weekly. It also warns not to wait for the filter lamp to come on since overheating may occur.

Copy following link:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html#maintenance

Gene
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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Clean water filter.
Delime heat exchanger.
http://waterheatertimer.org/How-to-delime-tankless-water-heater.html
Add tempering tank to preheat cold incoming water.
http://waterheatertimer.org/Tempering-tank.html
Check for bad single-handled faucet cartridges.
http://waterheatertimer.org/Crossover.html
Don't install multi-sensor computer-chip water heater to water lines and gas line and vent pipe since tankless will develop unsolvable problems.
Contact Rinnai and hear them tell you to call service technician, only to discover there are no qualified service technicians in your area who might be able to solve problem. 1-800-621-9419
Ask why the Rainnai site has much promotional information and no service manuals. Nor does Rinnai offer forum where tankless owners can freely exchange their endless unsolvable problems for all to see.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

The Rinnai will shut off it can't maintain the temperature you have set to within +/- 3 degs so I'd guess that might be the problem. The cause can be a few options. Check water flow first; any filters you have in tapware, main water flow etc. get cleaned. The Rinnai has a water line filter in the incoming supply, middle pipe under the heater just after the isolating valve. Gas supply could be the other option mainly being a possible intermittent fault in the gas regulator. Hard to check this one short of just changing it. Final option is some sort of electronic malfunction, pretty rare. I'd start with the water flow issue as you can do this yourself. Checking the gas will need a good technician with digital gas pressure guage to check incoming and working gas pressures; it might just need to be recalibrated. Just hasd a thought about the heat exchanger being scaled up if you are in an arera where water scale is a problem but this would normally take far less than 8 years to be a problem. Sorry can't be of more help; hard when it might be a few different causes.

Hello,
In these water heaters there is a part called a "flame sensor", if you can read the wiring diagram/schematic spend some time trying to find where it is at; it will be located directly in the burner compartment. It senses that the gas is lit and there is flame, if it does not then it will shut the gas off almost within 3 seconds.
Solution- Turn off the power to the unit completely and take the flame sensor out and clean it with a 000 steel wool pad. These flame sensors develop carbon from the gas and then stop reading properly. You can test the measurement if you had an electrical meter (uA is how it would be listed on your meter- most basic meters have this function).
Let me know if this works, if not I have another solution you could try (I'm pretty sure this will do the trick though) James

clean filter on the cold side coming in and clean or replace the aerator at the sink, rinnai works on water flow, common problem if your water hardness to high or if you have iron in your water

The Rinnai relys on good water flow to fire it up. In saying that it runs out of water; thats actually not possible. The Rinnai just heats up water as it goes. Usually faults for installs on bore or well water is a problem with water flow. Causes are blocked filters or your water pump from the bore starting to fail. I would expect you to have a large filter somewhere on the water line from the well. Try and find it and clean it out. The Rinnai also has a filter. Its like a plastic round shaped nut just under the heater on the middle connection. Turn the water off first, it should almost unscrew by hand, take it out and clean it (make sure you don't drop the O ring on it). Also some tapware have water filters right in the end of the spout, check these too. After you tried all this focus on the pump. Make sure no ther water is flowing, try the hot tap and see if it works. Do the same but slowly turn on a cold tap, slowly increasing the flow. Have someone out by the heater and see if the heater shuts down at any point. If it does it could be the water pump at fault. From what you have told me and I am certain water flow is the culprit here. Really focus on anything that might lessen the flow before you start messing with the heater. Best of luck.

this is a tricky one, it means no ignition,which could just be a dirty flame sensor, low gas pressure, or no spark to ignite the burner. sorry but this one requires a rinnai trained service man

if it's a gas unit you mite have to bleed the gas line in and out.