RTO Takagi T-M1 Mobius Gas Tankless Water Heater - Answered Questions & Fixed issues

Code 541 means the 2 way valve is not turning, that could be the valve has build up calcium due to hard water and the attached motor is not able to turn it, or the motor is broke or finally the controller (Compute Board is defective).The 2 wau valve sits behind another valve when looking at the unit on the left hand corner, it must be taken out first to gain access to the 2 way valve.The 2 way valve motor can be seperated from the valve by two screws and the valve can be manually opened but turning it to the horizantal position, there is a pin on that shaft.Turn kon the heater then but leave the motor connected, if the motor turns for short time then the PCB is most likely ok. This usually indicated that there is too much of build up inside the valve. If the tankless was properly with bypass valves (outside of the unit) installed then this can be easily fixed.Turn the unit off and run with an external pump and bucket with vinegar for about 30 minutes by using the bypass valves. This will clean the 2 way valve from inside and should turn then easily and the motor will be able to control it. This is usually beyond the DIY scope, call a real pro for that.http://www.justtankless.com

checked for long time final find out the sensors socket has some water in it and I dry it out and the heater fire up right away "hope this can help other people " good luck.

Generally tankless must be maintained on yearly basis. Error codes are usually stored in the computer memory until they reach a threshold and then the error code is displayed... it is possible the control board is bad.. or the sensor that feeds information to the control board is bad. Contact manufacturer or installer. Contact local service technician who is qualified on that specific brand. Gene http://waterheatertimer.org/Whirlpool-Energy-Smart-electric.html Water Heater Timers Save Money If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

the valve has a shaft with a small pin, it can be turned with a needle nose plier.

Error Code 541 indicates that the Two Way Valve is malfunctioning. This assembly consists of a small motor and a rotating ball valve that is operated by the motor. The replacement part is only sold as a unit (Motor and valve) for about $200. It is located in the lower left of the unit, behind the flow valve. (i.e. it is hard to reach in order to service it). You basically have to take out the exhaust fan, take out the flow valve in order to replace the 2-way valve. It's doable as a DIY, but it's not trivial. The valve could be crusty from deposits, so before taking everything apart, it would be wise to flush the heater for 45 minutes with anti-scaling and a recirculating pump to see if anything breaks loose. (using the service valves that should be mounted on the bottom of the unit)

to clear the 991 Takagi code, simultaneously press the bottom 2 grey buttons of the four just to the left of the flashing LED light. When the LED stops flashing, release and then press the reset button on the black panel about 8 inches above that

I HAD THE SAME PROBLEM. I CONTACTED TAKAGI WHO SENT OUT THE REPLACEMENT PART. AFTER INSTALLING THAT PART, IT WORKED FOR A MINUTE AND STOPPED. I CONTACTED TAKAGI ONCE AGAIN AND WAS TOLD "OH, THAT MOTHERBOARD GOES OUT SOMETIMES IF THAT FIRST PART GOES BAD!" THEY THEN SENT OUT A NEW MOTHERBOARD WHICH FIXED THE PROBLEM.

Owner Manuals

Bad faucet cartridge: walk-thru on following link http://waterheatertimer.org/Crossover.html If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

What water pressure reading do you have? IS there a mixer in the system? What is the exact model number?

no I dont think you have a mother board. If there wasone it would be in a box of some sort on the top or right near the top mounted on the side.

If you replaced the coupler, I would say the gas valve is bad. Go to you local supply store and get a new valve. you should have 3 connection on the valve, the main gas feed and the main burner and your coupler.

Make sure you turn off the water at the main, drain it all down and when you have all the connection moved get a large channel lock or pipe wrench and turn the valve counter clock wise use tape or dope on the section that goes into the tank and tighten it up, hook up your other pipes and test for gas leak with soap and water.

Make sure when you buy the valve you get a match to the kind of gas you have natural or L P one will not work with the other.

OH check for gas leaks

Best of luck Tom

First check and see if the dial on the gas valve is on the ON position. Next turn the thermostat up all the way.if it does not come on then, this sounds crazy, but, tap the gas valve twice lightly with the back end of a screw driver, sometimes a spec of dirt can clog the gas valve and this releases it. if it still doesnt come on, you need a Volt Ohms meter or multi meter, set the meter to millivolts, you want to connect the 2 leads from the meter to the terminals on the gas valve that the 2 wires from the pilot generator, located next to the main burner underneath tank. turn the meter on and the millivolts should read a minimum of 400 milivolts, if lower, replace pilot generator. If still doesnt work, replace gas valve.

That is not a model number that sounds familiar. Should be a tag on side of water heater behind cover, outside. If it has the little arm adjustment for temperature on top of gas valve, simply move it over a little to the left to increase water temperature, and try it until temperature is what you are happy with.
I'm assuming when you say it goes out completely that the pilot remains on and water heater re-lights when called for? If you adjust that temperature lever over, and water still doesn't get hot, you need to replace gas control, as thermostat is built in to it.

I am not sure they are available to non Hitachi service centres. https://documentation.hitachiaircon.com/glb/en/pac/rua-at3s

Cannot find the fault code . There are vidoes on u tube saying how to reset thr code By pressing the reset button . If this does not work youcan ccontact vaillent on there web page . I have a mate who works for them i will ask him as well

Do I need to insulate this heater out in the shed? Freezing temperatures

Call a engineer

The P8 fault can mean many things when it pops up on your Mitsubishi Electric wall controller. The P8 fault is activated when the indoor coil sensor does not change the temperature for a set amount of time after the compressor is (or should be) switched on.

Where does the tube sensor go

This one looks the same.https://www.ebay.ca/itm/133397559348They are made by Harper Wyman and using that model number, this is the result.https://www.google.com/search?q=Atwood+RV+oven+control+valve+57294But this shows more that looks similarhttps://www.google.com/search?q=Harper+Wyman+oven+control+valveAnd then if we go here and Zoom in, you will see MTZ 22300https://youngfartsrvparts.ca/products/used-atwood-wedgewood-oven-thermostat-57294Which leads us here and the Specs Sheet.https://www.copreci.com/en/gas-cooking/product-range/thermostats/with-safety-and-thermostatic-flow-regulation/372-mtz-22300-seriesand from there to here, and Parts Town stocks them!List Price: $ 318.24https://www.partstown.com/fagor-commercial/fgrc12008712..