Tankless hot water heater controller board not powering up when power is applied

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  • sam_sam_sam
    Badcaps Legend
    • Jul 2011
    • 6033
    • USA

    #1

    Tankless hot water heater controller board not powering up when power is applied

    I recently bought a used tankless hot water heater and the controller board is completely dead no power up when power is applied the display board works however the main controller board does not work correctly at all the fuse is good

    I bought a used replacement controller board that also had issues that I was able to fix and now the tankless water heater works correctly now

    However I would like to know if I could figure what happened to this controller board if possible

    Tomorrow I will take some better pictures of both side of both boards

    The transformer has resistance on the primary and secondary sides the rectifier diodes test good with a meter I have not checked with power connected to the controller board because I would have to make a jig to be able to check if I am getting secondary power from the transformer

    The power inputs are the white connector red wire ( L1 ) and a red connector the left pin which is black is
    ( L2 ) is the power pins for the controller board the right pin which yellow goes to the triac gate pin then other two pins on the triac go the power in and to the temperature limit switch and then to the heater element the other side of the goes to the other side of the power supply
    Attached Files
    Last edited by sam_sam_sam; 12-09-2022, 10:22 PM.
  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 30978
    • Albion

    #2
    Re: Tankless hot water heater controller board not powering up when power is applied

    pictures are shit.
    but you have a microcontroller - so you have a voltage regulator.
    find it and check it's input and output pins

    Comment

    • sam_sam_sam
      Badcaps Legend
      • Jul 2011
      • 6033
      • USA

      #3
      Re: Tankless hot water heater controller board not powering up when power is applied

      Well now the replacement controller board has an issue with the flow sensor it is not seeing it and it does not see the replacement one either and it is supposedly a new one
      The error message is “E4” flow sensor issue

      But what is weird is that even power cycling the controller board does not clear it which it should

      If I can find the right controller board for the flow sensor that is in this device I will try to figure out what happened to this controller board and the original controller board that does not power on at all which I have not had time to troubleshoot it more what I had done in post #1

      Because the newer controller board have a 4 pin flow sensor not a 3 pin flow sensor
      Last edited by sam_sam_sam; 10-26-2023, 07:21 PM.

      Comment

      • CapLeaker
        Leaking Member
        • Dec 2014
        • 8096
        • Canada

        #4
        Re: Tankless hot water heater controller board not powering up when power is applied

        What sensor is this? A hall sensor? Maybe check it and see if it works?

        Comment

        • sam_sam_sam
          Badcaps Legend
          • Jul 2011
          • 6033
          • USA

          #5
          Re: Tankless hot water heater controller board not powering up when power is applied

          Originally posted by CapLeaker
          What sensor is this? A hall sensor? Maybe check it and see if it works?
          It is a 3 wire hall flow sensor

          If I leave the power off for about 5 minutes it resets it self it seem like I have to have flow restrictors in both tankless water heater because ———>

          I have 18kw and a 27kw and I will explain why below

          The turn on rates are different from 18kw to the 27kw
          So if my wife is doing the dishes in the kitchen sink the 27kw does not turn on but 18kw one does but the shower heads are the opposite way the 18kw goes into an over flow or not staying on because depending on what water temperature you try to get and if you have two shower heads going it goes into a overflow on the 27kw

          Now you might ask why I have two well because I started using the 18kw first and found out that I can not run two shower heads at the same time I can with 27kw but depending on what each person temperature preferences are because my wife and son want to take the hottest shower possible this causes a really big problem with flow rate on both tankless water heater so what I going end up doing is put a flow restrictors in both tankless water heater to keep them from going into a overflow condition is only thing that I can think of and the instructions point out that depending on your situation might need to install flow restrictors

          These tankless water heaters also have another issue and that is the following

          If your flow rate is not at a certain point it never activates another heater element which is also an issue depending on what water temperature you are trying to achieve so I have only one heater element hooked up on each tankless water heater and I use two different electrical wiring circuits and 2 set of breakers for each tankless water heater
          Last edited by sam_sam_sam; 10-26-2023, 08:29 PM.

          Comment

          • stj
            Great Sage 齊天大聖
            • Dec 2009
            • 30978
            • Albion

            #6
            Re: Tankless hot water heater controller board not powering up when power is applied

            i'm confused.
            why does it have a flow sensor?

            i have tankless heaters and they have a pressure sensor on the input to detect a tap turning on, and a temp sensor on the output.

            Comment

            • CapLeaker
              Leaking Member
              • Dec 2014
              • 8096
              • Canada

              #7
              Re: Tankless hot water heater controller board not powering up when power is applied

              Originally posted by stj
              i'm confused.
              why does it have a flow sensor?

              i have tankless heaters and they have a pressure sensor on the input to detect a tap turning on, and a temp sensor on the output.
              I am not a pro with this, but a friend of mine has infloor heating with one of these tankless heaters. They all had a regulator board, a temperature sensor and a pressure sensor on the input too.

              Now I am confused Sam, did you defeat the pressure sensor? Because I don’t think that it is a good idea.

              Huh? Your hookup is a bit complicated. I need my coffee to work first. Lol
              Last edited by CapLeaker; 10-27-2023, 04:53 AM.

              Comment

              • sam_sam_sam
                Badcaps Legend
                • Jul 2011
                • 6033
                • USA

                #8
                Re: Tankless hot water heater controller board not powering up when power is applied

                Originally posted by stj
                i'm confused.
                why does it have a flow sensor?

                i have tankless heaters and they have a pressure sensor on the input to detect a tap turning on, and a temp sensor on the output.
                This is a flow Hall effect sensor that is used to detect the amount flowing through the heating elements

                Can you please post a picture of the type of sensor that you are talking about
                Attached Files
                Last edited by sam_sam_sam; 10-28-2023, 07:40 AM.

                Comment

                • sam_sam_sam
                  Badcaps Legend
                  • Jul 2011
                  • 6033
                  • USA

                  #9
                  Re: Tankless hot water heater controller board not powering up when power is applied

                  Originally posted by CapLeaker
                  I am not a pro with this, but a friend of mine has infloor heating with one of these tankless heaters. They all had a regulator board, a temperature sensor and a pressure sensor on the input too.

                  Now I am confused Sam, did you defeat the pressure sensor? Because I don’t think that it is a good idea.

                  Huh? Your hookup is a bit complicated. I need my coffee to work first. Lol
                  No the only modification that I did is instead of using the two inputs for each heater element I only use one on each tankless water heater because of what I described in a previous post

                  Originally posted by sam_sam_sam
                  I have 18kw and a 27kw and I will explain why
                  I would like to see the type of pressure switch that they are using in this type of tankless water heater

                  But I would like to modify the algorithm because I do not like the way that it is designed to work

                  This is the way the 18kw is setup

                  The way that this algorithm should work is that if you have at least 0.500 to 0.750 gallons pre minute ( instead of 1.5 gallon per minute which is the way that it is set up in order to activate the heater element you have to have a 1.5 gallon per minute and then you back it down to 1.0 gallon per minute )

                  Another issue with this algorithm is that when it detects a no flow situation it stay on for several seconds before it turns off the heater element why this does not need to be this way

                  The 27kw flow rate is different and off the top of my head I can not remember exactly what the flow rate needs to be for it to activate but it is different from the 18kw
                  Last edited by sam_sam_sam; 10-28-2023, 08:07 AM.

                  Comment

                  • stj
                    Great Sage 齊天大聖
                    • Dec 2009
                    • 30978
                    • Albion

                    #10
                    Re: Tankless hot water heater controller board not powering up when power is applied

                    i cant get a picture but they are also used on central heating systems - they use a rubber diaphram that presses against a microswitch to indicate pressure on the input - when water flows the pressure drops and switches the switch - turning it on

                    Comment

                    • stj
                      Great Sage 齊天大聖
                      • Dec 2009
                      • 30978
                      • Albion

                      #11
                      Re: Tankless hot water heater controller board not powering up when power is applied

                      do your flow sensors actually work?
                      if they have a spinning bit with a magnet - do they spin?
                      i'v seen similar magnetic coupled devices get scaled or gunked up

                      Comment

                      • redwire
                        Badcaps Legend
                        • Dec 2010
                        • 3904
                        • Canada

                        #12
                        Re: Tankless hot water heater controller board not powering up when power is applied

                        EcoSmart, Eemax, Rheem tankless hot water heater controller SMT18-36A

                        It's got jumpers to config the heater power kW. So that means no EEPROM I guess for special settings. This is proportional (phase) control using the triac? Or only ON/OFF? 4-pin connector is for the remote control.

                        You might have a difference in the flow sensors - the pulses per rev. but I can't see one ever giving a fault code because the impeller (magnet) stops on the Hall sensor or not. So the signal stuck high or low does not mean there is trouble. It's something else. The restrictors are at the shower head?

                        I would guess 4-wire sensor has flow plus a thermistor in it for incoming water temp possibly.

                        someone figured out the EcoSmart tankless hot water heater remote control protocol:
                        https://github.com/ryangriggs/EcoSmartLib
                        https://github.com/PhilRW/ecosmart-remote
                        It's pretty dumb, you can't get diagnostics or setting info.

                        P.S> - it's been 10 months, when are we getting good pictures of the controller board that went dead lol
                        Last edited by redwire; 10-28-2023, 11:37 AM.

                        Comment

                        • sam_sam_sam
                          Badcaps Legend
                          • Jul 2011
                          • 6033
                          • USA

                          #13
                          Re: Tankless hot water heater controller board not powering up when power is applied

                          Originally posted by stj
                          i cant get a picture but they are also used on central heating systems - they use a rubber diaphram that presses against a microswitch to indicate pressure on the input - when water flows the pressure drops and switches the switch - turning it on
                          If you ever find a part number or a website link you can please if for me because i would be interested in buying some

                          Comment

                          • sam_sam_sam
                            Badcaps Legend
                            • Jul 2011
                            • 6033
                            • USA

                            #14
                            Re: Tankless hot water heater controller board not powering up when power is applied

                            Originally posted by redwire
                            I guess for special settings. This is proportional (phase) control using the triac

                            The restrictors are at the shower head?
                            The first question I can answer for you the range is from 20 to about 36 amp
                            The second question is there is supposedly a use for the restrictors if you get an “E4” error message according to the troubleshooting manual that tech support provided when I was getting this error message when I first installed it ( yes you can reach an over flow condition this the reason there is troubleshooting mode on the controller so you can easily see the flow rate however you can not leave it in this mode without issues more than a couple of minutes before it errors out )

                            As far as the better picture I will take them tomorrow afternoon when the sun is up high in the sky for the best possible pictures of each of the two sides of each of the two board

                            The reason I did not post the better pictures is because I first of all I was not having any issues for several months then just recently it started giving me this error message again more often ( I had put a water valve to prevent it from overflowing the flow sensor but this not the best way to control the flow to each tankless water heater )

                            The reason there is an neutral wire is this panel is because it goes to another sub breaker panel box because the other breaker panel has a neutral wire in it for some light demand devices like a freezer which does not run all the time and nether does the tankless hot water heater so I can use this breaker can do both functions without any issues so far

                            The second reason is that I forgot about saying that I going to post better pictures of the controller board was this repair on the board that this post was about had low priority I was working on higher priority projects

                            To answer your second question yes the shower heads do have a restrictors however if you have more than one device going at the same time you might exceed the flow rate of the tankless water heater which what I do not understand is why the restrictors are not included in the box just in case need to use them and they are not cheap 4 different flow rate 2 , 3 , 4 , 5 gallon pre minute $35.00 plus shipping for $7.00

                            I ordered two sets of them in case I need two of the same size restrictors I will post a picture of them when I get in the mail

                            I also ordered a another controller board just in case the issue is with the controller board itself plus I want to easily clean the flow paddle wheel which the one that comes with it is very hard to remove it to clean it

                            The 27kw is a used one that had the bad controller board and some scale on the heater element that I cleaned before I installed it

                            The 18kw is the new one that I had bought first which is how I found out that it was not big enough for the demand of of our house hold

                            But I would not go back to a tank type water heater again

                            Here is some pictures of how I have it installed in my garage

                            The second picture is where I checking the installation of the tankless hot water heaters

                            The breaker that has the black and white wires are the ones that were use on the tank hot water heater that I had originally when I moved into the house

                            And yes this breaker box was modified for this project

                            One note the red and black and white wires are a #6 wire good for about 100 amps
                            Attached Files
                            Last edited by sam_sam_sam; 10-28-2023, 04:38 PM.

                            Comment

                            • stj
                              Great Sage 齊天大聖
                              • Dec 2009
                              • 30978
                              • Albion

                              #15
                              Re: Tankless hot water heater controller board not powering up when power is applied

                              just search "water pressure switch" and maybe include words like boiler or heater

                              Comment

                              • sam_sam_sam
                                Badcaps Legend
                                • Jul 2011
                                • 6033
                                • USA

                                #16
                                Re: Tankless hot water heater controller board not powering up when power is applied

                                I miss spoke about what “E4” is a temperature over 140*F
                                “E5” is the over flow rate but in the beginning I did get the “E5” error message

                                Here is the troubleshooting manual

                                https://cdn.badcaps-static.com/pdfs/...4dc5d0e9e5.pdf

                                Comment

                                • petehall347
                                  Badcaps Legend
                                  • Jan 2015
                                  • 4426
                                  • United Kingdom

                                  #17
                                  Re: Tankless hot water heater controller board not powering up when power is applied

                                  maybe you need a pressure vessel i know my gas one does . and a pump fed from a tank as mains pressure is not reliable .

                                  Comment

                                  • CapLeaker
                                    Leaking Member
                                    • Dec 2014
                                    • 8096
                                    • Canada

                                    #18
                                    Re: Tankless hot water heater controller board not powering up when power is applied

                                    This tankless heater is waaay different than the one I dealt with a while back. A friend of mine is using this for infloor heating.

                                    Comment

                                    • sam_sam_sam
                                      Badcaps Legend
                                      • Jul 2011
                                      • 6033
                                      • USA

                                      #19
                                      Re: Tankless hot water heater controller board not powering up when power is applied

                                      I have done a little research and found out that I might have to put a pressure regulator on the cold water to the tankless heater to control the pressure because I have noticed that the pressure goes up and down sometimes while taking a shower so this might be a reason why I am having issues with the temperature getting to hot or I might have a bad temperature sensor or something is wrong with the temperature section of the controller board which I have a supposedly a new controller board ( because the first replacement controller board was supposed to be new it turns out that it was a return *** yes I got a some of my money back because of it ) so let see if this is issue or not

                                      Electrical service and water service is owed by the city of Jacksonville and I can tell you that because I live in out shirt of the downtown Jacksonville and we have voltage sagging and running higher voltage other times

                                      Water pressure is lower in the morning and at night and higher in the afternoon or at least on the weekends so I like living in the boondocks where there are less house or it used to be that way not so much now

                                      We can not even get fiber optic cable in this area and who knows when that going to happen

                                      They need to upgrade the electrical system in this area you can not get 3 phase service down this street if you want it because you only have one high tension power line that service a lot of houses and churches and what ever else in the summer time when everyone is running their air conditioning you can actually see the lights dimming every so often and when it is really bad that the battery backup goes off letting you had a voltage drop of course it does not last long but that is not the point it is the fact that it does

                                      Not to mention that the roads around here need to be repaved which do not get done until it is almost not drivable anymore or the road sinks pretty bad

                                      And do not get me started with internet service and cable service and phone service all from the same company when it goes down you play hell getting back working again to make matters worse is that they tried to charge me for coming out to supposedly fix it and the very next night it went out again I did get charged reversed but I had to go to their service center to get it resolved forget doing this on the phone you will not get any where

                                      I am done ranting and raving about all this stuff
                                      Last edited by sam_sam_sam; 10-28-2023, 09:36 PM.

                                      Comment

                                      • redwire
                                        Badcaps Legend
                                        • Dec 2010
                                        • 3904
                                        • Canada

                                        #20
                                        Re: Tankless hot water heater controller board not powering up when power is applied

                                        Seeing the pics - I would check for a ground fault. If anything is shorted to the metal, it could make a lot of electrical noise on the sensors. Like a triac or heating element. Just check with an ohmmeter.
                                        Or ground the backpan like it's supposed to be...
                                        The sensor wiring is best away from mains wiring, not on top of it.
                                        Noise on the flowmeter wiring could make it look like too high a flow rate.

                                        edit: also noticed the 4-wire flow sensor has a second sensor inside, it appears to be optical... the wheel has 6 holes. So that I would think gets silt and dirt on it, then the optical signal doesn't jive with the Hall sensor.
                                        Last edited by redwire; 10-28-2023, 10:12 PM.

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