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RVSA Vehicle Service Academy (Attendance Notes from howson)

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  • #91
    Week 5
    Mon, 11 Oct (Day 21)

    Finished up with water heaters in the morning. Brief discussion on the tankless options available. Aqua Hot is a great choice and Truma apparently has excellent offerings, too. There's also a company called Precision Temp that has a tankless offering available.

    The odd duck in the lot that is neither a tankless nor a standard heater is an Atwood that is still available but apparently no longer made. When I figured out what they'd done it looked like something Cate&Rob would have thought up (it's a clever design).

    Click image for larger version  Name:	Atwood 16G.JPG Views:	0 Size:	99.5 KB ID:	67831

    Bob also showed up one of the latest Dometic designs, a WH-6GEA. All of the serviceable elements are on the front of the unit including the 120vAC element. (Nice!) The drain cover is no longer a plug but a cap. Much easier to remove and reinstall.

    Click image for larger version  Name:	WH-6GEA.JPG Views:	0 Size:	106.5 KB ID:	67832
    Tested out of water heaters with no problem.

    Next came a mind-bending lecture regarding an absorption refrigerator's theory of operation since we're now on to Refrigerators. No way I could possibly summarize except to write it uses heat to cool, and converts a liquid to a vapor back to a liquid and then again a vapor to create the cooling effect. Want to know more? YouTube is your friend. (RV Works has a decent video, though it is long.)

    Compressor refrigerators (of any type) are not going to be discussed.

    Howard
    Last edited by howson; 10-14-2021, 04:15 AM.
    Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

    Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

    Comment


    • #92
      Originally posted by howson View Post
      Week 5
      Mon, 11 Oct (Day 21)



      Next came a mind-bending lecture regarding an absorption refrigerator's theory of operation since we're now on to Refrigerators. No way I could possibly summarize except to write it uses heat to cool, and converts a liquid to a vapor back to a liquid and then again a vapor to create the cooling effect. Want to know more? YouTube is your friend. (RV Works has a decent video, though it is long.)

      Compressor refrigerators (of any type) are not going to be discussed.

      Howard
      You must be slipping Howard how absorption fridges work is basic thermodynamics (a course I liked) Energy gains and losses during change of state, Liquid to gas and back ....well at least on paper.

      I am surprised they are not covering compressors as they are coming stock on many brand units - or do you just call the factory folks for that? Its the same principle - compressor creates liquid under pressure and as it expands later it cools - like canned air getting cold as it expands out of the can as you use it.

      Hang in there and have a great evening.
      Keith
      Last edited by howson; 10-14-2021, 04:15 AM.
      2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

      Comment


      • #93
        howson

        Howard,

        On that new Dometic water heater there is no adjustment to the air/propane mixture, the other models usually have a slotted sleeve that one can slide to add or remove air. Could you please ask Bob how one is supposed to adjust the air/propane mixture on that type of unit? There is a post on here with a member asking this question, would be nice to shed some light on it.

        Thanks,

        Brian
        Brian & Michelle
        2018 Reflection 29RS Oct.2017 build date, EMS-HW50C , Lippert Remote
        2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K

        Comment


        • #94
          A mixing valve allowing a water heater to run at a higher temperature might be unusual in an RV but is relatively common in residential systems.

          Rob
          Cate & Rob
          (with Border Collies Molly & Angel and their kitty Gracie)
          2015 Reflection 303RLS
          2014 Ecoboost F150 with Heavy Duty Payload Package (retired)
          2022 F350 Diesel CC SB SRW Lariat
          Bayham, Ontario, Canada

          Comment


          • #95
            Originally posted by Country Campers View Post
            howson

            Howard,

            On that new Dometic water heater there is no adjustment to the air/propane mixture, the other models usually have a slotted sleeve that one can slide to add or remove air. Could you please ask Bob how one is supposed to adjust the air/propane mixture on that type of unit? There is a post on here with a member asking this question, would be nice to shed some light on it.

            Thanks,

            Brian
            Bob did point that out, Brian, during the lecture. There was no explanation or clarification as to "why". Bob mentioned that he and Mike, the school Administrator, hadn't been to Dometic or Suburban for two to three years, so they don't have info on this latest iteration of the Dometic.

            If I was to take an educated guess...it may be for the same reason the pilot adjustment screw was removed from the old "Pilot Model" gas water heaters. Those not knowing fully what they were doing adjusted the pilot too high, creating a situation where the flame was too hot. That in turn created other problems. The "fix" was to remove the adjustment. The air shutter, the slotted sleeve or holes on burner tube that allows for propane and air mixing adjustment, may be the same situation. Pic below for those reading this post that may not know what Brian and I are discussing.


            Click image for larger version  Name:	shutters.JPG Views:	0 Size:	97.4 KB ID:	67850
            Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

            Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

            Comment


            • #96
              Tues, 12 Oct (Day 22)
              Death by Powerpoint today...covered multiple generations of RV absorption refrigerators from the early manual models to today's A.M.E.S. (Automatic Manual Energy Selector). There was plenty of new information and some was quite in-depth.

              Bob has all of Dinosaur's boards (given to the school by the company) and it was quite evident inspecting them up close the superior build quality versus OEM boards. Many here on this forum have replaced OEM boards (on water heater or some other component) with Dinosaur boards, and based on what I've seen their stellar reputation is justified.

              Still memorizing all the components of the absorption refrigerator and how all the gas (and liquids) flow. Bob is one determined teacher...if you're in his class you WILL know how an absorber refrigerator works.

              Back to studying...

              Howard
              Last edited by howson; 10-14-2021, 04:14 AM.
              Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

              Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

              Comment


              • #97
                Originally posted by Cate&Rob View Post
                A mixing valve allowing a water heater to run at a higher temperature might be unusual in an RV but is relatively common in residential systems.

                Rob
                We had a mixing valve in our Titanium fifth wheel. Failed in the first year. Everybody I know that had an RV HW tank with a mixing valve either replaced it a few times or, like myself, got rid of it.
                Curious. Never heard of anybody with a residential HW tank mixing valve. There is no need. So. What brand of residential tank has a mixing valve?
                2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
                2021 Reflection 303RLS, Haloview RD7, Strong-arms, Micro-Air364

                Comment


                • #98
                  Originally posted by Scott'n'Wendy View Post

                  We had a mixing valve in our Titanium fifth wheel. Failed in the first year. Everybody I know that had an RV HW tank with a mixing valve either replaced it a few times or, like myself, got rid of it.
                  Curious. Never heard of anybody with a residential HW tank mixing valve. There is no need. So. What brand of residential tank has a mixing valve?
                  Some local codes can dictate that a mixing or anti scalding valve be used. If folks ever turn on the shower just after the hot water tank has cycled, they may experience scalding hot water even with the faucet set to prevent scalding. The mixing valve prevents this issue where the temperature leaving the HWT is set to the same temperature regardless of how is has cycled.

                  Jim
                  2017 Imagine 2600RB
                  2015 GMC Sierra 4x4

                  Comment


                  • #99
                    Scott'n'Wendy
                    Attached picture of the mixing valve on my residential water heater. (I did not install this . . . it came with the 8 year old house)

                    Rob
                    Attached Files
                    Cate & Rob
                    (with Border Collies Molly & Angel and their kitty Gracie)
                    2015 Reflection 303RLS
                    2014 Ecoboost F150 with Heavy Duty Payload Package (retired)
                    2022 F350 Diesel CC SB SRW Lariat
                    Bayham, Ontario, Canada

                    Comment


                    • Originally posted by MidwestCamper View Post

                      Some local codes can dictate that a mixing or anti scalding valve be used. If folks ever turn on the shower just after the hot water tank has cycled, they may experience scalding hot water even with the faucet set to prevent scalding. The mixing valve prevents this issue where the temperature leaving the HWT is set to the same temperature regardless of how is has cycled.

                      Jim
                      I had thought the only reason for the Atwood mixing valve was to run the hw tank at scalding levels intentionally, then mix in cold so it actually gives you more reasonable temp water than the 6 gal tank would normally be able to supply. In our house, I just set the temp to a reasonable level.
                      Which is why I figured there would be no need for a mix valve in a house.

                      Learning every day.
                      Thanks Jim and Rob
                      2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
                      2021 Reflection 303RLS, Haloview RD7, Strong-arms, Micro-Air364

                      Comment


                      • Originally posted by Scott'n'Wendy View Post

                        I had thought the only reason for the Atwood mixing valve was to run the hw tank at scalding levels intentionally, then mix in cold so it actually gives you more reasonable temp water than the 6 gal tank would normally be able to supply. In our house, I just set the temp to a reasonable level.
                        Which is why I figured there would be no need for a mix valve in a house.

                        Learning every day.
                        Thanks Jim and Rob
                        Scott,

                        This may be the case since my Atwood is easily capable of scalding. Maybe this is why the DW and I can shower almost back to back and not run out of hot water. For the home there is another scenario that can cause excessively high temps. To use hot water in short bursts which will cause the hot water tank to short cycle and build excess heat. The anti scalding or mixing valve will prevent all of this. I have one sitting on a shelf and will install it in our new to us place along with an RO system.

                        Your very welcome and I hope this helps.

                        Jim
                        2017 Imagine 2600RB
                        2015 GMC Sierra 4x4

                        Comment


                        • Wed, 13 Oct (Day 23)
                          In the lab today doing hands-on with Dometic and Norcold refrigerators. It was actually fun tracking down why there was no power to the circuit board, testing the thermistor, and a multitude of other tests.

                          One practical note to pass on. If you ever need to talk with Dometic, they need the Model, Serial Number, and Product No. If you're missing one of those pieces of information, you get to call back.

                          Click image for larger version  Name:	Dometic.JPG Views:	0 Size:	80.1 KB ID:	67984

                          So back to the lab. Between myself and my two partners we knocked out the vast majority of the required checks before lunch. After lunch there wasn't much to do, so I told them to turn their backs and completely disconnected all the wires from the circuit board. When they turned around I handed them the schematic and said, "Have at it!" They were initially shocked but both of them were easily able to trace the wires from the components to the proper plug and jack on the board.

                          I think I have 99% of the parts and theory down on the refrigerator. There was one "weak ammonia solution" tube that not labeled on any of the documents in the study material, so naturally I had to ask. Bob said, "There isn't a name--from now on it will be known as the Howard Tube!" Bob never misses a chance to rib a student. FYI, Bob was a Corrections Officer in upstate NY. Does that give you any insight?

                          Click image for larger version  Name:	Howard Tube.JPG Views:	0 Size:	91.6 KB ID:	67983

                          Tomorrow more lab. Bob is going to sabotage the refrigerators, so it should be fun troubleshooting why they aren't working. I doubt he'll give me an electrical problem--I strongly suspect it will something propane related. He's trying hard to stump me, so I look forward to the challenge. I'll let you know how it goes in the next report.
                          Last edited by howson; 10-14-2021, 04:14 AM.
                          Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                          Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

                          Comment


                          • howson , I know I'm getting old, but my calender shows this Wednesday, today, to be 13 Oct not 18 Oct as in your post. What am I missing?
                            Ted
                            2021 Reflection 310RLS
                            2020 F350 PS,CC,LB,SRW

                            Comment


                            • Originally posted by howson View Post
                              Wed, 13 Oct (Day 23)
                              In the lab today doing hands-on with Dometic and Norcold refrigerators. It was actually fun tracking down why there was no power to the circuit board, testing the thermistor, and a multitude of other tests.
                              When you have some decent information, good tools and a logical thought process, troubleshooting is a lot of fun in my book.
                              Problems occur when you have bad information, you don't actually understand the the theory, and/or second rate tools. Then repairs become expensive. Kinda like going to some dealers I've heard of...lol

                              Lovin' your posts Howard.
                              Last edited by howson; 10-14-2021, 04:17 AM.
                              2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
                              2021 Reflection 303RLS, Haloview RD7, Strong-arms, Micro-Air364

                              Comment


                              • Originally posted by TedS View Post
                                howson , I know I'm getting old, but my calender shows this Wednesday, today, to be 13 Oct not 18 Oct as in your post. What am I missing?
                                Ted - Howard howson was on cloud nine after getting a special part named after him *Howard Tube!" now if it was me - it would be normal to forget what day it is..........I guess what I am saying its not important.....or as a favorite sheriff would say "not germane to the situation" Howard will never live this down.....maybe his new handle should be Dr.Tube!

                                PS Howard - don't forget to take an apple to Bob tomorrow
                                Keith
                                2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

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