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  • #31
    Re: water heater heat loss

    Funny this post should come up now. I put a water softner in for a good friend of mine on saturday and before i got there he turned the water off drained everything down and turned of the water heater. Well I didnt know that he turned off the water heater and he didnt remember until monday morning when he took a cold shower!!! Man these things really are insulated well!

    Comment


    • #32
      Re: water heater heat loss

      More numbers:

      A 36,000 btu/h tank water heater at 60% efficiency is losing 14,400 btu/h.

      A 199,000 btu/h tankless at 84% efficiency is losing 31,840 btu/h. I'm still not sure how that is supposed to be saving me money. I really think my gas bill has gone up since I installed my tankless. I have no way of knowing for sure because all of my construction going on during the winter months, as well as my installation of my 3 heating systems at the same time. I do not have a good baseline to compare any numbers.

      I do know that I enjoy the endless hot water from my tankless. I do not enjoy the extra lead time it takes to get water hot though. I'm pretty sure my water bill has risen significantly as a result of this. I plan on installing a tank water heater before this winter, I'm just not sure how its going to be piped yet. I have considered having the tank heater with recirc lines to my kitchen and lavs, and keeping the tankless for the showers. I have also considered asking for help in piping them in series. Anyone want to help a DIY?

      The guy saving $40 a month and only paying 80 cents a therm. Thats 50 therms per month. Almost unbelievable.

      I also think there is no one size fits all right or wrong answer for tank vs. tankless. I think they are a better fit for the warmer southern areas that might have a higher incoming water temperature. Up north where I am, on city water, with my usage, I dont think the payback is there.

      Andy

      Comment


      • #33
        Re: water heater heat loss

        Andy, tankless's are modulating.
        They aren't 199KBTU every time they kick on, the 199 is when the heater is maxed, usually 3 to 4 fixtures simultaneously (for a whole home unit @ 6+ gpm).

        Even if you are maxing the unit and using the full capacity of 199 KBTU, the unit ONLY stays on for the duration of use.
        A tank type would stay on for 1/2 hour to reheat.

        As for your situation, if longer showers have created higher water bill due to the convenience of not running out of hot water...the LAST thing to do is leave it for the showers and put a tank in for everything else, your bill would definitely go up, yet you'd still have the same trouble.

        Comment


        • #34
          Re: water heater heat loss

          Originally posted by Ruudacguy View Post
          More numbers:

          A 36,000 btu/h tank water heater at 60% efficiency is losing 14,400 btu/h.

          A 199,000 btu/h tankless at 84% efficiency is losing 31,840 btu/h. I'm still not sure how that is supposed to be saving me money. I really think my gas bill has gone up since I installed my tankless. I have no way of knowing for sure because all of my construction going on during the winter months, as well as my installation of my 3 heating systems at the same time. I do not have a good baseline to compare any numbers.

          I do know that I enjoy the endless hot water from my tankless. I do not enjoy the extra lead time it takes to get water hot though. I'm pretty sure my water bill has risen significantly as a result of this. I plan on installing a tank water heater before this winter, I'm just not sure how its going to be piped yet. I have considered having the tank heater with recirc lines to my kitchen and lavs, and keeping the tankless for the showers. I have also considered asking for help in piping them in series. Anyone want to help a DIY?

          The guy saving $40 a month and only paying 80 cents a therm. Thats 50 therms per month. Almost unbelievable.

          I also think there is no one size fits all right or wrong answer for tank vs. tankless. I think they are a better fit for the warmer southern areas that might have a higher incoming water temperature. Up north where I am, on city water, with my usage, I dont think the payback is there.

          Andy
          You could always put in a small electric tank (not powered) and circulate with that through the tankless. Even a small 6 gallon will do. The Navien's have the 1/2 gallon tank built in for the circ so they get smaller draw to kick on the fire. But you can do it with any tankless.
          sigpic3:00, I mean 5:00, and work is done. Time to crack a cold one.

          Comment


          • #35
            Re: water heater heat loss

            Just quickly ran a few numbers. Not checked for accuracy though.

            If a tankless installation costs $1800.00 more to install than a traditional tank model then how would you come out investing that money & annual maintenance costs over 10 years?

            $1800.00 earning 5% (conservative) over 10 years. +
            $150.00 annual cleaning invested for the first 5 years. +
            $200.00 annual cleaning invested for the next 5 years.

            TOTAL investment available after 10 years= $5,687.36 or $47.39 per month. You have to save $47.39/month with a tankless to break even with a tank.

            I did not put maintenance costs on a tank model because if it doesn't cause trouble people will not maintain it. I know we've all seen some tanks only last 1 year but we've also seen them last 20 years untouched so I made a guess to give a 10 year scenario.

            People WILL call if it causes trouble. Which according to all that I've read from the experience on the Forum a tankless will need annual service. I increased $50.00 the second 5 years-you know why.

            Maybe everyone doesn't think this way but I constantly play offense/defense with all investment scenarios to maximize the end result.

            Something to think about.

            J.C.
            Last edited by BobsPlumbing; 08-26-2008, 09:05 PM.

            Comment


            • #36
              Re: water heater heat loss

              Originally posted by boillerman View Post
              You could always put in a small electric tank (not powered) and circulate with that through the tankless. Even a small 6 gallon will do. The Navien's have the 1/2 gallon tank built in for the circ so they get smaller draw to kick on the fire. But you can do it with any tankless.
              I think I understand. Good tip.

              J.C.

              Comment


              • #37
                Re: water heater heat loss

                Originally posted by JCsPlumbing View Post
                $1800.00 earning 5% (conservative) over 10 years. +
                $150.00 annual cleaning invested for the first 5 years. +
                $200.00 annual cleaning invested for the next 5 years.
                J.C.
                JC, annual cleaning?

                I give homeowners a brief tutorial on how to connect a $20 circ pump with two single ended hoses and 3 gallons of vinegar.

                Initial cost - $50

                Each year after it's maybe $10 for the white vinegar.

                In my state and a few others, gas co's are offering $300 cash rebates for installing them.

                Also, the one MOST overlooked fact, the cost of replacement for the next tankless.

                Comment


                • #38
                  Re: water heater heat loss

                  Thanks Duck. I was sure I had read that other plumbers were charging $150.00 to $200.00 for annual servicing/cleaning that a homeowner will not do. If not, I'll have to redo the numbers obviously.

                  Yes, replacement will be much easier on plumbers as long as the tankless manufacturers don't mess with the design too much.

                  J.C.

                  Comment


                  • #39
                    Re: water heater heat loss

                    Originally posted by DuckButter View Post
                    JC, annual cleaning?

                    I give homeowners a brief tutorial on how to connect a $20 circ pump with two single ended hoses and 3 gallons of vinegar.

                    Initial cost - $50

                    Each year after it's maybe $10 for the white vinegar.

                    In my state and a few others, gas co's are offering $300 cash rebates for installing them.

                    Also, the one MOST overlooked fact, the cost of replacement for the next tankless.
                    I do believe you that your local gas co. offers rebates. But why do they do so?

                    J.C.

                    Comment


                    • #40
                      Re: water heater heat loss

                      I gotta PEZ candy dispensor, and I'm not afraid to use it.
                      Northern Kentucky Plumbers Twitter Feed | Plumbing Videos

                      Comment


                      • #41
                        Re: water heater heat loss

                        $1800.00 invested at 5% for 10 years= $2,968.00 or $24.73/month.

                        Your monthly gas bill with a tankless would have to be $24.73 less than with a tank to save anything. Unless I missed something. Anyone tell me if I did as I'm trying to learn & not debate.

                        This does not include any maintenance for either.

                        J.C.

                        Comment


                        • #42
                          Re: water heater heat loss

                          Originally posted by DUNBAR View Post
                          I gotta PEZ candy dispensor, and I'm not afraid to use it.
                          Made me laugh. What's your avy? Looks like a Smiley with a sock in its mouth.

                          J.C.

                          Comment


                          • #43
                            Re: water heater heat loss

                            Originally posted by JCsPlumbing View Post
                            I do believe you that your local gas co. offers rebates. But why do they do so?

                            J.C.
                            GasNetworks - Efficiency Programs - Residential

                            Comment


                            • #44
                              Re: water heater heat loss

                              Originally posted by JCsPlumbing View Post
                              $1800.00 invested at 5% for 10 years= $2,968.00 or $24.73/month.

                              Your monthly gas bill with a tankless would have to be $24.73 less than with a tank to save anything. Unless I missed something. Anyone tell me if I did as I'm trying to learn & not debate.

                              This does not include any maintenance for either.

                              J.C.
                              Are you saying a tankless has to compete with a CD, 401K or stock portfolio?

                              Comment


                              • #45
                                Re: water heater heat loss

                                No, the tankless doesn't necessarily have to compete. But the investment does for me. Just presenting how I think about and do things. Others maybe do things differently.

                                J.C.

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