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  • #61
    Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

    Originally posted by Flux View Post
    We (family of 4) grew up on a 30 gallon oil fired hot water heater. The recovery rate was very quick, and back to back showers were no problem at all. Hands down the best water heater we ever had.

    With the price of oil so high now, my dad and I finally ripped it out and put in an 80 gallon electric.
    Flux,

    How much is your electricity that it comes out cheaper? I know a lot of places have it much better than we do. I'm assuming you still need the oil for space heating. IMO, one of the downsides of oil is you can't get away with little maintenance like you can with gas/electricity.

    Charles

    Comment


    • #62
      Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

      My calculation accounts for deadband. Your rules of thumb don't. If you try to cheat the deadband you end up cycling the element repeatedly. Very, very bad for reliability.

      The calculation doesn't include any flow restriction due to the dip tube. It assumes that the flow is limited by the tub fill valve, and that there's adequate pressure to achieve that flow. So, as usual, your comment is irrelevant.

      If you knew anything about system reliability, you wouldn't have to ask about failure rate. Every part has a failure rate, typically expressed as number of failures per some number of hours, usually per million hours. Don't get hung up with the "million hours" It doesn't mean the parts last a million hours. The failure rates of all the components need to be expressed in the same time base, then added up to give the system failure rate. So if you have two WHs, you have twice as many parts, and you get twice as many failures for the same period of time. That's half the reliability. Anyone involved with design of any sort of product knows that major goal is to design out parts. It makes the product less costly and it improves reliability by eliminating the failure rate for the parts that you design out. Now, if you designed a redundant system, you can improve your reliability with your two water heaters. But in this case, that's not what you've got. Your design does mean that you have what we call soft failures - you are still on the air after one craps out. But you still have to fix what broke, and you still have twice as much stuff to break. Therefore you have just given the homeowner twice the repair cost over the life of the system. You can argue that if you use twice as many parts, but they each don't work as hard, then the failure rates go down. This is true. But in your case, there isn't much eidence that the parts will work significantly less hard. The temp of a steel tank over the range of temperatures we're talking about will not affect the reliability. There is no thermal fatigue issue for steel tanks at 120, 130 or 150F. Those numbers are nothing for steel, nor are they anything for glass. Cycling between mid 80s and peak temp isn't going to matter either. What is going to matter is causing the electric heating element to on/off cycle too frequently. The element and the relay are designed for a certain number of cycles. It doesn't take a college education to understand that if you cycle them more frequently than they were designed for, those parts won't last as as long. Your dual system also has twice as many joints to leak, twice as many anodes and T&Ps to maintain, and you now need a 50A electric service.

      For the umptenth time, I have no issue with Rheem and their comments on condensation. Their engineers went to college, maybe that's why you can't understand them properly either. The problem is that you're predicting that OP is going to have this problem with his installation. There is nothing in the Rheem material that supports your argument. Do they give you any specific temps where this becomes a problem? No. Because they understand that they *can't* without evaluating the specific situation. So don't claim I am somehow contradicting Rheem. I'm not. I'm just saying that you're using this issue as an arm-waving argument to support your too-costly proposal. Fact is, the analysis shows that the tank temp never gets below 86F after the tub fill. It doesn't stay there for very long. Have you ever seen a glass of 86F water cause condensation?

      I agree with you that the electrics will recover slightly faster than the gas. When looking at recovery, I agree that one should look at the specs for two electrics independently and add them together. My erroneous comments were based on looking at the burner and the amount of water that had to be heated in the gas compared the the total wattage and total water gallonage to be heated with the electrics. The manufacturer specs don't support that conclusion. The dual electrics are (very slightly) better. It isn't a very big difference, but it is a difference. See that? I was wrong. Did you learn that it's not that tough to admit when you're wrong? It sure beats trying to defend your mistake with more arm-waving and nonsense. Know why? Because you can arm-wave all you want but it doesn't change reality. Teenagers try that... but most have learned, by the time they get to be twenty or twenty-five, that arguing an untenable position is foolish. Guess you're still a teenager, eh Mr. Expert?

      Which is also why it really doesn't matter how many people agree or disagree with you or me. It's not a popularity contest or an election. The numbers are the numbers. Your solution is too much for too little - almost no - benefit. The numbers show it. Common sense shows it. You keep saying that your cost for gas is too high, but who cares? None of this is about YOUR house. It's about OP's system. And your electric rates are opposite of mine BTW. I pay more - much more - the more I consume. I would bet that electric rates are going to go up, and that the days of getting rewarded for using more energy are numbered - probably a small number.

      Finally, regarding 104F, I really don't care what you believe or don't believe. Currently, outdoor self-contained spas are limited by law to 104F. Did you get that? *By Law*. THis has been the law for the past several years, when the extent of the health hazard was recognized. I believe, but am not 100% sure, that the same law applies to jetted tubs with heaters. Rinnai's 120F? So far as I know, there is no law on the books that limits what the temperature one can fill a standard bathtub to. And for a standard tub where the bather is not typically completely immersed, above 104F is not necessarily unsafe or a hazard, since your body can still regulate its temperature. But we're not talking about a regular bathtub, Mr. Expert Master, we're talking about a jetted tub. Again, I don't care what you believe, but if you want to read up on the subject, you can start at the manufacturer's sites that make such tubs. Guess what temp they recommend as the maximum? Yup, 104F. How many guesses did it take you?

      Comment


      • #63
        Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

        Here are the facts.

        Undersized water heaters produce more condensation when they are pushed to the limit. The chief by-product of gas combustion is water vapor.

        We are not talking about a spa....we are talking about his bathtub so your 104 temp doesn't apply. Thats probably why Rinnai doesn't limit their bathfill temp to 104 but allows up to 120 degrees.

        The higher the temp the more corrosive the water all things being equal.

        The higher the temp the more energy your wasting in stand-by loss

        The higher the temp the greater the liability if a person is burned by hot water....even if you consider it "Their fault".....Guess what,its never the persons fault that gets burned by you setting a temp over 120.

        Pressure vessels can only expand and contract so many times...the greater this expansion and contraction generally the quicker the fail rate.

        Experts and professionals do not increase temp to make up for smaller tanks leaving unsafe,wasteful operating conditions.

        Sounds like you just want to "get by".....with that attitude maybe you should be in another line of work that doesn't invlove the safety of homeowners and their guests or the public in general.

        Your trying to compare the reliability of an electric water heater and its parts to a gas fired water heater.....I suppose you dont have any experience with the reliability of the new FVIR gas water heaters.....let me tell you as a FACT they are not as reliable as the 1995 gas fired heater in your garage. If they are installed in a dirty enviroment they will fail and it doesn't take long. If they are installed in the living space then the vent is sucking your HVAC conditioned air out of the house and thats bad for the efficiency of heating and cooling the home. Remember that standard tank type gas heaters draft 100% of the time unless you have a negative pressure....and thats bad. And if your 50,000 btu burner operates for an hour you end up with about 5 pounds of water vapor....so you better have a proper vent or you'll end up with a couple quarts of condensate. Did I mention this condensate is corrosive? Water vapor is the chief combustion by product of natural gas. Understand?
        Last edited by TheMaster; 04-25-2011, 10:55 AM.

        Comment


        • #64
          Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

          Here is the fact:

          You will grasp at any straw to defend yourself.

          Comment


          • #65
            Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

            Originally posted by Andy_M View Post
            Here is the fact:

            You will grasp at any straw to defend yourself.
            This shows you just want to argue. Your not posting any facts and not discussing the topic any longer. Refrain from this if possible.

            Now back to the topic. Most experts agree that an electric water heater properly sized will last longer than a gas fired unit of the same quality tank. Burning gas produces corrosive by-products to contribute to this decline in expected life.

            The cost of a proper system may be more but it will provide a longer service life,safer operating condition,consume less energy(even if that energy costs more) and is more likely to meet demands of the home based on how its equiped...like with a lage tub and modern appliances. If they are installed its to be assumed that they will be used. The current owners are temporary in the 100 yr expected life of a home.

            Comment


            • #66
              Electric is 100% efficient

              Electric has no flue drafting warm air out of the basement and pulling in ice-cold air in the wintertime 24/7, chilling the basement.
              Electic is not constantly losing heat up a center tube, creating a draft which actually cools the water inside the tank.

              Electic does not require and draw in cold make-up air or combustion air, whichills the basement.

              No chance of carbon monoxide poisoning or leaking natural gas.

              Heat losses are minimal.
              I'd take an educated guess - but I'm unqualified.
              It ain't just soot, it's paydirt.
              "I swear, wherever Gift goes, argument follows." -Youtube comment

              Comment


              • #67
                Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                Just some food for thought
                1- tank type heaters can heat water up to 7500 hrs a year that you don't use it on avg for a family of four.
                2- if the tank is in an airconditioned part of the house it will add a load to the a/c and run more often as the ambient air around the tank maybe in the 70's while the tank is maintaining 120
                3- as a contractor i would never raise the temp above 120 at the heater thanks to lawyers
                4- 2 40's while they may do the trick will increase wasted heating to over 1500 hrs per year
                5- you might want to look into a rinnai condensing furnace. They can be mounted externally ,can be freeze protected ,and qualify for federal tax credits
                6- i have a 6 ft whirlpool tub and the rinnai provides more then enough hot waterr to fill the tub even with a waterfall type faucet
                7-some utilities offer rebates for upgrading or adding gas appliances such as stoves, heater's, pool heater's,dryer's ,etc.

                Comment


                • #68
                  Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                  Originally posted by Knezz View Post
                  My main concern at this point is cost over 6 years (tank and installation cost along with reoccurring monthly utility bill for 72 months).I’m using 70 gallon per day for two people (140 gallons per day for total water - 1/3 of total water will be heated as a guess). I’m also going with the FEMP recommendation.

                  My Electric Company is charging 0.1588 per kWh (includes all fees except the $7.25 monthly customer charge)

                  My Gas Company is charging 2.264345 Ccf (not including a monthly Customer charge of $12.00). 2.264345 Ccf x 1.024 therm conversion factor = 2.31868928 therm

                  $558 annual for electric + ($7.72 x 12 months – customer charge = $87.00) = $645.00 per year

                  $411 annual for gas + ($7.25x12months- customer charge = $144.00) = $555.00 per year

                  ***Am I correct in my understanding of comparing the two?***

                  Because the contractor is saying that the gas heater is $1,200.00 more to install than electric it would take me 13 years to recoup those additional dollars of installing gas if my understand of comparing gas to electric is correct?

                  Is it true that electric tanks usually have issues prior to gas as the elements in the electric go bad more? Or is that an old wives’-tale?

                  I used this site for conversion http://www1.eere.energy.gov/femp/tec...ters_calc.html (Thanks Andy M)

                  Edit.... error in my considerations. Andy M specifically underlined the fact that 140 gallons is total water usage - hot water is considerably less. With two bathrooms, dishwasher and the other normals would 1/3 of total usage be a reasonable gauge? If so, it might take me about 13 years to realize a savings in gas?

                  Does any of this make sense or am I barking up the wrong tree?

                  Regards.

                  My apologies to all. The tub is a standard 5' tub. The 60 gal is the overflow spec. The spec sheet doesn't say the fill. Bathing well is 42" x 20".
                  ------Will a 50 gallon gas heater pay for it's self over the next 7 year or so compared to a 50 gallon electric heater (gas unit and install being $1,200.00 more).

                  Thank you all for the responses.

                  Regards
                  Regards,
                  K. Nezz

                  Comment


                  • #69
                    Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                    Originally posted by Knezz View Post
                    ...------Will a 50 gallon gas heater pay for it's self over the next 7 year or so compared to a 50 gallon electric heater (gas unit and install being $1,200.00 more). ...
                    Since most water heaters are free-standing in an open basement, has anyone been able to determine the amount of heat being continually pulled out of the basement by the flue draft AND the amount chilling to everything else by make-up air drawn into the basement?
                    It is the TOTAL energy loss from the water and house and use of gas to make up for it which is most important.
                    Last edited by Robert Gift; 05-01-2011, 09:34 AM.
                    I'd take an educated guess - but I'm unqualified.
                    It ain't just soot, it's paydirt.
                    "I swear, wherever Gift goes, argument follows." -Youtube comment

                    Comment


                    • #70
                      Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                      Originally posted by Robert Gift View Post
                      Since most water heaters are free-standing in an open basement, has anyone been able to determine the amount of heat being continually pulled out of the basement by the flue draft AND the amount chilling to everything else by make-up air drawn into the basement?
                      It is the TOTAL energy loss from the water and house and use of gas to make up for it which is most important.
                      I would have no idea at this point of the year to determine that. I wouldn't even know where to start.

                      It is an unfinished stone walls basement in an Eastern city. Dead of winter can be 20 degrees F (every now and again it can drop 10 F lower). I now have a new gas heater in the basement and when I heat the house can heat the basement a bit but both my wife and I like it a bit chilly.
                      Regards,
                      K. Nezz

                      Comment


                      • #71
                        Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                        Knezz, it's a judgement call. But for me, I figure 50% is hot water. Laundry can be, and dishwashing is, a big hot water user. But the estimate needs to be your call. If you decide to up the percentage of hot, just re-run the calculator and make your choice.

                        With either but especially the electric, you are likely to want to turn up the water heater t-stat, especially if your incoming water supply is less than 55F and you like a warm bath. Others have stated that they don't like doing this. Again, it is your installation and your choice. I believe that water heaters should be run hot (a) to keep down bacteria growth and (b) to get the best performance. Many agencies and health departments in several other countries recommend or mandate 140F (60C) to control bacteria, especially legionella (cause of Legionairre's disease). It is not a rquirement in the US, but I very much like the rationale. Much has been made of the scalding issue, and it should be considered. If it's a concern for you, you can make it a non-issue by installing a simple thermostatic mixer at the WH output. These are $75-$100 on Amazon and an be installed now or later if you're on the fence. If you crank up the temp and use the mixer, you will get better performance, safer from bacteria, and no scalding, although energy costs will be higher if you run the WH hotter. I will probably put the mixing valve in when my current WH dies (expecting it to any time), but I don't have one now. Only adults (no tiny kids or elderly folks) here though, so it hasn't really been an issue.

                        Your tub being a 60 gal overflow as opposed to 60 gal fill really helps matters. Your fill capacity will be probably be in the upper 30 gal to mid 40 gal range, which should be fine with a 50 gal WH. You will see better performance with gas. Most of them have a better first hour rating and twice the recovery of the electric models.

                        You have to roll the dice a bit when it comes to future energy prices. Personally, I believe that electric is going to go up faster than gas, but no one really knows. If I am right about this, it argues for gas.

                        One last thing to consider might be replacement cost for the *next* WH. Once the gas venting is in, I imagine replacing the WH next time would be much less. This won't matter unless you intend to stay in the home for longer than the 6 year WH lifetime horizon you mentioned. Anyway, just something else to consider.

                        Good luck on your installation.

                        Comment


                        • #72
                          Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                          After much deliberation I decided to go with the gas heater. That was my first choice but the additional work of running the exhaust was pointing me towards electric. The congestion of getting the pipe out of the basement was a challenge as there is limited space. I removed the original chimney which demanded that I purchase a power vent unit

                          I decided on the Bradford White M-1-TW-50S6FBN . I’ve read quite a bit about the unit and most love it. The only questionable component is the gas control valve made by Honeywell. Some have had some concerns on the Honeywell part. I've read that the Bradford White gas valve was more reliable. I guess I will find out….

                          After doing a better calculation on cost I found that the gas heater is about $450.00 more that the electric 50 gallon unit. But… the electric unit is gauged to cost $280.00 a year more to run and a slower recovery time.

                          Thanks all for the help.
                          Regards,
                          K. Nezz

                          Comment


                          • #73
                            Re: Electric Hot Water Heater vs Natural Gas Hot Water Heater

                            In my opinion, compared to electric water heaters, solar or natural water heater would be a great choice. Not only it helps us to save energy, which is very important these days, but it also helps to save money on our electricity bills. Hence, I would go for natural water heaters.
                            plumbing phoenix

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