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  • On demand gas heaters

    Hi everyone.

    Was just wondering what you folks think about on demand gas water heaters.

    We will be buying a new older home and will probably have to do some remodeling and one of the things that have come up is this type of heater.

    The house will be 1 story with a full basement or a 2 story with a basement.
    We are looking for 2.5 baths and will probably have 2 sinks in the kitchen as well as one in the laundry room.

    I was wondering how many heaters would be best and also for what we want is it worth doing it and is a good way for hot water for the house.

    It will be install professionally but would like some ideal for when it comes down. We live in Washington state if that makes a difference.

    Any advise would be appreciated.
    shup

  • #2
    Re: On demand gas heaters

    shup: Do a search on this forum for tankless water heaters. You will find that most plumbers do not recommend them. I personally cannot say one way or the other, but I do have lots of respect for most of these guys. They know their business and will give you a straight answer. It seems like the tankless is expensive to maintain.

    Comment


    • #3
      Re: On demand gas heaters

      Originally posted by shup View Post
      Hi everyone.

      Was just wondering what you folks think about on demand gas water heaters.

      We will be buying a new older home and will probably have to do some remodeling and one of the things that have come up is this type of heater.

      The house will be 1 story with a full basement or a 2 story with a basement.
      We are looking for 2.5 baths and will probably have 2 sinks in the kitchen as well as one in the laundry room.

      I was wondering how many heaters would be best and also for what we want is it worth doing it and is a good way for hot water for the house.

      It will be install professionally but would like some ideal for when it comes down. We live in Washington state if that makes a difference.

      Any advise would be appreciated.
      shup

      If your doing a large remodel, where you can pipe everything in and do the install the correct way, then go with a Rinnai, get a certified installer.

      you will be fine. Tankless is expensive to retro fit, but if your doing a large demo, you can absorb some of the expense.

      Tankless is not for everyone, but there is energy savings and endless hot water.

      the savings are more then meet the eye, just call Rinnai support and they can break down the cost savings.
      sigpic

      Robert

      Comment


      • #4
        Re: On demand gas heaters

        I have an on demand gas water heater & I love it. It only heats water when I need it instead of keeping it hot all day for no reason. I replaced my electric water heater with it and my electric bill dropped $125.00 a month. My gas bill only went up $15.00 a month. I have a 3 bedroom 2 bath house.

        Comment


        • #5
          Re: On demand gas heaters

          OK....so this whole tankless water heater thing. I love the idea. From the perspective of user-friendly, and even "green" building, tankless is the way to go. Maintain comfort levels, but at a lower cost.

          So...tankless retrofit seems problematic. Is this just because of the way tankless heaters are designed to be used with a manifold system? Or is there some other "gotcha" with tankless I've missed somewhere? I get how retrofitting a manifold system into existing is a total ...well...PITA at the very least. Just trying to think of how to retro a tankless into my home causes me to have nightmares...and I don't do plumbing! Is there something beyond the manifold installation that I'm missing?
          I put it all back together better than before. There\'s lots of leftover parts.

          Comment


          • #6
            Re: On demand gas heaters

            Originally posted by bjdavis View Post
            I have an on demand gas water heater & I love it. It only heats water when I need it instead of keeping it hot all day for no reason. I replaced my electric water heater with it and my electric bill dropped $125.00 a month. My gas bill only went up $15.00 a month. I have a 3 bedroom 2 bath house.
            This persons electric bill did not drop $125.00 a month!

            Comment


            • #7
              Re: On demand gas heaters

              without repeating my post a dozen times. please do a search on tankless.

              i can tell you from personal knowledge, the savings will never add up.

              you're also limited to 4-8 gallons per minute depending on the size and the incoming water temperature.

              very few get installed properly and don't even think of a recirc system.

              please do some research on old post and then ask again.

              rick.

              added note, my monthly gas bill is only 15.00 a month with a 40 gallon gas heater. my dryer and stove are gas too.

              even if my bill droped to 5. a month, there would never be a payback for me.
              Last edited by PLUMBER RICK; 03-27-2008, 10:49 PM. Reason: added note
              phoebe it is

              Comment


              • #8
                Re: On demand gas heaters

                Thanks guys for the info.

                Plumber Rick, thanks I will do the search.

                shup

                Comment


                • #9
                  Re: On demand gas heaters

                  Originally posted by PLUMBER RICK View Post
                  without repeating my post a dozen times. please do a search on tankless.

                  i can tell you from personal knowledge, the savings will never add up.

                  you're also limited to 4-8 gallons per minute depending on the size and the incoming water temperature.

                  very few get installed properly and don't even think of a recirc system.

                  please do some research on old post and then ask again.

                  rick.

                  added note, my monthly gas bill is only 15.00 a month with a 40 gallon gas heater. my dryer and stove are gas too.

                  even if my bill droped to 5. a month, there would never be a payback for me.

                  That 4-8 gpm is the key for me. I will install them for my customers, but I try and talk them out of it. Around these parts, I try to have them put in indirect heaters.

                  Comment


                  • #10
                    Re: On demand gas heaters

                    Ain't it amazing how when the price of energy goes up the same gadgets get trotted out all over again. Tankless heaters are nothing new. They've been around for at least 40 year, maybe longer (I'm not in a google mood so you'll have to chect that for yourselves) but I do remember Paloma Pak and Aquastar and two or three others. I will admit the Rinnai is a much better, more refined product but the technology is nothing new. The key here is the gallons per minute. Look closely at your plumbing code. It says you must provide hot water to every fixture (that uses hot water) when they are all open at once. A quick look at the sfu (supply fixture unit) tells you right off that a 4gpm draw will not satisfy the code. Then those of you in the north east have been installing boilers with tankless coils capable of a paltry 2 1/2 to 3 gpm for years.
                    sigpic

                    Comment


                    • #11
                      Re: On demand gas heaters

                      personally I'd go with an AO Smith Vertex....tankless just have way too many issues.

                      Comment


                      • #12
                        Re: On demand gas heaters

                        Wait until they spring leaks like all water heaters will. People think there power vents are great until they get the bill for the new one! When the price of a new heater is lost in the cost of a big remodel or new home it's no big deal, but when it needs to be replaced , then people start wishing they had a standard vent W/H. If they become popular enough I'll be one of the only guys around to learn how to work on them. When they need to be replaced they will be a lot lighter then a tank water heater. If they have the money for one now then in 10 years I will show no mercy on price to replace or fix one. all the money they imagined they saved on efficiency will adequately compensate me for my time. I've had to work on 2 they were a pain in the neck. From now on it's going to be $150.00 an hour to watch me fumble around getting the thing to work!

                        VERY EFFICIANT AND YOU GET ALL THE HOT WATER YOU WANT.

                        It don't work that way folks!

                        Comment


                        • #13
                          Re: On demand gas heaters

                          Rinnai is top of the line when it comes to tankless.

                          On their web site they have a savings chart and all the information you need to make an informed decision.

                          The unit saves money in a couple different ways, one way is not heating 40 gallons of water when no one needs it, another way, is only heating the water you need, on demand.

                          the unit may not work at 199,000 btu until the flow rate is needed.

                          Take some time to research Rinnai on their web site and once again make sure you hire a certified installer.

                          As far as the comment as springing leaks, the poster needs to do his research also.

                          the heat exchanger is warrantied far longer then a tank 10 years.

                          depends on you and your needs. yes, tankless are not for everyone, but they do have a use and they are an excellent product.
                          sigpic

                          Robert

                          Comment


                          • #14
                            Re: On demand gas heaters

                            If you read throug the specs. here you will note that the best of these units is capable of 8.0 gpm. The combined supply fixture unit value of an average 2 bath house, with all hot water taps open at the same time, (yes, highly unlikely) is above the apacity of the unit and therefore non code compliant. Now I know full well that only an a-hole of an inspector would bag you on this, but he could. The usual residential unit installed only has a capacity of 4.8 gpm. If you sell these (and I do) it is vital to clearly explain to the customer that though the hot water supply can be endless, if there is too much demand on the heater it will not be. You can't take a shower, run the dishwasher and the laundry all at the same time.


                              • will have an endless supply of hot water 24 hours a day. Unique to the Rinnai tankless water heaters is the ability to utilize up to three water outlets simultaneously with a constant temperature of hot water. The Rinnai Tankless Water Heater supplies hot water at the rate of up to 8.5 gallons per minute continuously with no time constraints!

                            ModelDimensionsMin/Max BTU'sFlow RateTemp RangeR85e Plus

                            Height 22.9"
                            Width 14"
                            Depth 9.8"15,000 - 199,000 0.6 to 6.5 GPM
                            (50 F rise)
                            0.6 to 8.5 GPM
                            (35 F rise)Factory preset to 120 F

                            MC-91
                            Controller 96-140F included





                            R85i Plus

                            Height 22.9"
                            Width 14"
                            Depth 9.6"
                            15,000 - 180,000 0.6 to 6.5 GPM
                            (50 F rise)
                            0.6 to 8.5 GPM
                            (35 F rise)Factory preset to 120 F

                            MC-91 Controller 98-140 F
                            included


                            R53i Plus



                            Height 22.9"
                            Width 14"
                            Depth 9.6"
                            15,000 - 180,000 0.6 to 5.3 GPM
                            (50 F rise)
                            0.6 to 5.3 GPM
                            (35 F rise)Factory preset to 120 F

                            MC-91
                            Controller 98-140 F
                            included
                            R98i


                            Height 23.6"
                            Width 18.5"
                            Depth 9.3"19,000-237,0000.6 to 8.0 GPM (50 F rise) 0.9 to 9.8 GPM (35 F rise)
                            Factory preset to 120 F

                            MC-91
                            Controller 98-140 F
                            included
                            R98e



                            Height 23.6"
                            Width 18.5"
                            Depth 9.3"19,000-237,0000.6 to 8.0 GPM (50 F rise) 0.9 to 9.8 GPM (35 F rise)
                            Factory preset to 120 F

                            MC-91 Controller 98-140 F
                            included


                            R85i

                            Height 23 5/8"
                            Width 13 25/32"
                            Depth 8 13/16"15,000 - 180,000 0.6 to 6.5 GPM
                            (50 F rise)
                            0.6 to 8.5 GPM
                            (35 F rise)Factory preset to 120 F

                            MC-91
                            Controller 98-140 F
                            included


                            R85e


                            Height 23-5/8"
                            Width 13-3/4"
                            Depth 8-7/8"15,000-199,000 0.5 to 6.5 GPM
                            (50 F rise)
                            0.7 to 8.5 GPM
                            (35 F rise)
                            Factory preset to 120 F

                            MC-91 Controller 96-140F included

                            R53i

                            Height 23-5/8"
                            Width 13-25/32"
                            Depth 8-13/16"15,000 - 180,0000.7 to 5.3 GPM
                            (50 F rise)
                            0.7 to 5.3 GPM
                            (35 F rise)Factory preset to 120 F

                            MC-91
                            Controller 96-140F included

                            R53e


                            Height 20-7/8"
                            Width 13-3/4"
                            Depth 7-3/8"19,000- 150,000 0.7 to 4.9 GPM
                            (50 F rise)
                            0.7 to 5.3 GPM
                            (35 F rise)

                            Factory preset to 120 F

                            MC-91
                            Controller 96-140F included
                            R42e
                            Height 20-7/8"
                            Width 13-3/4"
                            Depth 7-3/8"17,700- 120,0000.7 to 3.9 GPM
                            (50 F rise)
                            0.7 to 4.2 GPM
                            (35 F rise)Factory preset to 120 F

                            MC-91
                            Controller 96-140F included


                            C85i


                            Height 23 5/8"
                            Width 13 25/32"
                            Depth 8 13/16"15,000 - 180,0000.5 to 6.5 GPM
                            (50 F rise)
                            0.7 to 8.5 GPM
                            (35 F rise)Factory preset to 140 F

                            MC-91
                            Controller 96-180 F
                            included

                            C85e



                            Height 23-5/8"
                            Width 13-3/4"
                            Depth 8-7/8"15,000-199,000








                            0.6 to 6.5 GPM
                            (50 F rise)
                            0.6 to 8.5 GPM
                            (35 F rise)
                            Factory preset to 140 F

                            MC-91 Controller 96-185 F
                            included

                            C53i
                            Height 23 5/8"
                            Width 13 25/32"
                            Depth 8 13/16"15,000 - 180,0000.7 to 5.3 GPM
                            (50 F rise)
                            0.7 to 5.3 GPM
                            (35 F rise)
                            Factory preset to 140 F

                            MC-91 Controller 120-180 F
                            included
                            C42e
                            Height 20-7/8"
                            Width 13-3/4"
                            Depth 7-3/8"19,000- 150,0000.6 to 4.8 GPM
                            (50 F rise)
                            0.6 to 5.3 GPM
                            (35 F rise)Factory preset to 140 F

                            MC-91
                            Controller 120-185 F
                            included
                            C42
                            Height 20-7/8"
                            Width 13-3/4"
                            Depth 7-3/8"17,700- 120,0000.6 to 3.8 GPM
                            (50 F rise)
                            0.6 to 4.2 GPM
                            (35 F rise)Factory preset to 140 F

                            MC-91
                            Controller 120-185 F
                            included



                            sigpic

                            Comment


                            • #15
                              Re: On demand gas heaters

                              don't forget to factor in the temp rise.

                              I think 8.5 is for 70 or 80 degree incomming water, we have like 50 or 60 here, so it cuts down on the flow.
                              sigpic

                              Robert

                              Comment

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