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Rinnai Continuous Flow Water Heaters

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  • Rinnai Continuous Flow Water Heaters

    Has anyone had any experience w/ these? The natural gas co here is offering up to an $800 rebate, plus I am told that there is also a $300 tax credit. Are they as efficient as the gas co claims & can they provide enough hot water for a small family. The unit I am looking @ #2530FFU, is rated @ 0.6 to 5.3 gpm w/ a 15,000 to 180,000 BTUH capacity.

  • #2
    roserx, i am not up to date on this particular brand and model. but they should be comprable to the noritz and tagagi.

    don't believe all the energy savings they quote. sort of like the fuel ratings on a new car window sticker. the heater only heats when water is used. basically you don't need to keep 30-75 gallons hot day and night. the standby heatloss is eliminated. instead of 34,000 - 75,000 btu's to heat the tank and reheat as needed, you heat the water that you're using at this time. no standing pilot or heat loss in the unit.

    my own gas bill is roughly 20.00 a month for 2 adults. this is water heating , clothes dryer, and cooking. very little need for running the furnace. so how much will i save on the 20. monthly bill with a tankless.

    the rebate is a good kickback to overcome the large cost of the unit and installation. a larger gas line needs to be run and a special stainless steel catagory 3 vent for indoor installations. i prefer outdoor with no vent.

    i other thing to keep in mind. these units are like a computer. lots of electronics. if something fails or you lose power, no hot water. with a tank type heater, there are only 2 items that fail. most of the time they last the lifetime of the heater. (5-15 years) power loss is not an issue.

    1 last thing to consider. 20- 25 years ago when solar heating was a big push. the tax credits and rebates almost paid for the units. today, you will spend more on repairs to the solar system, than what you will save in energy.

    the 1 benefit of a tankless is the unlimited amount of hot water that you can get per hour. this small heater is 5 gpm = 300 gph. that's alot more than a tank can deliver. but unless you need to fill a large bathtub or have lots of kids, i would think very seriously prior to this big purchase.

    ps. i've installed some for clients, i don't think i will put one in my house at this time.

    phoebe it is


    • #3
      Here's my three cents...

      I run a one man plumbing operation and I stopped installing all tankless water heaters. Most of my customers just weren't happy with them.

      In Northern California, the winter incoming cold water temp is around 40 degrees and in order to raise the water temp 60 degrees would reduce the average flow to about 3 gallons per minute...that's enough for one shower at a time, with nothing else running. Many folks are going to multiple shower heads and this just won't work with a tankless in the winter season.

      Also, unless the tankless is installed very close to the point of use, it takes awhile, sometimes, minutes for the water to get "hot".

      And lastly, as mentioned previously, repairs and maintenance are troublesome and costly. These are supposed to be flushed frequently (as much as monthly) to avoid scale build up inside the coils.

      A few of the folks seem to be happy with the tankless, I just wonder how happy they will be when they need to repair it. I can't and won't repair them, in fact, I don't know anyone that does repair them, in my area.


      • #4
        norcal, it sounds like we're on the same page here. a circulating line sort of defeats the so called savings on a tankless. here in southern calif. the lowest temp cold water is high 50's in the dead winter. the summer can reach low 80's. in fact i've been known to shower in the summer with cold only.

        unfortunatly the plumbers on commission who sell these heaters and don't know how to properly and safely install them will continue. the last one i fixed was installed on a 1/2'' gas line, the vent was hooked up upsidedown and didn't vent far enough from windows. in fact the gas meter was installed backwards along with the earthquake shut off valve. the amazing thing was the gas co. hadn't sent the owner a bill since the meter didn't move and the plumbing inspector had signed off on the repipe with the new tankless heater.

        see my post on under qualified contractors, plumbers and inspectors.

        more and more customers have asked me about the tankless heaters. there have been only a couple of applications where i felt would benefit from the tankless. 95% should keep a tank type heater

        my 2 cents and 4 cents. looking for a nickle

        phoebe it is


        • #5
          The Rinnai Infinity Range is becoming incresingly popular here in Sydney Australia.
          Customers seem to like the compact unit, and the fact that you only burn gas when using hot there is a rebate available.
          90% of the Rinnai units ive installed have been outdoor,often at the side of the house in a relatively narrow passage.The unit can also be installed in a recsessed box,flush with the outside skin of a masonry wall.
          My observations:

          water consumption is guaranteed to increase because the hot water doesnt run out.Just ask my teenagers.

          gas consumption is very similar to staorage type heaters.

          no electricity means no hot water.

          if water conservation is a priority like it has become here,and you have flow restrictors fitted to any outlet,be careful of the minimum flow rate required for the rinnai to work. too little flow equals no hot water.i've seen it many times.

          you might think this is obvious but double check which is the water and gas inlets when installing.ive seen this more than once,on homes built by project builders.

          Here, the increased gas demand can often be met by changing the utilities regulator at the gas meter to one with higher outlet pressure.

          on larege houses we have avoided "dead leg" or long delays for hot water by using multiple rinnais at the request of the owner/architect.each heater served a seperate area.

          In our climate they seem to work well when sized correctly.

          Soon i have to make the decision on what heater to put in my new house. I will miss my old gas lights and being power failure proof . The Rinnai is a contender. the full solar set up is really expensive and probably not a good idea since im building to sell.

          enough rambling fro me.


          • #6
            Originally posted by Australian Plumber Josh
            on larege houses we have avoided "dead leg" or long delays for hot water by using multiple rinnais at the request of the owner/architect.each heater served a seperate area.
            Doesn't this say it all.

            Now, you get "multiple" maintenance and repair troubles.


            • #7

              we think alike on the multiple installation.


              • #8
                water quality is a big issue on these. a water test needs to be done. if the owner does not have a water softner don't bother with a tankless. it will just lime up in a couple of years and be junk. the second issue is ph, if is to low it will eat the copper out of the tankless. and that is not a warranty issue. tankless water heaters are a copper fin of copper tube boiler. one way to get around the cirulation pump issue is to tie in a aqua stat and a timer in with the pump. on the run when you want hot water turn the timer on , this starts the circ pump, then when the aqua stat get hot it opens turning off the pump.


                • #9
                  Originally posted by wiarticfox
                  water quality is a big issue on these. a water test needs to be done. if the owner does not have a water softner don't bother with a tankless. it will just lime up in a couple of years and be junk. the second issue is ph, if is to low it will eat the copper out of the tankless. and that is not a warranty issue. tankless water heaters are a copper fin of copper tube boiler. one way to get around the cirulation pump issue is to tie in a aqua stat and a timer in with the pump. on the run when you want hot water turn the timer on , this starts the circ pump, then when the aqua stat get hot it opens turning off the pump.

                  Good grief. Think i'll stick to KISS...


                  • #10
                    Re: Rinnai Continuous Flow Water Heaters

                    As far as it taking water a while to get hot - have never had a problem - however it probably is a bit climate dependant. In Sydney it ain't a problem, but I imagine if you were in a place that went below zero you'd be in a bit of trouble.

                    sydney plumber electrician


                    • #11
                      Re: Rinnai Continuous Flow Water Heaters

                      All chime in 99 cents. This is a little long winded for a post but I think it has some pretty valuable information for those of you that want to go Tankless.

                      We just had all our guys certified with Noritz a couple of months back, because they have come out with some commercial units that meet some of our customers needs. I can’t speak about other brands but I can tell you what to look and what I have seen.

                      I would say the biggest mistakes I have seen with all brands of Tankless, is the inability of the person who sold it to the customer to understand plumbing mathematics. ie; flow rates, pressure drops, temperature rise, and fixture count calculations.

                      Case in point. I have a personal friendship with the owners of a very successful restaurant chain.

                      We have been handling there water treatment needs for years. These restaurants were converted houses that were built sometime around 1920. They have been added on too, re-pipped, you know the story. Anyways they have always had a problem with pressure drops at there dish machine at one of the restaurants every time someone flushes a toilet. The toilets were from the 1950-60's. You flush them and I swear it looked like 10 gallons of water was going down them.

                      Finally about two years ago they called me up and asked if I could look into this. We analyzed a years worth of water bills, there customer count and figured that within one year of replacing the toilets and changing the plumbing under the building they would pay for the investment. They agreed and we did the work.

                      About two weeks after the work was done one of the managers called me up and said that they were getting very low water flow all over the restaurant and no hot water.

                      I went and checked the work that we had done. New pressure regulator was working fine. Crawled under the building to make sure we had no leaks. Everything was fine. I go back to the water softener to see if maybe we had a fouling problem with the resin and were getting low flow through it. Open up the door to the heater/softener room and low and behold there are two brand new Noritz water heaters installed on the wall that were not there two weeks ago when we did the work.
                      I find out from the manager that they had them installed a couple of days ago. I ask him, so when did the problems with no heat and low flow start. His answer, "A couple of days ago".

                      To cut to the chase this is what was happening.

                      All tankless heaters have a flow control valve built into them. There motorized. The valve opens and closes by measuring the incoming water temperature, the temperature rise needed to meet the thermostat setting, and flow required. They open from partial to fully open depending on the demand. What was happening in this restaurant was every time the dish machine does a final rinse it has a hot water 3/4" valve that opens. This particular commercial dish machine needs about 15 gpm flow for about 15-20 seconds. It needs 140 degrees of constant hot water.
                      The end result was the tankless heaters were going on, but were restricting the flow of water because the demand was so high they could not meet the temp. rise needed to make it to 140dg.

                      In other words the dish machine was demanding more water then the tankless is providing so there was literally no water at any hot water faucet in the restaurant any time the dish machine
                      called for water.

                      As a courtesy to the owners of the restaurant I contacted the company that installed the units and asked if they could meet me at the restaurant. They agreed to send there service manager.

                      Ok, so if you read my "tips to the new guys" post, one of my sayings I live by is, "Perception is Everything"

                      The service manager shows up in a nice new truck, company logo the works. Very professional looking. He gets out of the truck with one of his guys and my perception of a professional company went out the door.

                      Both of them had on Dickies work shorts. No big deal, except they were wearing them half way across there A$$ so the bottom of the shorts were between there ankle and there knee. Tats all over there legs and arms. Shirts that were dirty, and smoking.

                      After five minutes of trying to explain flow rates, temperature rise calculations etc... these two idiots could not get it. As far as they were concerned the system was working fine, so they packed up and left. It’s a good thing because it was getting so confrontational that if they had stayed any longer it would have gotten ugly. The manager, who I also know personally was stunned.

                      I then called the owner of the company and told him that I wanted to see him out at the job, and what had happened with his boys. I also followed it up with a call to Noritz to get a Field Manager out there too.

                      That meeting took place the next day. This time the owners of the restaurant were there. The Noritz guy showed up first. I pulled him aside and told him what was going on, and that if he wanted to keep face with the owners someone needed to step up to the plate and resolve this problem at no costs. The solution was to install another Noritz unit.

                      The owner of the water heater firm showed up next. Pulls up in his $130,000 Porsche. Get’s out and is wearing his $10,000 Rolex, diamond pinkie ring, levis, $200.00 loafers, Izod golf shirt, and one of those western looking half jackets. It took everything I had inside of me to hold back from busting a nut laughing.

                      I pulled this guy aside and told him the same story. Figured since he was the owner, and license was issued in his name, (I pre-checked the company out with the Contractors Board) that he would have an understanding of plumbing mathematics. This guy was as clueless as his service people, but he finally came to the conclusion that I probably knew what I was talking about. So heeding my advice not to, he tries to up sell the owners a third Noritz unit. Dumb, Dumb, Dumb. What all these guys failed to realize was that I was friends with the owner. I had seen his bill, $8000.00. The units cost him around $900 apiece. The stainless venting, which there was basically nothing, probably cost him $800.00. He could have easily installed another unit, eaten the costs and made face. Plus sold them more units at the other restaurant. Nope not this guys ego got the better of him.

                      In the end they got thrown out, and a new commercial water heater was installed, at there expense.

                      The lesson to be learned here is you absolutely have to know plumbing mathematics and the technical specs of the tankless you want to represent.

                      Noritz, just opened up a new North America Facility in Fountain Valley, CA. If your in California I would highly recommend you stop in and see this place. There show room is second too none. They have comparisons of every competitors heat exchangers. They have working showers . Examples of at least a half dozen types of installations. They have a training facility.

                      One thing I like about the Noritz is they are on top of technology. There control panel has built in diagnostics which help you pinpoint repairs issues. I have not seen another brand out there that has diagnostics that go as deep as Noritz.

                      They have addressed commercial application needs and now have two units that can be applied to smaller commercial applications and meet code.

                      Like wiarticfox said know your water quality. If they have anything over four grains of water hardness, you might consider a water softener. If you don’t understand water treatment or don’t want to get involved with it, the Noritz units have the ability to be flushed out with a de-liming solution.

                      During our training I got to talking with some of there corporate people. It’s not every day a Commercial/Industrial plumbing firm goes through there training, so it’s a welcome conversation when they can talk technical and plumbing dynamics with one of there customers.

                      They did agree that water quality was an important factor. What makes it really sad is that the plumbers that install these units don’t understand that they can set up there customers on an annual or bi-annual flush service call. (PS. for Noritz, there manual requires that there units be flushed at least bi-annually) All you do is put the inlet and outlet on the unit into bypass. There is a hose connection at each valve. You take a bucket with a small submersible pump and connect it too the inlet, the outlet flows back into the bucket. Put in your cleaning solution and turn it on and walk away for twenty minutes to an hour.

                      The other issue with heat exchanger failure is improper installation. Venting done wrong, no condensate drain installed on the first 18" of the vent out of the unit. Condensate builds up and drips back on top of the heat exchanger, which cause it to solidify with calcium, turbidity, etc... Improper slope on the vent. Horizontal runs that are to long. I say an installation about three weeks ago that had all of these incorporated into it.

                      There are few other talking points, but I don’t want to drag this post out any longer.

                      There are a lot of savings with regards to tankless heater, and I can assure you that within the next ten years you will see legislation, probably start out here on the west coast that will require tankless installations in all residential homes.

                      If you want to go this route, absolutely understand plumbing dynamics. Especially flow rates, fixture counts and water column on gas sizing.


                      • #12
                        Re: Rinnai Continuous Flow Water Heaters

                        80% of tankless are installed wrong and are gettting a bad reputaion.

                        I agree, they are a perfect for new construction, and every new home needs to have one.

                        I admit that retrofits, when done correctly, can be expensive, but the unit can last 25 plus years if maintained properly.

                        Space savings is a huge plus, especially in commercial situations, where every square foot costs big $$$$$$$

                        You save every month you have one installed, go to their web site and check it out for yourself, make you own decisions, I can tell you one thing, I am installing one in my house in the near future

                        Rinnai has partnered with a recirculation manufacturer, Metland, they will provide sizing and answer other questions about recir and tankless units


                        Tanless is the future, better get on board. Most importantly, learn how to install them correctly.



                        • #13
                          Re: Rinnai Continuous Flow Water Heaters

                          Well I just can't resist, so I'll get my 2 cents in also.

                          I don't like the idea of condemming a product across the board. Truth is, if the delta t is within the manufactures specs, and the water conditions are tolerable, these units all perform pretty well. Will they save a fortune. Probably not. In fact it may be quite a few years for any savings past the installed cost to come into play. That said the plumbing code is the big hurdle here. Properly done, you need to add up the hot water sfu's to get the demand and then size accordingly. You can not always get away with installing the smallest, least expensive unit.


                          • #14
                            Re: Rinnai Continuous Flow Water Heaters

                            your right nhmaster a tankless heater can work and will deliver, they work well in columbia, the critical element is not only knowing your product inside and out but anticipating and carefully being able to guide the prospective buyer through the selection restaurant usage down here they in most cases are not permitted as a comm dishwasher is usually sized by the final rinse phase, gpm, temp and delivery, but for residential work if they are sized properly and the pros and cons are openly discussed and the unit is installed properly they can be a great asset[ and gas line sizing is the biggest problem i see a lot of installers think they can pull out a 40 gall heater and slap in a tankless in its place and have no clue how to properly size a gas system or even if the current meter is large enough to handle the additional load so they starve the system] i have personally installed a rinnai at my house been in service 4 years and love it


                            • #15
                              Re: Rinnai Continuous Flow Water Heaters

                              I Have The Rinnai in my house. But I got it at cost so it was a good deal for me. I have noticed savings in my natural gas usage but for customers I tell them to offset the cost differrence they will have to live in the house for some time. If a person is transient and is not planning on staying in the house for a while they will not recoup the money they spent on the Rinnia.