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Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

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  • #16
    Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

    In my case, my broken 50-gal tank water heater was put in when the house was built 20 years ago. If I have a new 50-gal heater installed at the same location, I would need to add an expansion tank and replace my current 3"-diameter 9-ft long flue (including 4 elbows) with a 4"-diameter flue in order to meet the current code requirement. Apparently some valves also need to be replaced with a new kind. This brings the cost of a replacement tank heater with a 6-yr warrenty to over $1150 - more if I want a better heater.

    So it sort of makes sense for me to consider the change to a tankless because of the 30% tax credit. Of course, even with all of that, it may still take me at least 10 years to recoup the difference : (

    I would stay with a 50-gal tank heater if that is the only thing I have to replace.

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    • #17
      Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

      not sure about the 4'' vent requirement since a 40,000 btu heater is still 3'' out here.

      the expansion tank is probably required due to a check valve or back flow devise on your water service.

      i wouldn't count on the payback due to required maintenance every year.

      i'm saving a whopping $5.00 a month with a tankless. most likely due to the fact there is no pilot lite on the tankless.

      the $60. a year savings doesn't cover a cleaning by a pro.

      you might want to read the dozens of tankless debates we have on the forum before you act

      i put mine in just to prove a point i already knew

      rick.

      don't forget you also need to replace the venting for your tankless too.
      phoebe it is

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      • #18
        Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

        I just had my Rinnai put in using a 2PSI split system. Just in case if this information can be useful for anyone: the technician who put it in adjusted the 2PSI line's regulator to 8.5 in w.c. for the Rinnai to use. Since the normal pressure line only provides 5 to 7 in w.c. according to the Washington Gas lady, I suppose the split system can be considered necessary for the Rinnai.

        Now, I am not sure if the tankless is a better choice for me than a tank one or not, but that is what I am stuck with for, hopefully, at least 20 years. I was told that since the city water I have is probably very good, I may not have to have the system flushed as often. I do like the space the tankless opens up. The down side I have noticed so far is the increase of the wait time at faucets. Even though I have the Rinnai put in at the same location as the old water heater, the hot water pipe still has to circle arount inside the Rinnai, go down about 1 foot, go back up about 3 feet before reaching the original hot water line. So each time I turn on the hot water, I have to wait a bit longer and waste a bit more water compared to before. I didn't think the difference could be so noticable. However, the cold water sandwich is not really noticable to me at least for now (summer time).

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        • #19
          Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

          onlearningcurve, I am glad to see you decided to go with a 2 pound gas system. Most of the calls I get for Rinnai service are for bad installations and gas pressure issues. You can have a tankless water heater on an ounce system with just enough gas pressure for your unit to function but not to full capacity. I am also glad to see you went to Rinnai's web site to find an authorized dealer/installer. When you do need service return to Rinnai's website to find an Authorized Service Provider.

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          • #20
            Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

            Thanks for the update. Do you notice any difference on the gas bill?

            I also now have a tankless WH and really dislike mine. Takes forever to get hot water. Here's my morning ritiual: wake up, walk into the bathroom, turn on the hot water, use the bathroom, brush teeth, THEN, I might have hot water for shaving.

            Never had such a problem before with a tank WH.
            Buy cheap, buy twice.

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            • #21
              Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

              It sounds like he just had it installed, so it will take a month or two for him to figure out any gas savings.

              What brand of tankless do you have?

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              • #22
                Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

                I have a takagi. It came with rental house.
                Buy cheap, buy twice.

                Comment


                • #23
                  Re: Gas line/pressure question for Rinnai tankless water heater installation (R75Lsi)

                  Right, I don't know about gas saving yet. It will take me a while to find out.

                  I did figure out how to get a trickle of hot water without wasting hot water: like what gear junkie does: turn on hot water faucet, wait for hot water to get there, lower hot water flow so the Rinnai turns off, then I can have my trickle of hot water for a while without keeping the Rinnai on.

                  I just realized another downside of having the Rinnai:
                  The exhaust/air-intake pipe goes straight outside. Doesn't it bring freezing cold air into the pipe and cools the house (via the cold pipe) in the winter time? I think I have to insulate at least the first few feet of pipe before winter! I am in Maryland so the winter can be cold.
                  Last edited by onlearningcurve; 07-08-2009, 10:36 PM.

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