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  • tankless question and shower valves.

    i guess my p.m box is full so now i'm getting visitor messages.

    i have no problem responding to your question, but the forum is for all to learn from and give advise to. so i'm posting the queston for all to see, learn from and give their pro opinion on.

    guys, have at it.

    Hi Rick,

    A little advice / knowledge would be appreciated. As a former General Contractor, i have ordered a Rinnai 94LSI hot water heater - Northeast PA 1.5 baths in house.

    I am asking this in advance of installing the Water heater, as people are having problems with hot water at shower. Aside from some of those people having an undersized unit, some problems may be related to the Pressure Balance control of the single handle tub / shower unit.

    My concern is that the tub / shower faucet may be the wrong type for the tankless unit. Could you give me a little advice on what types of faucet setup would be best for my bath - ie. pressure balance, thermostatically controlled or any particular brand / model? Any other advice regarding the general concern would be helpful.

    Craig

    craig, the big issue is the temperature differential from incoming to outgoing. aka the delta. depending on your winter ground water temperatures and demand, a tankless might not be a wise choice for the cold country.

    i would think a thermostatic valve would perform better than a pressure balance valve for your application. but remember that they cost more and are more temperamental.

    rick.
    phoebe it is

  • #2
    Re: tankless question and shower valves.

    The 9.4 unit will work but you may only get to use one or two fixtures at a time depending on how cold the incoming water is. The tankless will work with ANY shower valve,that doesn't matter. Make sure the gas line is sized to handle the unit firing under full load. Calculate your delta-t.

    Whats the coldest the incoming water gets? How far are the fixtures away from the unit once its installed?

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    • #3
      Re: tankless question and shower valves.

      Here is a footnote question about the Rennai and tankless water heaters in general.

      I assume the thing heats the water with gas and that electricity has to be on hand to trigger things and turn on and regulate the flame.

      OK, what happens if on some cold or stormy evening (no lightening, just wind and rain - or snow) the power goes off for several hours, even a whole day or so, and you or the wife or the kids are in desperate need of a shower? Will the Rennai still turn on or do you all take a cold shower?

      Note that a conventional, tank-type water heater will still have fifty or so gallons or hot water on hand to let everybody take an admittedly speedy, but still warm, shower.

      Howard Ferstler

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      • #4
        Re: tankless question and shower valves.

        there are very very few tankless that run on no electricity. but it's worse than that. the tankless can easily be affected by power surges.

        a gas tank type heater typically uses no outside power. therefore even in the dark, you have hot water.

        also with power outages, you will loose your freeze protection.

        rick.
        phoebe it is

        Comment


        • #5
          Re: tankless question and shower valves.

          Originally posted by PLUMBER RICK View Post
          there are very very few tankless that run on no electricity. but it's worse than that. the tankless can easily be affected by power surges.

          a gas tank type heater typically uses no outside power. therefore even in the dark, you have hot water.

          also with power outages, you will loose your freeze protection.

          rick.
          Yep , tankless is all the rage in my area.. Personally I have a 50 gallon gas for the above mentioned reasons. We tend to loose power ALOT in my area so everything I have that can be gas is gas. Although I am hearing that there are battery back ups for the tankless units, I am quite sure that is only good for a few hours .Then you're dead in the water.I have a back up generator for the house also, again mandatory...
          ''Beer is proof that God loves us and wants us to be happy" Benjamin Franklin

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          • #6
            Re: tankless question and shower valves.

            From what I have read, water is very resistant to temperature change, which is one reason it puts out fires so well. It cools the burning medium and defeats combustion. (The ability to smother the flames is obviously another.)

            Anyway, water stored in a well-insulated, modern water-heater tank is going to be resistant to temperature change, and once it is heated up it will tend to stay hot for a long time, even if no additional heating energy is applied. It obviously would take the same amount of energy to heat the water in a tank as it would to heat the same amount of water in a tankless situation, assuming the same energy source, such as natural gas. The only difference is that the tank-heated water would be stored instead of used immediately.

            Consequently, if water is being used on a regular basis in the home, where the stored water is not allowed to cool off much during non use, I can see no energy-related reason why a tankless water heater would be any more efficient than a tank type. More fashionable, maybe, but more economical, probably not.

            Howard Ferstler
            Last edited by Howard Ferstler; 07-31-2011, 05:48 PM.

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            • #7
              Re: tankless question and shower valves.

              Originally posted by Howard Ferstler View Post
              From what I have read, water is very resistant to temperature change, which is one reason it puts out fires so well. It cools the burning medium and defeats combustion. (The ability to smother the flames is obviously another.)

              Anyway, water stored in a well-insulated, modern water-heater tank is going to be resistant to temperature change, and once it is heated up it will tend to stay hot for a long time, even if no additional heating energy is applied. It obviously would take the same amount of energy to heat the water in a tank as it would to heat the same amount of water in a tankless situation, assuming the same energy source, such as natural gas. The only difference is that the tank-heated water would be stored instead of used immediately.

              Consequently, if water is being used on a regular basis in the home, where the stored water is not allowed to cool off much during non use, I can see no energy-related reason why a tankless water heater would be any more efficient than a tank type. More fashionable, maybe, but more economical, probably not.

              Howard Ferstler
              Your correct and thats why I like an electric water heater. It has no standing pilot and no center flue to lose heat through,keeping the water hotter for longer without using anymore energy before I have a chance to use it all. Virtually no standby loss.

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              • #8
                Re: tankless question and shower valves.

                An electric tank storage water heater is 100% efficient, it's only loss is through the jacket and with new ones that loss is minimal.
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