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Thread: Switch to Tankless

  1. #1
    DIY Junior Member chubyball's Avatar
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    Default Switch to Tankless

    Should I switch to tankless? My home was built in 1969 Northern Calif. My Natural Hot water tank is about to give up.

    What brand and size should I buy? Home Depot or Lowes? My current size water heater is 40 gallons, gas heater.

    The problem we always have when we are taking shower, we keep loosing hot water if someone turn water on in Kitchen at the same time.

    Could this problem cause from Gas Line BTU provide from Gas company? Expansion tank need? Larger hot water line?

  2. #2
    Master Plumber Dunbar Plumbing's Avatar
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    Buy the $5000 Rinnai tankless. Done.
    Read what the end of this sentence means.

  3. #3
    Master Plumber master plumber mark's Avatar
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    Talking 1969 water heater??

    You just need a new water heater.

    if yours is a 1969, I suggest you put in a 50 gallon gas heater for about 900... It will probably last you another 10- 20 years or so...

    Or Like Rugged stated,

    if you want to spend about 4- 5k, and get yourself up
    to speed with the Green Revolution...your neighbors will be sooooo jealous.....

    go for it... ...

  4. #4

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    I can get a complete Rinnai set up for $1000. Includes vent piping, isolation kit and water heater. Material for hook up is about another $300. If I charged $5000 I could make some serious coin.Name:  claptard.gif
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  5. #5
    Master Plumber master plumber mark's Avatar
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    Talking Serious coin.....

    Quote Originally Posted by Bob the Builder View Post
    I can get a complete Rinnai set up for $1000. Includes vent piping, isolation kit and water heater. Material for hook up is about another $300. If I charged $5000 I could make some serious coin.Name:  claptard.gif
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    yes , you could make some serious money,

    and their are many chargeing from 3000 to 6000 in
    our town for one...

    the big drawbacks are
    when or if the customers becomes disapointed with the system,
    and they want you to either make it work like their old tank type did,,


    or you have to go out and trouble shoot the
    thing in 6 months from now,

    or they simply want their money back...


    I would just rather steer clear of them and keep
    my name in good standing with the BBB

  6. #6
    In the trades Dana's Avatar
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    If you have hydronic (forced-hot-water) heating, the greenest-cleanest thing you can do is install an indirect-fired hot water tank to run off the boiler (for a lot less money than a brand new tankless-install, but still way more than a cheapo gas or electric 40-50gallon tank.) The net efficiency will be similar to that of a tankless, and it'll raise the overall efficiency of your heating system as well. And an indirect-fired tank will last pretty much forever- 3-4x as long as a standalone tank, 2x as long as a pretty-good tankless.

    A tankless will be significantly more efficient than a tank for families that use less than 80 gallons/day. (The less you normally use, the bigger the efficiency- standby losses on gas-fired tank heaters are atrocious, but as the volume increases standby losses are a lower percentage of the total. Tankless heaters have very low standby losses (zero, for all intents & purposes), but have "short cycle" losses whenever it has to fire up to deliver a quart or three for handwashing, etc. Their as-used efficiency is typically lower than their EF test in a lavatory-only environment, but beat those efficiencies in showers & laundries. Indirect-fired tanks running off the heating system boiler don't have flue losses and have better insulation coverage since they don't need clearances around a burner, etc.) Their operating efficiency is determined by the efficiency of the boiler, with some cycling losses. (An ~80% cast-iron boiler will deliver EF efficiencies in the 0.70-0.75 range during the summer, higher during the heating season.)

    If you're looking for a net payback, it'll be hard to rationalize a new tankless install for many folks on a net-present-value basis, but many states & utilities are offering subsidies.

    They DO take bigger gas lines than tank heaters, and venting/backdrafting issues have to be attended to. If you're trying to run multiple loads (taking a shower while doing the laundry, etc.) you'll need one with a pretty hefty burner unless you live in a warm-groundwater area. (199kbtu/h is big enough for most families. Under 150kbtu/h it depends a lot on the actual draw and the actual incoming water temp.)

  7. #7
    Master Plumber master plumber mark's Avatar
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    Talking let the green dream continue......

    [quote=Dana;

    If you're looking for a net payback, it'll be hard to rationalize a new tankless install for many folks on a net-present-value basis, but many states & utilities are offering subsidies.

    They DO take bigger gas lines than tank heaters, and venting/backdrafting issues have to be attended to. If you're trying to run multiple loads (taking a shower while doing the laundry, etc.) you'll need one with a pretty hefty burner unless you live in a warm-groundwater area. (199kbtu/h is big enough for most families. Under 150kbtu/h it depends a lot on the actual draw and the actual incoming water temp.)[/quote]

    I told a 69 year old customer today that he will probably have to live till he is at least 99 years old before hw would get a pay back off a tankless unit.

    if he lives till he is 99 and stays in the same house,
    he will acheive a net gain on his investment,

    (of course the unit cannot break down for the next
    30 years)

    so he will be carried out of his home with a smile on his face.....at 100

  8. #8
    DIY Member ChuckS's Avatar
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    Quote Originally Posted by Dana View Post
    Tankless heaters have very low standby losses (zero, for all intents & purposes), but have "short cycle" losses whenever it has to fire up to deliver a quart or three for handwashing, etc.
    One big drawback here, we had to get used to washing our hands with cold water.

  9. #9
    Master Plumber nhmaster's Avatar
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    If you loose hot water when someone turns the kitchen faucet on, you have a piping problem (undersized) Changing the water heater will have zero effect.

  10. #10
    In the trades Dana's Avatar
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    Quote Originally Posted by master plumber mark View Post
    I told a 69 year old customer today that he will probably have to live till he is at least 99 years old before hw would get a pay back off a tankless unit.

    if he lives till he is 99 and stays in the same house,
    he will acheive a net gain on his investment,

    (of course the unit cannot break down for the next
    30 years)

    so he will be carried out of his home with a smile on his face.....at 100
    Let's hope he makes it long enough to experience that thrill, eh? :-)

    You have to be some sort of prophet to be able to calculate what the price of energy will be even 3 years out, let alone 30. But I wouldn't count on 30 years of energy price deflation, or even staying dead-even.

    Standby losses on fossil-fired tanks are large, but distribution losses in most houses are also large. Standby losses on electric tanks are quite low. If this guy is living alone, taking 1 shower/week (whether he needs to or not), he'd be better off with a high efficiency electric tank but installed in a location to minimize distribution loss, (possibly with a point-of use mini-tank or two, if the kitchen sink has to call water from 70 feet away.) Once your standby brings your as-used EF under 0.3 electric tanks start looking pretty good.

    IMHO tankless units are best used in high nearly continuous demand situations (commercial laundries, teenage showers, fillin' the Jacuzzi, etc) or sometimes in extremely intermittent remote use (eg. weekend cabins). They make better hydronic boilers for low/moderate heating loads with high DHW peak loads than strictly as domestic hot water heaters (especially when coupled with buffer tanks &/or indirect-fired HW tanks.) But even without buffering they're demonstrably more efficient than tank HW heaters in combi space-heating/DHW applications- enough so that payback still happens in well under a decade at current energy pricing (even natural gas pricing).

    For low/moderate DHW users, payback is indeed quite long on fuel-savings, but may be "worth it" in convenience factor for many. They're space-efficient, combustion-efficient, and allow 5 back-to-back showers- there ARE low-net-use situations that really take advantage of tankless high-peak & continuous outputs. I've yet to encounter anyone who regretted making the switch, even if it was expensive and irrational from a simple NPV analysis. Whether it actually pays back financially in a reasonable time frame (or ever) depends on a lot of factors difficult to predict or control. Propane prices last year made the payback period on fuel savings alone seem pretty short. This year, not so much.

    But I woudn't bet huge money on the 69 year old guy needing to wait 30 years for payback, even if he only uses 20 gallons/day. In a 30 year time frame he'd need ~2 more tanks, independent of actual use volume, and at those low usage rates the tankless probably WOULD last that long. And at those volumes his tank would be getting a paltry ~40% net efficiency compared to nearly twice that for the tankless. Where the actual crossover occurs just depends...

  11. #11

    Default Really?

    www.tankless concepts.com He does them for less than $3K all day long, retrofits in DC! It's should not be more expensive out there for someone who knows what they are doing and is not a crook. Now I know some jobs are different and take more work but give me a break.

    Add 20+ years and no loss in effeciency like the tank, space savings, unlimited hot water and I say why would you ever install a tank in a house unless you are trying to flip it in a real estate deal?

    Go with a Professional grade, stay clear of any DIY brands and hire a trained installer for a good price. You'll be happy.

  12. #12

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    Being a plumber I have looked into the pros and cons of these devices and found a lot of cons. First of all is the price , the average tankless hwh is about $1,500 on up. A typical installation or up grade from a tank style hwh, with new gas main to electrical to venting could run ya about another $1,500 to $2,000 . Now all this plus the fact that a single tankless hwh might not give you the volume necessary to supply your home is a VERY large con. I live in the North East and our average winter water temp drops down to around 55 to 60 degrees. For a tankless to heat the water it has to restrict the flow rate to heat the water to the set temp, giving you less hot water. Yes, you will have endless hot water at 1 shower but you better not run the washing machine or the dishwasher, you could see a serious drop in pressure.

    A typical tankless will run at a max of 8 gallons per minute. Some high end shower valves with body spray systems can deliver 12 gallons per min, a single tankless just can't keep up. When designing a home plumbing system you have to account for max usage, just about all fixtures running simultaneously. Some of the homes that I have plumbed have 5 full baths, kitchen with 2 sinks, laundry room with slop sink, etc,etc,etc...

    Now don't get me wrong these things have their place. If you live in a small home with 1 bathroom or a condo, these things are perfect. But if you live in the northern half of the continent in the average new home of 2,500 sq feet or more with 3 or more baths then I would think they aren't for you. Unless you have about 10 grand to lay out for an elaborate system of these things then more power to ya. The average 3,000 sq ft home in my area would cost about $5,000 to upgrade from a typical 75 gallon tank style to 2 tankless hwh's.

    Now a tankless warranty is 20 years(prorated) opposed to 10 for a tank style. 75 gallon tank style $2,000. One time upgrade to 2 tankless hwh's $5,000. Say in 20 years you need to replace the tankless ones at a price of $3,000, you have spent $8,000. In 20 years with a tank style you will have spent $6,000 and did I forget to say that for $2,000 you get a power vent hwh which requires no pilot. Yes, you will save some money on fuel but the cons definitely outweigh the pros.

    Check out this link and compare for yourself, scroll down to the chart around the middle of the page.
    http://www.aceee.org/consumerguide/waterheating.htm

  13. #13
    Plunger/TurdPuncher kingsotall's Avatar
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    Awesome first post Thundr. Welcome to Terry's forum!
    I just post cuz I like to see my avatar.

  14. #14
    Illinois Licensed Plumber SewerRatz's Avatar
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    Quote Originally Posted by Thundr View Post
    Being a plumber I have looked into the pros and cons of these devices and found a lot of cons. First of all is the price , the average tankless hwh is about $1,500 on up. A typical installation or up grade from a tank style hwh, with new gas main to electrical to venting could run ya about another $1,500 to $2,000 . Now all this plus the fact that a single tankless hwh might not give you the volume necessary to supply your home is a VERY large con. I live in the North East and our average winter water temp drops down to around 55 to 60 degrees. For a tankless to heat the water it has to restrict the flow rate to heat the water to the set temp, giving you less hot water. Yes, you will have endless hot water at 1 shower but you better not run the washing machine or the dishwasher, you could see a serious drop in pressure.

    A typical tankless will run at a max of 8 gallons per minute. Some high end shower valves with body spray systems can deliver 12 gallons per min, a single tankless just can't keep up. When designing a home plumbing system you have to account for max usage, just about all fixtures running simultaneously. Some of the homes that I have plumbed have 5 full baths, kitchen with 2 sinks, laundry room with slop sink, etc,etc,etc...

    Now don't get me wrong these things have their place. If you live in a small home with 1 bathroom or a condo, these things are perfect. But if you live in the northern half of the continent in the average new home of 2,500 sq feet or more with 3 or more baths then I would think they aren't for you. Unless you have about 10 grand to lay out for an elaborate system of these things then more power to ya. The average 3,000 sq ft home in my area would cost about $5,000 to upgrade from a typical 75 gallon tank style to 2 tankless hwh's.

    Now a tankless warranty is 20 years(prorated) opposed to 10 for a tank style. 75 gallon tank style $2,000. One time upgrade to 2 tankless hwh's $5,000. Say in 20 years you need to replace the tankless ones at a price of $3,000, you have spent $8,000. In 20 years with a tank style you will have spent $6,000 and did I forget to say that for $2,000 you get a power vent hwh which requires no pilot. Yes, you will save some money on fuel but the cons definitely outweigh the pros.

    Check out this link and compare for yourself, scroll down to the chart around the middle of the page.
    http://www.aceee.org/consumerguide/waterheating.htm
    Hi there Thundr. I agree the install cost of going from a tank to a tankless system is very expensive. Also I agree it is not for everyone at this time.

    I am in the Chicago area, where our year round water temp is around 50 so to get the 120 water temperature we need to have a 70 rise. Noritz makes units that can provide 4.5 GPM to 6 GPM So most 2 bath houses can be plumed in with a single tankless unit. Now if they do have the super drown me showers yes you have to do multiple units, or design a system that can handle that kind of demand. As for homes with 3 or more bathrooms a two unit system would do the job nicely.

    OK now lets address, tank / tankless failures. When a tank leaks you have to replace the whole tank. When a tankless leaks, you replace the leaking part not the whole heater. A new heat exchanger is a lot cheaper than a whole new unit any day.

    I would recommend you take a level 3 class from Noritz, they will show you how easy it is to take a unit completely apart, along with how to properly trouble shoot a unit.

  15. #15
    In the trades Dana's Avatar
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    Quote Originally Posted by Thundr View Post
    Check out this link and compare for yourself, scroll down to the chart around the middle of the page.
    http://www.aceee.org/consumerguide/waterheating.htm
    The life cyle cost chart is grotesquely inaccurate, since there's no way it can account for regional differences in fuel costs & incoming water temps in different regions or differences in daily water volume use (which has a HUGE impact on the as-used EF of fossil fuel fired tanks, which suffer mightily from standby losses making low-volume use more expensive than less-lossy electric tanks in many situations). It could easily be off by as much as 300% on the actual costs.

    And they don't include a boiler driven indirect-fired option, which is THE cost/performance/efficiency right choice whenever the heating system runs off a hydronic boiler.

    The 13 year time frame for the analysis seems designed to obfuscate the cost of buying & installing a second tank heater while the tankless (or indirect they neglected to include) are barely into half-time on life-cycle.

    To know the true lifecycle costs of ownership you really need to measure stuff (like hot water volume and fuel metered at the HW heater)- tables like that aren't worth the photons comin' out of the screen, even if your eyes are good enough to read the fine print:

    1. Purchase costs include our best estimates of installation labor and do not include financial incentives.
    2. Operating cost based on hot water needs for typical family of four and energy costs of 9.5/kWh for electricity, $1.40/therm for gas, $2.40/gallon for oil.
    3. Future operating costs are neither discounted nor adjusted for inflation.
    4. Currently, there is too little data to accurately estimate life expectancy for tankless water heaters, but priliminary data shows that tankless water heaters could last up to 20 years. For all water heaters, life expectancy will depend on local variables suck as water chemistry and homeowner maintenance.


    Your actual costs can and almost certainly WILL vary (by quite a bit!)

    These people actually measure stuff:

    http://www.aceee.org/conf/08whforum/...s/1a_davis.pdf

    Note that in low volume use gas fired tank efficiencies fall off a cliff (even the electronic ignition forced draft tanks don't hit 50% efficiency for 28gallon/day users). For low volume or intermittent users a tankless would NEVER wear out. But tanks last about as long with low volume users as with high-volume users.

    And for high volume users, the payback in fuel savings plus the 2x lifetime would make even the high initial installation cost worthwhile. The high installation cost of a tankless is typically a 1- time deal, since it's the electric power, special venting, and gas line upgrades that account for the extra money. Cost for the units themselves isn't outlandish (except possibly for the condensing versions.) Replacement costs on a tankless isn't outrageous.

    No over-simplified financial analysis (not even yours ;-) ) has any chance of getting it right, but there are sometimes ways to know when a choice is absolutely wrong. But I've yet to run into anybody who went with a tankless who wanted to go back to a tank, even with the flow limitations & cold water-sandwich issues of a tankless (and 100% of my data points are in cold-winter-water New England.)

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