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  1. #1
    Join Date
    Aug 2012
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    43

    Tankless or Indirect Fired Water Heater?

    I buying a new oil boiler and trying to determine whether an indirect fired water heater really saves on fuel and how much.

    Currently I have a very old tankless unit. We have a family of four and we have been satisifed with the amount of hot water we get out of it. So, the only reason to get an indirect fired water heater would be to save on oil.

    On the one hand, it would seem to me (a rank amateur) that a tankless unit might burn less fuel. In the winter, obviously, the boiler is hot anyway. In the summer, the boiler will have to stay hot, but the indirect fired tank would need to stay hot too.

    On the other hand, I spoke to Weil Mclain's customer service and they assure me that the indirect will use less oil, but they cannot give me any data to show that, nor can they give me any idea how much less oil it will use.

    Can anyone give me a definitive answer why the indirect uses less oil and how much less oil it will use?

  2. #2
    Join Date
    Aug 2012
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    11
    Quote Originally Posted by newlyn View Post
    On the other hand, I spoke to Weil Mclain's customer service and they assure me that the indirect will use less oil, but they cannot give me any data to show that, nor can they give me any idea how much less oil it will use.
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 08-08-2012 at 04:06 PM. Reason: Non AOP member

  3. #3
    Join Date
    Dec 2007
    Posts
    4,685
    just to be clear;

    tankless is a unit that usually hangs on a wall, has its own fire to heat the water and only fires on demand?

    indirect is a stand alone storage tank, looks like a standard water heater, and is heater by an existing boiler. Some variations to this description are likely.

    what fuel is the existing tankless unit, I did not realize they had oil fired tankless units?
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  4. #4
    Join Date
    May 2012
    Location
    San Diego, CA
    Posts
    352
    Quote Originally Posted by newlyn View Post
    I buying a new oil boiler and trying to determine whether an indirect fired water heater really saves on fuel and how much.

    Currently I have a very old tankless unit. We have a family of four and we have been satisifed with the amount of hot water we get out of it. So, the only reason to get an indirect fired water heater would be to save on oil.

    On the one hand, it would seem to me (a rank amateur) that a tankless unit might burn less fuel. In the winter, obviously, the boiler is hot anyway. In the summer, the boiler will have to stay hot, but the indirect fired tank would need to stay hot too.

    On the other hand, I spoke to Weil Mclain's customer service and they assure me that the indirect will use less oil, but they cannot give me any data to show that, nor can they give me any idea how much less oil it will use.

    Can anyone give me a definitive answer why the indirect uses less oil and how much less oil it will use?
    Like what you said, the system really gets its savings when you are heating your house, during summer months the furnace basically acts as a conventional tank water heater; so it isn't necessarily wasting any fuel but you won't be seeing any savings in the summer except the fact that the boiler is usually a higher efficiency and that is better than the standard tank water heater.

    Unfortunately, I don't have any cold hard data of it compared to tankless, I guess some people just have to be the guinea pigs.
    You can call me Sam

    It should be a crime to be a mechanical engineer in San Diego
    Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7)

  5. #5
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,578
    Quote Originally Posted by newlyn View Post
    I buying a new oil boiler and trying to determine whether an indirect fired water heater really saves on fuel and how much.

    Currently I have a very old tankless unit. We have a family of four and we have been satisifed with the amount of hot water we get out of it. So, the only reason to get an indirect fired water heater would be to save on oil.

    On the one hand, it would seem to me (a rank amateur) that a tankless unit might burn less fuel. In the winter, obviously, the boiler is hot anyway. In the summer, the boiler will have to stay hot, but the indirect fired tank would need to stay hot too.

    On the other hand, I spoke to Weil Mclain's customer service and they assure me that the indirect will use less oil, but they cannot give me any data to show that, nor can they give me any idea how much less oil it will use.

    Can anyone give me a definitive answer why the indirect uses less oil and how much less oil it will use?
    My indirect saved me about 200 gallons a year.

    An indirect tank usally allows you to install a smaller boiler since you do not have to raise the water from 40 to 110 degrees immediately. I have a 2000 Sf colonial and make heat and hot water with a 77K input boiler and 40 gallon indirect.

    Be sure you have a contractor that will perform and understands heat loss. Do not include the indirect for boiler sizing unless you have 3 or more bathrooms.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  6. #6
    Join Date
    Sep 2010
    Location
    Lake Ronkonkoma, New York
    Posts
    530
    Indirect is the way to go. You do not have to maintain boiler temp and the indirect works like a thermos, loosing very little heat. I installed a Baisi triple pass boiler, that only fires during a call for heat or hot water, with a phase III indirect about seven years ago. I burn about 1/2 gallon a day during the cooling season and about 1-1/2 gallons a day during the heating season. It's heating a small three bedroom ranch on Long Island.
    If the women don't find you handsome, they should at least find you handy.

  7. #7
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    Of they make the water maker the priority zone the size of the boiler is irrelevant. You must have a weil McLain gold with small water tank inside? Have you considered new, propane boiler and indirect water heater? Oil is evpensive.

  8. #8
    Join Date
    Apr 2004
    Location
    long island
    Posts
    82
    Quote Originally Posted by Joehvac25 View Post
    Of they make the water maker the priority zone the size of the boiler is irrelevant. You must have a weil McLain gold with small water tank inside? Have you considered new, propane boiler and indirect water heater? Oil is evpensive.
    This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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    Last edited by beenthere; 08-09-2012 at 07:10 PM. Reason: n

  9. #9
    Join Date
    Aug 2012
    Posts
    43
    I may have used the wrong terminology -- by tankless, I mean a summer/winter hookup coil. I think some of you understood that.

    Don't know what brand boiler I am doing yet. I have another post asking for recommendations. The proposals I have received have been for a Bryant BW4 or WeilMcLain WGO4. I have found it difficult to find good info to compare and contrast proposals, so all advice is welcomed.

  10. #10
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    Quote Originally Posted by suzook View Post
    More expensive than propane????
    I forget how much but oil the most expensive fuel, 1/4-1/3 more, compared to natural gas its way more expensive.

  11. #11
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Could always go with coal, it's cheaper than natrual gas by a fair amount. Hard to find someone to deliver it in anything less than a truckload these days.

  12. #12
    Join Date
    May 2012
    Location
    Upper Michigan
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    Quote Originally Posted by motoguy128 View Post
    Could always go with coal, it's cheaper than natrual gas by a fair amount. Hard to find someone to deliver it in anything less than a truckload these days.
    A few years ago coal and pellets swept my area, people who bought a pellet stove and pellets when they had natural gas made me wonder what line of bull they were fed lol

  13. #13
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    Jan 2004
    Location
    Lancaster PA
    Posts
    67,874
    suzook, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.

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