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Should I stick with tankless coil?

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Hi all, I plan on replacing my oil boiler with a new Megasteam 288 oil boiler. I have a tankless coil on my existing Burnham V8 and it seems to be doing a good job of getting us hot water (two adults and a 4 year old.) Lately though it has been getting worse since the boiler is failing and the temp valve is not working correctly. We have about a 1000 sq foot apartment with one bath-- one sink in the kitchen and one small sink in the bath.. What are the pros and cons of sticking with the tankless coil for our new boiler? How much hot water does a typical tankless coil hold? Thanks. - Ollie

Comments

  • mattmia2
    mattmia2 Member Posts: 9,840
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    Either run an indirect off of the boiler or add a separate water heater. Keeping the boiler hot 24/7 year round for the tankless is expensive. There are ways to run the indirect directly off of the boiler water below the water line, using the indirect as a hx for a conventional indirect coil or to use the indirect to heat the potable water with a circulating pump and a storage tank. If you use the boiler as a heat source, make sure you make the indirect large enough that the boiler runs infrequently under small loads or that will really eat in to the efficiency of the system.
    SuperTechOllie_Hopnoodle
  • ethicalpaul
    ethicalpaul Member Posts: 5,757
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    Some people here seem to love the idea of keeping a boiler hot in the summer to heat a few gallons of DHW but the mere idea of it makes me convulse.

    Any standalone water heater would be better. Gas, or even traditional electric. But I recommend a heat pump water heater which is nearly free to run and often has state incentives available.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    SuperTechOllie_Hopnoodle
  • nde
    nde Member Posts: 86
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    Generally a coil is not as efficient (without a storage tank) vs a stand alone water heater. The coil is sized based on the boiler size so smaller boiler will have less gpm vs larger.

    Having said that if you are in an area like me where the boiler runs 6 months a year a coil is actually pretty efficient since if timed properly your hot water needs are "free" while boiler is making radiator steam. In 6 off months of non heating a coil is more wasteful but a payback on ROI for a standalone will be years out if like my case. So I stuck with the coil. I use approx $20-25 worth of natural gas/month in summer months including cook stove and boiler coil, so a standalone does not make economic sense for me, a wall hung will never pay back. Even a storage tank will be slow on ROI. Another downside of coil is if/when they fail later in the boilers life they can be impossible to remove without snapping the bolts or causing other issues. My last one went 23 year which surprised me, it was very crusty when removed from the boiler though!
    Ollie_Hopnoodle
  • ethicalpaul
    ethicalpaul Member Posts: 5,757
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    I will add it's nice for them to be separate so that if your boiler fails at least you still have hot water and vice versa
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    Ollie_Hopnoodle
  • JUGHNE
    JUGHNE Member Posts: 11,090
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    Paul, have you had a heat pump WH for some time?

    How about the outcome...enough HW for how many.....cost of operation?
    ROI?
  • jimna01
    jimna01 Member Posts: 36
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    as  a homeowner the last thing I want is a tankless coil . Running a boiler 24x7 to keep water hot wasteful and at todays fuel prices even more so. My house came with a tankless coil in a circa 1960 oil fired hot water boiler.  The coil clogged soon after I moved in.  I  installed a stand-alone oil fired water heater (electricity has always been expensive in the Northeast). When I replaced the boiler later on with a 3 pass cast iron oil fired (natural gas was not option at the time) and I replace the water heater with an indirect 30 gallon water heater.  You can’t run out of hot water, the 3 pass boiler is easy to clean and keep clean and I cut my oil consumption 33%.   I would still opt for a 3 pass boiler (they don’t take tankless coils) which only runs when there is a demand for heat ) but in this day I would look at heat pump
    water heaters.   There is no way I would ever install a tankless coil. 
    ethicalpaulSuperTechOllie_Hopnoodle
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
    edited January 2023
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    Tankless coil in an oil fired boiler is the worst idea ever. In the 1940s and 50s Levitt used them because they were less expensive to install one oil burner that does 2 jobs. Saved the builder money 1 time. Cost the homeowner in wasted fuel for years.

    Oil dealers were happy with the idea of selling some oil in the summer months. If you didn't use oil for hot water then you would probably use an electric water heater. Can't sell any oil for an electric water heater. Even though a tankless coil is probably less expensive to operate than a stand alone electric water heater... there are more cost efficient options.

    Proper installation of an indirect water tank off of a high efficiency boiler will pay for the additional install expense in as little as 5 to 8 years. The life expectancy of the equipment is over 20 years.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    SuperTechOllie_Hopnoodle
  • HVACNUT
    HVACNUT Member Posts: 5,870
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    Does the Mega Steam offer a tankless coil?
    SuperTech
  • Ollie_Hopnoodle
    Ollie_Hopnoodle Member Posts: 73
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    Ugh, i wish it was an easy choice! It seems like it would be better for the boiler to not have a tankless coil, and get an indirect instead. I have thought about just getting a heat pump water heater, too. They offer rebates now around 600 bucks for a 55 gallon. I’ll look into what the cost difference is between these two options. Thanks.
  • ethicalpaul
    ethicalpaul Member Posts: 5,757
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    JUGHNE said:

    Paul, have you had a heat pump WH for some time?

    How about the outcome...enough HW for how many.....cost of operation?
    ROI?

    I've had mine for I think over two years now, so not too long, but I have a 5 years parts and labor warrantee on it so I'll let you know after that!

    They come in 50 and 80 gallon and you can set them to use resistive for faster recovery if you find you need it. The cost of operation is amazingly cheap. 25 cents per day here, but everyone's usage is different.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • ChrisJ
    ChrisJ Member Posts: 15,859
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    JUGHNE said:

    Paul, have you had a heat pump WH for some time?

    How about the outcome...enough HW for how many.....cost of operation?
    ROI?

    I've had mine for I think over two years now, so not too long, but I have a 5 years parts and labor warrantee on it so I'll let you know after that!

    They come in 50 and 80 gallon and you can set them to use resistive for faster recovery if you find you need it. The cost of operation is amazingly cheap. 25 cents per day here, but everyone's usage is different.

    Will they honor that warranty for yours? Or are you SOL like many DIY?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    SuperTech
  • mattmia2
    mattmia2 Member Posts: 9,840
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    Have you seen many examples of actual denial of claims for DIY installs when the product was at fault rather than the install? I have had far more problems with supply houses than manufacturers.
    SuperTech
  • ethicalpaul
    ethicalpaul Member Posts: 5,757
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    Well they sell it through Home Depot so I'm pretty sure they'll honor it if need be
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • ChrisJ
    ChrisJ Member Posts: 15,859
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    mattmia2 said:

    Have you seen many examples of actual denial of claims for DIY installs when the product was at fault rather than the install? I have had far more problems with supply houses than manufacturers.

    No, I haven't tried.
    But my gut tells me we're on our own.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    MikeAmann
  • Ollie_Hopnoodle
    Ollie_Hopnoodle Member Posts: 73
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    HVACNUT said:
    Does the Mega Steam offer a tankless coil?

    It’s optional for the Megasteam288.
    HVACNUT
  • hot_rod
    hot_rod Member Posts: 22,353
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    nde said:

    Generally a coil is not as efficient (without a storage tank) vs a stand alone water heater. The coil is sized based on the boiler size so smaller boiler will have less gpm vs larger.

    Having said that if you are in an area like me where the boiler runs 6 months a year a coil is actually pretty efficient since if timed properly your hot water needs are "free" while boiler is making radiator steam. In 6 off months of non heating a coil is more wasteful but a payback on ROI for a standalone will be years out if like my case. So I stuck with the coil. I use approx $20-25 worth of natural gas/month in summer months including cook stove and boiler coil, so a standalone does not make economic sense for me, a wall hung will never pay back. Even a storage tank will be slow on ROI. Another downside of coil is if/when they fail later in the boilers life they can be impossible to remove without snapping the bolts or causing other issues. My last one went 23 year which surprised me, it was very crusty when removed from the boiler though!

    Free hot water from a crusty tankless coil in a boiler. Really?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTech
  • Kickstand55
    Kickstand55 Member Posts: 110
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    One thing needs to be mentioned, maybe two. Water quality. Mineral content AND chlorides wreak havoc with water heating equipment, boilers, tankless coils, gas tankless heaters, tank water heaters of all kinds including stainless steel.
    Best to have the water checked for minerals like calcium, manganese and chlorides. In Manchester, NH I have seen a multitude of issues resulting in chlorides massing with minerals and clogging mixing valves, T&P valves and fouling tankless coils.
    The short fix is a stepped, 20/5 micron particulate filter, a large carbon filter and a descaling cartridge with by-pass valving. Seems to work, if you can get the customer to believe it. Many won't due to cost, saying something like, "It's been this way for 40 years, not going to change it now" or "that's a lot of money".
    On the tankless coil attachment, The mating surfaces need to be sanded clean to bare metal, threaded holes chased with a tap and cleared. I use stainless steel studs, nuts and washers with Never Seize and thick Gator Hyde, EPDM, gasketing. Also, a very thin layer of silicone applied to both sides, allowed to cure for 10 minutes makes for a very durable seal, and easy to remove later. Fasteners must be re-torqued every year. (Yeah right!)
    MikeAmann
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
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    hot_rod said:



    Free hot water from a crusty tankless coil in a boiler. Really?

    That is what I was told when I worked for the oil company. "Where else could you get FREE hot water for 6 months, then from us, your dependable oil dealer!" If you put in a gas or electric water heater, then you will have a higher gas or electric bill for hot water all 12 months.

    That is what my father told me. and he would not lie to his favorite son!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    MikeAmannethicalpaul