Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Indirect Heat Exchanger v Indirect Coil?

kgk14 Member Posts: 24
Average homeowner looking for advice on domestic hot water storage tanks.  I'm planning to package a purchase of an oil boiler with an indirect hot water tank.  A Sys2K option includes the Sys2K heat exchanged tank, while another Sys2K or a Buderus option includes a Super Stor tank.  Can anyone tell me the pros/cons of either tank? 

Is there a better value tank available that would work with either of the above systems?  


  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    Do you know what size you need

    Did anyone perform a heat loss and DHW demand?

    I would go with Buderus g115/riello oil fired and a triangle tube smart tank...
  • kgk14
    kgk14 Member Posts: 24
    Tank size etc

    A heat loss calculation, which included a 15% leeway, equaled around 63,000 btu/hr.   My hot water needs include filling a 30 gallon bath tub, taking a shower, and running a dishwasher at the same time.  

    Heatpro... what size tank would you suggest?

     and do you think a Buderus G115ws/3 would work fine or would the house (2770 sq.ft.110' cast iron baseboard, 2 cast iron grates, 20' sheet metal baseboard) need a G115ws/4?  Is your nod to CI over steel just a personal opinion or based on value and performance in the field?
  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    my oppinion of Ci vs steel

    is just years of changing steel boilers that were under a decade old and seeing cast iron units last 40+ years with out issues... Plus IMO system 2000 has made me way too much money and I NEVER installed one, so that is all from service, if you catch my meaning...

    OK, as for your system and needs I would go with a Buderus G115ws/3 and a smart 50 {the boiler size is under what TT wants for this tank, but it will give you plenty of hot water}...

    The install is going to make or break you with any boiler, you want it piped Primary secondary.

    I would install it with Bumble bee pumps on your heating loads and an Alpha pump on your primary side, use a taco EXP zone controller {have each heating load and the tank fed by separate circulators}... and set the taco controller to priority DHW...

    I would use a 3250 plus aquastat with the os100 add on {that will be your control, ODR, and lwco all in one, a lot less money than a logimatic}, and the F3 riello burner , a lot of guys on here like the carlin but I like the riello best for the buderus oils...

    I would also install outside air to the burner box and a tiger loop with garber filter...

    So like I said you want this installed correctly and some times its hard to get a contractor that doesnt just want to throw it in and leave, but that is where it is up to you to know what you want...

    Let us know what exactly your system consists of and me or someone else can tell you exactly what to expect and maybe draw up a layout for you to show your contractor to ensure everyone is on the same page.. I probably already have one that will fit your needs drawn up...

    How many zones do you have and what kind of emitter {if radiant, base board, hydro airs, ???}
  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    I found one

    here is drawing from my proposal library, this shows a hydraulic separator where you can use closely spaced tees, you can pull the indirect from the primary, you can honestly do the pri sec system a bunch of different ways, I drew this for a job I did about 10 months back, it was around 100K BTU input with a smart 50, the taco exp controlled the primary circ, priority hot water and the zoning while the 3250 controlled the ODR and burner control you can wire that a bunch of ways, you can have the exp control priority dhw, there are a ton of options when it comes to piping and wiring.... I like wiring the taco control to handle all the circs and the DHW priority {simple, just connect zr to dhw circs L1 wire}...

    I like that 3250+, it has some decent features for its cost, ODR is a must when you are trying to save energy, but you will want efficient circs because the run times will be much longer...

    I hope this helps, not sure about the specifics about your system but this is pretty broad picture can fit multiple scenarios..
  • kgk14
    kgk14 Member Posts: 24
    CI v steel continued


    If I understand you correctly, you requested what my system would look like, I appreciate the offer and assistance.  If I misunderstood, please correct.  Here is what the proposed system would look like:

     Install (1) new Buderus G115/3 oil-fired Boiler equipped with a Riello Oil Burner and pipe into the existing Heating zones. We will also furnish and install (1) 45 gallon Domestic Hot Water HTP Superstor Indirect Tank onto the new Boiler System, existing Domestic Hot and Cold Water piping and provide Domestic Hot Water Priority Control.

    Heating System shall also be flushed with Fernox F5 Cleaner and treated with Fernox F1 Protector to maximize the heat transfer from the Boiler to the heat emitters.


    To furnish and install a Honeywell outdoor reset control system onto the Heating System controls for increased efficiency by lowering the Boiler water temperature as the outside air temperature increases. Control has a built in algorithm that will also increase the Boiler water temperature on a high demand for heat, i.e., when a thermostat is turned up several degrees after being away for the day.


    Please let me know if you, or anyone else, thinks the above proposal works with the house.  The house currently has two zones, and I would like to add a third in the future, and the indirect would need a zone.  The existing boiler is a tankless Burnham Jubilee.  The boiler vents into a solid chimney, that has a 6x12" clay flue, height is 30', do you see any potential condensation issues?   Let me know if you need any additional information.  Please do send edits, comments,enhancments etc.  I need good value and performance.  Thanks for the interest.
  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    Here is exactly how I would do it...

    ************ Heating proposes to install a Buderus G115ws-3 natural draft oil fired triple pass cast iron boiler with a Riello F3 oil burner using outside combustion air and a single line tiger loop ultra fuel feed/filter system. Said heating appliance will be piped in a primary secondary configuration utilizing a Grundfos Alpha primary pump and equipped with a Hydrostat 3250+ aquastat boiler control with OS100 outdoor reset kit. A Taco SR503-exp zone control will be installed in conjunction with three Taco Bumble Bee pumps to provide the circulation for the two existing heat zones and a new Triangle Tube Smart 50 indirect water heater.

    All pumps will be installed with Webstone isolation flanges and all zones will have a designated purging station, the primary secondary system will be equipped with a Spirotherm Hydraulic separator which will filter and remove air from the heating fluid...

    All equipment will be installed in accordance with local codes and manufacturers specifications, a combustion efficiency test will be performed before the system is placed into service...

    Anyway thats what it would look like, there is a lot more but you get the point..

    For the small cost difference, a hydraulic separator, delta tee circs, alpha primary, exp control, ODR, outside air, ect will make your system much more efficient... Get a contractor that likes going above and beyond and you will be happy with the result... Oil may be over $4 a gallon next heating season so 10% here and there is HUGE, is it worth retrofitting an old boiler? maybe not, but on a new install, its a no brainer...

    Also make sure isolation valves are installed, you want a valve on each end of each circ, a valve system on the water feed/ex tank, the more isolation the lower your repair costs will be when something fails and they dont have to drain down your entire house to perform the repair....

    A nice neat install will add value to your home and be easier to diagnose and repair....

    I would go Smart tank over superstore...

    you could follow my above drawing on your system, just take one zone off...

    As far as value goes..... That is not in the equipment since the equipment is so closely priced, that is in the contractor, you get a good honest contractor and you will get good value, the price difference between doing the system in my drawing that I did for my customer and a conventional system is not much in materials or labor {time and money}...

    As far as the Fernox system goes, I installed the TF system on a customers house, they bought it and I installed it, I am not impressed, if the system has an issue, OK, but if you do not have a water quality issue and you are not heating your water way past 180 I dont see the need... I will flush systems if they look filthy {rare with baseboard FHW systems} but I dont see a reason to spend the money on that stuff unless its needed... Dare I say "snake oil"?

    Sentinal makes some good cleaners, scale controllers, and conditioners, for a cast iron boiler and a tank in a tank indirect, I dont see the need... I went to 5 minutes of the fernox meeting, as soon as I hear "bottle of boiler silencer" I heard enough, on the way out I think I caught "bottle of leak sealer" and I then knew it was 5 minutes I would never get back...
  • kgk14
    kgk14 Member Posts: 24
    And a follow- up

    heatpro, Thanks much for specifics. Your thoughts on potential condensation issues in the chimney?
  • heatpro02920
    heatpro02920 Member Posts: 991
    proper setup

    Another reason I like using the Hydrostat 3250+ is that it has a mode for controlling condensation that will run the circulator at certain temps, but with primary secondary you shouldn't get very large swings supply to return and if the burner is setup correctly you should be fine...

    The reason I recommend these components is because I have put them together in enough homes to know they perform well... I have tried many brands of many products, and like what i like for a reason, that boiler, tank, control, burner, and them pumps work well in that situation. In the oil fired field its tough to make improvements in efficiency that the customer can see rite away, sure performance can be improved, I can me it quieter, smoother, look better, and more comfortable but can I save you money? With outdoor air, ODR, and delta t, you can, with primary secondary you can make your boiler run much longer, with priority dhw you will ensure hot water is there when you want it... put it all together and you have the best you can get {when it comes to oil}....