Indirects or Turbomax - Any Experiences?

Discussion in 'HVAC Heating & Cooling' started by PTN, Nov 2, 2007.

  1. PTN

    PTN New Member

    Messages:
    23
    Location:
    Norwalk, CT
    I have read several posts regarding indirect hot water heaters installed in conjunction with oil fired boilers.

    i have the same type of questions as to which indirects are good options but additionally, to add to the mix of products, i ran across a tank made by thermo 2000 called turbomax. it is suppose to be an indirect tank that works kind of like a tankless coil, only bigger. they claim better performance and faster recovery than indirect storage tanks while allowing the use of a much smaller tank size.

    i am impressed with the numbers and the rep i spoke to has a good technical background with real world calculations being done to figure out the correct application.

    i wondered if anyone had any actual experience with these units and what their opinions might be. longevity is always something to consider but without first hand knowledge, it's hard to get info.

    thanks for any help.
  2. PTN

    PTN New Member

    Messages:
    23
    Location:
    Norwalk, CT
    Incidentally, i am looking to pair the tank with a new yorker boiler, circa 1980 which will no longer use the built in tankless coil.

    thank again.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,892
    Location:
    New England
    Run some calculations for yourself. A gallon of water weighs approximately 8-pounds. A showerhead uses about 2.5 gallons/minute. One BTU will raise one pound of water 1-degree F. Where I live in the winter, the incoming water can be 33-degrees, so if you want it say 105 at the shower, you need 72-degrees of rise. Now, that is too low for say a dishwasher, or if you want hot water for clothes or dishes, so more is likely needed.

    See how many BTU's it takes to run a shower continuously. Figure out how cold your water is and how warm you want it to be. Filling a tub is much different than a shower...you don't want to wait forever for it to fill and it better be warm to hot when you do get in.

    Most houses do not need a boiler big enough to provide for a continuous use shower, let alone any simultaneous uses. Therefore, some water already heated to act as a buffer for those large or prolonged uses will allow the smaller heat source to keep up.

    A good quality indirect can be bought that has as low as 1/4-degree/hour standby loss. You heat it once, and it may not need to be reheated at all until you draw some hot water off to cool the resovoir off in the tank.
  4. PTN

    PTN New Member

    Messages:
    23
    Location:
    Norwalk, CT
    i guess the difference i see in the turbomax is that if i do a 40 gal dump of 110 deg water in 10 minutes, i still get 3.5 GPM continuous immediately following the initial dump.

    If i do the same thing with a 60 gal indirect, i estimate about 75% usable hot water in the tank (45 gal) before it gets infused with incomming cold water and i have to wait for it to recover.

    i have 133K net from my oil fired boiler to use (baseboard heat). at a minimum, i would like to run two showers or a shower and draw a bath simultaneously. i also have a dishwasher and a clothes washer in the house.

    Thoughts?
    Last edited: Nov 7, 2007
  5. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    PTN - you're comparing an indirect with indirects. One indirect, the Turbomax, claims to have a better heat exchanger.

    The proper way to compare your options is to look at first hour delivery. Make sure the comparison is as close to apples to apples as you can get it with equal BTU input and temperature rise. Specifically, compare equal tank size and BTU inputs. That'll tell you what the tank can do.

    On a side note, look at storage loses and construction material. The carbon steel tank on the Turbomax might not be a show stopper but I'd want to know it was going to last before laying out a kilodollar or two for a tank.

    Now the next side is figuring out what can really be delivered from the boiler. Look at pipe and pump sizing pretty closely. Moving 100,000+ BTUs from the boiler to the tank may take a bit of doing. In particular look at the circulation rate required by the indirect tank manufacturer.

    Don't get too hyped over the continous rate claim. Other indirects will have some continuous rate number also. Comparing first hour deliverability from similar tank sizes and with similar BTU input will be valid and tell you all you need to know about the heat exchangers.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,892
    Location:
    New England
    Get an indirect, or you'll likely be sorry, especially if you live in a cold area (with that size boiler, sounds like you do). With two showers, filling a tub, etc. simultaneously, you will greatly exceed 3.5gpm. If you make the indirect a priority zone, it will get all of the heat the boiler can produce while demand for hot water is occurring, so it will likely keep up if you start with a fair buffer. the spec sheets for the tanks will tell you for sure. You may have to interpolate, since they may not have your exact boiler heat graphed.
  7. PTN

    PTN New Member

    Messages:
    23
    Location:
    Norwalk, CT
    i have done comparisons on first hour delivery and that is where i got the info in my previous post.

    As far as continuous delivery goes, once you dump the initial load from a regular indirect, there is no continuous flow of DHW until the tank can recover and heat the newly infused cold water. On the other hand, the turbomax still produces a reasonable flow to be able to do at least another shower after the initial 10 minute dump. Granted, you will not be able to multitask using the continuous flow rate but at least you have some hot water as opposed to none from the regular indirect. This is the way the numbers seem to me.

    The turbomax is keeping a good buffer of 180 deg boiler water in the tank so i think that is what helps in allowing the boiler (on a priority zone which is what i want to do) to keep up.

    As far as piping and circulators go, my existing piping is what i need according to the literature i have read on both turbomax and other indirects. i will install whatever priority zone circulator the manufacturer suggests for my particular application in order to maximize the efficiency of the installation.

    What do you guys think? Thanks for all the input.
    Last edited: Nov 8, 2007
  8. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    I have a SuperStor indirect so I know what I'm talking about when I say that it continues to deliver heated water after the initial stored hot water is used. There is no waiting for recovery.

    If you look at first hour comparisons for a 33 gallon turbomax and a 30 gallon Superstor using ~ 100,000 btu input you'll see:

    Turbo max - 137 gallons of 140 F water, 100 F temperature rise
    SuperStor Ultra - 154 gallons of 140 F water, 90 F temperature rise

    Those two first hour ratings are essentially the same which means they have the same heat transfer capability.

    Now I'll state it plainly: The turbomax is marketing hype with a fancy looking heat exchanger.

    If you want a ten year warranty and a complicated heat exchanger with many connections within the tank then by all means go for it. If you want a lifetime warranty with a simple serpentine heat exchanger then price out the SuperStor or similar competing product.
  9. PTN

    PTN New Member

    Messages:
    23
    Location:
    Norwalk, CT
    Could you tell me what are the sizes of the boiler and the tank that you have so i could get a better idea of how your system is set up?

    thanks, this is great information.
  10. got_nailed

    got_nailed DIY Senior Member

    Messages:
    277
    I might be on a different track then some of you but I’m thinking 2 different ways on this.

    • Get a solar type water heater. They have a coil on the inside of them that you could use for your boiler. You would have to cut some of the top off to mount a thermostat for sending the hot water off the boiler. The units that I install are electric with 2 elements like standard water heaters. Explanation of the basics of how they work. You could install an outside heat collector for the summer time to help cut on power. http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12850

    • Get a water to water heat exchanger and put it in line with your cold inlet water. You would need a flow switch to send the boiler water. If you go this rout you need to look at the flow rates of the heat exchangers.


    I would recommend installing an anti scald valve off the water heater for the hole house. Watch the flow rates when you’re looking at them.

    You need to make sure that the boiler can handle the extra load or have it setup to only to send the water when it is not being used for heating the house. A few relays will do this to control the order of the valves.

    Watch the heat rating off the boiler to what ever you decide to install.
  11. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    I've got a ~74 MBTU output boiler and the tank is 40 gallons.

    PTN - My system's set up does not change the fact that the heat exchanger in an indirect works once the call for heat is made and there is no wait for recovery (unless you want a full tank of max temp water but that is no different from the turbomax).

    Through the indirect, my boiler can supply about 2 gpm with a 70 degree temperature rise. The simple serpentine heat exchanger can easily handle that. Look at the boiler size suggestion for the indirect to get an idea of the heat exchanger capacity. Alternatively look at the first hour capacity vs btu input to see where additional btus provide little benefit.

    This stuff isn't rocket surgery, it's simple heat transfer and that has been pretty well understood for, oh, the past 90 years or so. In my opinion the simpler the better when it comes to water-to-water heat exchange and potable water. A leak in that fancy turbomax heat exchanger will shut down the boiler until the tank is isolated. Why are they only willing to warranty it for 10 years when other indirect manufacturers are promoting lifetime warranties?

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