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Best Solution for heating Jacuzzi/Tub

JohnArnold
JohnArnold Member Posts: 19
edited January 17 in THE MAIN WALL
Hi All -

I am a complete novice in this area, and have read some of the forum - and it's been incredibly educational. I am working with a plumber, but still don't understand exactly what I need - so am looking for opinions - as I am sure I am not considering all elements.

We recently bought a new house with an approximate 80 gallon jacuzzi tub, and the issue has been we run out of hot water before it's half full.

I have an integrated water heating system: a Lochnivar Kinght 211,000 BTU Boiler, combined with a Techtanium TT55 Indirect tank. The plumber I'm working with recommended the Turbomax T45 or T65 to replace the Techtanium tank.

Recently, I discovered that the Jacuzzi would fill up with hot water if I back off the faucet a bit. It seems like its a very high GPM faucet, which was probably the cause of the issue - that current system couldn't keep up.

We are a family of 4 (two young children), in a 5 bedroom / 4 bathroom house with dishwasher and washer and dryer. In addition, we do notice we lose heat if we do the dishwasher, and take multiple showers - so despite getting the Jacuzzi to work by backing off the faucet, I'd still like to upgrade so I can fill the Jazcuzzi faster and ensure I don't run out of hot water when the dishwasher is used, followed by a couple showers.

I was planning on moving forward with the Turbomax T65. However, after researching - I am not sure I will get a significant improvement over what I currently have.

Based on my boiler, it seems with the Turbomax T65 I would get 7 gpm first hour, followed by 6 gpm continuous. With the Techtanium TT55, based on specs I've read, it seems I get 5 gpm first hour, followed by 5 gpm continuous. Now, I don't know if I am reading the specs right, but if I am - it looks like the improvement is not enough to be worth the cost. Ultimately I'd like to fill the Jacuzzi as quickly as possible, as we use it a few nights each week - and it seems like a small improvement (but maybe it's a bigger improvement then I think.

I've looked at tankless as well, and see one of the top Rinnai tankless can do 11 gpm - and is less than both the Turbomax T65 and T45.

If you'd be so kind - can you help me understand the best solution (or at least confirm if I am understanding correctly) so I can make the appropriate decision on how to move forward? Thanks in advance.
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Comments

  • Larry Weingarten
    Larry Weingarten Member Posts: 2,087
    edited January 16
    Hello, Just a few questions to start. How many gallons is the tub? How many gpm is the tub filling spout? What other uses are likely to be happening when the tub is filling? In other words, what is the likely maximum hot water gpm draw? With those numbers, we'll be better able to answer. :)

    Yours, Larry

    ps. One more... What is the coldest groundwater temperature?
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    Hi Larry - Thanks for following up. As I am not the first owner of the house, and it's tiled in - I can't see the specs for it. Based on comparing measurements online, my best guess is the tub is approximately 80 gallon. Regarding the Tub fill spout, I am not sure. I plan on testing it this weekend by filling out a gallon jug - but it seems that it's definitely on the higher end. I'll figure that out and post back to the thread. In regards to groundwater temperature, approximately 50 degree F.
  • JohnArnold
    JohnArnold Member Posts: 19
    edited January 16
    I just did a quick test and I don't know how accurate it is. I took a 3 quart jug and used a stopwatch to see how fast it would fill. I did it 5 times and averaged it together and got 3.6 seconds to fill. As that, I believe is 80% of a gallon, based on my measurements it would be a gallon in 4.5 seconds. This translates to 13.3 GPM at full blast, which is really high. That said, I think it's clearly at least 11 GPM. I'd love to be able to fill the tub at full blast, but at the very least, I want to make sure I can fill it more quickly than I do now.

    Reminding you that I am a total novice in this area, so if I am doing anything completely wrong - feel free to tell me. Here to learn.
  • JohnArnold
    JohnArnold Member Posts: 19
    Forgot to answer one of your questions. The only thing likely to be happening when the jacuzzi is being operated is sometimes dishwasher OR washer. That will change, I assume, as my children grow - so you can add a shower to the mix as well.
  • Youngplumber
    Youngplumber Member Posts: 518
    I think your answering your own question. If you want to fill the tub at full blast then there is only one choice, the one that is closer to 11 gpm. Just know your choice to want to fill at full blast will limit your ability to fill other things at the same time. Your saving 5 min or so by going with the heater that's capable of 11gpm. All of this really depends on what you think is worth it. You could always get a different tub valve that restricts you to match the flow with what your water heater is able to flow, but does that help you accomplish your goals? 

    What your wanting is really just a matter of preference and priorities. 
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    Thanks for the comment, Youngplumber. I haven't scoped out the installation cost of the Tankless, so don't know, necessarily, what the cost will end up being.

    Are you saying that the Turbomax will provide some improvement to filling the Jacuzzi, but more improvement regarding using multiple fixtures? Installation is easier because I already have an integrated system - but I guess my challenge is gauging what type of improvement I'll get from the turbomax (say the T65) for the cost, compared to my current set up.

    I guess bottom line, I don't know the positives / negatives of a tankless system vs replacing my current indirect with a Turbomax T65. If someone could be so kind as to explain them to me - I'd be in a better position to make a decision. Thanks again for all of your help.
  • Tim Potter
    Tim Potter Member Posts: 262
    You stated, "Based on my boiler, it seems with the Turbomax T65 I would get 7 gpm first hour" I think you are correct.

    You generally get about 80% of tank volume, so you can get about 50 gal's as fast as you want them, its the next 30 gals that are the problem.

    A couple of solutions: a) put a tempering valve on top of the turbomax & run it up to 160. that "packs more btu's into the tank", there by allowing more btus (gals of water at say 120* discharge) out of the tank.
    b) install the turbomax in series with your existing Techtanium, thereby giving you much more 1st hour gal's capacity.

    You have a massive boiler, what you are asking I believe is do able. I used a turbomax with a 80,000 btu boiler in the high Colorado mountains at a rental house at a Ski area, NEVER a complaint of no hot water even with 3 showers, (no low flow heads either). I highly recommend the Turbomax.

    You will definitly like the Turbomax.

    Cheers,

    Tim
    Winter Park, CO & Lenexa, KS
    JohnArnold
  • HVACNUT
    HVACNUT Member Posts: 3,807
    I'm no expert on this subject but if the TT55 is piped correctly, has the correct pump for the tank, then simply adding a thermostatic mixing valve should do the trick. Set the tank to 150°, and temper the domestic hot to 120°. 
    Even if you decided to go with the Turbo Max, the 23 should be more than enough. Especially if the boiler is giving it about 180K BTU's. 
    JohnArnoldSuperJ
  • Youngplumber
    Youngplumber Member Posts: 518
    edited January 16
    To be clear, are you talking about having multiple water heaters and you don't know which one to add? Or are you talking about replacing the ONE you have? 
    JohnArnold
  • hot_rod
    hot_rod Member Posts: 14,561
    How much, how fast, and how hot? Those are the questions you need to answer.

    You either store enough for that tub fill, a dump load, or generate it continuously. The second option requires plenty of horsepower :) or BTUs.

    What is the incoming water temperature, it can vary from 35- 55° this time of the year depending on where it is coming from.

    The least expensive option may be to add more storage capacity, maybe an electric HW tank. do you have a hot water recirculation system?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JohnArnold
  • Jamie Hall
    Jamie Hall Member Posts: 15,415
    It's all a matter of BTUs and how many you can store and how many you can create. No matter how you cut the math, that 11 gpm faucet on the Jacuzzi is going to require either that you store enough hot water somewhere for fast use, or that you create it as you go. The latter you are not going to do: that flow rate, at a typical temperature rise, will require a heating rate on the order of 400,000 BTUh. Once you deplete the hot water in your storage tank, you would need to heat the incoming water at that rate -- or allow it to complete the fill at a much lower temperature.

    Now your other uses are nowhere near that flow rate, so if you can space them out -- and perhaps, as has been suggested, cram more BTUs into your tank by running it much hotter, with a mixing valve -- you may be able to get by. On the other hand, if you restrict the flow of that usage to a rate which your heat input can manage (perhaps 3 to 4 gallons per minute) that would work, too -- but with the problem there being it would take a long time to fill the Jacuzzi, and it might well get too cool while you waited for it. On the whole, a really big indirect -- a SuperStor 60 or 80 DWN, for instance, might be the best way to go.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    Thanks for all the comments. To answer some of the questions water comes on at about 50 degrees F. My main question was if I am moving from a techtanium tt55 to a turbo max 65, will I get a significant improvement if first hour is 5 gpm for the techtanium vs 7gpm for the Turbomax. Since the turbomax is a reverser indirect and doesn’t sore domestic hot water, so I still get the 50 gallons as fast as I want them? If that’s the case, it would probably be worth it given the increase in size and GPM. Interesting suggestion to run in series with the Techtanium. I can ask the plumber, though I’m not sure if I have the room. That would probably give me the greatest yield.

    my other question is I am seeing rinnai tankless 11 gpm as a little more than half the price of the turbomax. Why would this be the case if it has such a high GPM rating? What’s the benefit of the Turbomax in this situation. I think I’m leaning toward the Turbomax, or Turbomax in series with the techtanium (if I have the room). If I am missing anything please let me know.

    thanks again for everyone’s help. It’s greatly appreciated.
  • JohnArnold
    JohnArnold Member Posts: 19
    edited January 16
    Ok - to the suggestion about getting just a big indirect, I looked at a burderus 80 gallon and first hour is 350 vs 417 for the 72 gallon Turbomax. I guess to rephrase my question does the conventional indirect give me more right away since it’s storing 80 gallons, or do I get more from the Turbomax as it’s storing more BTUs - just in the initial dump.

    and I believe I do have a recirculating system - but not sure of the details.
  • Jamie Hall
    Jamie Hall Member Posts: 15,415
    The number of BTUs stored is a function of two things: the volume stored and the temperature at which it is stored. If you are storing at a higher temperature and mixing down, you will get more final volume. Be sure when you are looking at the comparative numbers for the Buderus and Turbomax that you are lookng at the same storage temperature as well as volume.

    You still have a recovery rate problem, either way: Your boiler, putting all of its output into whichever tank you are looking at, will take upwards of 15 to 20 minutes to heat the thing back up -- assuming no other hot water is in use. Looked at another way, if the boiler is putting all of its output into the tank, you have at most about 6 gpm of hot water.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JohnArnold
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,581
    @JohnArnold

    I would put a mixing valve on your indirect. Get the indirect to 140 and try that. You can always raise the temp if need be. See how that works. It won't be wasted money it can be used on a replacement tank

    Of course what your asking for can be done. The question is at what cost $$$$$. How important it is and how many $$ and energy consumption are you willing to go for
    JohnArnoldSuperJ
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,087
    Hi @JohnArnold , One more thing to consider is how many of those 11 gallons are actually pure hot water. A rough rule of thumb is that 70% of the water for bathing is hot, and 30% cold. So, that would mean 7.7 gallons of your 11 need to be hot. The numbers can be refined by figuring the desired bath temp (likely not over 105) and wintertime incoming cold water temp. As others have put forth, more storage capacity and/or a mixing valve might do just what you need. Also, it might make sense to track down exactly how many gallons the tub holds just to the overflow and then subtract the water displaced by a person. It could be substantially less than 80 gallons. I probably displace something under 20 gallons myself B)

    Yours, Larry
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    edited January 17
    Thank you all very much for your help. The suggestions for a bigger indirect, a mixing valve, and potentially running the Turbomax in parallel with my existing Techtanium 55 are all very helpful and I'll discuss with my plumber.

    One last question however, so I truly understand the difference between a reverse indirect tank like the turbomax, and a regular indirect tank.

    With a regular 72 gallon indirect tank, I should have approximately the first 57 (80%) gallons as fast as I want them. Is this also the case with the Turbomax T65 (which is 72 gallon? Will I be able to dump 57 gallons of hot water as fast as I want them - before I get the continuous GPM rate?)

    And if I keep my current Techtanium TT55, and run it parallel with the Turbomax T65 - would I have 89 (80% of the combined storage of 127)- gallons as quickly as I want them, before the tank needs to refill?

    I guess my high-level question is - really don't understand the benefit of a reverse indirect tank like the Turbomax vs the regular indirect tank in 1 area:

    - Initial hot water dump I am able to make given the same size.

    From a continuous perspective, I get that because of the larger surface area, I am likely to have more GPM with the Turbomax.

    This will really help me understand what I am dealing with and make the most educated decision in conversation with my plumber. Thanks again for all of your help. Whether your a professional or not, it's incredibly kind to be able to provide this type of free advice to people like me - who are novices.
  • Jamie Hall
    Jamie Hall Member Posts: 15,415
    The TurboMax simply has a different way to route the heat exchanger, and it does make a difference.

    One caution with having two tanks used in parallel -- particularly if they are significantly different -- is in getting anything like the flow split between them to be the way you want it to be. What usually happens is that the flow favours one tank or the other -- sometimes to an extreme -- and you just don't get all the capacity of one of the tanks. It is possible to correct this with careful plumbing and the use of balancing valves (the simplest being a common globe valve, but there are other types) -- but that will ensure balance for only one flow rate.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JohnArnold
  • Zman
    Zman Member Posts: 6,466
    If we assume that your boiler is piped correctly and it is running in domestic priority mode, lets' run through the math on GPM output.
    If the water coming to the house is 45 degrees and you are trying to fill the tub with 105 degree water. That's a delta T of 60 degrees. Your boiler will only run at around 90% efficiency making hot water.
    211,000 btu's X .9 = 189,900 BTU output. 189,900 / 60 (delta t) /500 (constant) = 6.33 GPM actual production (this is why it will fill hot when you turn down the flow). Your boiler will not generate more hot water than that no matter what type of tank you have. So then it comes down to storage. If you upsize to an 80 gallon or larger indirect, reverse indirect, or extra storage and run it at 130 degrees or higher, you will probably be able to run the faucet wide open and get 80 gallons of hot.

    Another option is to run your exiting tank at 150 degrees and mix it down so you don't boil the kids :o , in that scenario you would only use about .63 gallons from the tank for every gallon you need at 105 degrees. You could probably fill the tub at full throttle doing it this way. Try cranking up the water heater for a few hours and try it.

    BTW, when you apply the same formula to on demand heaters you will find that they tend to overstate production.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    JohnArnoldepmillerSolid_Fuel_Man
  • JohnArnold
    JohnArnold Member Posts: 19
    Hi All -

    Thanks again for your advice. After researching extensively, and listening to all of your advice - I think I am going to go with the Turbomax 65 after all paired with my Lochnivar Knight 211k BTU boiler.

    I am going to describe why below, but if any is incorrect or I am misunderstanding - please tell me.

    - With the Turbomax, similar to a regular indirect, I will get a peak flow for 10 minutes of 58 gallons. This is the main reason I am choosing the Turbomax 65 over a smaller sized Turbomax tank This should be enough to fill the tub with one person in it very quickly. On The Turbomax specs it's saying I'd actually get higher than that as it's 417 first hour and 344 continuous. Based on my understanding as First hour = Peak 10 minute + continuous - it's actually claiming 73 gallons Peak 10 minute. I am not sure exactly how this could be the case, but if it's 58 gallon+ I should be fine.
    - The Turbomax has better continuous rates than a conventional indirect, and based on their specs at 200k BTU (I know I am getting a little less) I am getting approximately 345 continuous - so approximately 5.75 GPM after that. So, theoretically I could top off the bath and/or one of my other family members could take a shower. As my boys get older, this will be especially important.

    Things I am still not certain about:

    - As my boiler at 211k is on the smaller size of the input for the T65, I don't know how concerned I should be about recovery rate. I believe I am ok, because after that initial 58-72 gallons - I still have another 345 gallons to work with.
    - Similarly, I am not sure if I have to worry about short-cycling. My understanding is it's when an oversized boiler doesn't need to fire long to complete a task. So in this case, it would actually have to have to burn longer to get to replenish maintain the 180 degree 72 gallon water in the Turbomax 65.

    The Boiler is from the previous owner - and the house is 3200 square feet, plus a 1700 square foot finished basement.

    The only other option, I think is to get a conventional 80 gallon indirect. I'd get 64 gallons at peak for the jacuzzi - so an additional 6 gallons - but I wouldn't have the continuous rates the Turbomax has - so I wouldn't get the 6 gpm continuous, and I believe the recovery in the turbomax would be quicker. The only difference is price and size. I'm will to invest the extra money and have a slightly smaller footprint, if the Turbomax does what I think it will do.

    I'm treating this as both a short term solution to fill the jacuzzi quickly, and a longer term solution so I could have 2-3 showers going.

    Again, I appreciate everyone' advice - however - as I'm a complete novice, if I am misunderstanding please let me know.
  • Zman
    Zman Member Posts: 6,466
    Your continuous rates are limited by the boiler PERIOD!
    The rate published by indirect and reverse indirect manufactures are based off of the assumptions they have made about boiler output, incoming and outgoing water temps. If you study the assumptions they made, the math I posted above always checks out.
    Make the decision that you are most comfortable with but don't make it with bad math. Your boiler will not magically make more continuous hot water just because you read it in a brochure.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    epmillerSolid_Fuel_ManJohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    @Jamie Hall

    Thanks for the comment. Are you saying during that 15-20 minute recovery I am still getting 6 GPM, or that I have to wait the 15-20 minutes to get back to 6 GPM.

    Apologies, I think I understand this stuff - and the more I read, it seems the more confused I get :(
  • Zman
    Zman Member Posts: 6,466
    edited January 18

    @Jamie Hall

    Thanks for the comment. Are you saying during that 15-20 minute recovery I am still getting 6 GPM, or that I have to wait the 15-20 minutes to get back to 6 GPM.

    Apologies, I think I understand this stuff - and the more I read, it seems the more confused I get :(

    The boiler will start producing hot water continuously at the rate described above as soon as it detects the tank temp dropping. It will continue to make hot water at that rate until the tank comes back up to temp.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    JohnArnold
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,252
    If your tt55 is in good shape, I'd consider another tt55 and have your guy pipe them reverse return. 

    That way you have 110 gallons of storage. 

    80% of 110 gallons is 88 gallons and you will be covered at normal storage temperatures. 

    I dont like heating domestic water to 160 and mixing down. Dramatically reduced the life of the tank, and reduces the efficiency of the system on every DHW call. 

    Make sure its piped correctly, boiler side and domestic side both need to be reverse return. 

    The other option as hot rod mentioned is use an electric water heater as a storage tank coupled with your existing tt55. If you have a recirculation hot water pump this will be likely the cheapest option. 

    Muscle your way through it with storage, the boiler can only produce 6.33 gpm as zman so eloquently pointed out. The math doesnt lie. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    JohnArnold
  • hot_rod
    hot_rod Member Posts: 14,561
    Sounds like a problem one might have at the Hotel California😉
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    ZmanJohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    @Zman
    Thanks again for all of your comments. I understand that the boiler can’t make more than 6 GPM. As @Solid_Fuel_Man had suggested, I’m trying to muscle through with storage. 

    My understanding is that with the Turbomax  65, at 72 gallon, I will get 58 gallons as fast as I can use them - similarly to a regular indirect.

    The advantage of the Turbomax (I think) is due to it’s efficiency I can make better use of the 6 GPM, continuously, than a standard indirect. If that’s not the case - then I don’t understand if there are any advantages to the Turbomax, and I should just get an 80 gallon regular indirect. I’d buy another techtanium t55 and use them totgether as @Solid_Fuel_Man mentioned, but I don’t have enough room.

    I really appreciate your time and advice. I may have not explained well, or more likely am misunderstanding - but I am listening and do understand at least that the boiler can’t make more than 6 gpm, and that the manufacturers numbers are a product of input and output temps, BTUs, and other assumptions - and on’t necessarily correspond to real world application.
    Solid_Fuel_Man
  • Zman
    Zman Member Posts: 6,466
    I think it is a toss up on the Turbomax vs Indirect decision.
    The Turbo max has a real advantage as it is not a breading ground for nasties like legionella.
    A well maintained thermostatic mixing valve is especially important with the Turbomax, the discharge temp will fluxuate wildly based on flow rate and tank temp.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    JohnArnold
  • heathead
    heathead Member Posts: 140
    ok back to some thoughts all ready brought up. Measure flow of water. Can you find a five gallon bucket for checking water flow. The higher volume will help measure things a little better than just a small volume of water less error. Do you know the size of the pipes the current water heater are supplied with from the boiler and pump and speed- size of pump. Also fill the tub and time it and you can see exactly how much water it holds or at least get close. Do you know if you have a mixing valve on your current tank and what temperature the tank it is kept at now. I have a 68 btu boiler and 80 gal tank I keep at 127 deg and have never run out of hot water filling 60 gallon tub and 3 showers at a time. You boiler at 210 btu is large enough as people have said to supply 6 gal of hot water per min if piped correctly from boiler and pipe sizes are correct, and boiler temp kept high enough. Also when you fill the tub how long is it taking to fill because in that time you are making hot water during that. The 55 may be a little small but if you raise the temps it may shorten life a little but why not try that with mixing valve.
    JohnArnold
  • Youngplumber
    Youngplumber Member Posts: 518
    You could go crazy and feed your fill in the blank (large indirect, turbo max, T55) with a tankless.

    Have 11gpm of hot water replacing the 56 gal you use or run your cold domestic through a heat exchanger change your incoming water temp to lighten the load.

    My actual opinion is get a larger indirect and keep it at 140°.
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    edited January 18
    heathead said:
    ok back to some thoughts all ready brought up. Measure flow of water. Can you find a five gallon bucket for checking water flow. The higher volume will help measure things a little better than just a small volume of water less error. Do you know the size of the pipes the current water heater are supplied with from the boiler and pump and speed- size of pump. Also fill the tub and time it and you can see exactly how much water it holds or at least get close. Do you know if you have a mixing valve on your current tank and what temperature the tank it is kept at now. I have a 68 btu boiler and 80 gal tank I keep at 127 deg and have never run out of hot water filling 60 gallon tub and 3 showers at a time. You boiler at 210 btu is large enough as people have said to supply 6 gal of hot water per min if piped correctly from boiler and pipe sizes are correct, and boiler temp kept high enough. Also when you fill the tub how long is it taking to fill because in that time you are making hot water during that. The 55 may be a little small but if you raise the temps it may shorten life a little but why not try that with mixing valve.
    I don’t have a bucket handy, so I just filled the tub, to where my wife and I like it, with a 3 liter Poland spring bottle, 100 times. I realize there would be more accuracy with an 5 gallon bucket however. That said it means I can fill it with 80 gallons of hot water. I’ll ask my plumber to try the thermostatic mixing valve. 

    In regards to the Turbo max 65, my plumber said I’ll get 58 or so gallons right away, and can then top it off  at around 6 gallon per minute. 

    The best guess on the faucet is it maxes out at 11 GPM which means if I had all 80 gallons of hot water, I could fill it in 7 minutes+ if I had that 80 gallons in storage. If I had the Turbomax, I think I could fill the 58 gallons stored in 5 minutes, and then if I could top it off at 6 GPM, it would take another 3.5 minutes, so I’d have the whole thing full - I think - in 8-9 minutes. Which would be great, because now it takes around 20 - 25 minutes (based on my best guess) but I can measure it.

    Based on my boiler I know that I’ll continue to get 6 gallons per minutes into the Turbomax. But would I still get 6 gpm at the faucet, after the hot boiler water goes down in temperature enough in the Turbomax, or do I have to wait for the whole tank to recover. If I do, then other than some of the bacteria oriented benefits of the Turbomax - I don’t know if it’s worth it - rather have more water stored for the same money. But, if the Turbomax recovers much more quickly, then it’s ideal.

    Bottom line, if I could fill the tub in 10 minutes or less I’d be extremely happy.
  • Zman
    Zman Member Posts: 6,466
    I think that 6 GPM is a very respectable flow rate for a single family residence.
    I think that your real problem is that you (or your spouse) want to be able to open the faucet wide open and have it keep up.
    The easiest fix for your problem would be to install isolation valves on the feeds to the tub and throttle them down to 6 GPM. You could then turn the faucets wide open and fill the tub. I don't think anyone is going to put a stopwatch on it :D
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    JohnArnoldCanucker
  • heathead
    heathead Member Posts: 140
    Ok do you know what temp the water is at now in the water heater? Do you have a picture of the piping to the current indirect water heater from the boiler piping and size of the pipe and circulator pump ? Have you looked up the specs of your current TT55? how much water should you get based upon those specs. I used to have a 80 gallon tub that my wife wanter to use in the winter and we had a 50 gallon regular gas water heater 40 BTU. I would fill the tub with only hot water from the faucet hot side only, by the time it was done it was cold and mixed with the very hot water in the tub. It worked, but not perfect, I had also increased the temperature of the water heater in the winter. Not ideal and I know you want to fix this right and I agree with that. It could be that someone didn't pipe it properly or the temp is set way to low. I wouldn't move temperature up without a tempering valve on output. New IDWH is going to need a tempering valve anyway. Yes 80 Gallon heater should be just fine, but should the TT55 be able to do it at a little higher storage temp if piped properly and set at right temperature. In my current setup 80 gallon indirect I was on the fence between a 68 btu boiler and a 110 btu boilerr. I went with the 68 btu and have never run out of water with three showers running at the same time. I know now your on the fence now between the turbomax and regular 80 gallon IDWH. If the coil in the 80 gal heater has a coil that can transfer the 211 BTU's from you boiler, 6 gallons per min is a lot of water. I think the advantage of TurboTax is in commercial setting they can throw unlimited Btu's into into it and get unlimited hot water out. Where in a regular IDWH it would be limited to the amount of BTU's that could transfer from the coil size inside that idwh.
    JohnArnold
  • hot_rod
    hot_rod Member Posts: 14,561
    Why does it take 20- 25 minutes to fill now? If it is an 11 gpm valve?

    As Larry mentioned you don't usually fill a tub with 120°F water, you blend cold and maybe bath at 103- 105°. So you don't need 80 gallons of hot water. Larry suggested 70% hot 30% cold is what you fill with. So a 50 gallon tank of 120F should fill the tub.

    It gets more complicated if you want to run multiple HW draws at the same time? If so you need to define the GPM of those draws and how long you expect the multiple draws to run concurrently.

    The formula is 500X flow rate X ∆T = BTU required
    If you want 11 gpm of water raised from 50- 105°F = 302, 500 BTU/hr. You don't have enough boiler to do that, as Jamie mentioned you would need a 400,000 boiler. Your boiler could produce 7 gpm constantly, about 11 minutes to fill the tub with 105° water at a 7 gpm flow.

    The Turbomax could do that as it is basically a copper heat exchanger. Other type if indirects maybe could if they can move 190,000 btu/ hr through their coils..
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JohnArnold
  • SuperJ
    SuperJ Member Posts: 602
    edited January 18
    My $0.02.

    There are a couple of factors that should be constant regardless of your tank setup:
    1. Stored Water needs to be at 140F (for bacteria growth protection)
    2. If your water is actually at 140F you absolutely need a tempering valve (otherwise you have an extreme scald hazard)
    So start by making sure your current tank has a tempering valve (set no higher than 120F), and then make sure the tank is maintained at 140F.
    Do you currently have a tempering valve and is the tank at 140F? If not, then do this before you start replacing tanks.

    You will need the tempering valve on any of the new tanks you're considering so you should do it first, There's a small chance you may not need the bigger tank if your current tank is setup properly. Also make sure the boiler DHW production setpoint is sufficiently high. What is the boiler firing rate % during DHW production? Is it maxed out?

    Can you post a picture of the DHW piping of the current indirect tank?
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    hot_rod said:
    Why does it take 20- 25 minutes to fill now? If it is an 11 gpm valve?
    This is a good question; I don’t really know. Perhaps I’m backing off of it too much to ensure I don’t run out of hot water. Maybe I could push it a bit more. When I opened the faucet all the way, I’d get about 1/3 of the tank full and have no hot water for 20 minutes or so.

    Doing multiple draws would be great, but I’m ok if I can’t when the jacuzzis is in use. I just want to fill it relatively quickly.
  • JohnArnold
    JohnArnold Member Posts: 19
    SuperJ said:
    My $0.02. There are a couple of factors that should be constant regardless of your tank setup:
    1. Stored Water needs to be at 140F (for bacteria growth protection)
    2. If your water is actually at 140F you absolutely need a tempering valve (otherwise you have an extreme scald hazard)
    So start by making sure your current tank has a tempering valve (set no higher than 120F), and then make sure the tank is maintained at 140F. Do you currently have a tempering valve and is the tank at 140F? If not, then do this before you start replacing tanks. You will need the tempering valve on any of the new tanks you're considering so you should do it first, There's a small chance you may not need the bigger tank if your current tank is setup properly. Also make sure the boiler DHW production setpoint is sufficiently high. What is the boiler firing rate % during DHW production? Is it maxed out? Can you post a picture of the DHW piping of the current indirect tank?
    I think I have all/most of that stuff - but truthfully have no idea of what it looks like. One of the reasons I’m hiring a reputable contractor to redo it is because I don’t trust the previous homeowner. I’ll post pics shortly.
  • JohnArnold
    JohnArnold Member Posts: 19
    edited January 18
    Here are pictures. I don't know what anything does other than the boiler and the tank, so feel free to ask for more close ups of specific areas.

    Also regarding weather the tank is at 140 now, I don't know - truthfully. looks like a gauge coming out of it showing it at 170 last night when I looked - but that could be for something else. If it's not, I'm not sure exactly how to adjust the temperature.






  • hot_rod
    hot_rod Member Posts: 14,561
    edited January 18
    The grey box with the flex conduit on the tank is the temperature control, what is it set at? That would be the tank operating temperature within a few degrees plus or minus.

    The black circulating pump should rotate so the motor is not vertical.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperJCanucker
  • SuperJ
    SuperJ Member Posts: 602
    edited January 18
    hot_rod said:

    The grey box with the flex conduit on the tank is the temperature control, what is it set at? That would be the tank operating temperature within a few degrees plus or minus.

    The black circulating pump should rotate so the motor is not vertical.

    The red pump in the second last picture two needs to be rotated. The shaft/head should be horizontal.

    I don't see a tempering valve. Can you follow the pipe from the top of the tank and see if it enters a tempering valve? Should be too far from the tank if it exists. The small vertical copper pipe that runs parallel with the large one beside the tank may be the cold connection to the tempering valve.

    Looks like this...



    The temp reading you were measuring was likely the boiler water temp used to heat the DHW, it's commonly up around 170F during a heating cycle.

    Also, can you run a hot facet ideally one that's reasonably close to the tank and use a cooking thermometer to measure the hot water temperature (once it's as hot as it'll get).
    JohnArnold
  • JohnArnold
    JohnArnold Member Posts: 19
    edited January 18
    SuperJ said:

    hot_rod said:

    The grey box with the flex conduit on the tank is the temperature control, what is it set at? That would be the tank operating temperature within a few degrees plus or minus.

    The black circulating pump should rotate so the motor is not vertical.

    The red pump in the second last picture two needs to be rotated. The shaft/head should be horizontal.

    I don't see a tempering valve. Can you follow the pipe from the top of the tank and see if it enters a tempering valve? Should be too far from the tank if it exists. The small vertical copper pipe that runs parallel with the large one beside the tank may be the cold connection to the tempering valve.

    Looks like this...



    The temp reading you were measuring was likely the boiler water temp used to heat the DHW, it's commonly up around 170F during a heating cycle.

    Also, can you run a hot facet ideally one that's reasonably close to the tank and use a cooking thermometer to measure the hot water temperature (once it's as hot as it'll get).
    I think this is the tempering valve? One of the pipes says C and one says H - and as you can see, the temp is 100 degrees.



    Also, noted on the black and red pump. I'll see if I can find a thermometer to measure temp at a close by sink.
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