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How should I insulate this tank?

heatpro02920 Member Posts: 991
I went to a business this week, they have a 325 gallon uninsulated glass lined storage tank and 4 takagi tankless units with a 009 circulator.. 2 of the takagis are beyond repair the other 2 are working {with parts I took from the non working units}.. Anyway, the system worked for 8 years before they started having trouble, a previous company tried to get warranty support but because they are commercial that was a no go....

Anyway the business owner wants to get it all back up 100%, I sell Rinnai tanklesses so I said I can install 4 rinnai units, a new gas line {there are 2 1" supplys off a 1 inch header feeding 4 tanklesses, honestly dont know how it even works}, repipe it with a stainless pump {alpha maybe, I need to do the math}. an aqaustat {they are running 4 006's constantly now {well 2 since 2 are shut down}, and I am going to insulate the tank since there is nothing on it at all...

Heres my question, what can I insulate this tank with, its an AO 325 mounted horizontally, its a huge round tank, I was thinking build a box out of metal studs, then screw fiber wall panels on {the stuff they use in restaurant kitchens, its textured and white, home depot sells it, comes 4x8}, but what should I use for insulation? Should I have someone come and foam fill it, wrap it with fiberglass then fill it? I am at a loss here... I know it needs to be insulated the room gets so hot they installed a fan to bow the heat outside because they were worried about fire... its a small room I was told they seen it as high as 125 degrees in there on a 70 degree day, not sure if they are exaggerating, but it was hot in there yesterday and only 2 units were running and it was 40 out....

Any ideas for insualtion, or ideas for the install, if you can think of something better, has to be wall mounted {small room}... 4 rinnai tanklesses will be 800K BTU's, I have to do some flow calcs and see what will work best....I am thinking a single circ and I am going to pipe it different, they currently have it piped so the cold water enters the tank and the tankless units circulate water in the tank, then the building supply comes out of the tank..

I am thining keep the supply from the tank the same but feed the cold water through the tankless units, then install controls so the units dont see close deltas... The tank is only piped with 1"...


  • Snowmelt
    Snowmelt Member Posts: 1,387
    Band straps

    I would use bands strap . What was the gpm comming out of the unit, what model tk where they? I would go to takagi digital catalog page 35. Put an aquastat on the cold line / return of the storage tank, use a 0011 s.s. To get more of a flow.

    Also up grade that one inch to two inch and you will get roughly 5 multiply time 4 and you get 20 gpm roughly, so that's just a little over 15 minutes to heat up.

    One more thing I would do is put a check valve so the water goes into the tankless first. Then you can get 7 or 8 gpm machine so that's 49 gallons per minute.
  • heatpro02920
    heatpro02920 Member Posts: 991
    They only have 1" pipe going to the hose manifold

    I was thinking use 3 tankless units on the incoming cold water and the other one to maintain the tanks temp. I have done this a couple times before on a smaller and larger scale {not identical setup but similar}. As long as the tanks heatloss isn't 200K btus and the demand doesnt go over what the 3 rinnai units can flow...

    From taking a quick look at the use they have, I dont think the tank is even needed, but they have it so want to use it, It looks like they need around 10-18 gpm of 130 degree water, they have 3 3/4" hoses off a manifold that they spray at once, full hot no mixing valves... I don't know who thought they needed this huge tank and 4 tankless units but its there now, so I would rather have it piped so in a few years when its leaking I can get rid of it and just run the 4 rinnai units..
  • icesailor
    icesailor Member Posts: 7,265

    Can it be spray foamed?

    When it comes to storage tanks, I prefer to feed the street pressure through the tank with the cold coming in and the hot going out, with no restriction. Then, feeding the tankless's off the colder bottom of the tank, pumping through the tankless's, and returning into the cold water inlet of the tank where it mixes. That's how the old dead guys did it with side arm heaters. You get full pressure through the tank to the fixtures without any restriction through the heaters. That was before Delta T's, PONC's and all that high tech stuff. But it worked for them and always worked for me. The idiots way. I noticed that they were smart idiots.
  • ERF
    ERF Member Posts: 51
    Insulating Tanks

    Being the importer and distributor for Effecta boilers nationwide, I have had the opportunity to work with many end users on storage tank arrangements and have determined that insulating a 500/1000/2000 gallon tank with minimum 1.5" thick "Tuff R" polyiso board works great! In fact, right in my local town there are two Effecta users that have this arrangement and its been installed for 3+ years at each location (on tanks that are inside the living space-in a basement).

    In Alaska there is another 2 Effecta customers with this arrangement, 1 in Idaho, and so on.

    In the beginning (and currently on my Effecta 35kW system for the 5,000 hours of operation) I used blue board with the tanks wrapped in pink fiberglass on the inside of the blue board box). However, I noticed excessive heat loss after a short time and thus removed the pick fiberglass from the tanks and filled up the cavity on all sides with chopped fiberglass insulation and this has worked great.

    Yes, if I ever have to access my tanks it will require removal of the chopped fiberglass before doing so and this is why we switched to recommending simply a 1.5" or greater thickness polyiso board. Polyiso board is a very dense foam board with fiberglass strands in it for re-enforcement and typically a black side and a shiny reflective side. We put the shiny reflective side towards the tank to reflect the heat back towards the tank.

    It was amazing to us that this worked as well as it has but now that we found something that works were not messing with it.

    If you want to discuss further please call my cell at 231.343.3271.


    Brian Crawford, Up North Energy

    [u][color=#0000ff]www.upnorthenergy.com[/color][/u] Attached Files:
  • hot_rod
    hot_rod Member Posts: 19,263
    how pretty, and how safe

    sometimes hiring a pro insulator is worth the time and money.

    You need to be aware of fire codes if it is in a commercial business, not all foamboard products meet the flame spread requirements without additional protection, same with spray foam.

    These large Lochinvar tanks we see in commercial jobs have a foam with a cement type coating for fire rating.

    Or tanks can be site wrapped and sealed by commercial insulation contractors.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gordy
    Gordy Member Posts: 9,537

    Would it be easier to create a room around the tank to isolate it, and concentrate the partition walls as the insulating medium to the tanks?

    If the tank was not previously insulated just about anything is a step up.

    You really have not mentioned the purpose of the whole system.
  • Snowmelt
    Snowmelt Member Posts: 1,387

    Chances are you can use 3 tankless, you really have to see what the demand is, and just add 1 more. Another way to put it is if your going to put 3 tankless you might as wel do 4 tanks. That way if one goes down you can still operate.

    Know you have to size your pipe correctly and x amount of gpm you have to use a certain pipe size.
  • heatpro02920
    heatpro02920 Member Posts: 991
    Thanks guys

    There is a lot to think about





    I am going to look into Polyiso board, another idea a local contractor gave me was wrapping it with reflective bubble wrap and then insulating the box. I also have a call into a local insulation company that I have used before {for building insulation}, and a call to the local building inspector to see what he would be expecting to see..

    The company washes their refrigerated trucks out with the hot water, they used to have 6 garden hoses but now just have 3- 3/4" hoses with spray nozzles, but the spray nozzles {while I couldnt find a spec sheet on and have not yet tested gpm} don't have much pressure, more volume. They dont use high pressure or power washers because it makes a mess and wears out the coating in their trucks.. The move raw un covered meat with these trucks so they are cleaned every trip...

    I am going to have my helper go Monday and test the gpm on the hoses and get the rest of the info I will need to decide what direction to go...

    Thanks again guys..
  • icesailor
    icesailor Member Posts: 7,265
    edited March 2014
    More is better:


    Snowmelt is right, Add enough heaters to cover more than enough for the load at any pressure or temperature they select.

    I straightened out some issues in a distillery that had much higher hot water demands than I ever could imagine. They used it for hot water washing/cleaning purposes. I used a 199,000 BTU commercial heater with an existing storage tank. It worked fine for 20 minutes until the storage tank went down, If I had used 2 heaters, it would have lasted longer. I saw promotional literature for a Japanese heater manufacturer I used where they had MANY multiple heaters on a roof to supply needed hot water for a lense fabricating company. No tanks, just the tank less heaters with some control strategy to supply endless hot water.

    If it is meat and other biological as an issue, you need really hot water. If they get cheap, it will never work. If you want really dependable hot water, someone has to pay you to install it.  If you do tanks, it only extends the amount of time you have water, Then you have to recover. Put the amount of energy(BTU's) into the hot water supply.

    It sounds like it really needs something like a water heater used in car washes or concrete plants. A Scotch Marine boiler, run with a huge indirect coil. Like my son's father in law has with his concrete plant. If it is a 10 yard ready mix truck, and it is 20 degrees out, they have to supply enough mixed hot water to hydrate 10 yards of dry concrete, hydrate it properly and raise the temperature of Portland Cement, sand, gravel and additive to a set point well above freezing to meet engineered specifications to make it legal concrete. That's enough available BTU's in the hot water to warm the mix above freezing and still be warm enough for the pour. The same as in the summer, they have to use chilled water in the concrete mix so it doesn't get too hot in the form/pour.

    Something to think about.

    How is it provided now?

    Something like this:


    I looked for information on the water heater my son's father in law has. I can't find any. It is a Scotch marine type that runs on low pressure steam, under 15# so you don't need an operators license. It has all the required steam controls, it is filled with treated water, and has been running for about 20 years. The only thing changed on it was to go from a Beckett CF 1300 that wasn't low-high-low fire to a Carlin 950CRD that was. The Beckett was sized at the end of the range but the concrete dust wore out the vanes of the fan. At 13.00 GPH, a delayed ignition start was an exciting event. Solved by the 950 CRD.

    Maybe there is some issue now with that type. If it is anything of interest, I will find out. My son's FIL can cut a penny in half and get a nickel in change. So it must be effective and work. If the water temperature isn't correct, the mix will be rejected on some jobs.
  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    provided now

    the hot water is provided by their 325 gallon tank, and 4 takagi's {only two working}..

    I was thinking, use 1 rinnai 199K btu tankless to keep the tank hot {circulating on aquastat demand} and 3 more feeding the tank. I am almost positive 3 rinnais will supply them with endless 140 degree water to their hoses...

    They dont use a lot of pressure since it will make the blood splatter all over the place, more like a low pressure fountain rinsing the interior of the trucks down and out a drain... They specifically told me the pressure had to be kept low, and there is a 1 1/4" gate valve on the 1" hot water pipe...

    After I get a max gpm for their needs, I will compare that to what the 3 rinnais can provide if its enough I think I will pipe it how I am thinking with a single maintaining while the other 3 provide... If not I will have to have all four circulating...

    I dont think the tank is ever needed, but they have it and they paid over $7500 for it to be installed {before the takagis, just for the tank}... So they want to use it, I figure 4 new units and insulate that tank and they will be much better off than when I arrived...

    After I get the actual demand and what the insulation options together I can propose something, as of rite now I think 3 rinnais heating the incoming, then 1 circulating {a ss alpha} and build a box around the tank with metal studs and fiber board and insulate it with something that will hold in the energy and meet code while not costing a small fortune...
  • Snowmelt
    Snowmelt Member Posts: 1,387

    What model do you have, tm 32.or tk 3 , you really have to get the flow rate. If you want use 2 higher flow tankless, if you use navien you could use a commen vent and fresh air intake.
  • heatpro02920
    heatpro02920 Member Posts: 991
    I dont sell navian

    these are takagi jrs, they already each have a venting hole above them so hanging 4 rinnais and venting them wont be an issue...
  • Snowmelt
    Snowmelt Member Posts: 1,387
    edited March 2014
    Lowest flow

    There the lowest flow of like 3 G.P.M , are they vented with cat. 3 S.S., are they manifolded together with1 inch pipe minimum maybe 1-1/4, I would use 1-1/2 to play the flow nice.

    I personally would use 2 th-3, and the storage tank, does these existing heaters have fresh air intake, I think not. So i would take advantage of the 4 wholes and do a direct vent system.

    Direct venting

    Copper pipe being large enough for water flow

    Recirc loop has a high head , 009 or 0011

    That's what I would be looking for.
  • heatpro02920
    heatpro02920 Member Posts: 991
    I dont sell navian

    so I wont be installing them... And I dont think I will be installing 1 1/2" pipe for under 20 gpm.. the current units are vented outside, and I like using a ss alpha for something like this vs a std high head pump.. Since I am most likely going to only use a single rinnai unit for the circulating side, the alpha should do fine...
  • NYplumber
    NYplumber Member Posts: 503
    Rinnai & MCC

    Get the real time data of the water pressure and gpm of the spray heads then add for some more (in the event they use all six).

    Rinnais with the MCC control can cook the water to 180*f

    Your limiting factor will be reusing what you have there.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,573
    Water recycling

    If they are using a large volume of water, maybe there would be a way to collect, and recycle the water. Obviously some filtration is required, like reverse osmosis?

    A large spray wand, whose length is the same as the depth of the truck body, could be stuck in first to drench the interior first, then followed by some hand work by the cleaners.--NBC
  • heatpro02920
    heatpro02920 Member Posts: 991
    getting the real numbers today

    so I will know exactly what is needed... I was there while they were washing out the trucks, and from the smell and sight, of what was coming out, I dont think recycling is a great idea, although they said it wasnt always that bad, once was enough for me to be thankful I don;t work there......

    They have been there for years, and they have the washing, down to a science, they park the trucks on a ramp that leads to their docks with a huge drain directly behind the truck, they spray the truck with some cleaner that is pumped into a separate hose with a wand, then switch to the water hose and rinse it all out....

    Still not positive how to insulate the tank
  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    I went and got some measurements..

    Just drawing up a proposal rite now. I phoned in the price and got a verbal "OK" so just the formal proposal to get out of the way..

    I spoke with the insulation company this morning, he is going to insulate the tank with a reflective insulation and air gap, then insulate the enclosure that I am going to build out of metal studs and fiber board {rated to be installed behind ovens so codes shouldn't be an issue}... We are also going to insulate all of the piping. and seal up the room a little better than it is currently {at the request of the property manager}...

    As far as the hot water side of the job, I measured the incoming water temp at 54 degrees, the temp at the nozzle has to be 120 degree min., and I measured 2 of the nozzles with a 5 ga bucket and stop watch, one flowed 3.7gpm and the other was 3.4gpm so I figured 4 gpm each X 3 at 12....

    So 3 199k btu rinnais will supply that with no tank, but I am going to install the 3 with the tank so the cold comes into the first 3 rinnais and feeds the tank with hot water, then the 4th rinnai will be installed with a ss alpha pump and a johnson A419 to maintain the tanks temp when there is no demand, and it will of course also add to it if the 3 incoming rinnais dont keep up...

    That is the easy part the heat loss and energy bill are my concern because if they dont show improvement I am going to have to answer to that, I am not worried about the rinnai efficiency and reliablity they have proven themselves as far as I am concerned but I want to make sure the insulation side is going to hold the heat where it is supposed to be so they dont have to run the fans to cool the room down in the winter...

    I know others may install all 4 tanklesses circulating through the tank and actually rinnai shows it that way in the install manuals BUT, in my experience tanklesses {all brands} do not like close deltas, so having 3 of them running correctly and just using a single unit to maintain the tank {which wont be much since it is going to be fed with hot water}, is the most efficient and reliable way to install a system like this...

    I have my fingers crossed that the insulation will work, I got a quote from a company {amtrol recommended} to have the tank insulated and sealed and it was EXPENSIVE, and my insulation company said he will guarantee the way we are going to do it will work better and cost less.... So time will tell..

    Another issue I didnt notice on my first visit was a plug in each of the 4 prv's, no one knew how it got there... So I am guessing the prvs were going off and the old service company plugged them, so I am going to install an ST30 thermal expansion tank and T&P also...
  • hot_rod
    hot_rod Member Posts: 19,263
    Put it in writing

    As far as the promised DHW performance
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • heatpro02920
    heatpro02920 Member Posts: 991
    edited March 2014
    In writing

    they already dropped the proposal and deposit back off at the shop, but in the proposal it had a copy of the units outputs, and I stated "at least 12 gpm at 70 degree rise... which these units will do much more than that...

    Im not worried about legal recourse, I dont want to lose the customers faith, they give me a lot of work, I installed a buderus g615 at one of their other properties a coupe years back, and I can not count the refer units I have installed for them... This is a new building they acquired recently, with the employees, so I am dealing with the actual owner and the old owner who is now the manager.... Tricky, but we will get her done...