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Choosing an Indirect Hot Water Heater

PickyPro Member Posts: 13
Hi, I'm new to this board and have previously posted this to an earlier thread. I thought it would be better to start a new thread.

I am a general contractor and am doing research for my customer. The

plumber I use and my customer's plumber have given us a few options. We

are all set on sizing. My customer is wary because he had a glass lined

storage tank in the past, it failed and flooded his finished basement

and he's been living with a poor quantity of hot water from the existing

(probably scaled fouled) tankless coil in his oil burner. I explained

that it probably failed because he never maintained the anode. He wants

my opinion, on ss versus lined, because I have more knowledge about

water treatment in general and his water quality specifically. I

recently had his well water tested before and after his water

conditioner (softener). I wanted to find out if the system was doing its

job and if it was properly sized for his home and his water quality,

before I considered what type of hot water storage I would advise he

choose. Both plumbers gave us similar options of going with a storage

tank or an indirect and options for stainless or lined with anode(s).

The water tests showed 7 gpg hardness a pH of 6.7 and 16.5 mg/L of

chloride before and after the .75 cubic foot (24,000 grain) conditioner.

This proved my theory that the 16 year old conditioner was not doing

its job. After analyzing their water consumption and usage patterns,

checking the performance of the well and pressure tank, measuring the

static pressure and gpm flow at the tank and various fixtures throughout

the home we concluded that a new water softening system would be the

first priority. We will be upgrading to a 1.0 cubic foot system which I

will purchase, install and program.  I will have to retest for chloride

once the system is online.

Since the water will still contain chlorides ( I don't know how much

yet), both plumbers agreed with my opinion that stainless may not be the

best route.

I researched different manufacturers warranties on their stainless

versions and as I recall chlorides were acceptable up to a certain

limit, but just because they would replace the unit doesn't mean I would

jeopardize my customer having to experience another flooded basement.

Does anyone know if a stainless tank can be protected by adding an

anode? This is the only link I could find when doing a search for

"stainless steel hot water tank with anode" I will be speaking with one

of their reps today.  <a href="http://alliedboilers.com/indirect_fired_water_heater.php">http://alliedboilers.com/indirect_fired_water_heater.php</a>

We will probably be choosing a lined steel tank with one (and I'll add

another, if possible, prior to install) or 2 anode(s). We have decided

to go with an indirect instead of just a storage tank because we will be

bypassing and/or removing (any suggestions?) the boiler's tankless

coil. Then we still have to decide on a tank in tank design or one with a

coil. Would a stainless steel circulator be ok or is bronze preferred?

Any suggestions or opinions will be greatly appreciated. Thank you!


  • PickyPro
    PickyPro Member Posts: 13
    Opinions would be Appreciated

    Any opinions out there, on whether to go with a glass lined tank or a stainless steel tank, when the water will have approximately 50 mg/L of chlorides?

    Any opinions or experience on adding an anode to a stainless steel tank if it can accept one?

    Anyone have a favorite glass lined indirect they would suggest using?
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Use which ever tank you want.

    Put a clearwave (or something similiar) electric water conditioning device on the supply where it comes into the house. It will prevent scale buildup and descale your water pipes in most cases. Then you may not need a tank. If you put a tank in, set it in a pan and plumb in a waggs valve. That will prevent flooding in most cases when you have a tank failure.
  • PickyPro
    PickyPro Member Posts: 13
    Waggs Valve

    Harvey Ramer,

    Thanks for the suggestion.

    The Waggs valve with a pan would be a good flood preventer.

    I think we'll be ok with scale once the new water softener is working properly.

    Ever heard of adding an anode to a stainless steel indirect?

    What happens if the coil in an indirect fails? Does the boiler water enter the potable water or does the potable water enter the boiler?

    Which glass lined indirects do you like?
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    What happens if the coil in an indirect fails?

    If there is only one failure, the higher pressure of the domestic water in the indirect heater will enter the boiler, and probably pop the pressure relief valve.

    If the pressure reducing valve providing make up water to the boiler has also failed, allowing the boiler pressure to go up to the pressure relief valve setpoint, and that pressure relief valve has also failed shut, then it is possible for water to go from the boiler into the domestic supply. I am not a contractor, but I think it wise to assume that multiple failures can happen (Murphy's sixth law: if several things can go wrong, they will all go wrong, all at once), and that the boiler is filled with either potassium cyanide and water, or filled with some deadly bacteria that cause a slow painful death.
  • Zman
    Zman Member Posts: 7,573
    Potasium Cyanide?

    If you are filling your boiler with toxins you have larger problems. Bacteria will not live in a non-o2 environment. In all likelihood the failure will happen on the outside of the tank causing flooding.

    Did I miss some irony or are you really worried about nonexistent toxins going from low pressure to high?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    some irony

    Yes: some irony or exaggeration. I cannot imagine there is a good reason to put cyanides in an hydronic heating system, but I can easily imagine some cheapskate putting ethylene glycol in as antifreeze instead of propylene glycol. And ethylene glycol is kind-of toxic, though not as toxic as cyanides.

    "Bacteria will not live in a non-o2 environment." Some will; some won't. Aerobic bacteria will thrive only in an environment containing oxygen. Anaerobic bacteria prefer an environment lacking oxygen. They should do very well in a typical hot water heater.

    It seems to me that water could transfer from the boiler to the domestic water supply. When everything is working right, I agree that the 40 psi water in the domestic side of the tank would leak into the 15 psi water of the boiler and not the reverse.

    But if the boiler is at 40 psi because the pressure relief valve is stuck shut from lack of maintenance, and there is a pinhole from the domestic into the boiler, then the boiler will be at 40 psi until the boiler fires. Then the boiler water will expand, exceeding the domestic side and water will flow from the boiler into the domestic water of the indirect hot water heater. True, this requires multiple failures, but unless you have a Murphy's Law Proof system, it is a possibility to be guarded against. I know the installation instructions for my boiler and indirect say that you must not have anything in the boiler that you are not willing to drink (not their exact words). They would not say that if there were no risk whatsoever.
  • PickyPro
    PickyPro Member Posts: 13

    Thanks for making me aware of the potential hazards of an internal leak in either direction.

    I've already experienced the hazards of an external leak flooding a finished basement.

    That is why I'm trying to choose the best system for my customer and protect it to the best practical extent by not doing things halfhazardly.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Your water softener and electric

    water conditioner do 2 very different things. The water softener actually removes or dissolves particles. The electric water conditioner will do nothing for iron, however it aligns molechules in the water in such a way the prevents them from sticking to anything. Not only that but It removes existing scale over a couple months time in most cases. I would recommend both. This should help protect the coil in the indirect. If you still have concerns about a coil; go with a triangle tube smart water heater. They have a tank in tank design. I am not going to swear to it but I doubt if you need an anode if you use an electric water conditioner.

    You are doing the right thing. Educate yourself before you make the install.
  • Mac_R
    Mac_R Member Posts: 117
    Burnham Indirect

    Burnham makes a stone lined tank that will last for almost forever.  No anode rod because the tank is stone lined.  Here is the link. I use these tanks with any boiler I install outside of Buderus.  Have not had any issues with them.  They are a little heaver than a SS or glass.  You still have to drain them once a year to get rid of sediment.

  • PickyPro
    PickyPro Member Posts: 13
    Triangle Tube Smart Phase III

    Harvey Ramer,

    Thanks for the input.

    The Triangle Tube indirect is one of my top choices.

    I think Triangle also makes the Ultra Plus for Weil-McLain.

    They are both tank in tank designs and both have an "aux" port on top which I would assume can accept an anode. I contacted Triangle Tube early last week, to ask if adding an anode to

    their SS tank would void the warranty, and asked if they thought an

    anode would extend protection to the stainless. I have not yet received a

    reply from them.

    I'm wary of the claims that using an electric water conditioner will remove scale.

    But, thank you for suggesting the option.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    I have an electric water condotioner in my house.

    I know for a fact that they work.
  • PickyPro
    PickyPro Member Posts: 13
    Electric Water Conditioner

    Harvey Ramer,

    What brand do you have installed?

    Where did you install it?

    Did you check the pipes before and after?

    If so, about how long did it take to remove (all?) the scale?

    I may consider using one if I find much scale when I check the condition of the existing copper pipes, during the install of the water softener and the indirect fired DHW heater in a couple of weeks.
  • PickyPro
    PickyPro Member Posts: 13
    Burnham Stone Lined


    Thanks for the suggestion and link.

    I looked at the Burnham Alliance SL a while ago and liked what I saw. The only negative thing I heard about them was that sometimes the water stored in them has a smell that must come from stone lined tank. Other than that it seems to be competitively priced. It seems that they would work well with any water that has a higher chloride concentration, which would adversely affect a stainless steel unit.
  • Mac_R
    Mac_R Member Posts: 117
    Stone Lined Tanks

    I have not had any one tell me they have had a smell or any adverse effects from their Indirect.  I have installed quite a few in the last three years alone.  I have had two people tell me that there was a smell with a Buderus S120 indirect.  I drain the tank and re fill it and the problem goes away.  I am assuming that it is a problem with storage and not the tank.  Two out of countless is not bad.

    To protect the basement against a tank leaking I would just use a water heater pan.  Run a 3/4" PVC to a floor drain and there you go.  The chances of the tank catastrophically failing to the point the water is spraying out is next to nothing.  I guess it could happen.  But extremely rare.  A drip pan with the pressure valve piped into it should do well. 
This discussion has been closed.