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.

Hydro Therm Cast Iron boiler

Maui Member Posts: 4
My dad is helping me build a boiler, as my Weil McLain had a blow out last year.

I have the old cast iron radiators in most of my house, and will soon have baseboard in the rest.

So we combined two of these Hydro Therm boilers together to get more surface area heated from the burners. Not to mention that the water that is heated will remain warm because the cast iron will hold onto that heat a lot longer.(just like my radiators)

I know there is more work to be done looking at my pictures, but be patient it in the works;)

I am here to find some feed back on what kind of burner set up some of you might suggest.

My uncle had suggested a round cast iron burner, he said like the Edwards Boilers used to have in them.

Another idea, to eliminate the "WOOF" of the gas kicking in, was a Combustion Blower or Pressure Jet Burner.

Thank you in advance for your time.



  • Building your own boiler?

    WOW,,, I would definitely tread-lightly in this area!!

    I admire your attempt,, but manufacturers test & test again,, get approvals for components to meet the design criteria and then dictate the installation procedure!

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    I agree with Dave...

    You are taking a BIG bite of the proverbial liability sandwich with this. You will have NO homeowners insurance should something go wrong with YOUR boiler.

    No building code authority in their right mind is going to approve the installation, so again, no fire/liability insurance on your dwelling.

    I've done some crazy things in my days, but NEVER anything this crazy.

    I'd strongly suggest you re-consider....

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Maui
    Maui Member Posts: 4
    Hydro Therm Cast Iron boiler

    I am sorry. I was a bit hesitant to post on here, not knowing what kind of "Help" I was going to get.

    I am still optimistic that there might be an older boiler installer that might be on here.

    I was not asking if I should install this system or not.

    As I appreciate your concern, if you have no insight into my question please refrain from commenting.

    My grandfather installed boilers for a living, taking his kids with him to help him(my father). 4 out of his 6 kids have installed their own boilers and they are not in the profession.

    So it is very ignorant of you to assume that just because it isn't a nice clean packaged product that it wouldn't perform up to par. My system will run just fine, I will try to post pictures of the final product.

    Thanks again for your genuine concern and my safety.

  • clammy
    clammy Member Posts: 3,094
    good luck

    Maui not to be hard but slacking 2 hydrotherm boiler on top of each other seems like it is crazy ,you will never be able to get a burner larger enough for it to properly work  nor produce the proper amount of heat and in all likelihood it will condense plus there is only so many BTU's you can fly through that thing with a 8 inch flue collector and don't forget the draft divertor that needs to be installed on top of the collector which from the pics looks like you ain't got enough room for but i could be wrong,those boilers used a standard atmospheric  ribbon type burner, a gun type will not work being there is no chamber .Hydrotherm was a local company near where i live and i have never seem anything like you are proposing either coming from hydrotherm nor in my over 25 years in the field .When all is said and done the eff will be crap and your gas bill will be a small fortune .For less then 2 grand you could get a knock off weil mclean (willamson) be done in 1 day and get at least 81 % eff you will be able to sleep at nite ,if you stay this trail please do yourself a huge favor and get  a good CO detector it would be the smart thing to do being alot of people don't wake up in the morning from CO poisoning .Please don't take offense from my or the other posts i have meet ME and he may not be a old timer but his knowledge is way beyond most in all aspects of heating and he is telling you the truth peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853

    You are entitled to your opinion. I am entitled to mine. You are not required to use or acknowledge my opinion, but to say that I am "ignorant" of your situation causes the hair to stand up on the back of my neck. Especially when there are lives at stake here.

    If stacking sections is such a good idea, why didn't the manufacturer think of it first? Trust me, they did, and after testing realized it was a BAD idea. You have your sections set up in a counter flow configuration. Flue gasses going up, and water going down.

    This means that the coldest water will be in direct contact with the coolest flue gas temperatures, and it IS going to condense itself to death in short order.

    And although I MAY be a rookie compared to your Grandfather and or father, I have 35 years worth of field experience to back my opinion up.

    What I stated about a lack of insurance is FACT. If you don't believe me, call your homeowners insurance company and ask them their opinion. Do the same with the local authority having jurisdiction.

    You also have a conventional brick chimney, and it can not survive the acid attack of the flue gas condensation. It will fail, dropping bricks and mortar into the chimney, blocking the flue gas passage ways, causing a spillage of carbon monoxide, possible loss of life and building.

    No one in their right mind, internet or not, is going to suggest a burner that you can stick in there. If you don't feel that we are giving you the help you are looking for, maybe you should seek help somewhere else. What you are doing is WRONG.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    Very Dangerous

    What you are doing is extremely hazardous and will result in serious damage or injury. Mark E. has given you good advice. You'd be wise to listen.

    I've seen some very poor systems and system designs in over 40 years in the pipe trades, but your "system" surely wins the Oscar for potential catastophic failure.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,314
    on the radiator end of things

    are they steam or hot water radiators? as for your idea with your boiler, I grew up in the trade and we had several resourceful guys that worked for us over the years. They would retrofit old boilers and reuse old burner styles and parts to make boilers they felt were better then they could buy. Truth be told they were never right and often were close to being blown up or driven broke due to the problems they had created. These were some of the best minds I have met in the heating trade and they had two or three generations working on heating and plumbing. Instead of getting bothered by the negative comments please heed the warning.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Maui
    Maui Member Posts: 4
    edited September 2010
    Still learning

    I am still learning, so please I ask of you all patients. I am sorry for flying off the handle. ME it did help when you explained why, instead of just saying not to do it.

    Another question about what I found on the web at http://learnpowerengineering.net/LPE/PartB/Bf02/blrs6005.htm

    "Possibility of enlarging boiler capacity" is what caught my eye. Is this old info?



    ( I was unable to copy the pictures too, so maybe just use the link)

    Horizontal Sectional Cast-Iron Boilers

    Fig. 9 shows a cutaway view of a cast-iron boiler with horizontal sections. The sections are stacked on top of each other and only one nipple connects two sections.

    Figure 9. Cast-iron boiler with horizontal sections.(Hydrotherm)

     Cast iron sectional boiler, cutaway showing water sections

    The nipples are placed at alternate ends so that the water is forced to travel back and forth through the boiler from the bottom up as illustrated in Figure 10 (a). The hot gases travel upwards in a zigzag pattern through the gas passages in the sections, Fig. 10 (b).

    Figure 10. Water and gas flow.(Hydrotherm)

    Objective Two

    When you complete this objective you will be able to…

    List the advantages of cast-iron sectional boilers over watertube and firetube boilers.

    Learning Material

    Advantages of Cast-Iron Boilers

    Although cast-iron boilers are limited in the maximum pressure they can endure, they have a number of advantages which justify their use as heating boilers in preference to steel boilers in many heating systems.

    Some of the advantages are:

    1. The high resistance to corrosion.

    Corrosive conditions, although highly undesirable, may occur on either the water or the fireside of the boiler. Cast-iron offers a higher resistance to corrosion than


    2. The ease of assembly.

    Assembly of the various sections and parts of a cast-iron boiler is quite simple and

    does not require highly skilled, expensive labor as does the assembly of a

    steel boiler.

    3. The choice of assembly location.

    The boiler sections may be assembled at the factory and the boiler shipped as a

    complete unit, or the sections may be shipped separately and the boiler

    assembled at the site.

    Since the boiler consists of sections which can be transported through regular

    doorways, work on a new building need not be held up waiting for the arrival of

    the boiler. This also means that a boiler in an existing building can be

    replaced by a new cast-iron sectional boiler without tearing out walls.

    4. Possibility of enlarging boiler capacity.

    When additional heating capacity is required in a building, another boiler could be

    installed. However, when cast-iron boilers are in use, the capacity of the

    existing boilers can be increased by the addition of one or more sections to

    each boiler, which could mean a considerable saving in money.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,314
    In the information you shared

    you will note that hydrotherm only went so high before starting another stack of pancakes. Why do you think they did that? The information you share is true but it is merely a drop in the bucket for what you will need to design your own boiler. A little information can be a dangerous thing. Condensation in a cast iron boiler if not accounted for will clog passages for combustion gases and lead to failure of the sections. I would also note any source that says skilled labor is not needed to assemble a cast iron boiler is absolutely correct, just as skilled labor is not needed to perform surgery or build a skyscraper. Skilled labor is required to assemble a boiler correctly though.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    If you're willing to learn, we're ready to teach...

    The boiler design you are working with gets 90% of its heat transfer done in the first and second section. That energy transfer is in the form of radiant energy. The balance of the sections constitute the balance of the energy absorption capacity, that being convective and conductive in the balance of the cast iron sections. The additional sections also help produce the stack action necessary to move the flue gas up through the heat exchangers. They have to do this because cast iron is such a poor conductor of thermal energy, compared to some of the other materials used, and partially due to the thickness of the heat exchangers themselves.

    For example, a horizontal tube steel boiler does essentially the same thing, but it may only have 6 tube bundles from bottom to top. A copper fined tube boiler, and a steel finned tube boiler only have one section of heat exchanger, because they are so efficient in transferring the radiant energy form the flames to the water.

    The boiler you are dealing with is designed for a maximum normal operating efficiency of 80%. If you extract more than 80% of the energy available, it causes the heat exchanger to condense, which does a number of things, including rusting out of the actual heat exchanger itself. It also drops water on the running burner, which fouls the burn process, cooling the flames and disturbing the flow path of the combusted gas byproducts, producing a significant and dangerous amount of carbon monoxide, and will plug the flue gas passage ways with a fluffy black, explosive carbon material.

    Under ideal conditions, this gaseous CO is kept within the flue gas passage ways, and is taken out of the house by the chimney. All it takes to upset this delicate balance is a whole house exhaust fan, that can draw these deadly gasses into the living space.

    There is another reason why the heat exchangers are only so tall, and that reason is that you are dealing with an atmospheric burner. It mixes primary air with the natural gas at the face of the burner, then burns that mixture at the face of the burner. As the flames cause the heated air to rise, secondary air is introduced into the flue gas stream, and it has to be specifically proportioned. If the secondary air is too much air, it causes the flames to be quenched, and again, produces a significant amount of CO.

    At the very top of the boiler sections, there is a draft relief hood. The function of this hood is to provide a physical disconnect between the combustion chamber, and the chimney to which it is attached. Without this disconnect, way too much primary and secondary air is drawn into the combustion process, upsetting a very delicate balance, and again, causing way too much CO to be produced.

    By stacking extra sections on top of each other, you will extract too much heat out of the flue gas, and as I explained before, the flue gas will condense in the boiler and the masonry chimney, causing the mortar that is holding the brick work together to dissolve, allowing bricks to fall into the chimney, blocking the chimney, causing CO to spill into the living space from the required draft relief hood.

    In contrast, if the sections had been made of a proper type of corrosion resistant stainless steel that was impervious to the acidic attack of the condensate, AND the flue pipe was made of a similar material that could avoid the attack of the acidic fluids, AND you had a burner that wouldn't see the liquid dripping into and onto the burner, AND you had the ability to modulate the primary air and fuel in a proportional manner to match the boilers output to the real time load, THEN, and ONLY THEN would your idea be acceptable.

    But, if you could do all of that, you would call it a modulating/condensing high efficiency boiler, and you'd have about 150 other manufacturers in the world to compete with. ;-)

    The most that you can squeeze out of the boiler design that you are working with is 80%. The new modcon boilers run 92 to 99% efficient, depending upon how they are used and what they are being used for. I have seen them at 100% efficient for a brief moment on my combustion analyzer.

    Avoiding condensate production is so critical that there are numerous manufacturers of devices that guarantee that the boiler will never see a return water temperature of less than 140 degrees F. These devices insure that the boilers efficiency doesn't exceed the 80% that it is rated for, and that it will not condense in the combustion chamber or the chimney.

    In the dissertation that you presented, it states that cast iron is corrosion RESISTANT, not corrosion free. In the photograph that you provided, I see a reddish rust in the bottom of the combustion chamber. This is what condensate corrosion looks like. EVERY boiler condenses when it is started from a cold start. What is important is how long it is allowed to condense, and that time has to be as short as possible, otherwise the metal components of the boiler, including the burner section, will fail.

    It also states increasing boiler CAPACITY, not boiler efficiency. There is a big difference between the two and the reason that similar sized boilers are piped in parallel, not series.

    Stick around here, and you are guaranteed to learn a LOT of good things. Most of the people frequenting this site have seen the results of other peoples mistakes, and some of us have made mistakes in our journey. I know I have...

    Got questions?

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Maui
    Maui Member Posts: 4
    Back to the begining

    Ok, so I came on here to find out what burner people might suggest to install.

    *I got a VERY STERN response that I will blow up my house. However now you admit that it can be done.

    *How dare I think about stacking two together. So I found some info that backs up my ability to add more "pancakes" to my boiler.

    *Now I am getting told it won't be 99% efficient.

    *Well hold on I never asked anyone that I have a EXTREMELY efficient boiler, nor did I ask if I should stack them together.

    *So the initial negative response I got on here was because ...?

    *I want to make my own boiler, not being extremely efficient, or because I got a boiler for free and for a minimal amount of money I can get a furnace working before winter.

    Of course I am willing to learn, and I agree with a lot of what your saying. It seems like every time you come up with a new speed bump(stacking them together, efficiency)

    FYI- I do have a liner in my chimney, not stainless... but not just mortar and brick either.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    edited September 2010

    I just went back through every post, and nowhere did I see any mention of explosion.

    You have been educated. If you want to continue on your path, purchase numerous CO detectors and place them throughout your home. Keep an eye on the base of the boiler, and the flue pipe, where you will see a white fur growing, indicating trouble. Good luck in your venture.

    It is obvious that you are going to do as you see fit regardless of what you are told by some of the best experts in the industry.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Gordy
    Gordy Member Posts: 9,546
    To Maui

       Why are you so offended??

      I think anyone should be thankful for a 15 paragragh reponse to the dynamics of boiler construction, and operation. To try and help you out.

      These people are not getting paid to help you, but yet take the time to do so because this is what they love to do. Just because its not what you want to hear you are some how offended. 

    These guys are the best of the best. Do yourself a favor, and listen.

This discussion has been closed.