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Anyone heard of a Heiss Masonary Heater/Boiler?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by boatboy63, Aug 1, 2010.

  1. boatboy63

    boatboy63 Member

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    I was just looking around on ebay and saw a "Masonry Heater" mentioned. I know the spelling is incorrect, but that is the way it was listed. It is made by Heiss Heaters and is said to have secondary combustion. The model shown is not listed as a boiler even though it is and is said to have secondary combustion. You can see it at www.heissheaters.com. I was really surprised by the price as it is less than half of a common gasification unit. They are talking about ceramic masonary which I assume means this unit is made from refractory ceramic. They also claim that due to it's "thermal mass", it has the equivalent of 1000 gallons of storage. I have to say all the numbers sound impressive but I don't know how well this would hold up in the real world.

    Just wondering if anyone has seen or heard anything about them. It sounds like a good theory, but I don't want to be a guinea pig. Also, I am in no way affiliated with them but just thought the product was an interesting concept.

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  2. 4acrefarm

    4acrefarm Member

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    looks interesting, but I haven't, heard anything about them. I do like the idea of masonery boilers.
  3. Floydian

    Floydian Feeling the Heat

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    I would be wary of any manufacturer that gives very little meaningful info on how the unit works. They say "secondary combustion"
    but they do not show how this is done. No real info on heat transfer either.
    And then they claim 6500 lbs. of "break through masonry material" is equal to 1000 gal (8300 lbs) of water. This is just not even close.

    Noah
  4. boatboy63

    boatboy63 Member

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    I like the idea too. I want to build a gasifier, as I can't afford to spend $6000+ on a factory built one. All that scares me on one of these masonary types is that the top is sealed and would be hard to get into if there should be a leak. I also wonder what would happen in the event of a crack in the ceramic allowing water to leak back out. I know that the masonary/ceramic (over time) would hold heat longer than steel. I just wonder how they "seal" the water chamber without water contacting any block and getting into the flow system. We all know that block will tend to allow water to seep thru ovr time. I know they are probably using the ceramic refractory to line and seal the block, but all it takes is a small crack to let the water seep. They also claim "Many customers are reporting 16 hours of heat for 2500 square feet on a half fill and up to 24 hours of heat fully filled." Well, I would hope so. From my calculations, their firebox is around 50 cubic feet.

    Oh well, at least it is a new concept that is giving my mind a workout.
  5. Fred61

    Fred61 Minister of Fire

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    The first thing that set me back after clicking on the link was what appeared to be barn door strap hinges on the door. Next was the claim that the heat storage of the ceramic was equal to 1000 gallons of water. I would have to assume that they have developed a material with a superior specific heat than water. I know better than that! The page that was supposed to describe how it works only displayed a couple sample plumbing schematics.

    I would stay away until they wow us with some substancial facts that indicate how the unit works and doesn't cause us to question their claims.
  6. zoecat

    zoecat New Member

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    i may be mistaken but that trailer looks like the type that is used to transport concrete casket vaults.
    if this boiler is being made by a concrete precast company what is their area of expertise and knowledge of boilers?
    just my 2 cents.

    zoecat
  7. emw0932

    emw0932 New Member

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    I agree they don't describe how it works enough for anyone to be willing to buy it, like the heat exchange and what it's made of. I havn't done any calcs but while water does have a much higher specific heat, another material can store just as much heat as long as its Temp differential is larger. Water can't be stored very hot with out alot of pressure, a typical storage tank might be 140 F to 210 F max? Giving you 70 deg temp diff. How hot can refractory get? 2200 deg F? Still, I'm not saying that they're right just saying it's a possible claim.

    Heat storage capacity is proportional to specific heat and temp diff, (they each have equal weight in the equation)
  8. Floydian

    Floydian Feeling the Heat

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    You are absolutely correct. That was a boneheaded comment I made. There I was,all annoyed with a misleading statement, and I went and did the same thing.
  9. DaveBP

    DaveBP Minister of Fire

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    If they are storing their heat at very high temps, what happens when the circulator stops?

    At the price I've seen for castable refractory ceramics I wonder if the majority of all that weight is other than plain old concrete.
  10. Fred61

    Fred61 Minister of Fire

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    Perhaps I'm missing something. I understood by their description that there was a small amount of water in the vessel. If that's the case, what's going on with that water if the surrounding temperatures of the ceramic are at temperatures exceeding 2000 degrees?
  11. HVAC tech

    HVAC tech New Member

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    I bought one of these units. The price is great. I don't see any true gasifaction, rather the same basic concept of all single stage units with different materials. It does hold the water temperature at 130 F for 14 hours with a 20 F outside temperature. My inside temperature is between 70 F to 75 F my home is 24 by 65 two story. The instructions do state that water must be circulating at all times. I have a back up generator here so that isn't an issue. I also replaced the controls on the unit choosing Honeywell over those that came with it. The other nice thing I find is you don't get burns from touching anything but the steel door.
  12. man016

    man016 New Member

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    Dont buy one of these heaters. I did and they dont back the 10 year so called warranty. Not even the original warranty on the componets they installed on the units. And the door is a manufacture defect. You cant install metal into concrete,what happens to metal when it gets really hot? EXPANSION! The one I have is cracked up all around the door. I think a class action law suit may be in order.
  13. Digger873

    Digger873 New Member

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    I went to their factory, they are not using refractory cement.
    They are using specially mixed concrete poured around 1/2 copper pipe.
    They do have an engineer involved and they are improving their design with time, but still it is just concrete and cracking is an issue.
    I had the opportunity to see and touch operating units while I was there.
    I doubt if the thermal mass equals 1000 gal of storage but it certainly stays hot much longer than steel so there are benefits.
    I think its an interesting idea but I wasnt ready to buy one as they still need to work on the mix of concrete or go to a refractory cement mix.
    I have to say their gasification unit worked but by their own admission it used a lot of fuel to achieve the desired results.
    They did tell me they were still working on the design and the unit I saw was not the final design.

    One thing about it, the price is very attractive compared to most others.
  14. Duetech

    Duetech Minister of Fire

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    HVAC tech, I was in a fix for heat and bought one (for a price you won't find now). I would also state that I have had similar results as you though perhaps not as good. Air tightness of the home may have a lot to do with that though.

    To whom it may concern>>>The term "ceramic" could be a loose canon here since firebrick is made in much the way that cement blocks are cast. The cement here is a special mix and the unit is re-rodded and wire meshed and the unit is cast like "ceramic". The problem I see is cracking and wood consumption. I do not know if the cracking will lead to water leaks in the future but at present I don't have a problem with water leaks.
    Having owned a gasifier I would suggest that this heater works more like an older simple catalytic style wood stove where the "extra burn chamber" gives the gases more time to burn before exiting the heater. My unit came with a stated 10 year warranty but I see the new ones only express one year (the last I looked).

    Physically I believe the Heiss heater gets hotter than a regular OWB because the "ceramic" sides allow the fire to get hotter since it doesn't come in immediate contact with the heat transfer source (i.e. steel water jacket). It's more of an "insulated" thermal transfer. From friends with OWB's I think that my heater is probably more responsive to useable heat recovery after a shut down.
    We had a power outage that lasted two days and thankfully I was home at the time. I had just loaded the heater about an hour before we lost power so I removed as much of the wood I could safely handle, shut the air inlet at the blower and pulled the chimney (double wall to replace the single wall that came with the unit) and capped the hole with a plate of steel. That was a Tuesday. Power came back on Thursday night so I restarted the circ and looked for leaks. None were visible by Friday so I decided to clean out the heater and reload. I found coals still going so I just loaded the boiler up and did the recommended break in fire.

    I have put my own aquastat to use to replace the heat control that came with the unit as it did not function correctly and am in process of building a blower cut-off in case the circ stops working. This heater works as an open system. Mathematically I have deduced there is no likely way the unit I have has it's own storage of 50 gallons+/-. The unit is less sensitive to mc but has a much bigger appetite than my gasifier did. BUT... it worked for me, is working for me, is simpler to use and I think the cracks can be repaired and really do not pose a problem because of the re-rod infrastructure. Having spoken to the builder I have wrapped the unit in 1/4" fanfold insulation (except at the chimney and the face of the unit) to improve it's output and reduce atmospheric thermal loss. The door looks weak compared to a standard OWB but seals remarkably well....

    The trailer used to deliver my unit was an old propane tank trailer. Would I buy another one??? For the money I spent it was cheaper that two years of fuel oil but the last word is I would rather build a real outdoor heat on demand gasifier.
  15. man016

    man016 New Member

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    The unit holds about 15-20 gallons at best. Its made of masonary mortor,I was told. I was at there plant not much of a operation. Minnesota man.
  16. Como

    Como Minister of Fire

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    So it is a reinforced concrete box with copper tubing inserted. I can not work out if it has a metal cover, does not seem to be insulated. Sort of looks like an OWB.

    I wonder if they could include a Pizza Oven in the design.

    I am sort of familiar with Masonry Chimneys, they seem to be putting it outside which seems contra logical.
  17. Duetech

    Duetech Minister of Fire

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    man016, I visited there too but did not arrive at a time they were pouring so I did not get to see the "skeleton" but I would be surprised if it had 10 gallons in it. By design it really doesn't need storage in the unit. I opted to use the 50 gallon barrel for storage as that allows me to put the circ at the lowest point in the system and puts the option to monitor refill in the house and not outside. It is more or less a fledgling operation with a very small crew.

    Como, the exterior of the heater is just painted masonry conpound which I have never found to be dangerous to the touch except at the door. Some places are too warm to leave your bare hand for more than several seconds. I use my heater at a cooler temp (150*f) than my gasifier supplied (about 172*f). I believe the wood consumption would go up too much to justify and besides the mfg recommended 155*f as about the max for efficiency.
  18. man016

    man016 New Member

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    The door is not insulated and the frame work sits inside the mortor,the new style. The old style seemed more practical with the door being flushed mounted with hinges mounted to the mortor,less stress. I dont believe they are working with a engineer. I talked with them for a while at there plant,sounded like trial and error. My big issue right now is the warranty they dont practice what they preach. If your going to sell a product stand behind it. MNman.
  19. man016

    man016 New Member

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    cava2k, I asked for a cross section they failed to produce one or even describe it.
  20. Como

    Como Minister of Fire

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    It was -18F here last week and the wind was howling.

    Wouldn't the heat loss from an uninsulated 'radiator' this size be massive?
  21. man016

    man016 New Member

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    como,I put mine in a small shed blanketed with R-30 insulation and at times it struggles. Minnesota man.
  22. Duetech

    Duetech Minister of Fire

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    man016, It seems I have the older model as my door is flush mounted and as you say uninsulated and +1 on the waranty issue. How you gonna stay in business if you don't have follow through? I'm still learning the characteristics of the heater but I still want a gasser.
  23. bigburner

    bigburner Feeling the Heat

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    my biggest concern would be the construction of the heat exchanger. would like to see a shop drawing. Portland cement in a non load bearing situation will hold up pretty well once all the water evaporates out of the mix, a slow cure will prevent explosive spalling. 1800F is what I have read, I have a poured wall lined with fire brick and I have had it to 1000F with no issues. Rebar and concrete expand and contract at exactly the same rate for all intentional purposes. I like the design as a starting point, would be fun to expand on the base product. The unit is a simpler poured version of a Russian wood boiler. The brilliance of the design is an encapsulated heat exchanger, if you GW and Steon guys had a version of this, no fouling. just got to get the design right for heat transfer, this unit probably ides pretty well also. The guys with cracks, some ram refractory or if they are small just spread on some mortar, the box should always be negative any way.
  24. bupalos

    bupalos Member

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    It's a great principle, both on the burning and storage side. But all the devils would be in the details. The biggest ones are concrete breakdown from thermocycling, and where and how is the pressure relieved if the water does stop? I guess the pipes could generate (and handle) huge pressures being encased in concrete, but wherever it did blow could be interesting. I suppose the heat migration into the water would be sort of slowish.... Definitely to make any sense the whole thing needs to have radiant barrier and much more heavily insulated than water tanks. You're talking about a delta T several times higher. I think you'd start at 12" of fiberglass and go up from there.

    Isn't embedding copper directly in cement supposed to be a no-no? am I thinking of something else?

    Very interesting all around that these are out there operating. Sounds like people are having some success even treating them as regular boilers.
  25. Duetech

    Duetech Minister of Fire

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    bigburner & bupalos, There is no direct "fire to piped water" heat exchanger in the unit I have. All the pipes are encased in the concrete. It's just a cement burn chamber with a 6" hole in the upper portion of the burn chamber, near the door, to let the exhaust out. That hole goes through about 4" concrete and does a 90* and proceeds topwards the rear of the heater then 90's up through the roof. From what I have gathered here and from the mfg the heat is extracted from the heated concrete via copper pipes. Via the mfg... concrete is not friendly to copper if there is water present to cause a reaction between the copper and concrete. Once heated the boiler/heater should be dry (that does not say much for the off season though).
    This is an open system with no pressure. My circ draws from the res. (lowest point in system) in my basement and flows to the boiler and back. Theoretically in an over heat situation there are no obstructions to prevent the boiler from venting back through the pipes creating some splashing (and possible pex melt down via steam) and so should not experience a rupture due to trapped water in the system. Over heat can occur if there is a circ malfunction and the blower continues unchecked, so a blower shut down safety switch keyed to water flow would be wise. Via standard operation the blower draft plate is only open far enough to allow the boiler to work properly. "Drafting" incase of power outage would probaly not occur as long as the blower draft plate is not wide open (and possibly not even then). As well water level must be monitored but since the water only gets a chance to evaporate into the home and not the atmosphere there is not much evaporative water loss as compared to an OWB. I am only seeing about 3-5 gallons per 7-10 days.

    Shut downs for what ever reason have allowed air to get in to the system but the flow from my Taco 007 was able to over come any trapped air and purged the system. My sidearm dhw exchanger and my air/water exchanger are set up in "counter flow" orientation.

    Como, Yes there is heat loss and insulating the unit would be a great plus but because the concrete is semi insulative by design the heat loss is nothing compared to an OWB with bare steel exposed. In general there are only a couple of hot spots on the boiler (i.e. the uninsulated door and the chimney) and though I have felt greater warmth pockets towards the back of the boiler and the left wall adjacent to the blower inlet but outside of the door and chimney i have found nothing to create serious concern. 12" insulation like bupalos suggests would probably make one LARGE improvement on fuel econmy.

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