# Anyone heard of a Heiss Masonary Heater/Boiler?



## boatboy63 (Aug 1, 2010)

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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## 4acrefarm (Aug 1, 2010)

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


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## Floydian (Aug 1, 2010)

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


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## boatboy63 (Aug 1, 2010)

4acrefarm said:
			
		

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


 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.


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## Fred61 (Aug 1, 2010)

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.


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## zoecat (Aug 2, 2010)

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


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## emw0932 (Aug 4, 2010)

Floydian said:
			
		

> 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



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)


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## Floydian (Aug 5, 2010)

eman717 said:
			
		

> Floydian said:
> 
> 
> 
> ...



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.


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## DaveBP (Aug 5, 2010)

> 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.



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.


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## Fred61 (Aug 5, 2010)

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?


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## HVAC tech (Nov 3, 2010)

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.


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## man016 (Jan 2, 2011)

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.


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## Digger873 (Jan 2, 2011)

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.


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## Duetech (Jan 2, 2011)

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.


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## man016 (Jan 3, 2011)

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.


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## Como (Jan 3, 2011)

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.


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## Duetech (Jan 3, 2011)

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.


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## man016 (Jan 3, 2011)

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.


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## man016 (Jan 3, 2011)

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


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## Como (Jan 3, 2011)

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

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


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## man016 (Jan 4, 2011)

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


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## Duetech (Jan 4, 2011)

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.


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## bigburner (Jan 4, 2011)

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.


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## bupalos (Jan 4, 2011)

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.


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## Duetech (Jan 5, 2011)

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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## man016 (Jan 5, 2011)

The blanket of insulation I used is over the burner. The door front is exposed,


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## bupalos (Jan 5, 2011)

Yeah I thought the pipes were all encased. It really is intriguing as it solves some big hydronic problems. So how hot does the outside of the thing get at it's hottest? I mean, does the whole block get to 300 degrees if you don't pull a bunch of heat off it? It's hard to see how it accounts for much storage if it doesn't get pretty hot. 

I guess this theoretically sounds like an excellent idea, I just don't know why the concrete wouldn't just go to pot in a couple years if it's not refractory. Do you really mean the whole thing is cast of the same material? So the firebox itself is just portland mortar? Isn't it spalling? 

Also I don't know why, with this approach, there wouldn't be a lengthened flame path ala a regular masonry heater. Do you know your exit temps?


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## Duetech (Jan 5, 2011)

bupalos said:
			
		

> Yeah I thought the pipes were all encased. It really is intriguing as it solves some big hydronic problems. So how hot does the outside of the thing get at it's hottest? I mean, does the whole block get to 300 degrees if you don't pull a bunch of heat off it? It's hard to see how it accounts for much storage if it doesn't get pretty hot.
> 
> I guess this theoretically sounds like an excellent idea, I just don't know why the concrete wouldn't just go to pot in a couple years if it's not refractory. Do you really mean the whole thing is cast of the same material? So the firebox itself is just portland mortar? Isn't it spalling?
> 
> Also I don't know why, with this approach, there wouldn't be a lengthened flame path ala a regular masonry heater. Do you know your exit temps?



The recommendation by the mfg was ideally limit max temp to about 155-160*f. Because of the insulative quality of the cement the exterior might get a couple of mediocre hot spots (i.e. some where you would not want to leave your hand but that depends where the fire is at in the combustion chamber) but otherwise about 110*f on mild days cold days it's a bit cooler. We have a couple of outside cats that love to sit close to the sides of the unit so you know they would not do that if it was too hot. No I do not know the exit temps but I had to go to a double walled chimney pipe to prevent creosote blockage of the chimney and sometimes the double wall is too hot to handle with bare hands.

The unit comes with its own temp regulator (I replaced mine with an aquastat and relay that came off my gasifier) that controls the blower. The mfg recommends the smallest opening for the blower draft to get the boiler working and there is a damper in the chimney. My unit is  a little over 4' tall and the upper foot or so is a dedicated extended burn chamber of sorts but I would think it oly adds about 3' to the burn path. There is no firebrick in the unit but it is not just portland but a proprietary blend . 
The mfg gives directions for "tempering" the unit with a slow fire for the initial burn and every burn after that where the unit has had a time to cool down. 

My sincere opinion on the thermal storage is different than the mfg as I think it is the coals that are in the ash that gives the unit it's thermal output range. When I go to clean the unit I have to start by not adding wood and just rake the coals and unburned charcoal in a pile in front of the blower port several times. As long as it is not windy I can get 6 or 8 hours of very usable heat before shoveling the ashes out. I do have some cracks in my unit that are a little displeasing to say the least. But if in iterperet spalling correctly I have no chips or flaking of the composite mortar.
Bear in mind I bought this unit in 2010 and this is my first season with it.

The circ runs 24-7 so there is always a potential heat draw on my system as I have a water/air hx and a sidearm on my lpg dhw. But when the water is up to temp there are times that the relay indicates the blower is off and I have gone to the unit and found the blower off. I know the blower has been off in excess of an hour durning heat draw but I do not know how much longer. I am in process of building a blower circuit interupt keyed to water circulation so I don't have to worry about circ failure and thermal over heating with the unit.

The unit design has fostered ideas for me and I want to try my hand at a true gasifier that leans toward idle time and hot water on demand and no real storage eventhough storage could and would be an option. Gasifiers are easily more picky with the wood you burn but have a much quicker response time and lower wood consumption. The link in this thread will put right on the Heiss web site and I have never had a problem getting a response from Mr. Heiss.  :roll:


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## bupalos (Jan 6, 2011)

That kind of clarifies that the mass of the boiler probably really isn't really providing all that much storage. If I understand you correctly, it sounds like the outside gets maybe 100 so I'd guess the whole mass averages less than 250. It also sounds like a lot more heat is leaving the thing through the stack than a masonry heater, which you'd expect if you're talking about maybe 5'-6' of masonry flame path. But I see no reason this can't be reconfigured with a faster burn and longer path.

I really think this approach is interesting though and probably where boiler tech will go in the next 10 years. This is a "solid state" garn. Combustion can be very simple and very efficient. Makes total sense, but you need the right materials. Please do keep us updated on how the "cement" holds up. What does it seem like? Is it like firebrick or what?


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## bupalos (Jan 6, 2011)

BTW do you know the total weight?


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## Duetech (Jan 6, 2011)

The model which I have (middle of the road) was supposed to weigh in at around 4500lbs. He said the trailer he was using was rated at 5k. I built a block pad that he backed over and positioned the boiler on. At the time I bought mine he said the bigger model had to be built on site.

Compsition is more like concrete but you can see little "hairs" protruding out from the surface when you first get the unit. Glass impregnated??? I don't know if any refractory cement is blended into the mix.
You could be right on the mass average temp. In the box it is probably hotter than an OWB though. There is no "shaker grate" or an ash clean-out door so the ash tends to chike out some of the coals. Air distribution on my model is offset of the left side. I have opened the blower damper plate to force more air in to the chamber and the uint heated up faster but it also goes through the wood a bit faster. Will try to keep you posted on the cracks.


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## man016 (Jan 6, 2011)

The unit works just like a instant hot water heater,nothing more with no storage. I installed a primary storage tank, 40 gallons with temp, built a side arm, 3/4 encapsulated in a 1 1/4 x 5ft,  threw the A/W exchanger, then in floor heat loop to a secondary storage of 40 gallons. My storage tanks consist of used hot water heaters. two pumps run the system, one for the loop and one for the floor heat. Believe it or not I have drawn up to 25 hours of heat at 20 degrees. At 6 below and 20 below wind chiil this week Ive pulled 14 hours on a fill. And by the way the whole system is tucked away in my basment. The dampner on the combustion fan is half way,and yes the cracks...Minnesota man.


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## HVAC tech (Jan 9, 2011)

Thanks for the input on the unit. I feel a unit isn't a gasifier if it only has one stage. the gases don't burn as completely as a two stage unit. I've had no trouble with my door though the gasket had to be replaced within a month when I first got it. What prices are they going for now? I see most these outdoor units going down in price rather than up. I was going to add the insulation to the outside, but as I have a woodshed built around it the heat keeps the wood dry and me warm when I go stock it up. The building stays about forty degrees inside with only the stored wood for insulation. It's minus 5 here today and my unit is keeping me warm using about a rick a week. That's about the same as everyone else, so though high I can't complain. What water temperature are you using?  I have never had any confidence in "warrantees" . That was another reason I liked to unit as repairs can be made with furnce and retort cement.


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## man016 (Jan 9, 2011)

I payed $2500. The aqua stat is set at 145 which coincide with the temp gauge on the primary storage tank. Do you have the new style door? . About the warranty I had a faulty aqua stat It took two weeks,but they sent one.


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## HVAC tech (Jan 11, 2011)

I don't think so I bought mine last year, The door works fine but the gasket glue didn't hold. I bought a better gasket and better glue, havn't had any problems since.  I replaced the aquastat when I installed the unit. I had a Honeywell remote unit so I use that set at 140, I am satsified with what I got for my money. There are tons of outside woodburners but not to many for such a reasonable price. Many of my friends here have steel units that only last about about five to seven years then the steel gets so thin they can't repair them any more. I've repaired a lot of heat exchangers similar with retort cement and if I need to repair it I have silver solder to use instead of soft solder so I can repair this one for years if needs be. I also added extra water capacity to the system. Being shielded from the wind in the woodshed is a nice plus for me all around. I'll keep you informed of any major problems or adjustments that improve performance.


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## RickH (Jan 13, 2011)

Do the tubes that are incased in the concrete, wrap all around firebox? Are they in the bottom of it? Just to compare on a 20 degree day with my Seton i can maintain 170 degree water for maybe 6 hrs max. I will have coals for maybe 8 hrs, but thats it.I am using a HX in forced air, 2400sf, new construction. To say the least I am very dissapointed. Cant even consider to try to heat my shop. Thanks

Seton w-90


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## Duetech (Jan 14, 2011)

The owners is not too expressive where the heat tubes are located. I used an EKO40 to heat my home for four winters. Loved the output and generally had water in the 170's. The firebox was too small to make me real happy but the house temp was usually kept around 70-72while home and 68-69 while out. With the Heiss the temp is kept around 68-69 and 66 when we leave. The difference in wood consumption between the two will keep you jumpin' with the EKO the most economic to run. However the 14 hr+ burns with the Heiss are nice. Comparatively the Heiss model I have has a firebox 4x what the EKO does. An EKO with adequate storage is by far a more efficient system. Heiss says to insulate thier heater to extend loading intervals. I have used a little on my for test purposes and have seen an improvement. Would like to put about 2" mineral on it and see what will happen to the wood consumption. 

Isn't Seton and GW more or less the same?


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## RickH (Jan 14, 2011)

The Seton only has exposed tubes in top and down back. 4-6 hrs on a load and only 66-68 in house is not a good thing. When it gets real cold (10 & below for us) you might as weel turn gas back on. Why did you switch & would you buy another Heiss? The price is very attractive. Do you have the storage tank they supply with it in  use? Thanks for the info


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## DaveBP (Jan 14, 2011)

I just got home this this early AM from work so maybe I'm missing something in this thread... wouldn't be the first time. 

Isn't this thing just a welded steel wood stove with copper tubing wrapped around it then dropped into a mold box and encased in concrete?


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## Como (Jan 14, 2011)

That is how I read it.


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## Digger873 (Jan 15, 2011)

> Isnâ€™t this thing just a welded steel wood stove with copper tubing wrapped around it then dropped into a mold box and encased in concrete?



Nope, no welded steel anything. Its just a concrete box (reinforced with rebar) with 1/2" copper tubing poured in to the concrete. I know the pipes are in the sides but it was never clear if they were in the top or not. I dont think they were.
They form the firebox with 2x4s and osb plywood and then burn the forms out.



> I am using a HX in forced air, 2400sf, new construction. To say the least I am very dissapointed. Cant even consider to try to heat my shop. Thanks
> 
> Seton w-90



Isnt a W-90 only a 90,000 BTU boiler. I would think 2400sq ft is probably using most if not all of that 90,000 BTU's.
I could be wrong but my 1450 sqft house has a 55,000 BTU heat load at 20F.


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## man016 (Jan 17, 2011)

I was told the tubes end up in the top. Most of the heat is in the top with the extra heat chamber,make sense?


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## mlbeardsley (Apr 4, 2012)

I bought a unit several years ago and for the price you cant beat it. I bought their middle sizes unit that was said to do 3000 sq ft. My house is 2500 sq ft and a 500 sq ft garage. My piping underground was sorry to say only wrapped in fibrglass batting and is probably soaked and keeps the grass green all winter. im sure im losing alot of heat in the ground but my unit doesnt go through that much wood, about 7 cord. I keep the house about 76 degrees and the garage around 60-65f. My friend bought a new one and they are 100 percent refractory to take the temp and are insulated. They also have flow switches incase water flow stopped and digital aquastat. the door is now insulated as well. the units look nice and may trade my old one for a new one. I have had a blower go bad last season and they sent one out the next day. I am pretty happy with their product.


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## tom in maine (Apr 4, 2012)

Although this is an interesting concept, unless you can use the heat off the shell of such a massive unit like this, you are really taking a beating in efficiency. And, as someone else mentioned, copper and concrete are not really that compatible.


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## 456wood (Apr 4, 2012)

I also am interested in the concept. Insulation would be a huge plus if its outside.  
Mlbeardsley  does your unit not smoke much like they advertise?


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## maple1 (Apr 5, 2012)

My thoughts, along the same lines as some others, are that it looks like a very good concept. If you could put one of these inside in your basement, I think they would be hard to beat for efficiency - there has to be some large-ish losses having one outside. But even then from some info posted by users here on wood consumption etc., they don't seem to be doing that bad outside. With well installed undergound piping & extra insulation around the unit, I'd be tempted to try one. Wonder how much their 'Eco Extreme' gasser is? Even better if it gets put in an outbuilding that you want/need some heat in anyway.


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## 456wood (Apr 5, 2012)

If one was to somehow retrofit a firebrick lining into the firebox should add some life to it. Although this would slow heat tranfer  I wonder if it would add much thermal storage (less idling). But then again it may be harder to hit design temp. Any thoughts? Also seems like it would be fairly easy to pour another section on top to extend flame path. Would have to add more copper pipe though.


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## ISeeDeadBTUs (Apr 5, 2012)

I think its called a Fleiss heater . . . and it's not hott at all


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## woodsmaster (Apr 5, 2012)

maple1 said:


> My thoughts, along the same lines as some others, are that it looks like a very good concept. If you could put one of these inside in your basement, I think they would be hard to beat for efficiency - there has to be some large-ish losses having one outside. But even then from some info posted by users here on wood consumption etc., they don't seem to be doing that bad outside. With well installed undergound piping & extra insulation around the unit, I'd be tempted to try one. Wonder how much their 'Eco Extreme' gasser is? Even better if it gets put in an outbuilding that you want/need some heat in anyway.


 
 If the double wall pipe is to hot to touch it can't be very efficient. The heat is going out the chiminey.


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## mlbeardsley (Apr 6, 2012)

tom in maine said:


> Although this is an interesting concept, unless you can use the heat off the shell of such a massive unit like this, you are really taking a beating in efficiency. And, as someone else mentioned, copper and concrete are not really that compatible.


  Concrete used to use flyash and that used to cause problems with copper and concrete. The fact is that the concrete is alkaline and very dry so the corrosion wont happen. The unit is controlled by an aquastat and smolders most of the time storing heat. when my furnace draws heat it pulls that stored heat off.  When the water temp falls it kicks the blower on and will bring the temp back up. I have had it for several years and dont even clean it out in the summer. Its a great idea that works.


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## mlbeardsley (Apr 6, 2012)

456wood said:


> I also am interested in the concept. Insulation would be a huge plus if its outside.
> Mlbeardsley does your unit not smoke much like they advertise?


 My unit will smoke at first when its first started up and cold but when its hot inside the firebox the secondary burn will kick in very fast and just have heat waves coming out. I dont get much creosote because the firebox gets so hot which helps with getting the heat out of it. The exhaust goes through a baffled system that pulls the heat off.  I know they insulate them now but mine was bought when they didnt offer it so i used double foil fire resistant foam and use half the wood.


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## zufrieden (Jul 1, 2012)

To those of you that are using this for a few years.  How is it now that you have had it a few seasons?  Are there any major concerns?  I saw this and am considering one as my first outdoor boiler.  
Thanks


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## stee6043 (Jul 5, 2012)

zufrieden said:


> To those of you that are using this for a few years. How is it now that you have had it a few seasons? Are there any major concerns? I saw this and am considering one as my first outdoor boiler.
> Thanks


 
I do not have any experience directly with these boilers but I would strongly recommend anyone do a bit of reading on available wood heating appliances before making a purchase as big as this one.  I personally am learly of the claims made on their website and don't see how they can be even remotely efficient.  If you'd like a quick barometer of the company I'd suggest you call them and ask for details on their "guarantee" regarding being the lowest maintanance boiler on the market.  And compare their warranty to others.  That's where I would start if I were in the market and considering this unit.


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## Northstorm (Dec 31, 2012)

I recently bought the standard model 5000 (Fall of 2012).  It has updated most of the features that many of you complained about.  It now has a honeywell digital aquastat.  It now has a flow meter to turn off the blower in case the pump stops working.  The door is very solid and INSULATED on the inside.  The insulation on the outside of the entire unit I assume is equivalent to putting it in a shed.  There is a small release valve at the top of the unit for any trapped bubbles in the internal coils, but concerns about high pressure really don't apply to an open system like this, since the water returning from the heat exchanger runs into the indoor storage tank, releasing any bubbles and preventing any pressure build up. At the end of each cycle the bubbles are released and a new cycle starts by sucking up the less turbulent water at the bottom of the tank.  The blue pex hose removes water with the aid of a pump that runs continuously pushing it thru the flow-meter (which keeps the power switch to the blower activated), and runs into the heater thru the copper coils.  It gets very hot fast since it only has to heat the hot water running thru the coils rather than a 200 gallon storage tank.  The negative side is that without a huge supply of hot water, it (the water) cools down quickly once the coals get low. 
Northstorm


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## HeissHater (Mar 12, 2013)

Hey everyone out there wondering about heiss heaters, do your research and choose another company I have owned a 2010,2011 and now a 2012 model 3000 unit. I replaced first two units because of failures with the products heiss sells you, such as pump failures and them using me the customer as a guinea pig to improve their product. I have had to do more research to educate myself along with Heiss on why I had my numerous issues. My 2010 model was the first one they actual insulated on the exterior and the copper pipes inside were all soidered, well I had a circulating pump failure(which creates diesater for the boiler) and the boiler overheated resaulting in the soidered joints to come apart and crack the boiler, which released all the water and delaminated all the insulation. Boiler now destoyed in 3 months of ownership they tell me they will be releasing a new boiler for 2011 called the elite series but I will have to pay for the upgrades( which I thought was complete BS) so I agree just so I would have a boiler again. Well I waited 3 monthes for the new boiler, now it is middle of July and I finally get the new boiler and was so upset about their comnication and ignoring my calls. Found out they were filling other new customer orders before getting mine!! I start new season with new unit again and 2 months in the season my heat exchangers plug up with scale out of my lines from sitting over the summer. This resulted in another over heat of the boiler,this time the lines inside stayed togather because they said they braised in the new units, but the exterior insulation exploded off it. the unit was fuctional but not hold heat as well. Being only the second year with a boiler I asked Hiess what would cause this scale build-up in my system. They had now idea and told me they had never seen this before, but they would have a water test done for me to figure it out. NEVER HAPPENED!! So I do my own research and find out that most boiler companies have water testing to know if you need any type of chemical assistance. Come to find out my hard water was what caused the scale to build-up over the summer and eventually pluged my heat exchangers. I call them about the flow control switch that was suppose to come with the Elite series, but mine didn't??? They told me I would have to purchase it from them. Again complete BS in my mind With many phone calls about my destroyed unit and telling them I was going to take action against them if they did not resolve my problems we finally came to a conclusion. Another new unit went into the works, this time I waited another month for the new one and still had to pay for an upgrade again!! Now with a 2012 unit I just had my whole front door and door insert laying on the ground. To make a very long and aggrivating story short.....THREE STRIKES AND THEY ARE OUT I am done with this company


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## outdoorlover83 (Apr 27, 2013)

HeissHater said:


> Hey everyone out there wondering about heiss heaters, do your research and choose another company I have owned a 2010,2011 and now a 2012 model 3000 unit. I replaced first two units because of failures with the products heiss sells you, such as pump failures and them using me the customer as a guinea pig to improve their product. I have had to do more research to educate myself along with Heiss on why I had my numerous issues. My 2010 model was the first one they actual insulated on the exterior and the copper pipes inside were all soidered, well I had a circulating pump failure(which creates diesater for the boiler) and the boiler overheated resaulting in the soidered joints to come apart and crack the boiler, which released all the water and delaminated all the insulation. Boiler now destoyed in 3 months of ownership they tell me they will be releasing a new boiler for 2011 called the elite series but I will have to pay for the upgrades( which I thought was complete BS) so I agree just so I would have a boiler again. Well I waited 3 monthes for the new boiler, now it is middle of July and I finally get the new boiler and was so upset about their comnication and ignoring my calls. Found out they were filling other new customer orders before getting mine!! I start new season with new unit again and 2 months in the season my heat exchangers plug up with scale out of my lines from sitting over the summer. This resulted in another over heat of the boiler,this time the lines inside stayed togather because they said they braised in the new units, but the exterior insulation exploded off it. the unit was fuctional but not hold heat as well. Being only the second year with a boiler I asked Hiess what would cause this scale build-up in my system. They had now idea and told me they had never seen this before, but they would have a water test done for me to figure it out. NEVER HAPPENED!! So I do my own research and find out that most boiler companies have water testing to know if you need any type of chemical assistance. Come to find out my hard water was what caused the scale to build-up over the summer and eventually pluged my heat exchangers. I call them about the flow control switch that was suppose to come with the Elite series, but mine didn't??? They told me I would have to purchase it from them. Again complete BS in my mind With many phone calls about my destroyed unit and telling them I was going to take action against them if they did not resolve my problems we finally came to a conclusion. Another new unit went into the works, this time I waited another month for the new one and still had to pay for an upgrade again!! Now with a 2012 unit I just had my whole front door and door insert laying on the ground. To make a very long and aggrivating story short.....THREE STRIKES AND THEY ARE OUT I am done with this company




Just shut our model 3000 down for the year! Worked great!  Ash is a chore to clean but only had to do twice last winter. Not looking forward to whats in it but was told it won't hurt it.

Sounds like Heiss Heaters was more then fair with you. Its your responsibility to test your water. We did andand found we had hard water. We used a family members water to fill it.
Did they fix your door right away? Is the unit working good now?
Thats amazing that you plugged it up and over heated it and it still worked.


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## TCaldwell (Apr 28, 2013)

looks like this design is a large greenwood


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## BoilerMan (Apr 29, 2013)

TCaldwell said:


> looks like this design is a large greenwood


Thats what I was thinking.  Only with a cast in HX. 
We all know what the GW/Seatons do with no provision for secondary air..........
TS


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## Gravel Roads (Dec 19, 2013)

zufrieden said:


> To those of you that are using this for a few years.  How is it now that you have had it a few seasons?  Are there any major concerns?  I saw this and am considering one as my first outdoor boiler.
> Thanks


I've had mine for three years. Each year I've had them out for repairs, and even if the part is under warranty, they charge a hefty service charge. I'm 3 years in now and I wish I had never purchased this unit. It regularly needs cleaning due to soot build up. This year I have started having smoke leaking through the handles that they used to lift it off the truck. I also have smoke leaking through the new door that they installed last year for $250. As soon as I can, I plan on spending the money on something that doesn't break so frequently


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## Gravel Roads (Dec 19, 2013)

boatboy63 said:


> 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.


I have had mine for three years. I was okay with it the 1st year. Not so much the 2nd year, and this year, the siding is cracking and leaking smoke. When I sent a complaint to the company, they suggested that I clean the stack. When I told them that I had JUST done this, they didn't respond. I wish I had purchased something else


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## Gravel Roads (Dec 19, 2013)

boatboy63 said:


> 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.


I bought one three years ago. In my opinion, it's junk


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## kuribo (Dec 20, 2013)

I have heard and read a lot about these boilers. All bad. Buyer beware.


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## Gravel Roads (Feb 16, 2014)

mlbeardsley said:


> My unit will smoke at first when its first started up and cold but when its hot inside the firebox the secondary burn will kick in very fast and just have heat waves coming out. I dont get much creosote because the firebox gets so hot which helps with getting the heat out of it. The exhaust goes through a baffled system that pulls the heat off.  I know they insulate them now but mine was bought when they didnt offer it so i used double foil fire resistant foam and use half the wood.


I need to be fair here, I bought one of the first units, and for them it was a learning curve. I heard that they changed their design and that the newer stoves are better. Even with the problems that I've had, I can say that the unit paid for itself already, and it's still out there heating my home today


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