Post in 'The Boiler Room - Wood Boilers and Furnaces' started by boatboy63, Aug 1, 2010.
The blanket of insulation I used is over the burner. The door front is exposed,
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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:
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?
BTW do you know the total weight?
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.
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.
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.
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.
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.
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
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?
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
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?
That is how I read it.
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.
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.
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?
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.
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.
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 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 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.
I think its called a Fleiss heater . . . and it's not hott at all
If the double wall pipe is to hot to touch it can't be very efficient. The heat is going out the chiminey.
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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