EKO or Econoburn?

[Father John]

I would greatly value an opinion on the merits/need of water storage. Our monastery will be installing a wood gasifier to heat our hydronic radiant floors, and have been looking most seriously at EKO and the Econoburn. The importer for the EKO very kindly explained why a storage tank was so valuable, and it made great sense to me. The people at Econoburn kindly explained why a storage tank wasn't needed really, and that also seemed reasonable.

Is the technology that different between the two boilers or is something else at play here?

Many thanks for the help.

 

[Grover59]

I am at this time building a storage tank, I ran last year without it, and I was fine I have a Black Bear Boiler which works much like what you are considering. I want the storage because it will allow me to be more flexable as to when I have to stoke the boiler. In my opinion the tank would work great with radiant floor heat because you can bring the temp of the tank down lower and still get usable energy from it. If you seach here in this forum you will find many threads and comments on why or whynot a storage tank.

Steve

 

[Eric Johnson]

Welcome to Hearth.com and the Boiler Room, Father John. I'm glad to hear that your monastery is serious about wood heat and wood gasification.

I think gasifiers and hot water storage tanks are made for each other, especially in a warmer climate like you're likely to see in southwestern Virginia.

The reason you want storage if you can afford it is that modern gasifiers such as the EKO, Econoburn and Tarm run most efficiently and cleanest when going full-bore. So if you can run them at the optimum level in any weather, and stash any heat that you don't use immediately into the tank for recovery later, you're going to use less wood, create little-to-no smoke and extend the life of your boiler. Think of the hot water storage tank as a battery.

In my opinion, the reason manufacturers and dealers tend to downplay the need for a tank is that most customers have enough trouble getting over the sticker shock of the boiler and installation cost alone, and it's hard to make the case for spending half again as much for a tank. I think they assume, rightly so, that once you get the boiler and realize the potential of the tank, you'll add it later. And that's not an unreasonable approach. I don't have my tank working yet, so I'm running my EKO without it, and it works great. It will be even better with a tank, but it's not absolutely necessary. I look at the tank like cruise control and air conditioning in a car: You don't need it to get from Point A to Point B, but it sure makes those long summer drives a lot more bearable.

So, you were getting an accurate answer from both people. There are no fundamental differences between those two boilers that I'm aware of. It's just a different sales approach, IMO.

As Maine says, there's a lot of discussion of the relative merits of storage tanks in this forum, both from people who are using them, and those who are not. I don't think we have any Econoburn users onboard yet (one dealer, who may be using one), but it's just a matter of time. Plenty of EKO and Tarm owners, too, plus a number of other brands you might be interested in learning about.

 

[Nofossil]

I'll echo the comments by Maine and Eric. I'll also suggest that there's more planning and engineering involved in sizing and setting up a storage tank and the associated heat exchangers. Again, lots of discussions in other threads. It's something where it may be difficult to find anyone in your area with the experience to do it for you, so dealers may fear that suggesting it might scare you away.

It's worth doing a heat loss study and determining both peak and average heat loads. From that, you can determine how long a tank of a given size could heat your building. Tanks are great, but too small a tank may not be worth the aggravation.

 

[kuribo]

Nofossil-

could you tell me what your heat loss is at your design point, and what outside temp you are using for your design point? Thanks....

 

[Father John]

Eric, thank you very much for the explanation of the dealer's attitude about storage. I am trying to determine storage type and size right now, since we will be using some of the aerated concrete blocks left over from the monastery construction to build a boiler/wood storage room off the end of the garage. I am wondering if the aerated concrete (because of its thermal mass inertia) would be a suitable material to use for a tank, or would epdm lined plywood be better?

Also, is a flat plate hx suitable for a 1000 gals tied to an EKO 80, or are copper coils/loops required?

Thanks again for the valuable opinions.

Father John

 

[Father John]

Sorry to ask a well worn question. I have only just found the discussion about cinder block walls and swimming pools for tank material.

Although our total area is over 11,000 sq. ft., our total panel output is 228,255 Btu/h, and the total panel back loss is 48,347 Btu/h. There are 14 zones in the building, each zone with its own manifold, circulator, circuit setter for flow control and attached to the boiler loop with 2 Grundfos injection mixing pumps (that is, half the zones on each injection system). The system was ably designed by Embassy Industries, but installed by us, so not a professional installation. Everything seems to work as planned though.

I am curious to know exactly what info I will need to measure to size the storage tank and determine type/size of hx?

As far as average loads go, the system currently has 2 Burnham V84 oil boilers attached, each rated I think at 144,000 Btus. Since our design temps were 0 degrees outside and 70 inside, we have never run more than one boiler at a time. We planned to put in the wood fired main boiler when construction was over, but with oil prices what they are I think time spent in the woods is more than justified now.

 

[Eric Johnson]

Beautiful setup, Father John. I'll wait for the heating pros to comment on the specifics, but methinks you will want more than 1,000 gallons of storage if you can swing it. We also have one member, leaddog, who is running an EKO 80. Hopefully he will provide some insight, too.

As to a flat plate vs. copper, copper is the tried and true, but I think an external hx like a flat plate has potential. But there are basic differences between the two approaches that you need to consider, probably with the help of someone with a lot more experience than I have. The good news is that you size the hx to the size of your boiler, not your tank, so a bigger tank does not mean more expensive copper or a bigger flat plate.

 

[Nofossil]

Nofossil-

could you tell me what your heat loss is at your design point, and what outside temp you are using for your design point? Thanks....

My design is based on a peak heat loss of 30,000 BTU/hr at -20 degrees. Seems about right based on actual experience.

 

[Nofossil]

Sorry to ask a well worn question. I have only just found the discussion about cinder block walls and swimming pools for tank material.

Although our total area is over 11,000 sq. ft., our total panel output is 228,255 Btu/h, and the total panel back loss is 48,347 Btu/h. There are 14 zones in the building, each zone with its own manifold, circulator, circuit setter for flow control and attached to the boiler loop with 2 Grundfos injection mixing pumps (that is, half the zones on each injection system). The system was ably designed by Embassy Industries, but installed by us, so not a professional installation. Everything seems to work as planned though.

I am curious to know exactly what info I will need to measure to size the storage tank and determine type/size of hx?

As far as average loads go, the system currently has 2 Burnham V84 oil boilers attached, each rated I think at 144,000 Btus. Since our design temps were 0 degrees outside and 70 inside, we have never run more than one boiler at a time. We planned to put in the wood fired main boiler when construction was over, but with oil prices what they are I think time spent in the woods is more than justified now.

You can come and do plumbing here anytime - that looks great.

Since you can get by with only one burner, your peak load must be less than 144,000 BTU/hr. Based on the size, it may not be much less, though. In sizing a tank, consider how long you'd like to wait between fires. A day would be a reasonable minimum. Water takes 1 BTU to raise the temperature by 1 degree. Water weighs 8 lbs/gallon so a 1000 gallon tank weighs 8000 lbs, and will absorb and return 8000 btu per degree. If you assume that the tank can be heated to an average temp of 160 degrees, and that you can extract usable heat down to 90 degrees, that's 560,000 BTU of usable storage. At a peak load of 100,000 BTU (just a back-of-the-envelope number for illustration) you could go 5 or six hours between fires at the coldest time of the year with a 1000 gallon tank.

You'll want to estimate your average heat load (you can do that by looking at your monthly oil bills) and work up an actual estimate. My gut says 1000 gallons might be a bit small, but its a tradeoff.

Hope this helps.

 

[pbvermont]

My understanding of the size of heat storage tanks is: the bigger, the better. Of course the major limiting factors are construction materials, methods and the space you have to allocate to the tank.
By the way, when calculating BTU storage capacities of tanks, use the figure of water weighing 8.3122 @ 77degrees F. Not to be nerdy about it, but when discussing a thousand gallons of water or more, that .3 makes a difference in your calculations.

 

[Father John]

From what I heard today it seems that Econoburn has just committed to STSS to sell their tanks when storage is needed in future installations. This seems odd in light of what Econoburn told me just a day ago, about storage being needed by other boiler designs, but not by them.

Econoburn did say they thought the EKO was not very heavily built, in comparison to their boiler, but I just got the shipping weight of the EKO 80 - 2380 lbs on steel pallet, incl. wooden crate - which sounds pretty heavy to me. At only 65% of the cost of the Econoburn, is the EKO too good to be true? Are there any hidden problems with the EKO?

 

[Eric Johnson]

I think they're both good boilers. EKO is made by Orlan, which as I understand it, is a well-established and respected boilermaker in Europe. Econoburn is manufactured in the U.S. by an established and respected boilermaker, even though the wood-burning line of boilers (Econoburn) has only been on the market for around a year, I believe. Having never seen an Econoburn, I can't comment on its relative build quality, but I have heard that it's very similar in design to the EKO. I'd like to see one up close. Tarm is comparable as well, though I don't think they make a boiler as big as the 80, which I think is 285K btu/hour. That's a biggie.

Parenthetically, when I was shopping for my boiler, a comparable Enonoburn was about 33% more than the EKO. Because of the exchange rate (Euro vs. $), the EKO model I bought is now $1,000 more than I paid. And guess what? So is the Econoburn, even though the exchange rate isn't a factor for them.

EKO has a 5-year warranty. I don't know what the Econoburn's is, but that's probably a factor worth considering as well. The Tarm warranty is 20 years. The Tarm tanks and heat exchangers are also supplied by STSS. I'm not sure what Zenon offers in the way of storage.

 

[leaddog]

I'm not an expert by any means but here are some ideas. I have a eko80 with 1300gal storage. I went with the eko80 because I wanted to be able to use longer wood. (40in). After having the eko running now for 3+ months here are some of my opinions. I don't think that the 80 Puts out more btus that the 60 per hour but because of the larger wood chamber it will put out more per loading. I base that on the idea that both have the same size and number of nozzels hx tubes etc.
If you are going to be useing large storage That could be a factor.
On storage , if you are going to have to build your boiler room you might consider building your storage tank in the ground. By digging a hole and useing the blocks for walls you can insulate under and around the outside with foam, line it with epdm and have a tank that is structurally sound. You can make a large volume tank that way and the cost per gal would be less for a larger tank. Also you can make it deeper, like 8 or 10ft, an not worry about the water pushing the walls in. A deep tank would give more stratifcation which is a plus. You could very easilly have 3000gal at a low cost.
I like my eko but another idea is the Garn. It has the storage build in and would be very adapable to any boiler room you might build. I know some here have a garn and there is a dealer here in Michigan (heaterman) I think that might chime in and be able to tell you more. They cost more but if you are going to build storage and a boiler room they are a proven boiler.
leaddog

 

[Eric Johnson]

It's rated for 80kw vs 60 for the '60, leaddog. But I defer to your more experienced opinion.

 

[Father John]

Thanks for the notes about the Garn. I did attempt to look into Garn, but after leaving a couple of messages, and having heard no response, I think they are not interested in our project. Those I talked to at New Horizons and Econoburn were exactly the opposite: very interested and very helpful.

As far as building a subterranean tank goes, that wouldn't be too hard. We still have a Kubota mini-excavator and a small pile of rebar left over from our major construction, so I could easily build a reinforced aerated block tank, and waterproof it. Would this not complicated the hx installation, or the connections that are needed, though?

I am still not exactly sure I know how many lines will have to go in and out of this tank.

 

[Donl]

now.

You can come and do plumbing here anytime - that looks great.

I showed my wife the picture of the monastery plumbing. She said to me that that is exactly what a fellow can do when he doesn't have to take into consideration the WAF.

 

[leaddog]

I know that is the rateing , and I maybe very wrong ( won't be the first time) but with the nozzels being the same, fans same and heat tubes the same the only difference I can see is the length of wood chamber. I have one more block in the bottem and so the area of the gasification is larger. maybe the added area of the wood chamber will put off more gas and so the nozzels will burn hotter but the nozzels are two and look to be the same. I really don't think it makes a difference because with the 80 you will get a longer hot burn than the 60. That may be how they come up with the rateing is by the total btus per load per burn time. If you have enough storage to use the btu's in the 80 then you are better to get it, if not then the 60 will work.
From what I see in boilers in general the btu's are a subjective thing. They have to size them so the small is small and the large is large. It makes a difference what you burn, how you burn, and how efficient.
like I said just my take on it.
Leaddog

 

[leaddog]

From what I heard today it seems that Econoburn has just committed to STSS to sell their tanks when storage is needed in future installations. This seems odd in light of what Econoburn told me just a day ago, about storage being needed by other boiler designs, but not by them.

Econoburn did say they thought the EKO was not very heavily built, in comparison to their boiler, but I just got the shipping weight of the EKO 80 - 2380 lbs on steel pallet, incl. wooden crate - which sounds pretty heavy to me. At only 65% of the cost of the Econoburn, is the EKO too good to be true? Are there any hidden problems with the EKO?

when any manufacture tells you that their product is better than and other with out proving their point they become suspect. To sell a product you only need to show how your product will do the job it is intended to do.
I feel the eko is very well built and is build to do the job. I have not seen a Econoburn. I have looked at some of the other gasifiers out there and most of them have their selling points. Everyone has to look at them and look to see what will fit their situation. I narrowed my choices to the Tarm, Eko, Wood gun, garn. They all seemed to be good but the eko fit me.
Leaddog

 

[Eric Johnson]

I don't see where an inground tank would make any difference in the hx installation, function or piping. I think it's a great idea.

DonL's reference to the WAF is "Wife Approval Factor" by the way. But presumably you have somebody else that you need to keep happy.

 

[BrownianHeatingTech]

As far as building a subterranean tank goes, that wouldn't be too hard. We still have a Kubota mini-excavator and a small pile of rebar left over from our major construction, so I could easily build a reinforced aerated block tank, and waterproof it. Would this not complicated the hx installation, or the connections that are needed, though?

I am still not exactly sure I know how many lines will have to go in and out of this tank.

The heat exchangers drop in from the top, so piping isn't an issue.

Making sure the top cover seals well, is, or you end up with a steam room. If you're doing an in-ground, you also want to take safety into consideration, so folks don't use the cover for a walking surface, or even for storage, since you'll want it to be light enough that it can be removed every couple of years, at least, to maintain the water quality. You also want to make sure to insulate the tank well, or you just end up heating the ground.

Regarding the boilers, the Econoburn is an extremely high quality boiler. It's one of the best-built boilers around, and it comes with a price that matches its quality.

A 2000-3000 gallon tank would serve you well. 4000 would be even better, but it all depends on what you want to spend. Bigger tends to be better, within reason. At your heat loss (based on the one boiler being able to heat the place), a 4000-gallon tank would likely handle the better part of a day, at the maximum load, and longer than that when the load was less (warmer weather). I think even 2000 gallons would make you very happy in terms of infrequent boiler tending.

Joe

 

[heaterman]

Father John

I sell both Econoburn and Garn and I think for your particular application I would go with the Garn for the following reasons.

First of all, you do want a substantial storage or "buffer" tank. The high mass of your infloor heating system will be handled much more ably by the appropriate mass to counteract it. What many in this business don't grasp is that the load generated in bringing a slab of cement up to temperature is greater than the amount of heat needed to maintain it and the room. It's like a huge flywheel in that it takes a lot of energy to get it spinning but a much smaller input to sustain it once "running". The use of a "buffer" tank will provide a shock absorber for the initial load while allowing the boiler to "recharge" the tank at it's leisure. When the slabs are up to temperature and you have the boiler sitting at 170-180*, you now have gobs of btu's stored up to use as needed when the slabs cycle or the weather changes. Overheating a Garn boiler takes a severe lack of attention because you have 1,500 or 2,000 gallons, depending on the model, to play with. The Garn has this storage capability integral to it's design in that the tank is part of the boiler itself.

I really like the fact that when you open the fire door on the Garn, you will not be given a convincing simulation of what standing at the gates of Hades must be like. Smoke bellowing and flames licking at your face just don't happen due to the very intelligent design of the airflow on the Garn. The combustion air is drawn through the firebox rather than pushed into it like any other wood burner I have seen. This is a powered draft instead of a natural draft created by a chimney as in the case of an Econoburn or Eko. As a result of this there is a negative pressure at the feed door rather than a positive pressure. It's nice to keep the fire inside where it belongs.

Control for the Garn consists of a simple wind up timer that contols the run time of the combustion blower. Dial in an hour and a half if your water temp is close to target and you only need a half a load of wood to get back to 180* (or whatever * you pick) or fill it all the way and wind it up for 3-4 hours. Walk away and forget it. This would be a decided advantage where you may have multiple operators.

The fact that the Garn is an open or non-pressurized system can be viewed as positive and negative. Negative in that it means you will need to incorporate some type of heat exchanger to isolate it from the sealed and pressurized side of your system. Positive in that it can never "blow up".

In defense of the company as far as poor communication is concerned, they have been absolutely swamped with work and a planned addition to manufacturing capability this fall hasn't materialized due to floods experienced in Minnesota which caused a shortage of electrical service equipment needed to bring their expansion on line. Martin Lunde, the owner of the company and designer of the Garn boiler has been out West engineering the heating system being used in a very large corporate retreat for (get this) an oil company. They are very short of help so if you would like to contact someone regarding one of these units, please feel free to call me at 231-920-4808 at any sane hour of the day. I'd be happy to lend what meager expertise I have to your project.

All of this is not to say the Econoburn or EKO would be a poor choice. It's just that by the time your build or buy storage which your system really needs, you have virtually the same cost and probably more effort involved as if you purchased storage and boiler in one unit.

I hope I have shed a little light on your path.

May you have a Joyous Christmas season and a Happy New Year.

 

[Eric Johnson]

I agree that the onboard hot water storage offered by the Garn is probably a more economical solution in many cases than discrete heat storage, especially when you can replace an expensive copper coil or other copper contrivance with a flat plate heat exchanger. But in most residential applications (though perhaps not in a large facility like a monastery), I would think that being able to bypass the storage and go directly into the zones has some real potential advantages. Momentum and flywheel effects are great, but only when you're ahead of the game. Get behind, and you're in for a long, long wait. And as clean as EKOs, Econoburns and Tarms burn, I suspect the Garn is even cleaner. It's a really nice rig, I agree.

As for pressurized boilers blowing up, it's not something I've ever lost a lot of sleep over. If it's a concern, why not put in more than one pressure relief valve and/or some other scheme like an aquastat-activated zone valve that virtually guarantees safe operation? I know boilers occasionally blow (as do water heaters), but I think that's a red herring.

 

[Father John]

Many thanks to all who commented about our needs and the boilers available. Thanks also to Nofossil for the kind words and the excellent page with the unusually lucid description of how these systems work.

I remain quite interested in Garn, and hope that we will be able to speak to the company itself before purchasing. I don't have any great fear of a boiler exploding, and putting the unit out in an aerated concrete building will guaranty no danger to life or limb if the unthinkable should happen. The Garn may work well for us in that we have not yet waited for the concrete floors to cool down before we begin to heat in the fall, so have never had to heat entire zones from a "cold start". We do have enough fuel oil and a diesel generator to keep us going for quite a few weeks if it got really bad, so even during ice storms I don't think we would have to wait for the boiler to heat up frigid zones.

On the other hand, who can predict the future? I see now one of the major differences between the Garn system and the wood gasifier coupled with a tank.

 

[Eric Johnson]

Let us know how your project proceeds, Father John.