EKO or Econoburn?

Father John said:

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

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You might want to consider filling the voids in those blocks, if they have them, with vermiculite for extra insulation.

It would be easier and cheaper for you to put a heat exchanger for DHW on the supply line after you get it to the distribution point, so there's no need to run a separate line out to the boiler. You can use an external hx on your existing water heater or an indirect water heater & put it wherever you want., probably right next to your existing water heater.

Father John said:

That sounds like a better idea to me, not least because it is easier. I guess a homemade shell-and-tube of copper would do it.

On the boiler question, it looks like somebody who knows the fellow at Garn will be contacting them for us, so hopefully we will finally be able to see what can be done.

It occurred to me to wonder whether the wiring on the EKO, being from Poland, caused any difficulties when you have to hook it up over here? Are there any other things aside from electrical matters which cause problems in the translation?

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My EKO came with a standard 110 volt US-style plug, just like a food processor. Kind of funny on an appliance that's so large. The controller is dual-voltage, and mine has an added internal transformer to step up the voltage to run the 220V blower. No voltage problems at all.

My only issue was that the pipe threads were not exactly correct - I had to rent a threading die and dress them up in order to get standard Chinese-made US NPT pipe fittings to work. I think they've addressed that issue, as I haven't heard of anyone else having that problem.

Once in a while I wonder how easy it will be to get a replacement blower if mine fails. The more of them that there are, the easier it's likely to be.

Speaking of 'translation', the version of the manual that I got is far more entertaining than informative.

The eko's now come wired for 110. That includes the blowers, controler, and pump. My 80 was wired for 110 but they mistakenly lift the stepup transformer on and it blew up the controler. Covered under warrenty. The pipe threads were standard so I had no trouble hooking it up. Parts seem to be available and seem to be very reasonable through CozyHeat.
leaddog

The older 60s and 80s had flange connections to the supply and return ports, but they've been replaced with standard 2" threads. I didn't have any problems with that. My wife wondered why the supply pipe extends so high up above the top of the boiler (I don't have much headroom in my boiler room). It's so you have enough clearance to get the top covers off.

I had no trouble with the electrics. Just hooked it up and ran. Mine did come with a small electric gizmo that looks kind of like a fuse or something. I've never figured out what that's for. I guess I could post a pic if nobody knows.

The nice thing about having two blowers, leaddog, is that if one goes down, you can block off its nozzle and keep going with the other one. They're nice quiet blowers.

To a first approximation, look at your oil deliveries from last year. Oil provides about 115,000 BTU per gallon in a typical boiler. If you know how many gallons per month you used, you can do the math. Since you only use one boiler, it will be less than 140,000 BTU/hr.

I can't speak for nofossil, but I suspect he will prescribe what's known as a heat loss calculation on the spaces you're trying to heat. You can download a free one here:

http://www.heatinghelp.com

Or hire a heating contractor to do one for you. Oftentimes that's included for free if you're asking them to spec and quote a system for you. You may have had one done as part of your oil boiler installation, and it would probably still be valid if your physical plant hasn't changed too much since then.

A couple more items I thought about the other day pertaining to our discussion here:

1.) Boiler weight doesn't tell you a whole lot about relative quality, though I agree that heavier is probably better. However, much of the weight in a modern gasifier is refractory cement, both at the bottom of both combustion chambers and cast into the doors and other parts that don't have water behind them. My point is that you can build a heavy boiler that scrimps on the steel. I'm not saying that's the case with either of the quality boiler you're considering, just pointing out that it's not necessarily a good basis for judging quality.

2.) And yes, you can build your own shell/tube heat exchanger for domestic hot water. I built mine for less than $100. They're called sidearm heat exchangers, and the great thing about them is that they work on gravity on the domestic water side, so that you can get by with one less pump compared to some of the alternatives, such as a conventional shell/tube or a flat plate. I have a thread around here somewhere describing how to build one and how they work. Maybe I'll update it with some actual specs if I get a chance. It's not the perfect DHW setup, but it's pretty good, and it's a satisfying DIY project to boot.

https://www.hearth.com/econtent/index.php/forums/viewthread/8168/

Finally, we have a couple of dedicated Garn owners who participate here, so no matter which way you go, I think the Boiler Room has got you covered. As you may have noticed, the learning curve on these things is diminished significantly when you can compare notes with other people who have them.

My understanding, soley based on lurking around professional heating websites is that your "design day" is either the coldest average day for your area, or close to it. Then in most cases you size the boiler to heat the space to a reasonable temp. on that day.

With oil or gas it's not a big deal having a boiler that's bigger than you need for the vast majority of your heating days, because gas or oil simply turns on or off as needed. Wood, on the other hand, doesn't lend itself to abrupt starts and stops. Once you load the firebox, you pretty much need to let it run its course. That's where hot water storage comes in handy. It gives you the flexibility to fire hard even on relatively warm days.

With a storage tank, you can either undersize or oversize your boiler to some extent and get away with it. And there are legitimate reasons to do both.

How's that for confusing the discussion?

checkout this thread by TCaldwell garn boiler feedback pleaseHe used a simple analog clock wired into the oil burner relay.
If the boiler fires the clock starts then stops when the burner stops.
after 24 hrs you can do the math x the burner gal/min rating, etc...
best of luck!

I have had a clock hooked to my burner for the last 20 years, now I also have one hooked up to my aquastat for the blower on my wood boiler. This clock is a new electricl alarm clock that has a light and is located in my bedroom this way I know when the blower is running and how long without having to go down stairs. Next I will get the remote thermometers this is a hobby, but it is also saving me lots of money at the same time.

Steve

Next thing I'd do is take your annual consumption and divide it by the degree days for your area for the heating season - that will give you gallons per degree day. Then, look at the peak annual weekly degree days and multiply it out to get gallons per week. Divide by seven and multiply by 115,000 and you'll a reasonable seasonal worst case based on actual consumption rather than the more extreme daily worst case used to size oil boilers.

http://www.wundergound.com has an almanac. There's a link on the left side of the page - a place to choose a data and a 'Go' button. The 'daily' tab has the best data - look at data for each Sunday to get a good profile. One of the things it shows is actual and average degree days for the whole heating season (from July 1, I think).

I'll help crunch the numbers if you'd like.

I think The Garn is the best setup for your situation . As we all know, heating systems are designed for the coldest day of the yr., but we only have a few of those each yr. If you already have an existing heating system it is not a bad idea to undersize your new wood boiler. If you do use concrete block, epdm liner and styrofoam on the outside for your storage tank, don't forget to factor in the thermal mass of the block.

Father John said:

Next thing I’d do is take your annual consumption and divide it by the degree days for your area for the heating season - that will give you gallons per degree day. Then, look at the peak annual weekly degree days and multiply it out to get gallons per week. Divide by seven and multiply by 115,000 and you’ll a reasonable seasonal worst case based on actual consumption rather than the more extreme daily worst case used to size oil boilers.

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I will need to get the brain warmed up to keep up with you nofossil; it must be the biting wind we're having here.

I found that over the last 8 years we averaged 4980 heating degree days. I am still looking for the file with the oil bills in it, so I will take 2000 gals as my number for now. Dividing the gallons by the degree days I get 0.4 gals (although I do remember the bills well enough to think this number is much too low).

Where I am stuck is with the peak annual weekly degree days. Does this mean how many degree days are in the week with the most degree days of the year? Presumably that would be in January?

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Yes - I don't remember when the coldest week is, but January seems about right. If you go to the almanac that I linked to, you can look at two dates in January a week apart and look at the average 'season to date' degree days. For us up here, a typical week in January might be 330 degree days. That would be about 47 degree days per day. If we had your oil consumption of .4 gallons per degree day, that would be about 19 gallons. At 115,000 BTU per gallon, that would be about 2,000,000 BTU/day. Dividing by 24 hours, about 90,000 BTU per hour average during the coldest week.

Father John said:

Now that I am beginning to grasp the use of water storage, it is for that exact reason that I am trying to see what the actual heat loss is, as opposed to the calculated heat loss at zero degrees outside. From what I have read, the pros do not expect us to spend more than 2% of the season at the outdoor design temperature. I think it has actually been 4 or 5 years since we got down to zero here, and that was only one morning. Wind chill (we are having a lot of it right now!) is another matter.

So, basically I am trying to determine how much water storage our building should have for average times. Our initial design temperatures were zero outside and 70 inside, in which case it was predicted the building would require 276,602 net Btu/h (228,255 Btu/h as radiant panel output and 48,347 Btu/h being the expected heat wasted from the back of the panel, i.e. towards the ground).

Cost will probably prohibit sizing the water storage for this worse case scenario, so I am trying to find a reasonable average to design for, which will let me guess how long between fires during "average" weather. Since I don't have any regular fuel bills to calculate from, what would be the next method?

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As an amatuer in these sorts of things, it seems to me like it almost doesn't matter what your average consumption is - build for as close to your worst case as economically feasible, and experience will rapidly teach you how often you will need to fire depending on the weather. As mentioned earlier, the tank is essentially a battery. The size of the tank will determine how much "charge" you can put in it - the heating demand is equivalent to the current draw, which you can presume to be somewhere between your worst case scenario and zero - the amount you are drawing from the tank will say how long you get to run before needing to fire up the boiler to "recharge" the tank. Presumably you could put some instrumentation on the tank that would tell you when it needed firing, though I'd expect experience would quickly make that redundant.

Gooserider

I'll agree with Goose on this one. You don't want to choose a boiler that's way oversized, but something close to your worst case would be fine. In your situation, you could fire up oil to help out on your infrequent zero-degree days.

For the tank, bigger is almost always better. My average heat load is around 20,000 BTU/hr and I have an 880 gallon tank. I can skip days at both ends of the season, but during winter I build a fire that burns an average of about 7 hours per day, and the tank carries me between fires so that the house temperature stays constant. I don't have radiant, so I can't use as much of the heat in the tank as you''l be able to.

Question for Father John:

Do you have any make up air or ventilation equipment for air exchange in the building(s)? If so this would have to be incorporated into the actual heat loss for the structure. I see a duct in one of the mechanical room pictures but I'm assuming that it's there to provide combustion air for the boilers.

Father John said:

That is a good question heaterman, and a fact which I believe was probably left out of our original heat loss study. We do have a Greenheck 200 cfm fan in the end of a main vent line, which exhausts all the bathrooms. The duct in the basement is for make-up air. It has two motorized dampers which we wired to the firing controls on the boilers.

Nofossil, I worked it out that our average heat loss was probably about 90,000 btus/hr last year. This seems to correspond with experience, since a 144,000 gross Btu boiler should produce about 120,000 net btus/hr on the smaller nozzle (which I think is what's in there).

The smallest Garn (if that isn't a paradox) is supposed to be able to store 920,000 btus, so I guess that would mean for us an average day would require two burns, more or less.

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90,000 BTU/hr seems like a very reasonable number in light of everything else you've mentioned. I don't know what the BTU/hr rating is for the Garn when it's firing, but if it stores 920,000 btus then you can go ten hours between fires - probably a bit more, since the building itself has some mass and it will presumably be warm at the end of your fire. Of course, the 'between fires' interval will be shorter in cold weather and longer in warmer weather. My average pattern is seven hour fire, seventeen hours living off the tank. When it's really cold, it's more like 12 and 12. When ist's warmer. it might be 8 and 40. The tank gives you some flexibility.

When Garn calculates their 920,00 BTU of heat storage, do you know what temperature they consider to be 'depleted'? For baseboard heat anything below 120 is pretty useless, but for radiant you can use stored hot water down to around 90 degree - a big difference.