AA Vs. EFM

I'm trying to find out EFM 520 and AA 130 or 260 owners opinions on which boiler is the best long term as far as performance and longetivity. an EFM expert already told me some of the advantages of the EFM 1) Its airtight 2) Large span of adjustment with air and feed, 3) Less unburnt coal 4) Less noisy( noise wouldn't bother me though) Any AA owners want to chime in on why they are desirable boilers. Has anyone ever owed both at different times. I would be curious to find out how each did in the same setting. Thanks

I have an Axeman, but I sell Keystokers, EFM's and AA. All of them are great boilers. I would say that EFM and AA are the best out there. The EFM is extremely quiet and a great performer with all kinds of power. The burner is fabulous as well. The AA is a bit noisier (a clinking sound, or as I like to say the sound of saving money), but will easily run for 24 hours without any intervention on your part. Also, the anthratube will not jam on an oversized piece of coal like the EFM will. The AA can use a smaller flue, and has an induced draft which is real nice. Cost wise they are about equal and either way, you will be well served with the unit you choose. If you need more than 130k btus, I would get the EFM, as it goes up to 214k btu.

Mike

Hi Salem,

FIrst, let me say that I have only been running my AA-130 since Nov 2, 2008 - so just coming up on three months now. I can't offer any comparisons to other alternatives. So, my observations:

Pros:

The AA is exceptionally well built. I get the sense, and comments on tis board, indicate that this thing will last forever. For the first 6 to 8 weeks, I kept a close eye on things. Except for emptying ash, I'm comfortable that I can ignore it.

I get virtually no unburnt coal. The only times I've seen any is right after starting the fire and after turning thermostats down from 70 to 55 when we were going away for nearly 5 days. I did start the fire twice as we lost power for 3 days in December and the fire went out. Interesting observation is that I believe I still could have maintained the same fire more than 36 hours after we lost power - coals were still glowing. 72 hours was just too long.

Great company to deal with once you get past the gatekeeper on the phone. You can get the owner on the phone.

Buils the coal bin big enough and you don't have to fill it very frequently. I was initially concerned about filling the bin in case something happened at the auger tube. Nothing to be concerned about so far. It simply just feeds the coal with no problems.

Cons:

You can't totally ignore it. I add oil to the transfer head wick oiler every so often. Not a big deal though. Somewhere in here someone referred to burning coal as a hobby so it's not really a problem.

The biggest complaint I had is that I had to paint it myself (they did include the paint, but no primer). The real problem is that is difficult to paint when it's put together.

Also, the DHW coil is 1/2" copper. I would have preferred 3/4" as that's what I have now. Right now I'm not using the coil because of this. I'm not saying this is an issue, but I didn't want to make the switch.

For the $$$ you pay for the AA, I think it should include an ash bin.

Comments (neither pro nor con)

The boss (wife) refers to it as a locomotive - it does have an industrial look to it. Mine is in the cellar, so who cares.

Ed...

trying to compare an axeman to an efm is like trying to compare a lincoln to a caddillac

If it's longevity you're asking about, from what I've heard & read, the AA will outlast the EFM by 14 days. It's well known that the EFM will barely last 100 years and the AA will easily last 2 weeks more. There was one guy that used wet coal in his AA however and it died 5 weeks early, so perhaps it's a toss up.

I have an AA, but only been on line with it for half a season. Of course I go check it often as it's my new toy, but the reality is all I do is empty ashes. It just simply needs no attention once it's dialed in. Once a year change the oil, that's about it. I like it as it burns pea size coal. I feel there's less problems with feeding the pea size. I do get a bit of unburned coal in warm waether, but the AA's extra efficiency makes up for it. I like the self cleaning feature too. Barring uncommon problems, it truly will go a year with only ash tending.

Even though I'm partial to the AA, certainly you can't go wrong with the EFM. They are both top of the line.

Based on my experience both operating and maintaining, as already stated they will both last beyond your life time here are a few thoughts, I'm sur eothers will chime in with things I have forgotten:

EFM:
Quieter, more adjustable and happier at low loads like making DHW during the summer.
Wear parts auger and tube, bushing in pot, bunch a small parts in the stoker ratchet assy (look in the EFM thread for the breakdown)
Burns rice or buck, can be an issue for buying coal in the middle of winter, builds up fly ash more quickly

AA/AHS/Bethlehem/Boston Boiler works
More efficient, smaller, slightly cheaper than an EFM new, auger will last 20 years,
wear parts, rollers on grate, bushings in transfer head, bearings that support auger, belts, cyclonic separator cone
Burns pea or buck, generally doesn't need cleaning as often due to design and air velocity

Both units have the same failure modes, electric motors, boiler controls, and need periodic maintenance like gear oil changes. generally speaking the EFM might be a tad easier to learn for adjustment and operation than the AA design, but once you learn it the AA design is a piece of cake to operate. I also don't agree that the AA design will have more unburned coal as a general rule, unless it is not properly adjusted.

My personal choice is for a new tight and well insulated home I would go with an EFM, for an older drafty and more energy inefficient home I would go with the AA design.

Hope this helps a little.

The biggest difference is visual. One looks like a coal boiler and the other like something out of Willy Wonka.

Why is there such a differenece in the potential BTU output? Can either unit be run on a less than recommended flue size?
Is the AA260 more comparable to the 520?

How small a flue can the 260 be tied into?

I am considering these options for my own home and I am really torn as to which way to go.

I like to idea of the greater BTU's from the 520, but I saw member Prets setup and it was awesome and his house was toasty warm.

I truly love readign all these comments on here. I hope to have my decision made soon and start working on an install so everything is ready to go for next winter.

mof1964 wrote:Why is there such a differenece in the potential BTU output? Can either unit be run on a less than recommended flue size?
Is the AA260 more comparable to the 520?

How small a flue can the 260 be tied into?

The EFM has a slightly lower total max out put, I think around 218,000BTUs. The Axeman runs to 230,000BTUs.

The chimney questions are relative to it's height, details about its construction and appliance install conditions. So the easy answer is yes but do your homework.

I don't have either but the AA is top feeding which results in BUMPING ( small explosions) once in a while.

the EFM is bottom feeding, no BUMPING problem

Both seem like mechanical monsters compared to my simple VF3000.

Check your chimney size if you are going to use a existing one.

I can't speak for or against the EFM. I have never seen a model or an install. I did investigate it, but I was mostly worried about 1) the solid center shaft auger jamming, 2) the availability of rice coal in the winter and 3) an installer who related a story about coal gas with his (but he said the problem was cleared up with a chimney cap and a baro so this wasn't my biggest concern).

As for the AA 130 that I own, I love it. I only have to tend it once every two days in this kind of weather, about every 3 days in the fall and spring. It's efficiency makes up for any unburned coal you may find in the ash. Its efficiency is derived from a two pass fire tube design.

The design of the auger, grate and ashing mechanisms is brilliant in its simplicity. That simplicity translates to a very smooth and reliable operation. I noted that the brochure said that "the grate is unconditionally warranted for life". Having researched coal burning in general and found that, in days goneby the grate was the most vulnerable part on a coal burner due to heat warping, I thought that the warranty was wonderfully generous. Then I realized that the fire is NEVER on the grate! That is the true brilliance of the AA design.

Though I don't remember what the EFM is made from, the AA is a steel boiler. That's significant. The boiler is strong. Steel is stronger and more resilient than cast iron. It can endure thermal shock better than cast and is less prone to cracking.

The open center auger will rarely jam. I tested it by feeding some chestnut thrown on top of the peas. It fed without issue though I don't recommend it on a cold winter night.

Combustion bumps are not an issue of the AA per se, they are an issue of chimney draft, which should be correctable. AA induced bumps can occur if buckwheat is used and the operator fails to remove the plug in the inspection door. I have never had a combustion bump.

As far as noise, yes it has some noise but it is not an issue. You aren't going to put this in your living room. It's a boiler for your basement. It sounds about like any furnace or boiler from the sixties or seventies. It's not as quiet as one from the nineties or the 21st century. There is the fan noise and a light tinkling of coal coming up the tube. Standing next to it, you can have a normal conversation. Mine is located in my basement directly under my bed. There is insulation which deadens the sound. Yes, I can hear it come on but it sounds reassuring. It won't wake you up but, if you are up, it lets you know you'll be warm.

syncmaster wrote:Both seem like mechanical monsters compared to my simple VF3000.

Harman VF3000 Verti-Flow Stoker Boiler
Specifications

Fuel Rice Coal
BTU Range 5,000 to 95,000+
Heating Capacity 3,000+ sq ft
Hopper Capacity 250 lbs
Flue Size 7 inches
Weight 915 lbs
Depth 47.19 inches
Height 55.05 inches
Width 23.21 inches
Water Capacity 50 gallons



I don't see how the mechanisms are that much different in simplicity.

AA 130-m
Specifications

Fuel: Pea or buckwheat
Rated BTU output: 113,000
Heating Capacity (sq ft): this is silliness, as it depends on heat loss calculations for the specific home
Hopper capacity: auger feed; build a bin to suit
Flue size: 5 inches
Weight: 930 pounds
Depth: 56.25 inches from front to bin wall
Height: 41 inches
Width: 23.5 inches
Water capacity: 21 gallons

http://www.axeman-anderson.com/pdf/anthratube.pdf

I think they are both mechanical monsters. (and that's a good thing)

Matthaus, Why the AA design for an older drafty house? Thanks

I think Matthaus means that the AA is underutilized in a smaller tight modern home.

I have a 2400 sq ft of tight modern split entry home including my garage where the boiler is. I probably could heat twice the space (with similar insulation) for just a little bit more in fuel. I still save $800/ year against fuel at 2.25/gal.

The capacity of this unit is 113k btu/h. The problem is that the minimum output is maybe about 20k btu/h (and that's a guess). It needs a good load for maximum efficiency.

One of the suggested usages of the Axeman and the AHS is for industrial process hot water.

How can you determine if the AA130 is going to be big enough? If and when I put a unit it I will have it in an unfinished basement?

I heat approx 2400 sq feet of some older type contruction, (all brick with new windows and doors) the newer part of my home is 2x6 built and heavily insulated.

My basement temp doesn't drop below 50 even on the coldest weather. My living space is heated by oil/hot water baseboard with a 120000 BTU oil burner from 1966.

I just need to make sure that whatever unit I put is capable of heating everything and also ny basement for the future. The basement will be approx 700sq feet when finished. It will be insulated and pretty tight. It is already plumbed with hot water baseboard.

My wife likes it pretty toasty. I would like the unit for baseboard and domestic hot water.