Coal-Trol on EFM 520

They guys at coal-trol tell me that a controller for a boiler will be available soon. I run an EFM 520, 12 months a year and burn about 6 ton of coal (5 in the winter). I'm thinking this controller will create a small efficiency in my furnace in the winter...but ESPECIALLY in the summer. Any words of encouragement or caution??

Nothing against the Coal-trol, but I'm not convinced it would be much of a benefit for your EFM. An EFM stoker has an adjustable feed rate, so you should be able to closely match the BTU input to your heating/hot water needs. The other problem is that the feed rate is manually set via the slip collar on the ratchet assembly, so it isn't something that can be varied on the fly by an electronic control.

If you want to maximize the efficiency of your EFM, keep it clean, insulate the boiler and piping, make sure the draft is correct, make sure the fire is correctly adjusted (no more air than necessary for a proper ash ring), and lastly...don't run the boiler at a higher temperature than necessary to do the job.

At 6 tons per year, I think you are doing very well already.

x2 on Rob's comments.

How is it supposed to save anything measurable, especially in summer? The unit normally would sit without using any coal or electricity for at least 55 out of every 60 minutes, and as Rob points out is fully adjustable to match output and load. Assuming you're making DHW in summer, don't sell short the BTU's that requires.

Mike

Thank you both for your thoughts....I'm under the impression that the coal-trol will regualte the feed. As soon as I can confirm that, I will share.

I'm also thinking about a house I may sell in the next couple of years, where an "automated" system may not be as intimidating to a potential buyer. Additionally, If the coal-trol does what I think it will....I just really believe that when you automate something, and use a computer, rather than a living, breathing person, your results are going to be FAR MORE accurate.

Turth is, you guys know more about EFM's than I ever will...so I'm not trying to argue, I'm actually surprised someone hasn't tried something similar already and posted results on this topic.

chimley wrote:I'm under the impression that the coal-trol will regualte the feed. As soon as I can confirm that, I will share.

I can't see how it can accomplish that, but I await your feedback after you talk to the Coal-Trol guys.

chimley wrote:I'm also thinking about a house I may sell in the next couple of years, where an "automated" system may not be as intimidating to a potential buyer.

Unless you have made the boiler mostly "hands-off" with a huge coal bin and an ash removal system, I don't think a fancy control is going to make or break the deal.

chimley wrote:I'm actually surprised someone hasn't tried something similar already and posted results on this topic.

I have done plenty of experiments, but I have been lax posting the results (I figured most people don't care). From what I have observed, I can tell you that the biggest variable in daily coal consumption (assuming you held everything else constant) is the boiler's operating temperature. Recently I did an experiment with the feed rate...basically I monitored the outside temperature and DHW usage for 24 hours, then I doubled the feed rate and monitored everything for another 24 hours. I got lucky with the weather...the average outside temperature was within 1 degree between the two days, there was little/no wind, and each day had two showers and two loads of laundry. The results were too close to call. The stoker had exactly half as much run time on day 2, so the amount of coal burned was the basically the same for each day. With the higher feed rate the boiler rapidly reached the high limit and skipped timer cycles as a result. I concluded that any efficiency lost by operating at the higher feed rate was cancelled out by the reduced number of timer cycles.

If you want to try and save some coal with fancy controls, look up a Hydrostat 3250 aquastat...this control will change the boiler's operating temperature based on observed heat demand...very useful for systems with multiple zones; especially if some are small, a bathroom for example. You can also set the control pre-purge the boiler down to 135 degrees before the stoker is allowed to start. This wouldn't work with a tankless coil, but in the right application it would help avoid short cycling from small heat calls and provide longer circulation times.

Rob R. wrote: From what I have observed, I can tell you that the biggest variable in daily coal consumption (assuming you held everything else constant) is the boiler's operating temperature.

If memory serves me correctly (and it often doesn't ) I think you've rediscovered a portion of the second law of thermodynamics (i.e., the part that says the rate of heat transfer is proportional to the temperature differential). Put another way, in any given environment the boiler normally would lose less heat by operating at a temperature closer to the temperature of its surroundings. Of course your boiler room may wind up being colder, but it makes sense that it saves fuel.

Mike

It wont work, don't waste your money

spoke with Coal-Trol today...they are confident they can produce a unit that will IMPRESS the boiler burners. This unit will require you to put coal in one end and remove ashes from the other....THAT'S IT!!

Can't wait! I have seen a unit in operation on a hot air Keystoker..and it was impressive. I'm optimistic and eagerly waiting to outfit my EFM DF520!

..tried to get the prototype, but they are reluctant to release until they have full confidence in the unit. Hopefully this thread doesn't die before we get something tangible from Coal-Trol.

There is no doubt that the variabale stoker firing rate can be accomplished with the old technology of the 50 s and certainly with the ease of direct digital controls that are used in todays large insitutional hvac systems. The cost and the clutter it would take a little of the magnificance away from the stoker. You could even ramp it up and down with your smart phone while traveling. I am ultimately a member of the kiss society though .

I'm all for KISS too. We apparently define the word SIMPLE differently.

What could be more simpler that not adjusting feed/air settings, timer settings and upper and lower limits on the aquastat? I understand this is an "art" for some users, and thats fine. We all have our hobbies. One of mine is not tinkering with my furnace. I would love to put it on cruise control and have piece of mind that I have an efficient unit.

I'm an EFM user since 2005, bought a reconditioned unit, moved it to my basement, piped and wired it in and built a coal bin on my own (plus 2 buddies). Yes, I have an emotional attachment to this unit that I brought to life, but it's time to cut the apron strings if the technology presents itself.

Don't get me wrong, this in not a high maintenace unit. But I'm not going to overlook an opportunity to make it better.

well. right now all I do on the 520 is put coal in one end and take ash out the other...

SO I am not sure what all anyone else is doing!

In any case I am all for technology upgrades though too. I guess I would like to see it but I again am not sure how much of a difference it may make.

I burn about 6 to 7 tons per year depending on the winter and keep it 72 inside and frankly am very happy at that!

Okay Mark. If you are burning your 520 for 12 months out of the year, and not having to make ONE adjustment ....you really have this furnace mastered!!!!

I'm sorry.....even if you are only burning in the winter, I find it hard to believe you make No adjustments.

Give me a break !

It may be hard to guess what the boys at "Automationcorrect" are gearing a boiler control towards.

But, I would imagine it's something that will do a bit of learning and remembering of what was was needed to satisfy a pattern of recent calls for heat and base the next call to allow for what would be anticipated and attempt to stop short, reducing the normal drift upward that would occur afterward. This would be a constant re-adjustment method based on each new and changed pattern of the heat load.

Besides controlling the burner, I would look to see it possibly varying the aquastat setting similar to what an outdoor reset does based on a remote sensor located outdoors sending feedback to the controller, adjusting it up and down accordingly.

Not sure how they will handle calls for heat that are solely in response to DHW loads because DHW use would be trickier to pattern than the dwellings heat load which is based mostly on outdoor temperature swings/patterns. DHW load can be sudden, random and could be heavy,light or somewhere in between. Nothing like typical outdoor temperature swings. And tankless and indirect DHW both present different sets of controls to be utilized.

Anyhow, time will tell...but my guess is it doesn't follow the stove control approach at all.

chimley wrote:Okay Mark. If you are burning your 520 for 12 months out of the year, and not having to make ONE adjustment ....you really have this furnace mastered!!!!

I'm sorry.....even if you are only burning in the winter, I find it hard to believe you make No adjustments.

Give me a break !

My dad runs the same settings all year. As Mark says, coal in one end, ash out the other. Experiments aside, I have been running the same settings since Labor Day.

chimley wrote:Okay Mark. If you are burning your 520 for 12 months out of the year, and not having to make ONE adjustment ....you really have this furnace mastered!!!!

I'm sorry.....even if you are only burning in the winter, I find it hard to believe you make No adjustments.

Give me a break !

Believe it, Axemans and EFMs tend to be set and forget devices.