Better OWB efficiency?

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warm in VT

New Member
Hearth Supporter
Sep 24, 2008
56
Northern Vt
After reading a couple of posts relating to this, I thought I would post this and get others thoughts. On my e-classic, the furnace fires after the water temp drops 5 degrees. (for me this is usually once every hour or two and runs about 7 minutes). This is a factory setting and not one that can be changed by the owner to my knowledge. Why would it not make more sense to have the furnace fire after a 10-15 degree drop in temp.? This would still leave plenty of heat stored in the 450 gal. tank and would be more efficient and cut down on the creosote build up due to longer, hotter burns. The only thing I can think of would be the furnace sitting longer without firing and having trouble re-lighting again when calling for heat after being shut down for that long? I would love to think that someone from CB would be on here at least monitoring peoples comments and perhaps chiming in with some answers.
 
I don't know about the CB, but data that I've seen suggests that OWBs get about twice the efficiency at full throttle than they do when they're idling most of the time. That's probably true of almost all wood burning appliances. That suggests at least three strategies to improve efficiency:

1) Buy the smallest possible unit so that it needs to run a higher percentage of the time. Perhaps, modify the unit to reduce its output.

2) Use storage - build a fire, run flat out charging storage, then let the fire go out and get heat from storage.

3) Build small fires. Run flat out, let it go out, build another when you need heat again. Some folks have done this using timers so that coals are preserved at the end.
 
Don't get me wrong, I am very happy with the way this one runs. I have been burning since Oct 1 non stop and have used a little better than a cord maybe and have not used a drop of oil or propane for the DHW. I was just thinking of basically a combination of your suggestions #2 and #3. To stretch the time between burns and draw down the temp of the storage then get a longer burn time to re heat it to increase efficiency and have a longer, hotter burn. I guess I am bit by the same bug as everyone else on here. I just want to keep tweaking things to make it better and more efficient.
 
I probably don't live far from you. I bought my EC2300 from the VT dealer across the lake. My boiler has been using about 2 full (up to top of firebrick) loads per day. Loosely filled hardwood (ash). I have a long piping run (installing second pump on return line this week - total piping run 400 1" PEX up and back buried 3.5 feet down) and looking to see if there is a good way to measure temperature at inlet of heat exchanger (first one is 50 plate) and inlet of second exchanger (30 plate for DHW) plus on return. I tried one of those laser guns from Craftsman but reflections off new copper gave squirrely readings. Do you have temperature indication on yours?
 
Google "Redi check smoker thermometer". I also have the eclassic. This thermometer is for a barbeque, but works great for monitoring 2 points on your system. I put one probe on my HX plate and the other on my aquastat. Its wireless, so I take it with me when I want to keep an eye on temps. My furnace runs between 180 - 185. My themometer on the HX shows 168-173, so I always know the exact temps. Love it!!

PS: We are getting 24 hr burns on the eclassic. Day temps 45, night temps 25. House 1900sf.
We had jerry rigged it with the paper clip to keep the fire alive during above 50 temps. Now with the clip out the unit
seems to burn less wood. :)
 
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