What would cause this

[trumpeterb]

I have an EKO40, and I have the temperature set for 167. The boiler heats up without a problem, the fan shuts off. I return several hours later, and it is now 175-180. It remains there most of the day. The fan only seems to need to kick on
when a zone valve opens and the cooler water enters the boiler, but when it is idling, the temp is much higher than I have it set for. I checked the main air intakes, and they are set at 9mm, and the secondary intakes are also set at 3.5 turns,
just like the manual suggests. I will say that I am getting 17 hour burns out of a load of wood....that is nice....but it isn't burning very cleanly, I don't think. I have no thermal storage with the system, which stinks, but I don't have any room for tanks.
Any ideas why the temp continues to rise?

 

[maple1]

I have no experience with on EKO, but think that there is still a lot of heat in it, even after the fans turns off. And not a lot of water volume - so temps are bound to raise after the fan shuts off, unless there is some water going to loads. I don't think there is any way around idling & dirty burning with little or no heat demand and no storage. Sounds to me like it's working pretty well like it should be - unless I missed something.

Anybody else?

 

[flyingcow]

+1....

 

[goosegunner]

I ran my Econoburn without storage last year and 5 degrees was a typical overshoot after the fan shut off. I ran my underground loop continuously and I have quite a bit of copper that was exposed in my boiler room.

Personally I would not go for maximum burn time with your EKO unless you really need to, like at night or when at work.

At peak burn with a full load of wood and coals you could end up with more of an overshoot.

But a bigger concern will be production of creosote from too much idling. Load small and often to reduce idling as much as possible.


gg

 

[taxidermist]

I think 17 hrs on a burn is not a good thing for you........I know it sounds crazy!! That tells me you dont have much heat load right now and your boiler is in idle mode all the time. Remember your fan purges air into the chamber in cycles, this in its self will ad air to fire box and cause temps to rise above your thermostat setting.


Rob

 

[willworkforwood]

..... I will say that I am getting 17 hour burns out of a load of wood....that is nice....but it isn't burning very cleanly, I don't think. .....

The other folks have it pegged - the boiler is operating correctly (but not efficiently). You're located quite a distance from central Mass, but I believe your Weather up to now has been somewhat similar to ours (record warm temps). I've had a large number of time periods throughout the entire Fall where the boiler has been shut down, just like in early Fall/late Spring (this is NOT a complaint ) . These shutdowns are from 2 hours all the way up to extended shutdowns of 16 hours. And, we've never even come cose to fully loading - probably 1/3 full has been the max so far. But our boiler and wood supply are in the basement, making frequent loading no problem at all. So the question is, do you have to fully load your EKO? If it's a long distance from the house, or no one is home during the day then you're up against it. The bottom line is that without storage, the more right-sized fires you can run (or no fires at all), the better off the boiler efficiency will be. The "good" news is that finally seasonably cold Weather has arrived, so your bigger loads will now have a place to go ;-).

 

[ISeeDeadBTUs]

I ran my Econoburn without storage last year and 5 degrees was a typical overshoot after the fan shut off. I ran my underground loop continuously and I have quite a bit of copper that was exposed in my boiler room.

Personally I would not go for maximum burn time with your EKO unless you really need to, like at night or when at work.

At peak burn with a full load of wood and coals you could end up with more of an overshoot.

But a bigger concern will be production of creosote from too much idling. Load small and often to reduce idling as much as possible.


gg

+1

Though my unit is designed differently from yours and gg's, I actually prefer 4 to 5 hour burns. That is not always possible, especially when away for work or attempting to get an 8 hour shut-eye.

17-hours is NOT good for a wood-fired hydronic, and is still an hour short for a good bra. Ease up on the loading until it gets colder out!

Jimbo

 

[maple1]

Bra?

Or girdle?

 

[stee6043]

I believe you may be setting new records for longest burn in an EKO 40. Your heat load must be unbelievably low. Almost to the point you could heat your whole house with a 100W lightbulb!

Like everyone else is saying the overshoot is very normal.

You're going to save a LOT of wood if you minimize the idle. At full-bore that EKO will burn through a full load of hardwood in four or five hours,. +/-. Imagine how much of that wood goes up your stack when the EKO isn't doing any work for 60-80% of your load cycle? Yikes....

 

[flyingcow]

Bra?

Or girdle?

:coolsmile: Good pickup! :lol:

 

[trumpeterb]

I wish I had room (and the money) to purchase storage tanks...and the knowhow to pipe them in. I did start filling the boiler with less wood, and that did help a bit. I also started waiting to fill it until almost all of the embers were also gone instead of piling wood on top of 6 inches of coals. That also seems to help a little. I was not as concerned about the overshoot on the temp. I realize this is normal. The thing I worried about was when the temp would be down to 165 or so for a while, the fan would not kick on, but then the temp would rise to 170-175, and once to 183, without the fan kicking on at all. This happens after a zone valve has opened and the temp had been at 161-165 for a while. It was like the boiler was heating the water without the need for the fan. Weird. I wondered if my air intakes were too open, but it doesn't seem so. I also wondered if my gaskets were leaking air, but I see no smoke coming from around the doors. I then thought that maybe the fan "flap" was stuck open, but I didn't find this to be the case either. The only other think I am wondering is if my chimney draft is too strong, but I have no idea how to even go about checking this.
Colder weather is heading my way....hopefully that helps too.

 

[Duetech]

I ran my EKO40 for four years without storage. I would check the settings again and get a good take on your gasification. If your flame is in the blue/white (versus blue/yellow) catagory you are supplying too much secondary air and it don't take much of an adjustment to make a big difference. Factory suggested settings didn't mean much with my unit because I could turn the primaries completely off and still get gassification. But secondary air routing is where the boiler gets it's passive oxygen flow when the boiler is in idle mode. If you have a strong draft and your secondary air supply is too wide you can get a "passive" gasification caused by the pull of the draft. My unit is an older model and does not have the adjustable fan (just fyi) so I don't know what your purging cycles are like but mine were robust for a few seconds and that could also contribute to the overshoot scenario. You have seen that smaller loads will help. You already have heard that creosote will be a problem plugging things up and that will effect boiler efficiency too but it also very corrosive and if your 40 is a super then the turbolators could end up adding some trouble i.e. mine were suspended by pins that were held in place by cotter pins that rusted through because of the corrosion and dropped two of the trub blades down into the heat tubes (I went to ss nuts and bolts). What I am about to say may fly in the face of conventional acceptance and is not intended to offend but due to the loacation of the combustion chamber in this model of gassifier the heated wood has to generate some pressure to cause much smoldering (the smoke has to pass through the coals) and I would venture to say there is a likely catalytic cycle that starts happening when the boiler goes into idle. That being said, and as eveidenced by trickling smoke, idling will cause your boiler to lose efficiency but even that lowered rate is better than the standard OWB. Also it is not the same as an OWB which are possibly more efficient when idling. My 40 fed an a/w exchanger and a dhw sidearm so it probably reacted differently than yours does because I had a consistent water flow going through my exchanger 24-7. My annual wood usage was 6.5-7 cords of wood but then I also used my unit for summertime dhw. The baiscs for your over shoot though are probably rooted in too much oxygen getting to your burning fuel source.

 

[taxidermist]

what is you control setting for Nn and Nu?

If these are set to factory you are still getting a purge of air every 6 min for 5 sec to keep your fire going.

If you want to check you draft watch my video at the bottom of this post.

Rob