How to avoid EKO fans quitting when there is high heat demand

tuolumne · Jan 28, 2009

I have my initial fan time set to the maximum time of 90 minutes, and working time set to the default of 30 minutes. I find that the fan sometimes quits prematurely and says FUEL when I still have gasification. When the demand is high, the boiler may run for 30 minutes and not hit the setpoint, but still be holding steady or rising slowly. I do not want to change the 30 minutes much, because that will just put out my coals at the end of a burn. I aniticipate this problem being difficult once I am charging the storage tanks. I just swapped out a very noisy 008 circ on the boiler for a Grundfos 1558. This helps get up to temperature a lot by slowing down the water in the boiler loop. When I am up to temperature I go from speed 1 to speed 3 manually if I want to get more heat to the zones.

Questions:

What is the best time setting?
Is there a way to base shutoff on temperture change rather than a setpoint?
Should my boiler (clearly oversized) be able to hit temp in time even under high load? I may be burning wood that is not dry enough. i.e. will this problem go away with properly seasoned firewood?

Eric Johnson · Jan 28, 2009

I'm working on the same issue, but haven't figured it out yet. It's not a big deal, but occasionally I'll get the FUEL message when there's still plenty of wood in the firebox. I think it may have something to do with the boiler not coming out of idle mode correctly. I'm burning very dry wood. It still does it, but it would probably be a bigger problem if you were trying to burn wood containing excessive moisture.

Nofossil · Jan 28, 2009

Yet another control problem - this is an interesting one. Being a chicken, I've elected to wrap my controller around teh EKO controller rather than replacing it. I have the old one so I have fewer options than you guys.

Here's my thoughts:

I think the EKO gives up if you don't reach a certain mysterious and undocumented minimum outlet temp for some period of time. On mine, the minimum seems to be 65C if the outlet setpoint is 80C. It may be the case that selecting a lower outlet setpoint would also give you a lower 'fire is out' threshold.

If you're not getting above that minimum for long periods when the boiler is actually running, then you have one or both of the following situations:

1) The flow rate is so high that the boiler can't add much delta T to the water passing through

2) The incoming water is too cold, so even adding 20 degrees doesn't get it high enough to exceed the minimum value that the EKO controller is looking for.

A slower flow rate solves #1, and playing with input protection or load management could address #2. I do all three things to keep my EKO controller happy.

slowzuki · Jan 28, 2009

I was gonna say a low return temp protection should solve the issue.

leaddog · Jan 28, 2009

I have my controller (new Style) set to -- on the first burn time and 3hr on the second. I also have my modulating valve set so no water leaves the boiler until it reaches 180* and my boiler pump doesn't come on untill 170* I have storage so this works for me. That said I think that if you have the new controller that if you set the first burn to 4hr you should be ok. The new controller will go to 90, 2hr,3hr,4hr.
leaddog

taxidermist · Jan 28, 2009

leaddog said:
I have my controller (new Style) set to -- on the first burn time and 3hr on the second. I also have my modulating valve set so no water leaves the boiler until it reaches 180* and my boiler pump doesn't come on untill 170* I have storage so this works for me. That said I think that if you have the new controller that if you set the first burn to 4hr you should be ok. The new controller will go to 90, 2hr,3hr,4hr.

leaddog

Les What command is this on the controller? for the burn times?

I had not had a fire in the boiler for about 16 hrs and when I went out in the am my fan was still running?????

RJP Electric · Jan 28, 2009

I have mine on FD 4 means 4 hours on initial startup to get to desired temperature, sometimes I turn it off then back on to reset it if I expect it will take longer.
FB 2 means 2 hours on run time to get up to temperature
If you have a -- that means no shut off
I also have my circulator setting at 170º, it works great, no need for a set point controller.

leaddog · Jan 28, 2009

The FD and FB are the comands. I think the fd is set to -- in the default but you can change that to 1-99min, 2hr,3hr,4hr and the fuelburn FB is the same. handy once you figure out how you burn as it gives alot of flexiblity to leave coals.

copied from manual
No-fuel testing time during fuel firing start [Fd60] - after switching to
WORK mode, if water temperature doesn't reach temperature set with the
thermostat in programmed time, the control process will be turned off and
the display will show the message: [FUEL].
You can return to previous mode by pressing STOP button.
No-fuel testing time during work mode [Fb30] - in WORK mode, if
temperature of water in the boiler decreases below temperature set with
the thermostat, by hysteresis value, and don't reach temperature set with
the thermostat in programmed time, the control process will be turned off
and the display will show the message: [FUEL]. You can cancel the alarm
by pressing STOP button.

termite · Jan 28, 2009

You can also turn one or both of these functions off by selecting "--" from the menu. The most likely scenario for that would be running your boiler full tilt into storage. Even without storage and the boiler set at a lower temperature you will still get "fd" and "fb" shutdowns if the burn bridges temporarily and the temperature drops below the hysteresis value.
I think the functions were a good idea but you are probably better off using other means to determine if the fuel has been exhausted. After a couple trips to the boiler room to find the "fuel" message displayed with a full smoldering load of wood I disabled them and haven't looked back.

tuolumne · Jan 28, 2009

Thanks for these tips. I did not know that I could go beyond 90 minutes. That will help with startup when we come back from a long weekend to a cold house. (Who am I kidding, I like making multiple trips to the boiler room to check on 'er!) I hesitate to set Fb much longer than 30 minutes so as not to put out the coals when I really am out of fuel. I have a 144 degree danfoss valve, and currently have the pump set at 150. That has helped, it was previously at 144. I think I will move the pump setting up to 170, that sounds like it may help a lot on the fuel burn time. My primary loop circulator will still be pulling some water through the boiler once the danfoss opens. The condition I am now fighting seems to happen with the boiler around 170 and all zones calling. It just never got past that quick enough. I typically keep my setpoint at 195 unless demand is very low. I have had a few E2 warnings when we were away and then the boiler quits for good. This has only happend since I swapped circulators. Apparently, the 008 ran water through the primary loop fast enough to dissipate the heat even with no zones calling. Now I have my dump zone cracked open when we leave to avoid that issue. I'll report back on 170 degrees once I see the results. Thanks.

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How to avoid EKO fans quitting when there is high heat demand

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