FHG 40/50 .. boiler set point temperature
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Beagle Dad
Member
I operate my Froling 20 with a return water temperature of 155 or 158 depending on how long I want the burn to last. I set the boiler setpoint to 78C (173), and leave the limits at the original settings of 85 I believe. The 78 allows more room between setpoint and the limit should the middle of the burn get hotter than tyipcal. This happened a few times in the early days.
Here"s my in and out temps .. Was thinking of raising the boiler temp up a bit to try and stop slumbering towards the end of the burn. To get 180f and higher I'm pretty sure she is slumbering.
Beagle Dad
Member
Slumber happens when the boiler reaches setpoint plus the value entered as (shut down above setpoint __ °) If you set the setpoint to 82C (180F) and set the slumber differential at 5 then you should be able get 180 to the tank. As the return water to the boiler rises the ID fan will slow down to maintain the 82C setpoint. If your boiler pump is sized to a 20°F temperature rise across the boiler then you should stay out of slumber even with a 77C or 170F return temperature. The Froling can reduce BTU output by 30 to 50%, depending on how much wood is in the fire box.
velvetfoot
Minister of Fire
Just curious, do you guys have an issue when a load comes on while the boiler is running, as far a controlling temps? I haven't run my system on pellets this year yet, but with the mixing valve controlling return temperature, and the boiler modulating at the same time and then a load or two coming on or off, can the controls get 'mixed up' when reacting to each other? I recall that happening when I 'flew too close to the sun' with return temp, and the boiler shutting down sooner than it should.
Hey VF. could you try this link and click on the charts tab and see if it works for you? http://96.54.66.117/
velvetfoot
Minister of Fire
OK wasn't sure , good to know.. you can click on any rectangle on the right and it will display on the graph.. the circs and demand show in bar form on the bottom. click on the coloured lines on the right of the graph and it will remove them. The flue gas you have to x10. My wife just lit a fire not too long ago, so its all in operation mode now.
velvetfoot
Minister of Fire
Beagle Dad
Member
You can see the number of hours in Slumber from the System Menu. If you think you Slumber every burn the hours should increase. Your last burn the boiler output reached close to 185 which should be near the limit where the Slumber maybe set to trigger. Since the boiler in temperature was at 170 you may not have hit the slumber. Can you confirm that your ID Fan was at its minimum before the Slumber.
The solution is really just to add less wood if you want to avoid over taking the storage capacity.
The solution is really just to add less wood if you want to avoid over taking the storage capacity.
I know it was slumbering ,I sent the kid out to look. I'd like to charge my tanks to 185f top to bottom.. I will set the boiler temp to 185f and see what happens, when I get a chance. As far as the slumbering goes I don't think it's a big deal as it's usually near the tail end of the burn.
velvetfoot
Minister of Fire
I don't know, boiler out dropped off pretty quick after it hit 185.
Do you have any other sensors on the tank? It'd be interesting to see how hot the bottom gets, or the gradient in general.
edit: I wrote that before that last response.
edit2: What's the absolute max before it slumbers, 185? If you set it at that or too near absolute max, modulation might start happening too late and then it goes to slumber because it couldn't modulate it down in time.
Do you have any other sensors on the tank? It'd be interesting to see how hot the bottom gets, or the gradient in general.
edit: I wrote that before that last response.
edit2: What's the absolute max before it slumbers, 185? If you set it at that or too near absolute max, modulation might start happening too late and then it goes to slumber because it couldn't modulate it down in time.
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jebatty
Minister of Fire
IMO relying on modulation to deal with excess output is not a good strategy. Reduce the wood load, always have sufficient storage to accept the output.
What is your boiler temp set at ? What temps do you get your storage up to. Is your boiler circ 120v or 240v ?
I don't usually put too much wood in, Still trying to get a handle on judging the load size, its a lot different beast than my EKO 40 was. The burns last a lot longer and its more output.
Yep exactly.
I have only the basement slab for storage, which is insufficient for any operator but works perfectly for me because I know how to limit the fuel loading and timing.
I forget how I did it but I have the Froling dialed up as far as possibly before it will slumber, and that's at 93 C. The controls would not let me set a higher temp and it's conservative, the boiler thermometer never gets near that high.
Boiler setpoint is dialed as low as I could go and run perfectly, 72 C as I recall, so it spends most of its time at low fire.
The 400 gallon tank would be nice and necessary, and in the future. This as it is could not work better and it is the Froling that made my system. It is only necessary that the operator limit the fuel loading and timing. With seasoned softwoods, that would only be one or two largish pieces on a coal bed when the boiler has been running and the slabs are up to temp.
My fuel consumption is very low and the burns can be mostly effortless when there is no operator error.
Basement slab is always on when the boiler circ is on, slaved to it, to maintain constant load on the boiler when burning. Constant low load.
Edit to add: Ride through heat from the slab when the boiler is off also, could not be better. House is now at 68.0 and if I checked there's not a half degree variance anywhere in the house. The heat spread, penetration through the house, is perfectly equal. That's with two small burns yesterday and the Froling having exhausted its fuel and being off since ~ 3:00 PM yesterday, 1 to 2 degree space temp drop with the boiler off for 17 hours. Could do the same again today, (probably will) two small 3 hour burns for 7 hours on, 24 hours of heat.
You can see why I say "Thank You immensely".
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jebatty
Minister of Fire
Keep in mind that each pound of seasoned wood has about 6000 btus of heat available. Try weighed wood burns to get a better understanding of how much wood you can load as related to your storage and demand.
Froling 20/30 set up as a 20 and then turned down farther from the factory settings, max fan speed is 75%.
1200 sf basement slab and another ~ 2100 sf living space, saltbox style partial second floor. Yes of course 40 gallon indirect. In the winter when I'm burning for heat I could wash the car with free surplus hot water from the indirect. I have the most awesome heat.
Space temp reads 70.0 most of the time. Firing is very simple. If I'm cold I put wood in the boiler and if I'm warm I stop.
I have a lengthy single line of pallets stacked with prepared wood for this season, mostly soft maple and some oak on pallets and top covered in the sun for one year. Wood stacked about 6 ft high.
Entering the burn season I clean the yard and burn the lowest quality first, bark, ants, and rotted.
I've cleaned off maybe 3 1/2 pallets of the prepared wood but that line of pallets budgeted for this year stretches well over 60 ft of pallets.
Have to measure it more closely and post some photos.
jebatty
Minister of Fire
I'm of the opinion that although the Froling controller has setings for different kwh output, those may not actually operate as the settings might suggest. The induced draft fan does speed up and slow down, but the loading unit has constant flow. Modulating by controlling the oxygen/air input, if in fact that is happening, certainly does something, but wood burns best at an optimum oxygen supply, and reducing that supply may reduce the output, but I think it also reduces efficiency. I think a far better procedure is to follow the manual which clearly indicates that the Froling should not be loaded for output over the burn greater than can be accepted by storage (or the system demand).
velvetfoot
Minister of Fire
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