CB EC 2400/Super Cold Weather/Temp Differential Question

[Bob Lentz]

It's super cold here in CO right now - trying to tweak my setup to prevent my Propane furnace from firing. I just raised my high set point to 190 from 185 where it has been since purchase.  Don't seen any increase in wood usage. however, i am wondering that during super cold months, if it makes sense to decrease the temp differential form 10 to like 7 degrees?  i have noticed that in super cold weather, when boiler gets down to low set point, the water temp can fall as much as 10 degrees farther due to demand before fire is restored and temps start to rise.
Thoughts?

[stratford 50]

I live in Northern NH and -30 to -40 below usually happens couple times a winter, saying that I run 5 degree differential and it will still drop 3-4 degrees until it gets rolling. My set point  is start @ 180 shutdown 185 and I'm heating almost 5000 square feet, hope this helps.

[doctorb]

Sounds a little fishy to me.  Here's my thoughts, FWIW....

If your temp drop goes that far below the restart temperature, a couple of things could be happening.

1.  The time that the furnace is "resting" between reaching the high water temp shut off point and restarting is so long that it is taking quite a while for the fire to rekindle, once the fans start blowing.  This seems very unlikely since it is so cold right now.  And your stove must not remain idle very long.

2.  Your fuel may not be seasoned, so that it takes longer for the coals to get hot again, delaying the heat from being produced and allowing the water temp to drop much further than it should.

3.  Your requirements for heat are so great that any delay in restarting the coal bed is leading to this marked drop in water temperature. 

I run my stove between 185-195 degrees.  It's now my 7th heating season with my CB 2300.  My installer told me to run it that way so that I get over 180 degree heat to the house for my HW baseboard.  I would ask....

Do you have temp gauges on the inflow and outflow lines in your basement?  If so, what are the readings?  Are you losing a lot of heat into the ground between the stove and your house?  Are you returning relatively cold water to your stove?  If so, then your house is swallowing this energy and spitting it outside.  Is your house well insulated?

I have seen my stove temp drop to 181 and, very rarely, 179, before reversing and cycling back up to 195.  I have noticed that this is affected by the ambient outside temperature, but I've also noticed it's dependent upon how efficiently the stove is running.  So, how are the air channels and openings?  Back sided solenoids clean?  Fuel nice and dry?  Is the firebox in need of a cleanout?  All of these things, and more, can affect your OWB performance.  Give the amount of temp drop you're seeing, I'd make sure you have checked all the regular maintenance boxes so your stove is operating at peak efficiency.  What are you burning?  Spruce?

Sorry about all the questions when you posted for answers, but it's a multifactorial issue.  Looking at stratford 50's post, you seem to be losing a lot of heat somewhere, or your stove is not running as well as it might.  Best of luck and let us know what you find.  I don't think this is a temp differential problem.  Just my opinion.

[Gearbox]

If your useing a inside fuel boiler just lower your high limit on your aquastat . I have a peerless and came preset at 180 . I lowered it to 160 now it only kicks on for 2-4 min. then reaches high limit and the flame shuts off

[martyinmi]

I RAISE my differential to 5 degrees when it is cold. I typically keep it at 2 or 3 degrees when the temperatures are a bit warmer. Mine came from the factory with the differential set at 10 also. It sometimes smoked badly for as much as 5 minutes or so when it began a cycle, and once in a while it would drop a few degrees before it would begin to pick back up in temperature. Rarely does it smoke for for than 30 seconds with the differential set lower now.
The nozzle in a gasser needs to be kept hot for them to gasify properly when they are called upon to cycle(800 plus degrees if I remember correctly).

[stratford 50]

Here is another thought, I had to replace the controller on my 2400, reaction chamber temp wasn't reading correctly. Once I changed the controller my water temp was off 10 degrees, I know this because when I shutdown to change the controller water temp was 185, it took a couple minutes to change the controller and when I pushed the power button on the new controller it read 195 ?? I also have a gauge on the incoming water in my basement that confirmed that the new controller was off by 10 degrees.

A call to CB and they walked me through the steps to change the water temp to make it read correctly. It is very important to verify what your water temp is other than what the furnace readout displays says. You may think your water temp is @ 195 and it is actually 185.

I also installed the Firestar XP readout in my home so to monitor my furnace and I'm using the Wi-Fi with my computer to set up a graph which will record your furnace performance right to the minute if you so choose. This is a great tool and I highly recommend it to all with the 2400 model. Sorry to run on but important info.

[gspren]

   My stove is a conventional, not a gasser, and I have a 4 deg differential, was originally 10. The only time the temps drop way below kick on is in warmer weather where it had a long idle and then someone takes a long shower using heat before the stove gets back to temp, this doesn't happen often. In colder weather if I hear the oil burner kick on I need to go check what's wrong, maybe bridging of the wood, but it's rare.