Quadrafire Santa Fe shutdown on medium

[pelletburn]

this is a Santa Fe C, clear control box, no OAK. the stove shuts down on medium, thermostat is calling, thermocouple indicator light is green, auger is -not- running past initial feed.

the stove runs fine on low or high. on low, the light stays green, but the auger continues to run (and the stove operates as expected). on high, the light changes to red after a while.

when operated on high, to the point where the thermocouple indicator light changes to red, then toggling to medium, the stove will run for a couple hours, then the light turns green and the stove shuts down. on low, with the indicator green but the stove functioning normally, the igniter turns off - i can see when it's on, and the stove is only pulling about 100W.

i have cleaned out the stove to the extent possible without taking off the blowers (toothbrush, pipe cleaners, vacuum with flex tube attachment, etc.). not counting the blowers (which i admit to have never cleaned prior to the problem), cleaning routine was per manual - accessible burn chamber area every bag, baffles/heat exchanger/hopper. chimney flue and stove exhaust are clean.

if the stove is operating on medium and shuts down, resetting restarts the cycle.

this is a new problem at the start of this season - did not have this issue the prior two seasons. "mileage" on the stove is about 7 tons of pellets.

all parts are original. no modifications. i have re-seated the control box (stove unplugged), other than that, nothing intrusive. problem is stable/reproducible, no changes after cleaning blowers and re-seating control box.

i don't have a clamp meter sensitive enough to measure the thermocouple in operation.

would appreciate any suggestions.

 

[Mt Bob]

Hopefully one of the Quad people will assist you, but 2 things, inspect end of thermocouple, although it could still be erratic if looks good, and make sure it is pushed to the end of the ceramic cover, and cover is positioned properly.

 

[Tjune54]

That sounds like a control board issue. The auger should turn after stat up as long as the led is green. It will shut down if the led does not turn red after 8-10 minutes. Even in low burn the led must turn red for continued operation.
The control board adjusts the feed rate for H-M- and low.

 

[pelletburn]

That sounds like a control board issue. The auger should turn after stat up as long as the led is green. It will shut down if the led does not turn red after 8-10 minutes. Even in low burn the led must turn red for continued operation.
The control board adjusts the feed rate for H-M- and low.

i am very reluctant (paranoid?) to do surgery without a firm safety net. the stove is primary source of heat, and while i have backups, i wouldn't characterize either as "firm."

that said, i should have one in place soon-ish, along with a donor control box to use for testing and a thermocouple.

the issues haven't changed. i agree that this is likely a control box fault, but i don't have the necessary information to troubleshoot and don't want to open the enclosure to look for any obvious damage. also agree that the thermocouple indicator should turn from green to red on low - it does not, running that way overnight. i use the thermostat as an on/off switch, so the stove doesn't cycle - this is continuous operation.

this morning i switched the stove from low to high, waited for the light to turn red, then switched to medium. confirmed yet again it'll start shutting down after a couple hours: light stays red, eventually turns green and goes off.

it can also be a failing thermocouple, but i don't even want to attempt to squeeze the voltmeter probe leads into the wiring harness connector without that firm safety option readily available. the stove operating completely normally on high, with thermocouple indicator at red, and same for low but the indicator staying green suggests humoring the inner paranoid voice.

 

[Tjune54]

Have you opened the manual feed rate control rod fully? The stove may not be feeding enough pellets for med and low operation. If the rod is all the way out there is an adjustment knob on the control box that will plus 10% on the auger feed rate also. I will look for instructions for this adjustment.

 

[pelletburn]

Have you opened the manual feed rate control rod fully? The stove may not be feeding enough pellets for med and low operation. If the rod is all the way out there is an adjustment knob on the control box that will plus 10% on the auger feed rate also. I will look for instructions for this adjustment.

i've touched it once, readjusting to original after knocking it out of position during cleaning accidentally. that was at least a year ago. the flame looks correct on all settings, including when the stove runs on medium during the two hour window when it runs. if i start the stove on medium, the auger will not operate at all after the initial "burst."

i didn't know of an adjustment for the feed rate on the control box, so i haven't touched that.

the pellets were purchased from the dealer, premium hardwood. burning leftovers from last season now.

i discovered the problem when the temperature dropped to warrant running on medium overnight, and the stove shut down after toggling from low to medium at 1a or so. (of course)

i did talk to the dealer; the assessment was that this will likely end up being troubleshooting by parts swap-out as the scenario doesn't match a known/deterministic fault case.

 

[pelletburn]

quick update on where this stands, in case it's helpful to someone.

i've tried a new control box - identical behavior. while i do have a replacement thermocouple in hand now, the problem seems to have gone away.

i'm on my second bag of this year's pellets, purchased from the dealer as last year's but different brand (still premium hardwood).

visually, i cannot identify any damage to last year's pellets; no tell-tale puffy "blooming" look from moisture.

note that on low, i still have a green light. on medium, with newer pellets, it's red now, just as on high.

still have some old bags and will try to reproduce. chasing this with parts replacement doesn't seem worthwhile. in the Santa Fe C, there doesn't seem to be a way to test the thermocouple while in operation without a sensitive enough clamp meter.

 

[steelersfootball88]

ever pinpoint the culprit? having the same condition on my santa fe insert. mine too appeared to correct itself for a period of time but has started acting up again

 

[pelletburn]

ever pinpoint the culprit? having the same condition on my santa fe insert. mine too appeared to correct itself for a period of time but has started acting up again

no. it happened again earlier this season and went away. came back yesterday. i took advantage of the warm weather and deep-cleaned the stove, too. temperature dropped in the evening quite a bit (enough to run on medium), and the stove shut down. i ran it on high overnight.

same symptoms as previously. i even still had about half a bag of pellets in the hopper that ran fine on medium.

the flame looks good on high, barely there on low and kind of like an ok low when on medium. the light stays green when on low. i switched to medium, the light eventually changed to red - briefly, then back to green and the stove shut down shortly after.

 

[pelletburn]

just to spite me, the stove has been running fine on medium for the last three hours or so.

 

[Former Farmer]

Check the ceramic cover over the thermocouple. It needs to be in contact (touching) the thermocouple. There should be instructions in your owners manual on how to set the length sticking over the burn pot.

Did you take off the ceramic cover and make sure it is not full of ash?

 

[pelletburn]

i haven't touched the thermocouple; hadn't even considered there is ash to clean out there. will take a look when i have an opportunity.

i have a spare thermocouple/ceramic cover and, eyeballing, it looks like the current setup should be good.

the stove ran fine on medium from early evening overnight.

what the manual describes as "nuisance shutdown" seems to occur early in the heating season. or the weather pattern like last weekend: 60F followed by a sharp drop to 30.