room temp probe; odd behavior

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.

cac4

New Member
Jul 11, 2008
376
Essex County, MA
experimenting w/ the new stove...Accentra free-standing, corner install.

I had the room temp probe coiled up on the floor right under the room air intake grate behind the stove. The stove maintained 70 in the room, as per a digital thermometer on the other side of the room. no problemo...

I decided to crank it up a bit, to see how this would affect temps in other rooms, etc. So I turned the setting up to 75. stove kicked itself up, for a little while, but started backing off when the temp had only gone up a degree or so. So I moved the probe out from behind the stove, as far as it could reach (which isn't very far), and put it along the baseboard. no change.
Next step: move the thermometer next to the probe, to see what the temp is there. (pita cuz it takes so long for the thing to adjust to a new temp). After a few minutes, it reported 75. ok...working as designed. stove thinks its 75 degrees.
I think whats happening here is that there is quite a bit of radiant heat coming off the sides of the stove, and that is being reflected into the walls in this corner, and the probe is going to pick that up, instead of the actual air temp.

So I moved the probe up to the window, and had it hooked onto the latch between the sashes. Thats higher than the stove, and should have the opposite effect of making the stove "think" its colder in the room than it actually is. The end of the probe was about 3" from the glass. I put the thermometer right next to it, to monitor.
Stove kicked itself up, but again, not very much. Flame wouldn't go above a medium height. I switched the fan switch to high range, and cranked it up on the dial...it kicked in on high for a short while (minute or 2), then shut off. every few minutes it would kick back on to full-blast for a short while, and then turn off. The thermometer never went above 71.5.
I have the feed rate set to 4; I don't think that is restricting the output, though, because when the stove starts up, the flame is as high as can be. The stove can make a bigger fire, if it wants to.
So this is a bit confusing. could the probe be bad? Is the end of it supposed to be completely encased in what looks like heat-shrink tubing?

next step, I suppose, is to extend it further away from the stove, but I'll have to pick up some wire to do that. Or, I guess I could open the window, and put it outside...see what it thinks of that!
 
The probe is actually called the room sensor, and it is supposed to look like that. I will admit that it doesn't look very good. These sensors can indeed go bad. I had a scary experience with a bad one that made the stove grossly over heat sending the room temperature to 89 degrees when it was set at 70. The dealer gave me a new room sensor, and it (P61A) has been working like a champ ever since.
 
Chuck,

One thing I noticed is that the probes are not dead on precise. I have my probe extended up and along a wall and I keep a thermometer right at the end of the probe. I have noticed that I have to keep the stove dial set about 4 or 5 degrees warmer than what I want the temp to be at the thermostat. It does however maintain that tempature very steady.

I also have thought that sometimes the stove may set to a low flame shortly after rising and sometimes maintains a low flame. As odd as the stove seems to control itself at times, it does always maintain a steady tempature (as advertised) at the thermometer. I have learned to just let the control panel it do it's thing. As long as the stove keeps the tempature steady, the temp knob on the control panel and the probe reading don't seem like a big deal if they don't match exactly, at least according to my thermometer.

Maybe ParotHead is on the forum and can answer this, but since the stove automatically adjusts itself (feed, temp, blowers, etc.), I wonder what the interval is between it reconfiguring itself when something changes. In other words if we adjust the temp dial, does the electronics immediately adjust for the change or is there an interval that it polls for changes?
 
yeah, well...the "odd" part seems to me to be that 70=70, but 75=71.

If the dial settings were uniformly "off" from reality by a few degrees, thats no big whoop; But different behavior at different settings has me puzzled.
 
got some thermostat wire last night, and extended the probe, moving it a good 10 or 12 feet away from the stove. That seemed to do the trick. I wasn't measuring actual room temp, but it ran at a much more steady rate.
 
Status
Not open for further replies.