Vent pipe temperatures

the magnetic stick ons are not that accurate, and certainly when you are dealing
with low numbers you need to be able to read in single degrees, not in large increments...
I use an IR gun. Some aren't that more expensive than the stick ons.
Those are not good on silvery/shiny surfaces either.
You need to paint a flat black circle somewhere, and read that temp...

The IR guns are great for checking which pellets are hotter,
and measuring the side of your stove..

Dan

 

Mine is a magnetic stick on stack thermometer I had from wood stove days.

It used to be stuck on the catalytic burner in the stack above our old Earth stove wood monster.

 

Yessss, the IR would be far more accurate for sure.

My rule.
If I can lay my hand on the pipe and not hear it HISSSSSS, then it's safe.

If the paint is stinking then it needs my attention.

 

Oh yeah.... with wood or coal, and we did both,
you can smell the heat... then you should check the stove!!

The mags are ok for a general idea. I always had one on the pipe, and one on the stove..
But for testing or comparing, they really vary way too much..

Dan

 

Wood magnetic from the old wood stove burning era, not too accurate as everyone says. General approx. temps required to feed the brain cells as I load the pellets in.

 

I have one of those IR guns and you are correct about the surface needing to be dark for the most accurate results. But if comparing pellets is what you are after, then it would be perfectly acceptable to use one on the non painted surface as long as one was consistent with where they take readings from.
In the past, I have used a thermocouple at the vent exhaust outside and I believe I was getting temps in the 200℉ range. May have to try that again but sounds about right.
When I test pellets for heat I use the thermocouple at the convention tube dead center and then compare feed rates. What I have found is they all are pretty much the same heat wise when they feed at the same rate. *( I have not tested 100% DF yet) but have tested maybe 20-30 others.

 

Heat Exchanger / Room air (convection), K2 thermoprobe, top tube (center), 1 inch from tube outlet,

Internal (stack) temp: thermoprobe, internal to stove, in exhaust stream, directly behind combustion blower motor,

Outer wall of DuraVent double-wall pipe: IR Thermometer (OEM brand) / magnetic "Wood Stove" thermometer.

 

Hey

I'm still in the design stages on the new control panel, so maybe I will install a pyrometer in the panel and a little thermocouple in the vent adapter right at the exit of the fan housing.

Been thinking about installing a small volt meter to be able to adjust the draft fan speed.

Factory specs are given for the various feed rates, and having a meter would be sweet.

 

HEY HEY HEY

Check this out

Panel Meter, LCD, Snap-in. AC Volts & Amps. | MPJA.COM


Perfect.
Add this to the panel and a pot right along side the meter to tweak the fan speed into the sweet spot.

 

The problem I have with the shiny surfaces, is that the temps are so far off from the actual temp..
When I want to compare pellets, I measure the side of the stove in the same spot...
which is flat black.. I'm not overly concerned with the stovepipe. Because it is usually
a low temp.
The higher the temperatures you are recording, the larger the spread.
So smaller variances, are more detectable.
But.. that's me. Not saying it's the "only" way.

Dan

 

I like it - looks like exactly what you would need, and it looks good too.

 

It took only 12 minutes to find what you're looking for

 

Convection air temp was up in the 250s this morning so I took another reading of the outer vent. 189 at the connection to the stove and 170 where it goes into the thimble. I thought it would be higher so I cranked up the heat and checked again. Highest conv temp I could get with my mix of pellets was 275 and the outer vent only climed to 195/175. I also checked the inside vent temp at the end cap and it was 345. Total vent length is about 5-6 feet from stove to end cap.

I use both, an IR gun and digital thermometer with thermocouple.

 

Took a bit more.

Ended up getting an analogue 0-150 volt ac meter off ebay
New old stock

Will mount that in the panel with a 1m ohm pot along side the meter.

Installing a 680k ohm resistor across the terminals of the phase controller will keep the voltage from dropping too low, then run the pot parallel to the resistor to give variable control.

The draft fan needs to run between 70 and 107 volts depending on the feed rate

With this setup I can tweak the beast right into the sweet spot.

Once I get it nailed I can mark the meter face with a little green dot or ???

ebay is my fav spot to shop.

 

you know, CleanFire, I have never paid any attention to the pipe temperature.....I'm more a "check the draft" kinda guy (as all you folks probably know by now). As someone mentioned, those stove thermometers aren't real accurate, and I also have an IR unit, but rarely (almost never) use it. Usually just to show folks that the left side of their old Accentra Insert is markedly cooler than the right, indicating that they plugged their left tube off. I would think quite alot would affect these temperature, maybe enough to make them misleading.....outside temp, pellet type, draft reading, room temp, pipe brand, location, stove type and setting, etc......to me, likely too many variables to make the data anything but misleading.

 

Thanks for the feedback LW, I understand what you're saying, that every stove setup is different / what works here may not be applicable elsewhere. That makes perfect sense.

I asked because I am in the process of a new stove project to reclaim waste heat from the stack (venting) for use to warm our downstairs basement/crawlspace: good news here is the stove parameter 'tuning' I did back in November is paying off well, just cleaned the lower venting and got maybe 1/8 cup of black carbon soot from it, no appreciable ash buildup to speak of.. Which means the ash is staying in the stove, where it's supposed to.

It looks like I will need to incorporate more robust data gathering into the reclaimer unit design up-front, established ports for the thermoprobes needed.

I will need to know at the start what the stack temp. drop will be from input (from the back of the stove), vs. exit vent -> to the chimney, to determine flow rate through the reclaimer coil / prevent stack temps. from dropping too low.

Thanks again LW, that feedback helps.

 

After doing an EXTREME cleaning the airflow is waaaaaay up, the pot is staying real clean (Relative term considering the stuff we burn)

The vent temp with the magnetic thermometer is down around 130 F most of the time and this is a good thing.

Sadly so is the heat output.
The fire pot burns up all or nearly all the materials and the fire stays low in the pot too.

A trade off.