I was bored so I ordered an Auber thermometer and probe for my furnace. Never had a temp issue. Just for curiosity. To be honest, when my HVAC guys did the chimney and stovepipe when I was building the house, they used galvanized as they weren't wood guys. I thought about replacing it but that was 6 years ago and no discoloration so I guess it's definitely not getting that hot. Anyways, I have two 90s in my single wall with a vertical section which would be the right place for the temp probe. However, that's where my baro lives. Should I put the probe before it or after it? My original thought was before it as the baro will have a cooling effect. But then I thought if I put it before the baro, I'll be getting firebox gas temp and not flue temp. Coming out of the back of the furnace horizontally I have 12" then 21" vertical after that with the baro about centered in the middle top/bottom. Everything I read says 18" but that's for a straight vertical exit from a traditional wood stove and without a baro. Thoughts?
Welcome to the rabbit hole! Galvanizing starts to deteriorate at 392*F, so chances are it has off gassed some by now, certainly inside if not out...the outside is the part that can get you though (toxic fumes) I have swapped everything over to stainless, as standard black pipe was rusting out too fast for my liking. We have a local shop that makes it and their SS pipe is barely higher priced than standard steel at the hardware. I'd mount it both before and after that baro...2 holes...just thread a lag screw/bolt in the hole when that hole is not being monitored.
Yep, I figured if anything, it gassed on the inside which is not really a concern. Outside looks new though. If I could find a local shop that could make me up some stainless, I'd be all over it. I may look around after this burning season but am not hugely concerned about it. As to the probe, I guess I could check both before and after. Which would be your priority? Again, I'm not really concerned and only bought this thing as a curiosity out of winter boredom. Do you think the 18" recommendation still applies even though the first section of pipe is horizontal Dave? I'll have to check the outside temp with my IR thermo. I can't recall if I've ever seen it at 392...
Probably before...that's where mine is. I think so...mine is the same way...I only insert the probe 3" though, since its sensing the temp from the tip. Spray a patch with some flat black paint...that's the only way so get an accurate reading from an IR gun...shiny or rough surfaces throw it off a bit (and how much is an unknown)
I pull mine every couple weeks...since I monitor all the time it becomes obvious when its dirty. I just have it shoved in the hole, and it fits tight enough that just the act of pulling it out cleans it...that holds it in place too.
Well, that was easy. Done in about 15 minutes. Very satisfying to my OCD to watch the temp change based on blower operation. It also climbed right after raking the coal bed forward to burn it down before a reload.
I would also put it before the baro. You know that temps after the baro will always be lower. Sometimes much lower if the baro is more open due to weather. Since in a furnace, the flue collar is already many feet after the firebox (and with a fan blowing over it) you aren't going to get temperatures that you can compare with the stove guys. It should read much lower than the normal 400-800 we want above a stove. You can put the probe right after the flue collar if that works for you.
I have it 18" and right before the baro. It's interesting. I won't say life changing but fun to watch for sure...
