Flue temp thermometer recommendations.

[TechWrench]

I have an older Mendota wood burning fireplace. Which after a lot of experimenting, I think I have finally figured out how to use it for best effective heat generation.

One thing I would like to do is to able to get an accurate read on the flue temps. Since it is a built in install, and the flue goes up the outside of the house, in a fully enclosed wood framed chase, one of those magnetic units wont work. My only access to the flue is the space just above the firebox, in the plenum area. The built in portion of the flue, about 10 inches, before it exits the top of the unit is available, but it is recessed about 15/20 inches from the front stone facing, and hidden from immediate view by a removable grate that the heated plenum vents into the room from. I am thinking that if I could find a temperature gauge that uses a wired remote sensor that could be attached directly to the outside of the enclosed flue inside the upper plenum, with the temperature read out mounted on the vent grate that might work.

Anybody have any ideas or thoughts on a temperature gauge that would work in this situation?

Thanks.

 

[bholler]

I have an older Mendota wood burning fireplace. Which after a lot of experimenting, I think I have finally figured out how to use it for best effective heat generation.

One thing I would like to do is to able to get an accurate read on the flue temps. Since it is a built in install, and the flue goes up the outside of the house, in a fully enclosed wood framed chase, one of those magnetic units wont work. My only access to the flue is the space just above the firebox, in the plenum area. The built in portion of the flue, about 10 inches, before it exits the top of the unit is available, but it is recessed about 15/20 inches from the front stone facing, and hidden from immediate view by a removable grate that the heated plenum vents into the room from. I am thinking that if I could find a temperature gauge that uses a wired remote sensor that could be attached directly to the outside of the enclosed flue inside the upper plenum, with the temperature read out mounted on the vent grate that might work.

Anybody have any ideas or thoughts on a temperature gauge that would work in this situation?

Thanks.

Auber instruments makes them

 

[TechWrench]

Auber instruments makes them

Thanks, I will check them out.

 

[TechWrench]

Thanks, I will check them out.

Long time for update, but here it is. I ordered an Auber AT200CHIM kit with the flat washer thermocouple probe, and finally installed it last week. As I said earlier, the only practical place to install the probe was on the pipe inside the upper heat plenum above the burn box. Since the internal height of this plenum chamber is only 16", I had to install the probe to the pipe about 15" above the top surface of the burn box. There is a steel plate baffle in the top of the fire box, so the flame has to go thru a small (3' x 8') opening in the back of the baffle before it can travel to the center of the top of the burn box where the flue is. The pipe is a single wall steel pipe, about 1/8" thick. I drilled a hole and ran a 10-32 tap in it. I used a short machine screw to attach the probe eyelet and washer to the side of the pipe. I mounted the monitor unit on the wall to the side of the stone facing surrounding the fireplace. I can easily read the monitor from across the rom. After a few nights of burning, I found the flue temps to be lower than I expected. The highest temp I saw, while in a 3/4 full box burn with a good bed of coals was in the 345-375 range, and as fire burned down, it quickly dropped to under 300. If I turned off the blowers, the temp would climb 50-75 degrees. The flue above the fireplace plenum is standard double wall insulated pipe, and runs straight up an outside chase for about 18' to the cop of the chase and is topped with a wind blocking cap. I dismantled and cleaned the fireplace and flue several weeks before my first burn, and as in last year, the amount of creosote build up was minimal, with the majority of it within the 1st 6-8' feet of the pipe.

Since this fireplace is an aux heat source (I have oil/hot water for my main heat supply) I don't burn it all day, I just start it in the afternoon, and let it burn out when I go to bed. In the winter I tend to burn it 5-7 days a week, depending on outside temps and how I feel. With the way this unit works, I don't see how I could possibly get flue temps up to 500 let alone some of the temps I have seen reported here. Since i don't seem to have a creosote build up problem, I am assuming that the lower flue temps are not going to be a problem.

Any thoughts?