Chimney Temps

[pistonslap]

I have a whole house add on wood furnace. It was given to me by a friend. It is an older model with an air chamber and thermostaticly controlled blower. After I get a good bed of coals and want to get an overnight burn going, I will load the furnace about 1/2 full. Even when I close the stovepipe damper and let my spring controlled air inlet control the burn, my chimney teperature will be at 1100 degrees for about 20 minutes to 1/2 hour. Is this dangerous or normal? After the initial high temp it settes in at about 800 degrees. I had a professionally installed stainless steel liner installed in my brick chimney.
Thanks
Tom

 

[Dave_1]

Tom,

Contact the respective heater & metal chimney manufactures & repeat what you have stated here.

Dave

 

[elkimmeg]

At the temps you recorded that seems dangerous to me 1100 degrees inside the vent???? Whow.

Sounds to me overfiring time to check gaskets and button that beast up. get it under control

did you see that vent pipe start to glow red? or brownish color?

 

[pistonslap]

What I have is a Condar Chimgard Thermometer installed on my fluepipe. I read in a different forum that when you read a fluepipe thermometer, you double the reading. Is this true? The thermometer is divided into 3 ranges, yellow (low temp), orange (effecient burning) and red (high temp). The high temp starts at 475 f. to 900 f. By actual reading on the gauge it is 550 f. for 20 min to 1/2 hr then drops back to 400 f. Is it wrong to double that reading? Also, after reading the instructions again I noticed that it says to mount the thermometer at least 12 in. above the stove. My flue comes out of the back of the stove not the top. I had it mounted a little below the top. The highest I can move it is 8 in. above before the flue goes into the chimney. I'll check the readings after awhile and see if it makes a difference. The flue isn't getting brown or orange.

 

[Dave_1]

We have used a Condar for @ 25 years mounted on the stove pipe 24" above the outlet of the heater flue.

Condar recommends a minimum of 12" above the stove.

<snip>

Thermometers attach magnetically, directly to metal flue pipe. Optimal location is at eye level, no less than 12 inches above the top of the stove. (If temperature of the flue will exceed 800°F, magnetic strength will decrease and thermometer could fall and burn floor. Drill small hole in fluepipe, place safety screw through eyelet in center of thermometer. If preferred, the surface thermometer may be secured around fluepipe using a wire, through the two holes on sides of thermometer.)

<snip>

(broken link removed to http://www.condar.com/meteruse.html)

Contact Condar & ask them about the doubling of temp before accepting it as a correct operating procedure. It just might be, I've just never heard about it until your post.

Have a good one,

Dave

 

[Robbie]

I'm going to make a wild guess, use the exact reading your temp. gauge says, do not double it.............why would they make a temp. gauge you had to double ?

Why not make an accurate reading ? I think they did, your stove temps. sound ok to me, but I am just a second year newbie so double check with the pros here.

Your placement sounds ok too.

Robbie

 

[begreen]

I have a whole house add on wood furnace. It was given to me by a friend. It is an older model with an air chamber and thermostaticly controlled blower. After I get a good bed of coals and want to get an overnight burn going, I will load the furnace about 1/2 full. Even when I close the stovepipe damper and let my spring controlled air inlet control the burn, my chimney teperature will be at 1100 degrees for about 20 minutes to 1/2 hour. Is this dangerous or normal? After the initial high temp it settes in at about 800 degrees. I had a professionally installed stainless steel liner installed in my brick chimney.
Thanks
Tom

Is the flue thermometer surface mount? You'll need a probe thermometer to accurately measure the flue gas temps. Otherwise one is just guessing. 550 surface temp is fine. You'll have to ask your stove installer what the normal operating temps should be.

 

[Todd]

What I have is a Condar Chimgard Thermometer installed on my fluepipe. I read in a different forum that when you read a fluepipe thermometer, you double the reading. Is this true? The thermometer is divided into 3 ranges, yellow (low temp), orange (effecient burning) and red (high temp). The high temp starts at 475 f. to 900 f. By actual reading on the gauge it is 550 f. for 20 min to 1/2 hr then drops back to 400 f. Is it wrong to double that reading? Also, after reading the instructions again I noticed that it says to mount the thermometer at least 12 in. above the stove. My flue comes out of the back of the stove not the top. I had it mounted a little below the top. The highest I can move it is 8 in. above before the flue goes into the chimney. I'll check the readings after awhile and see if it makes a difference. The flue isn't getting brown or orange.

Instead of doubling the reading you add 50% to figure the inside temps. So a reading on your surface thermometer of 550 would be about 825. Or you can buy a probe thermometer

 

[pistonslap]

The more I think about it, the more it makes sense. I worked in a machine shop in the seventies and I did a lot of heat treating in an electric furnace. Anything above 1000 degrees starts to glow. Nothing is glowing on the flue or on the furnace. I e-mailed condar and should have an answer on the temperature soon. But there is no reason that they would graduate it in half degrees. I think whoever wrote that in that forum must have been thinking along figuring the inside temps and got the formula wrong. This is my second season of burning and I didn't use the thermometer last year and had hotter fires a few times with no problems. I think I was concerned over nothing but I will always try to err on the safeside.

 

[BrotherBart]

The more I think about it, the more it makes sense. I worked in a machine shop in the seventies and I did a lot of heat treating in an electric furnace. Anything above 1000 degrees starts to glow. Nothing is glowing on the flue or on the furnace. I e-mailed condar and should have an answer on the temperature soon. But there is no reason that they would graduate it in half degrees. I think whoever wrote that in that forum must have been thinking along figuring the inside temps and got the formula wrong. This is my second season of burning and I didn't use the thermometer last year and had hotter fires a few times with no problems. I think I was concerned over nothing but I will always try to err on the safeside.

Hey, better to ask than not.

 

[pistonslap]

I just recieved a reply from the temperature gauge manufacturer. They said the gauge gives the actual surface temp of the flue. They also said the temps I am getting are normal.

 

[Dave_1]

I just recieved a reply from the temperature gauge manufacturer. They said the gauge gives the actual surface temp of the flue. They also said the temps I am getting are normal.

Well, that ought to give you some peace of mind.

Did you ask them about the readings being taken only 8"up on the stovepipe?

Dave

 

[webbie]

Also, consider that a center temp of even 900 or 1000 does not mean the interior surface of the stainless steel is at that temperature. Air is moving by it quickly both on the inside and the outside.

Of course, it is tested to a much higher temp - 1800 to 2100 - again the gas temp and not the ss pipe temp.

Stainless can take a LOT of heat for a LONG time. Those patio heaters with the aluminum disks over top of them (as used in So. Ca and outside of certain restaurants) have a stainless steel chamber around the burner that glows red hot each and every time that you use it. Same with a lot of other burners, such as kerosene units, etc.

So stainless can take the heat.

I have FLOORED Condar gauges many a time. When they are on the stovepipe and that hot, they may actually fall off - this happens only when some creosote buildup inside the pipe ignites.

 

[pistonslap]

I moved the guage higher on my flue. It comes out the back of the stove. not the top, so it's about an inch higher than the top of the stove but about 2 feet away from the back. My temperature readings are lower now. It's 40 degrees outside and my 2 1/2 story house temp is at 77 while my flue temp is reading 375. My plastered over lined brick chimney is warm to the touch, but not hot, so I guess everything is okay. Thanks for the help.

 

[hardwood715]

I have FLOORED Condar gauges many a time. When they are on the stovepipe and that hot, they may actually fall off - this happens only when some creosote buildup inside the pipe ignites.

Yikes I wouldn't pick it up without gloves! Imagine not being home, I would think it would ignite something. A rolling firestarter! Cause and Origin team at fire scene, Hey I think it started with this stove temp guage!

 

[tradergordo]

For probe (courtesy of Condar):
"When used on horizontal pipes, add 6% to the readings due to lower heat transfer."

"When installed properly, a probe thermometer reads flue-gas temperature to within +- 5% full scale. If placed closer than 18" from the top of your stove or furnace, the thermometer will read slightly high. Creosote on the stem of the thermometer will have little effect on the readings."