Engage Fireview Combustor Before Stove-Top Reaches 250 F

[4wheelcycle]

I love my new Fireview and I have enjoyed learning how to burn it properly. I recently added a combustor probe thermometer and I also use an IR gun to check the flue surface temperature about 18 inches above my stove.

In email inquiries with Woodstock Soapstone I learned it is not necessary to wait 45 minutes or so for the stove-top thermometer to reach 250 F. My new routine is to get my flue surface temp up to 350 to 375 F, which takes less than 10 minutes, let it burn about 10 more minutes to fully heat the combustor, and then raise the bypass lever. Since the flue surface temp is about half the internal flue temp, a surface temp of 325 F or more indicates the temp inside the flue is well-above the 500 F temp needed to ignite the combustor.

Watching the combustor probe temp I see that the temp behind the combustor is about 500 - 550 F just before I raise the bypass lever. After the combustor is ignited the probe temp rises to around 900 F. I note the stove-top temp rises to about 450 F, so the stove-top thermometer is a good 50 percent proxy for the temp behind the combustor.

As others have noted, once the combustor is ignited the flue surface temp drops significantly and may even drop below the 250 F level which is ordinarily needed to prevent creosote formation. However, the combustor burns flue gas components that might otherwise form creosote, so I understand it is OK for the flue surface temp to drop below 250 F if the combustor is operating.

 

[sam_j]

I've started mine with the stovetop temp as low as 150. I don't have a way to check flue temps. I'm assuming you have the stainless steel combustor as do I.

 

[Woody Stover]

Welcome, 4wheelcycle! Hope you're enjoying the Fireview as much as I am.

I think my combustor probe is actually indicating the temp near the flue exit, and that the higher temp at the tip of the probe (when the combustor is working) is diluted by the time it gets to the dial, because the probe is 8" long.

On a cold start with the bypass open I will run the combustor probe steadily up to about 900 or 1000, starting with the air at 3 and cutting it back as the probe approaches the desired temp. I've got a surface thermo lying on top of the snout of the stainless tee right behind the rear-vent flue collar, and that's usually around 450-500 at this time (it would no doubt read lower if it were 18" up the pipe as recommended.) I adjust the air and let the stove run there for about 10 or so minutes. The stove top meter usually indicates somewhere around 180 or 200 when I close the bypass, and the combustor is usually glowing within ten to fifteen seconds. The combustor probe doesn't go any higher when the combustor starts glowing so that's why I think the actual temp at the tip isn't making it back to the dial. I took the magnet off the probe shaft so the probe tip is probably about 5/8" from the back of the combustor. I think that Todd is probably getting higher cat temps indicated by his probe, since he drilled through the top and has a shorter probe which doesn't lose as much heat. The probe on my Dutchwest is only 1.5" long...

Someone asked me if I had trouble seeing the probe dial as the back of the stove sits in the fireplace opening, but when I went back to answer, I couldn't find the thread. What I did was to bend a paper clip so that it would grip the nut that's on the front of the combustor dial. Then I adjusted the rest of the paper clip to align with the 1000* mark on the dial, and bent it far enough out from the dial face so that it doesn't interfere with the movement of the indicator. That way I can see when the indicator is around 1000 when viewing the back of the dial from outside the fireplace.

I'm liking the stove but need just a little cold weather to really crank it up on some Black Locust... :coolsmile:

 

[4wheelcycle]

sam_j,

I just bought and installed my Fireview last summer, so it does have the stainless steel housing and screen around the combustor. I didn't know the combustor itself is stainless steel. It's covered all over with tan colored reactive metals, so didn't realize it is actually stainless steel underneath.

Woody Stover,

Looks like you have been into the stove monitoring business for some time - I like your trick with the paper clip! My probe is easy to read because my Fireview is on an open hearth, not built into a fireplace.

Before my new Fireview I had a mid-seventies Jotul 118, with cast images of moose and woodcutters on the side. With that stove I just put in the wood, got my air flow going with newspaper (and maybe a little spritz of high grade kerosene - oops, not supposed to mention that) and then I let it rip. I didn't need no stinkin' thermometers and I never had any creosote buildup. However, I did manage to warp and crack the the inside side baffles.

I actually live right near Woodstock Soapstone and I have always admired the (expensive!) Fireview. Last summer I finally bought one on a $600-off sale, then in the fall they had an even bigger sale when the new stove came out. Up through mid-January I followed the Fireview instructions and waited about 45 minutes on each burn for the stove-top thermometer to reach 250 F before I engaged the combustor. Then one day I was cruising the Internet and I learned about combustor probes at the Condar web site. It occurred to me that if I could measure the temperature near the combustor I might not have to wait 45 min. for the stove-top to reach 250 F. I emailed Woodstock Soapstone and they said I could engage the combustor as soon as the flue surface temp 12-18" above my Fireview reaches 350 F or so. I want to be sure the combustor is fully heated to 500 F and I also want to burn off any early creosote deposits, so I let the stove burn with the flue surface temp at 375 F for about 10 min. and then I drop the bypass damper.

Woodstock Soapstone told me I needed to get the 8" probe because a shorter probe would not be measuring the temp close enough to the combustor, so they apparently think the temperature reading on the longer probe does not get diluted on the way to the dial. The probe reads about 400 F when my flue surface temp first gets to 375 F, but it rises to 550 or even 600 F after 10 more minutes. At that point I engage the combustor. The probe then rises to 900 F or so over the next half hour and the stove-top thermometer seems to reach about 50% of the probe temp with a 20 minute lag.

My wife and I love the Fireview - it's like having and open fireplace in our family room!

 

[Todd]

Welcome to the forums, great looking install you have there. I had some creosote problems this year and I think part of the problem was watching cat and flue temps, and engaging too soon. I also changed my setup over to top vent to get a little better draft so my cat probe isn't there anymore. I may install a thermocouple probe through the rear of the stove which would be much more accurate than the Condar probes.

Stove top temps do lag behind somewhat, you can be less than 200 stove top and still have internal light off temps according to my old cat probe. Now I just releye on external flue temps to get up around that 350 or so mark, usually in 10-20 minutes, and it lights off just fine.

I think it is very important not to cut any corners by engaging too soon. Get that chimney good and hot for 10-20 minutes to help with the draft. Cat stoves run very low flue temps, right on the edge of too cool, so if you have an outside chimney like me it's a good idea to let her rip in the bypass mode to bring those flue temps back up.

 

[Backwoods Savage]

When we first installed the new SS cat in October it did fire off really quick. However, within maybe 6 weeks we found the cat was not lighting off so quickly. So we went back to 400-500 flue (single wall) and 250 stovetop and have had no problems since. We did pull the cat once but did not need any cleaning. I did brush the fly ash off the screen and that did help. Just for kicks I may look at the cat again though and no problems because we let the stove go out on a daily basis most of the time this winter. Just don't need that much heat.

 

[Woody Stover]

Woodstock Soapstone told me I needed to get the 8" probe because a shorter probe would not be measuring the temp close enough to the combustor, so they apparently think the temperature reading on the longer probe does not get diluted on the way to the dial.

As I said, I'll run the probe up to about 900 with bypass open, then I light off the combustor but the probe reading doesn't change much. On the Dutchwest, the probe would quickly climb to around 1200 after firing off the cat. That's why I'm curious about the setup Todd had; How close to the combustor was the tip and what kind of temp readings was he getting after light off. One problem with that probe is that if you leave the magnet on, the tip is probably 3/4" or more away from the combustor. On the Condar site they said it should be within a half inch, and I saw somewhere (maybe in the instructions that came with the probe from Woodstock, can't remember) that 1/4" was mentioned.

I think it is very important not to cut any corners by engaging too soon. Get that chimney good and hot for 10-20 minutes to help with the draft. Cat stoves run very low flue temps, right on the edge of too cool, so if you have an outside chimney like me it's a good idea to let her rip in the bypass mode to bring those flue temps back up.

Agreed. I'm not usually in a big hurry to get the stove settled in, and don't like to burn it any hotter than I have to, so I will generally bring it up to temp at a moderate pace and not drop the bypass door until I can be sure that it'll light off quickly.

love the Fireview - it's like having and open fireplace in our family room!

Compared to having no window, I bet it is. Having burned the Keystone, the Fireview now seems like I'm looking through a keyhole. :lol: It would be sweet if they came up with a bigger window that I could put in the stove. That would probably involve tearing down the stove, though. I get a better idea what's going on in the firebox if I can see the top of the flames, which is harder to do with the smaller window.
Nice-looking install! Looks like you have the metallic blue also. Mine doesn't look too blue but I sure like that color.