Not getting enough heat - New Drolet 1800 - Do I need a flue damper?

[macgyverman]

Hi all, just had a Drolet Escape 1800 installed in our insulated basement. The house is a 2005 split level with about 1225 sq ft per floor. We're located in Ontario, Canada. It's currently -14C out.

I've operated a few wood stoves here and there in the past and it's always been my experience that when cranked all the way up, a stove will make a reasonably sized room unbearable to be in.

I've played around with the air inlet damper and the flue temp will hit 1200F if I leave it on full open (which obviously I don't). With the inlet damper fully closed, the flue temp drops to a reasonable 400-600F. The flames will calm down to a low "boil" instead of shimmering masses. From what I can tell, the stove is drafting properly.

The wood was delivered cut and split back in July. It was left stacked until November and then brought in the garage. The delivery guy told us the wood had been split 2 years ago. I don't have a moisture meter, but I'm inclined to believe him since some of the oak has gone a dark silver.

All that to say : I have no experience with this particular model of stove, but it seems to eat through my wood and the house temperature is not changing. It's warm in the room with the stove, but only if it's been running for 2-3h with constant reloading. By no means are the temperatures unbearably hot. I can stand within a few feet of the stove quite comfortably. The house never breaks 23C inside, and the furnace is still kicking in.

What am I getting wrong here? I'm about to borrow an IR camera to look for cold air leaks and check the stove surface temp.

 

[DAKSY]

Watch your wood. Is it bubbling?
If so, it's too wet. Verify it with a meter.

 

[macgyverman]

Watch your wood. Is it bubbling?
If so, it's too wet. Verify it with a meter.

Sorry, should have mentioned that there is no visible water. I'm not hearing the wood hiss either, so if it's wet, it can't be that wet.

I'm in the process of getting a meter to check it. Where I'm confused is that the flu temperatures easily get very high, so the fire is certainly putting out a lot of heat. I'd expect wet wood to keep the flue gas temp down.

 

[EbS-P]

I have an 1800 insert. Where are you measuring flue temps? Are you able to measure stove top temps? How tall is the flue?

I have 24’ of liner nearly straight. I determined I needed a damper. Stove top was over 700 with air full closed. measuring flue gas temps at the appliance adapter I could not keep below 900. Now I only hit 900 at my peak. I played with blocking off secondary air and primary air holes. Damper is more effective at keeping the air balanced.

 

[macgyverman]

I have an 1800 insert. Where are you measuring flue temps? Are you able to measure stove top temps? How tall is the flue?

I have 24’ of liner nearly straight. I determined I needed a damper. Stove top was over 700 with air full closed. measuring flue gas temps at the appliance adapter I could not keep below 900. Now I only hit 900 at my peak. I played with blocking off secondary air and primary air holes. Damper is more effective at keeping the air balanced.

I think I actually read your thread. I've just borrowed an IR camera, so I'll hopefully be able to get stovetop temps. I'm not sure how high it reads. If not, I'll look for an IR laser thermometer.

The chimney is about 20 ft outside, connecting at the foundation. It runs about 3 ft horizontally, and goes through a slight S shape and then down another 3ft to the stove.

If set the air intake to the minimum, my flue temperature does drop to the "normal" range. I don't recall exactly what temperatures those are but I believe it's below 800F.

The chimney didn't draft the other day when it was 2C out, it was actually back flowing and smoked up the house. A quick paper fire solve the issue though.

 

[EbS-P]

Do you have a 6” liner in the exterior chimney? Two 90s and 3‘ horizontal on 23’ would definitely be less draft than I have.

I had full blow torch with flames wrapping around the baffle with no damper and air full closed. It looked too hot but stove top was not crazy hot. I put in a load of wet wood (Leak in my tarp) and was astounded as the difference (less heat).

Now with the damper I can cut the burn rate and keep temps in check.

 

[begreen]

How is the flue temp being measured? Does the stove have single-wall or double wall stove pipe connecting it to the chimney?

 

[ABMax24]

400-600F with the damper closed isn't out of line, but it could be a little bit lower, assuming this is measured with a flue probe.

These 2.4cuft fireboxes flow a significant amount of air through the secondary system though, and it can mask an overdraft issue by diluting the flue gases with enough cool air to make the flue temps seem normal.

 

[Todd]

Sounds like a large house, maybe stove is a bit undersized for whole house heating? Try fan blowing cooler air down to lower level where stove is located to help push the warm air out.

 

[EbS-P]

400-600F with the damper closed isn't out of line, but it could be a little bit lower, assuming this is measured with a flue probe.

These 2.4cuft fireboxes flow a significant amount of air through the secondary system though, and it can mask an overdraft issue by diluting the flue gases with enough cool air to make the flue temps seem normal.

My guess when looking at the intakes the unregulated secondary air is 4x primary when it’s full open. It’s about 2”x4”. This is the secondary intake

 

[macgyverman]

Do you have a 6” liner in the exterior chimney? Two 90s and 3‘ horizontal on 23’ would definitely be less draft than I have.

I had full blow torch with flames wrapping around the baffle with no damper and air full closed. It looked too hot but stove top was not crazy hot. I put in a load of wet wood (Leak in my tarp) and was astounded as the difference (less heat).

Now with the damper I can cut the burn rate and keep temps in check.

Yes, it’s a 6” liner on the exterior chimney. I’m starting to think my wood is somehow still wet after being cut and split so long. Sometimes I have to close the air intake to keep the flue temps down, and sometimes even at full open I’m not reaching 600F

 

[macgyverman]

How is the flue temp being measured? Does the stove have single-wall or double wall stove pipe connecting it to the chimney?

Hi, sorry for the lack of detail on my part. There is a flue gas probe about 2ft from the top of the stove. The stove pipe is double walled 6”.

 

[macgyverman]

Sounds like a large house, maybe stove is a bit undersized for whole house heating? Try fan blowing cooler air down to lower level where stove is located to help push the warm air out.

I was actually under the impression it was oversized when I ordered it, but I was disappointed with the firebox size. It’s rated for a 2000 sq ft house in our climate range. AFAIK this is usually measured based on the house footprint and not the sum of all floor areas.

 

[macgyverman]

My guess when looking at the intakes the unregulated secondary air is 4x primary when it’s full open. It’s about 2”x4”. This is the secondary intake

View attachment 291539

Im still learning about EPA stoves and the second air intake. Not sure what the numbers translate out to as far as heating, but I’d expect that they would be calibrated to produce the correct amount of heat. The only variable is if the chimney is losing it all.

I measured the stove top temp with an IR camera last night. The hottest I can get it to is 270C or about 550F. At this point, the flue gasses creep to around 1000-1200F.

Usually, the stove runs around 180C or about 340F, if I keep the flue gasses in check.

 

[EbS-P]

How soon after lighting or reloading do you get good secondary combustion? This is how I know my wood is wet. It takes a long time. On a good dry reload load 10-15 minutes and I have good secondary combustion and I am turning the air down. If the wood is wet I have to leave the air open longer

 

[Woodcutter Tom]

I am interested in how this works out for you.
I have the 1800's baby brother, the Escape 1500. This is my second year with it. All last year I struggled to get heat out of the stove. Best STT I could get was about 350 F. My run times were short; burning thru a load every few hours. I did get a lot of heat up my flue. 1000- 1100, close to 1200 F at times measured with thermocoupler probe at 18" above stove top. After a discussion with SBI, it was determined that I had way too much draft. The air coming out of the secondary tubes was moving too fast to heat up and it was sucked up the flue too quickly. My manometer was displaying .18 - .20 inches of water column. SBI suggests .03 -.05 " WC. for my stove. I installed a damper in my stove pipe. It was a bit late in the season to really know how it would work.
This year I am controlling my draft with the damper...and I am using some larger splits of wood. I get quite a bit more heat at the STT and I get much longer runs. 6 - 8 hours. Load up at 8:00pm and there are coals to ignite new load at 7:00am.

BUT...quite a bit more heat is not hot and it is not good enough. I can get 540 F fairly easily with a flue temp of 700 - 800 F. That takes too long to heat the house. I am trying to figure out how to get the elusive 625 F STT.

 

[ABMax24]

My guess when looking at the intakes the unregulated secondary air is 4x primary when it’s full open. It’s about 2”x4”. This is the secondary intake

View attachment 291539

From what I see in my own stove the restriction on the secondary system is at the holes in the tubes themselves. On the 2020 version of the SBI 2.4 cuft firebox that works out to about 2.05 square inches between all the holes in all the tubes. On the primary side the hole in the damper plate (plus at least on small boost hole), and I believe this hole is about 3/4" (don't quote me on this, my stove is a 2015 version and is different) which puts this at about 0.5 square inches of surface area. So to assume you get about 4 times the secondary air seems close to me.

Why do the surface areas matter? In essence a crude approximation of airflow is to assume the secondary and primary systems are a simple orfice, there are then 2 variables that determine airflow through an orfice (stove) and therefore to the fire, that's the surface are of the orfice (the size and number of openings in the tubes, and the size of the primary air intake at whatever setting you are measuring) and the differential pressure across those orfices, in this case caused by the stove draft.

For whatever reason, this stove seems to be more sensitive to draft than others, something I noted as well very early on with mine, and can quickly enter a runaway condition with enough stack height. More heat = more draft = more airflow to the fire = more heat and so on, until something breaks that cycle (like a flue damper) or the stove runs out of fuel.

 

[macgyverman]

How soon after lighting or reloading do you get good secondary combustion? This is how I know my wood is wet. It takes a long time. On a good dry reload load 10-15 minutes and I have good secondary combustion and I am turning the air down. If the wood is wet I have to leave the air open longer

Pardon my ignorance, but how would I identify secondary burn characteristics? Is there a flame pattern to look for or are we simply talking about being able to bring the air intake down and keep combustion going?

 

[EbS-P]

Pardon my ignorance, but how would I identify secondary burn characteristics? Is there a flame pattern to look for or are we simply talking about being able to bring the air intake down and keep combustion going?

I call it the jets of flame that are due to the air coming out of the burn tubes.

 

[macgyverman]

I am interested in how this works out for you.
I have the 1800's baby brother, the Escape 1500. This is my second year with it. All last year I struggled to get heat out of the stove. Best STT I could get was about 350 F. My run times were short; burning thru a load every few hours. I did get a lot of heat up my flue. 1000- 1100, close to 1200 F at times measured with thermocoupler probe at 18" above stove top. After a discussion with SBI, it was determined that I had way too much draft. The air coming out of the secondary tubes was moving too fast to heat up and it was sucked up the flue too quickly. My manometer was displaying .18 - .20 inches of water column. SBI suggests .03 -.05 " WC. for my stove. I installed a damper in my stove pipe. It was a bit late in the season to really know how it would work.
This year I am controlling my draft with the damper...and I am using some larger splits of wood. I get quite a bit more heat at the STT and I get much longer runs. 6 - 8 hours. Load up at 8:00pm and there are coals to ignite new load at 7:00am.

BUT...quite a bit more heat is not hot and it is not good enough. I can get 540 F fairly easily with a flue temp of 700 - 800 F. That takes too long to heat the house. I am trying to figure out how to get the elusive 625 F STT.

Interesting! I'd certainly want to measure that. Any information on where to get a manometer and how you're connecting it to read draft?

How big of a house are you heating with it? I can't imagine how small the 1500 is. I'm finding the 1800 really small for loading...I can only get 3 big splits in there and I'm always hitting the damn air tubes when I load it.

If I load it up at 11pm, I barely have coals at 5am.

 

[macgyverman]

I call it the jets of flame that are due to the air coming out of the burn tubes.

You mean like seeing "rolling" flames coming down from above the wood? I rarely get those. It needs to be really loaded up with wood for that to happen. I can't wait for that moisture meter to arrive to check this out.

 

[kborndale]

Yes, it’s a 6” liner on the exterior chimney. I’m starting to think my wood is somehow still wet after being cut and split so long. Sometimes I have to close the air intake to keep the flue temps down, and sometimes even at full open I’m not reaching 600F

More than likely your wood dealer was less than honest about when the wood was split.

 

[macgyverman]

More than likely your wood dealer was less than honest about when the wood was split.

I’m inclined to agree. I’ve just tossed a log on there an hour ago, with the air intake on full open, and it’s still barely lighting up. The log is just turning to char.

I’ll have a moisture meter shortly and then I’ll be able to confirm.

However, would this be entirely responsible for the inadequate heating? I understand that it takes a heck of a lot of energy to boil the water away. However, if I’m reaching 550F on the stove, should that not be sufficient to heat up the house like crazy? Right now, all it’s managing is to keep the temperature stable at 22.5C.

 

[ABMax24]

I’m inclined to agree. I’ve just tossed a log on there an hour ago, with the air intake on full open, and it’s still barely lighting up. The log is just turning to char.

I’ll have a moisture meter shortly and then I’ll be able to confirm.

However, would this be entirely responsible for the inadequate heating? I understand that it takes a heck of a lot of energy to boil the water away. However, if I’m reaching 550F on the stove, should that not be sufficient to heat up the house like crazy? Right now, all it’s managing is to keep the temperature stable at 22.5C.

2450sqft total, assuming -10 outside, and holding 22.5c at 550f stovetop isn't terrible.

My house is 2200sqft over 3 floors and does about the same.

I often shoot for higher stovetop temps though, I generally like to see 650f and will even push to 750f when the heat load requires it. IIRC max temp according to SBI (parent company of Drolet) is 840f.

To me it sounds like wet wood is at least part of your problem, I find at 22-24% I have a hard time pushing beyond 600f stovetop, at 18% and under 750f is easy to attain and I get a much cleaner and longer lasting burn.

 

[EbS-P]

Not many coals 6 hours later sounds like an over draft. With a good layer of ash On the bottom I can have coals up to 12-18 hours later. I have found wet wood tends to coal up and they last longer, But with less heat.

Coming from 1.7 cu ft F400 to 2.4 it seems cavernous at times.