Troubleshooting wood furnace is newly acquired home

[Jdepiazza]

Hello. We recently bought a timber frame home that has 2 traditional furnaces, and 1 DS Stoves Kozy King coal/wood burning furnace.


I grew up with wood stoves so am comfortable running them, but this one has posed a few challenges I need some help with.
Here’s my setup:
1 electric heat pump serves upstairs of house
1 dual fuel high efficiency unit heats first floor
Kozy King sits in the middle of the two.
Duct work connects cold air returns to Kozy king, and to plenum on each electric furnace.
The heat pump furnace has a gravity baffle installed on top of it to stop airflow from wood furnace going backwards into electric furnace.
wheb we had new dual fuel furnace installed, they eliminated the gravity baffle, but I had them install a manual blast Gate in the plenum at the top of the new furnace, just below where the duct for wood furnace inlet is.

so here’s the issues I’m having:
A) negative pressure: I’ve filled the house and basement with smoke both times I’ve fired this thing up. I’ve opened exterior doors and windows to basement to get a draft going. What else should I be doing?

b) the bigger issue is that once the furnace comes up to temp, it just doesn’t seem to push out the heat. I have set the draft blower to low setting, and the blower fan to high. Even when I isolate the air flow to the first floor duct only, the vents closest to the furnace are blowing warm air, but it’s not enough to heat the house. It will maintain temperature. So if the house is already 68 degrees, it will keep it there. But it seems to me that this thing Is sized large enough where it should heat the entire house.

c) the thermostat or blower doesn’t seem to be set correctly. I’ll set the thermostat to 72 degrees and the air temp is 68, so it should be calling for heat. Even though the thermometer on the front of stove says it’s in the burn zone, the blower will cycle on and off, which doesn’t seem right to me. So I’ve pulled the button out so that the blower runs all the time while the stove is running

house is 2 story, 3500 square feet. 2nd floor is much smaller than first. Timber frame, well insulated with low e windows.

heres Some pics of the setup. Any help would be greatly appreciated!

 

[Jdepiazza]

I should have also mentioned that I’ve made sure that my dampers are open for both cold air returns and duct to plenum.

I have also tried using the fan on the dual fuel furnace to distribute the air from the wood furnace better, but the results were no different. In fact, this seemed to make the wood furnace approach the over firing level on the temp gauge on front of stove, so I shut that back off and just used the blower on wood furnace with the blastgate inserted.

 

[moresnow]

Did you get hands on direction from the original owner before purchase? Even a written directive would be of benefit. The wood stove fan cycling is likely correct. Did you alter the gravity grate prior to using the system?

That entire setup looks like a handful! Cool idea but......
A furnace guy will be commenting shortly I imagine. Good luck.

 

[ckr74]

I'd be concerned about that plastic humidifier be that close to the top of the furnace. That's quite a set up.

 

[Jdepiazza]

Did you get hands on direction from the original owner before purchase? Even a written directive would be of benefit. The wood stove fan cycling is likely correct. Did you alter the gravity grate prior to using the system?

That entire setup looks like a handful! Cool idea but......
A furnace guy will be commenting shortly I imagine. Good luck.

Unfortunately we did not get any direction from previous owner. I have reached out to him with hopes that he’s willing to give me a crash course on it. He is a small business owner so not sure when he may have time to help me out.

by gravity grate are you referring to large shaker grate in bottom of stove where wood is loaded? If so, no we did not modify it.

 

[sloeffle]

You are about 10 miles down the road from me.

I can’t help you with your setup, but I’d definitely only run the wood burning furnace when you are around. If you loose power I’d be afraid of melting the humidifier and then you’ll have a flooded basement.

 

[brenndatomu]

Holy moly, some tin knocker got a nice bonus after he got done with that job! Never seen so much ductwork in one house!
Wow, I feel like I don't even know where to start with this one...how about this, is your wood dry, I mean really dry, not just "seasoned", and if so, how do you know this?
What do you have for a chimney? Height?
Are you opening the furnace bypass when loading? Closing it afterward?

 

[brenndatomu]

And I agree, that humidifier is bad news there...

 

[Jdepiazza]

Holy moly, some tin knocker got a nice bonus after he got done with that job! Never seen so much ductwork in one house!
Wow, I feel like I don't even know where to start with this one...how about this, is your wood dry, I mean really dry, not just "seasoned", and if so, how do you know this?
What do you have for a chimney? Height?
Are you opening the furnace bypass when loading? Closing it afterward?

Yeah it took me awhile of studying the pipes and dampers to even figure out how this thing was plumbed. Someone sure had fun installing this one.

While I don’t have a meter to measure moisture content, the wood is dry. Got this wood from local gentleman that had it stacked inside garage for several years. Him and his wife are getting older and no longer use their wood burner. is mix of oak and other hardwoods.

When stove is up to temp, gauge on front of stove will be in the 400-600 range which according to it is the ideal burn zone. Anything hotter than that it says is over firing. When the stove is in burn zone, the plenum above the wood furnace is hot, but you can pit your hand on it without getting burned. Obviously the further you go from that point towards the primary duct work, the pipe gets slightly cooler. The stove itself seems to be hotter and I’m not going to attempt to put my hand on it. Is it possible that it’s just not running hot enough?

Chimney is double insulated stove pipe that goes out through basement wall, then up side of house and above roofline. If I had to guess, pipe is at least 8-10 foot above roofline.

not opening furnace bypass while loading. Bypass is closed. Loading doesn’t seem to be a problem. No puff back or smoke while loading. Smoke/negative pressure is only a problem at start up.

 

[Jdepiazza]

You are about 10 miles down the road from me.

I can’t help you with your setup, but I’d definitely only run the wood burning furnace when you are around. If you loose power I’d be afraid of melting the humidifier and then you’ll have a flooded basement.

Thanks for advice on humidifier.

 

[Jdepiazza]

And I agree, that humidifier is bad news there...

Thanks. Doesn’t seem to really work right anyway, so may uninstall it just to be on safe side.

 

[brenndatomu]

OK, just read through things again...2 things, open the bypass while loading, and for a bit afterwards, once the fire and draft are established you can close the bypass.
second thing, put the duct blower on low...that's a pretty typical setting for any wood or coal furnace...the air has to pass by the furnace slow enough to pick up some heat...think of the hot potato game...a quick touch doesn't transfer much heat...hold on to it for a second longer and you are now in trouble...

 

[brenndatomu]

the thermometer on the front of stove says it’s in the burn zone,

Just FYI, those are just generic stove pipe thermometers...not specific to any one machine, and certainly not to be relied on as to the state of the fire on a DS furnace specifically ...as far as how its labeled. It will give you relative readings though...just ignore the labels...might ask DS about what temps to expect on the external face of the furnace (and where exactly)

 

[Jdepiazza]

OK, just read through things again...2 things, open the bypass while loading, and for a bit afterwards, once the fire and draft are established you can close the bypass.
second thing, put the duct blower on low...that's a pretty typical setting for any wood or coal furnace...the air has to pass by the furnace slow enough to pick up some heat...think of the hot potato game...a quick touch doesn't transfer much heat...hold on to it for a second longer and you are now in trouble...

Ok great. I will try that. What speed do you recommend I run the draft blower on? Low, medium or high?

Also there’s a little vent window on the side of the draft blower that you can manually open and close. It’s riveted on one end so it basically just pivots with enough tension to hold it in place wherever you leave it. I’ve been running the draft blower on low, and have that side vent cracked open maybe 1/4”.

it seems that if draft blower is on higher setting or vent is open further it may let too much air in and cause it to burn too hot?

I don’t know if this will help or not, but once it’s fully loaded, it will run for about 3-4 hours before it needs loaded again. Does that seem right?

 

[Jdepiazza]

Just FYI, those are just generic stove pipe thermometers...not specific to any one machine, and certainly not to be relied on as to the state of the fire on a DS furnace specifically ...as far as how its labeled. It will give you relative readings though...just ignore the labels...might ask DS about what temps to expect on the external face of the furnace (and where exactly)

Great. I will check with them. Hadn’t considered that.

 

[brenndatomu]

What speed do you recommend I run the draft blower on? Low, medium or high?

Will have to experiment with that...the higher the speed the hotter the fire should be (and the shorter the burn time)

Also there’s a little vent window on the side of the draft blower that you can manually open and close. It’s riveted on one end so it basically just pivots with enough tension to hold it in place wherever you leave it. I’ve been running the draft blower on low, and have that side vent cracked open maybe 1/4”.

I had a setup like this on my old Yukon Big Jack...really didn't like it...running the blower just made the wood disappear, and I never did find a spot for that teardrop door that I was happy with...eventually just quit running the draft blower and just ran it like a large whole house manual wood stove...hope you can find the "happy place" for yours...

once it’s fully loaded, it will run for about 3-4 hours before it needs loaded again. Does that seem right?

Well, yes and know...seems to be pretty normal for those older style wood furnaces, especially with forced air combustion...but it is not normal for a well designed modern wood furnace...useful heat for double to triple that time is more typical.
I'd ask DS how to set/run that draft blower, and what to expect from it...but this machine is a lot like my old Yukon (other than this one does have secondary air tubes I think) and I just ended up sending it down the road...I wish you better luck though!

 

[Jdepiazza]

Will have to experiment with that...the higher the speed the hotter the fire should be (and the shorter the burn time)

I had a setup like this on my old Yukon Big Jack...really didn't like it...running the blower just made the wood disappear, and I never did find a spot for that teardrop door that I was happy with...eventually just quit running the draft blower and just ran it like a large whole house manual wood stove...hope you can find the "happy place" for yours...

Well, yes and know...seems to be pretty normal for those older style wood furnaces, especially with forced air combustion...but it is not normal for a well designed modern wood furnace...useful heat for double to triple that time is more typical.
I'd ask DS how to set/run that draft blower, and what to expect from it...but this machine is a lot like my old Yukon (other than this one does have secondary air tubes I think) and I just ended up sending it down the road...I wish you better luck though!

Thank you. I will call DS Stoves and see what they have to say.

for what it’s worth the stove really isn’t that old. It was manufactured in 2016 and installed in 2017. It does have the secondary air tubes in it.

 

[grader]

i cant see how any stove with a forced draft can make a secondary burn work, unless the secondary air is also forced in. natural draft draws the air in through both the primary intake and the secondary intake if it has secondary burn set-up. a blower pressurizes the firebox, thus preventing any secondary burn from happening, as its the heated air that ignites the smoke.

 

[brenndatomu]

i cant see how any stove with a forced draft can make a secondary burn work, unless the secondary air is also forced in. natural draft draws the air in through both the primary intake and the secondary intake if it has secondary burn set-up. a blower pressurizes the firebox, thus preventing any secondary burn from happening, as its the heated air that ignites the smoke.

And that's part of the problem with the Firechief FC1000 too...primary and secondary air come from the same place...a draft blower...air is just going to take the path of least resistance, generally the primary path. In most "tube type fireboxes" primary air gets regulated, secondary is just preset, throttling them both at the same time/same amount is not a good idea IMO.
I was wondering about the air source(s) on these DS machines too...

 

[Jdepiazza]

So posting a follow up in case it helps others.

The negative pressure problem: primary issues seem to be that the chimney is just stainless double insulated stove pipe running on outside of house. Which is fine, except that when it is cold, the chimney is full of cold heavy air. Secondly, timber frame homes are known for being air tight, some say too air tight. So with wood furnace being in basement surrounded by warm air, and 40’ of cold air sitting in the outside pipe, cold air just wants to rush back down chimney. The solution was to create a heat source inside the stove that would create the warm air draft I needed without generating smoke. Aftersome head scratching decided to open some exteriors doors to basement to let some air flow in, then put a heat gun on high setting inside the firebox resting up against the firebrick. Close the door and let it run for 5-10 minutes. Stick hand in firebox and feel fir cold air. When no cold air, light a small fire. And we are off to the races with no smoke.

replaced the stove top thermometers and discovered old ones were reading between 50-100 degrees off and they were in wrong location anyway.

DS STOVES advice: run stove between 300-400, max 500 sustained Degrees. Run draft blower on low with teardrop door open between 1/8”-1/4”. Experiment with blower speed between medium and high. Followed these instructions and it seems to work well. A little finesse with the teardrop door and I can hold a steady temp for 3-4 hours between refills.

I reset limit switch settings on thermostat to factory specs. Blower cycles on and off

also bought a meter to test moisture content to make sure wood was dry enough. Some of the wood was too dry with moisture content in single digits, while other stuff was 13-18. The dry stuff was burning too hot too quickly, so with the meters help, learned that a mix of the two woods burns nice and steady.

as far as getting it to heat house, just ended up experimenting with opening and closing upstairs versus downstairs plenum, return air, running one or both electric furnace fans only to help circulate the air.

Ultimately found best combination is to let the first floor furnace blower fan run on circulate, turn off the upstairs furnace fan, open the plenum and returns for up and downstairs. It doesn’t heat the space up fast, but it will heat the entire 3500 sf house and keep it a comfy 72 degrees.

Also found that I can run the wood and electric/propane furnaces in parallel with each other. Heats up MUCH faster when both are cranking out heat.

just in time too since we are expecting near 0 degree temps this weekend

thanks to all that offered advise. Hope this helps someone else out down the road.