Wood Furnace issues (Energy Mate)

[j7art2]

I'll briefly explain what I've got here and the issue I'm having. I have included a ton of pictures to help show the system I have, etc. Sorry I can't get further away from it, there's a wall in the way.

I decided to resurrect my Energy Mate wood furnace this year. It pipes into my normal furnace, and the furnace blower is supposed to blow the hot air through the house. It hasn't been used in 10 years or more according to the previous owners of the house. I cleaned the chimney, repiped the system, and cut all new firebrick for it, re-gasketed it (twice) then decided to start using it since my dad has offered to give me 2 face cords of seasoned ash. I grew up using a wood stove my whole life, but never a complicated system like this. The system was obviously used, as it took me nearly 4 hours to clean the creosote from the system.

Drafts pretty well for a 25 foot chimney (some back draft sometimes -- I've set my smoke detector off a few times, but I didn't have a window in the basement cracked) and has its own separate thermostat, ran by a limit switch.

Long story short, the whole system seems to work pretty well I think, but I'm having a few issues that I cannot seem to resolve no matter what I do. I stupidly messed with the limit switch before taking a picture of where the previous owner who obviously used it had the settings. The furnace blower kicks on to blow the hot air through the house, but even with a raging fire going and the damper completely closed (I guess mine can be totally closed and still vent fine, it's more of a bypass) I'm only getting lukewarm air through the house, even with the manual thermostat cranked up and the front blower raging and acting like a bellows. Can anyone explain why? I can't afford to spend $3000 on propane again this winter with my first baby on the way.

 

[j7art2]

Since the pictures were taken, I've since upped my limit switch settings to see if that helps (it didn't).

Also, I have a toggle switch on my front bellows blower of my wood furnace that goes up to the limit switch. Not sure if that switch is an on/off switch (it does turn the fan on and off, but it may do more) or something else like a bypass to get the fire going manually if you need some draft.

 

[laynes69]

Maybe series from what I can see? Your limit settings should be around 90-100 off and 140 or 150 on. A larger fire equals warmer air. Make sure the bypass lever is pushed in when burning. This is a time of year where you shouldn't need a full firebox. Once it gets colder, things should improve.

 

[JustWood]

Maybe series from what I can see? Your limit settings should be around 90-100 off and 140 or 150 on. A larger fire equals warmer air. Make sure the bypass lever is pushed in when burning. This is a time of year where you shouldn't need a full firebox. Once it gets colder, things should improve.

Agreed.
I played with mine from factory settings and ended up a little higher to get a clean burn. Chimney was creosoting up fast. I think I ended up 10-15 degrees hotter than factory for "on". IIRC I'm at 105 and 170

 

[j7art2]

Bypass lever on the limit switch? As in, having it on manual instead of automatic?

The blower in the front has a switch, but I don't know if it actually does anything other than turn the blower on and off.

 

[j7art2]

Also, I'll make sure I set the limits to those settings. I've tried it in every position almost, and I'm still getting lukewarm air in my vents. Last night the furnace was NICE and hot, and I had about 4-5 pieces of oak and ash going with the front blower going, furnace fan going, and the fresh air intake wide open and the thermostat set at 80 (for testing purposes). It didn't climb past 69 in the house.

How would I know if my limit switch is bad? I don't know if this is the issue, and it does turn, but they obviously sell replacements for a reason.

 

[laynes69]

The lever on the front of the furnace is the bypass lever, make sure it's in when burning. As long as the furnace is kicking on and off while burning, the fan control is working. If your burning that much wood and that's the highest you got the home, either something isn't right with the ducting or furnace or it's your home. My register temps average around 90-100 degrees on a normal fire and it's more than enough to heat our home.

 

[j7art2]

Okay, so the switch you're referring to is the switch on the fresh air intake fan in the circled picture, correct? It doesn't go in and out, just left or right for me. One seems to be on, the other direction seems to be off. There may be more to it than that, since it is also controlled by the thermostat upstairs. Even with the switch on, if the thermostat is not set at the right temperature, it won't kick on.

There is a button on the limit switch that can be pushed in and pulled out, which is a manual and automatic modes for the limit switch.

 

[laynes69]

No, your limit/control controls the main blower, the thing your circled in the pic is the forced draft which should operate off a thermostat. The bypass lever is the lever or handle above the loading door. Pulling it out sends all heat up the chimney, pushing it in allows for more heat into the home. You do not want that forced draft operating continuously unless you want a steel forge in your basement.

 

[j7art2]

Yep, damper (at least, on a wood stove, that's its equivalent i guess, even though I also have a damper on the metal flue pipe going into the brick chimney) is all the way in when firing and still not getting lots of heat for some reason. It still allows for smoke to go through when fully closed, but I think it's designed that way on purpose.

There is however a sort of metal flap when I open the loading door below it though that's about 2-3 inches long that seems to be on hinges. I don't have a picture of it, but could take one if needed when I get home. No idea what this thing is, but it's inside the furnace itself, right in front of the door. I have no idea of it's relevance, if any in this case.

Last night, the furnace was pretty dang hot, and I still wasn't getting heat pumping through the house with the furnace fan blowing. I had the slider above the door fully closed, but the pipe damper fully open. I tried closing that some too, but if I close it too much, it snuffs the fire and didn't seem to make a difference either way. I'm not sure if the second damper in the pipe is even necessary.

 

[maple1]

The metal flap thing just sounds like a smoke door - stops smoke from rolling out when you open the door. Or that's the idea.

Are you measuring stack temps?

Are you sure the main blower is coming on? Any changes at the registers if you turn up the other furnace stat?

Might help to get a IR thermometer gun & trace your duct temps. How dry is your wood? The fire might not be as hot as you are thinking it is.

 

[j7art2]

Ash is seasoned 2 years. Oak is thin amish hardwood slab, seasoned about 6 months.

I got a new magnetic thermometer for my pipe today; the previous one I had in the picture there didn't work out of the box. It was registering 100 degrees and was hot enough to leave me a burn blister. We'll see exactly where I'm at.

I discussed this issue with the local guy at Family Farm and Home (equivalent to Tractor Supply or Rural King in my area) and he mentioned that there should be a blower that blows the hot air from the wood furnace into the normal furnace. I was under the impression that the normal furnace fan simply sucked the air out of the wood furnace and into the house. If this is the case, I bet that fan isn't working if this model has such a thing. The question is, where the nine hells is it located? I don't see any place for a fan anywhere on this other than the fresh air intake fan in the front.

 

[maple1]

As laynes69 said above, this looks like a series install. I.e., the heating air will all go through both furnaces one after the other, no matter which one is doing the heating - which I would tend to think would only involve one fan, which would come on if either furnace was heating.

I have no experience with hot air furnaces, so don't know how common that type of setup is - and I think that's about the limit of my input into this one. But 100 degrees isn't very hot for a flue temp - I'd likely get an IR gun too so you could double check that along with your duct & furnace surface temps. Maybe also a moisture meter to double check your wood.

 

[j7art2]

That's what the magnet thermometer said. It was hot enough to leave me a blister burn, so I know it was significantly hotter. 100 is enough to touch and still be comfortable. The old thermometer wasn't working right. I got a new one today.

The MM is on the list to get. The ash sounds like a baseball bat when tapped (I've heated with wood my whole life, but it was a simple wood stove, not a complex beast in the new house) is nice and grey, with split ends. It's not the wood for sure.

I'll report back with my findings when I get home and get a fire lit. I appreciate the help thus far.

 

[brenndatomu]

Hi J! That type of furnace is known for chewin through some wood, but also making some real heat in the process! Something is up here. We'll get ya going. Not trying to be a smart Alec, but just so we are all on the same page here...gonna cover the basics.
1.Your bypass baffle (correct term) is attached to that knob on a rod right above the loading door, it should be out for loading and maybe a bit longer on a cold start just to warm the chimney. It's normal operating position is fully in. When pushed in it makes the smoke/gasses/fire contact more of the firebox for a longer time. When it is out it just helps keep smoke out of your face when loading, well, that and that swinging flap you mentioned.
2.That key (or flue) damper (correct term(s) on the chimney pipe should be left fully open until yo get this thing hot, and then only partially closed. Best case scenario would be to set it using a manometer, but one thing at a time. We can address draft issues later. Along that line though, what size is the chimney liner?
3.The toggle switch on top of your draft blower (correct term) is just a manual switch for building the fire up after loading. The pivoting tear drop shaped door on the side of the draft blower should be wide open when building a fire, you can cut it back once things are rolling, I'm not sure if the is another draft control on this furnace or not?
4.The limit switch (correct term) is the third picture in your original post, it should be set somewheres in the range of 100-120 off, 140-160 on, and the high limit left alone, they are usually pinned at 200 or so. This is what controls when the furnace blower runs, sending hot air throughout the house. It may or may not have a button that can be pushed in to make the blower run constant. The furnace blower is coming on correct?

Just FYI, when on "high fire" (draft blower running) the chimney pipe thermometer will probably read 3-500* (you may regret the silicone on the pipe, most high temp silicone is only good for 600* or so and it really stinks the house up much beyond that temp) the pipe shouldn't need to be sealed if everything is working/installed correctly. It is hard to tell in the pic, do you have the chimney pipe installed with the male ends toward the furnace? They should be, that keeps creosote from running on the outside of the pipe making a fire hazard.
Alright, enough for now...

 

[j7art2]

By all means, you aren't bring a smart Alec. You guys are the experts here, not me, which is why I'm here. The wood stove I grew up with was simple. Start wood on fire, flip room blower on, adjust damper, walk away and enjoy warmth. If too hot, crack a window. Lol

Your post was very informative and helpful. I can also turn my fan on manually upstairs via the thermostat.

I've gone through almost half a face tinkering with it, and I'm going to set everything to the suggested settings and set my thermostat to 85 to test it and see if I get more than just lukewarm air.

I have been keeping the draft blower running most of the time. It seems the thermostat controls when that kicks on. I imagine its always running because its trying to get the house to whatever I set it at and can't.

I don't know what direction the pipe is going, but its all sealed. I'll check when I need to tear it apart. The RTV was a peace of mind for me, and is easy to remove and reapply in a cleaning. If it becomes bothersome, there's always plan B.

The furnace blower is coming on, yeah. I can feel air coming through the vents, it just isn't hot. Warm at best, just room temp with a small hot fire.

Not sure of chimney liner size. Its clay and 25 feet up, and my buddy who cleaned my chimney (hes a small guy and I'm not) broke my extension ladder in the process of coming down. Even if I wanted to look, I couldn't right now. That's a story for a different day though.

I hope that answers your questions.

 

[laynes69]

Is the heat from your woodfurnace sucked into the return of the central furnace, or is the air from the plenum of the central furnace ducted to push thru the woodfurnace?

 

[j7art2]

I have no idea. The thing on top of the wood furnace is the main ductwork that goes throughout the house it looks like. I think that's what you're asking.

 

[j7art2]

I think this is what you're looking for.

 

[brenndatomu]

Yeah, from the pics I'd say the wood furnace is the last point of contact before the hot air hits the supply ducts. The duct coming into the Aprilaire box of the fossil fuel furnace is the cold air return.

You may wanna try shutting the draft blower off and just run the draft "door" on the blower wide open, see what happens. A lot of furnaces are "natural" draft anyways. I know the last wood furnace that I had with a draft blower would EAT wood! 'Course it should still make some heat!

Not sure of chimney liner size. Its clay

OK, I bet the flue is pretty good size, it may not draft real strong, prolly don't need the key damper, but it doesn't hurt to have it though. Like I said earlier, once we get this thing going, it would be interesting to get a draft reading on that chimney. A Stainless flex liner may be a good future investment...?

 

[j7art2]

Wow... well, i just discovered the problem I think.

I've been under firing all this time. I finally got the temps in the right range (and lo and behold, the house was getting warm! HOLY COW THIS THING PUTS OFF SOME MONSTEROUS HEAT DOWNSTAIRS!!)

The bad news is, is that I ran into another slew of problems in the process and flooded my entire basement with smoke.

First, my door gasket will NOT seal properly. This is the SECOND time I've replaced the gasket. Once it got to proper temperature, it just started flooding with smoke. I took out a half inch gasket, and the first time put in a half inch and that didn't resolve the issue. The next time I put in a 5/8 (biggest I can get) thinking that would resolve it.

Secondly, my first elbow from the wood furnace to the steel flue was just bellowing smoke too as if the RTV wasn't even there.I have no idea why this is (and you're right, it stinks like nasty rotten popcorn) and I'm going to need to seal it with something else. Any recommendations? I'd prefer something non-permanent if possible so I can pull the piping apart to clean it.

 

[brenndatomu]

The pipe smoke may have just been the paint curing, it will smoke and stink each time you hit a new temperature threshold. If it was combustion smoke coming out then you have crappy draft! Was the key damper clear open? You shouldn't need to seal the pipe joints but if you still wanna, I have used high temp aluminum "duct tape", or get a tube of furnace cement at the local hardware/stove shop/farm store wherever.

 

[j7art2]

Key damper was at a 45. I can try it wide open and see if it makes a difference.

 

[spirilis]

Chimney exterior to the house?

 

[j7art2]

Yep.

And with the key open, the smoke is drafting properly. Bren, you are a lifesaver there. I would have been chasing my own tail. The smoke has to go SOMEWHERE. If it can't go out, it's going to find the next best thing. My basement.