wood furnace/not enough heat

[Frozen Canuck]

In your situation in Newfoundland a PSG Caddy will likely be the easiest to find as well as a dealer network, qualified installer, service tech etc. All of which are important for a heating unit that you may have a 20 - 30 year relationship with. The wood consumption in your above post is excessive to say the least unless you are heating 10k sq ft or more & poorly insulated at that. Seems we have very few happy owners of combo units, likely due to both designs being compromised. Myself I would have a dedicated wood unit & a separate unit for backup fossil. Buy the best quality that my budget could afford in both cases.

 

[wardk]

Intake for the plenum comes from cold air intakes on the first floor and second floor of my house. As for combustion air it is supplied from the frontside of the furnace. Before I made the addition I had to keep the draft a little more than halfway open above the door to get enough heat to heat the plenum. Now I can turn it way down almost closed and get constant heat and double the burn Tim of before.

I had a wood electric furnace and I think Gasifire's question is on the money. You have to supply external make up air to that furnace or it will suck cold air in from every nook and cranny of your house.

 

[Downeast Farmer]

I have the Cl86/96 and have the same issue. The problem with this furnace is it will not heat the plenum unless the fire box is full. I used to fill mine at 12 in the night and 3 to 4 am the oil would cut in. I spent a week fooling with it last year and found that the heat was not rising and going out each side of the heat exchanger and out the chimney. This was not caused by excessive draft as I adjusted the flapper on the chimney and it was not the issue. I kept checking all parts with the temp gun and with a half full firebox the plenum was at only 72 degrees. Finally I made two plates for each side of the furnace two inches wide and 10 inches high with a piece of flat bar that fits in the track on each side of the stove. This blocks part of the area around the heat exchanger forcing the heat to rise before it goes out the chimney. Wow what a difference I could close down the draft and the furnace would run for hours and hours.

 

[Downeast Farmer]

I have a Newmac wood furnace and it acts just like Fred says his did. I'd sure like to try out your modification, but I can't quite visualize it. Any chance you could make a diagram or send a picture?

 

[georgia hillbilly]

I can speak VERY HIGHLY of our Charmaster. It doesnt suffer from electronics, water pipes, or short burns. It is by design meant to keep bed of coals forever. here's my recent post https://www.hearth.com/talk/threads/extremely-satisfied.115648/#post-1562959

 

[BoilerMan]

It doesnt suffer from electronics, water pipes, or short burns.

I think your definition of suffering may be a bit subjective. Most on here have all of the "suffering" you refer to, and our wood consumption is quite low compaired to what we had previously.

TS

 

[Mark Ellsworth]

I have a fire in at the minute but I will get some pictures for you tomorrow. Basically it is a piece of 2" by 1/8 flat bar 10 inches long which covers the opening on either side of the back of the firebox which causes the heat to rise and heat the plenum. I have another piece of larger steel welded on a 90 degree angle to fit in the slots on both sides of the furnace to keep the plates in place. I have also found with this furnace you can't shovel all of the ashes out of the firebox or you will not get any heat either. I keep the ashes just a little below the door or flush with the door. If you go below this the only heat you will get is warming your hands with the door open.

 

[Mark Ellsworth]

Sorry about the quality I have been burning briquettes the last week or so and they are a bit ashy.

 

[Stone house]

I am looking for any input concerning my 8yo Newmac oil wood comb furnace. When I use the oil, (which is rare) it heats the house fine. When I heat with wood, it struggles to get the house much over 60 if it is 20 or below outside.
It is a big rambling farmhouse(3500sqft) with r38 wall insulation and mostly newer insulated windows.
The fires that I burn are cranking hot hardwood fires. So hot that you cant get your face too close to the fire box.
That hot fire does not translate into a warm house. I also go through 10 full cords per year (oct to april)
I am pretty good with maintenance, dismantling and cleaning the angled steel chimney (6') that goes to the house chimney 2 to 3 times per year. I also scrape the soot that accumulates around the plenum, and change the air filters yearly. Any suggestions to improve this situation would be appreciated.

I am finding the same issue ... Burning through a ton of wood and oil
Costs a fortune .... Considering switching out if we can not get this furance functioning well - help !

 

[MacYoung]

Hi Stone house..... I'm also disappointed with the lack of heat when we are burning wood in our Newmac wood/oil combo. Yesterday we were warm and toasty when the temperature was just below 0 C, but we are burning oil tonight because it is -20 C. Thank goodness we don't have many cold nights like this!

Mark's advice about leaving more ashes in the firebox seems to be helping compared to previous seasons. Mark's modification pictured above looks very interesting... I'm tempted to try that too. I run the inducer fan all the time to improve the combustion, but it likely hurts our wood consumption. I'd love to hear more suggestions to improve the performance of this furnace.

 

[Stone house]

Hi Stone house..... I'm also disappointed with the lack of heat when we are burning wood in our Newmac wood/oil combo. Yesterday we were warm and toasty when the temperature was just below 0 C, but we are burning oil tonight because it is -20 C. Thank goodness we don't have many cold nights like this!

Mark's advice about leaving more ashes in the firebox seems to be helping compared to previous seasons. Mark's modification pictured above looks very interesting... I'm tempted to try that too. I run the inducer fan all the time to improve the combustion, but it likely hurts our wood consumption. I'd love to hear more suggestions to improve the performance of this furnace.

I actually called the newmac rep and had a long chat with him... Long story our model is an old beast but he did have w few suggestions and I think they helped
Load wood towards the back and pull ashes to the front near the door
Also recommended a 1 inch steel plate with holes drilled in to burn on ( as we have the grates ) and we were losing our hot coals down to the bottom

Run inducer fan and drop the damper down
Make sure the fan is on automatic as we had It running constantly on manual
Mode and half the time it was blowing cool air as it was not allowing the heat to
Build
We have been in a blizzard watch here today minus 20
And still burning wood in
Our crazy old stone fahouse
I am sure we will need oil on tomorrow
But this seems to have helped !
Good luck and stay warm

 

[Mark Ellsworth]

Try out the plates in the back of the furnace. I guarantee you will find a major difference. I open the draft on the furnace until the wood gets burning really well and then shut off the draft completely. I have not had any luck running the fan all I found it did was blow the heat out of the furnace and reduce temperatures. Without the plates I would have to run the draft a little less than half just to get the plenum hot enough for the blower to kick in and man did it eat wood. Grab a temperature gun and read the temperature on the duct work just above the firebox. I was only getting 70 degrees before I added the plates. The reason I mentioned leaving the firebox full of ash is the heat is being sucked out of the furnace. The closer the fire is to the top of the furnace the more it will heat the furnace and the less time it has to be sucked out before it has a chance to heat. I have been thinking about trying a plate across the top of the firebox near the top of the furnace to force the hot air forward and up to the top of the furnace before exiting. This is how all of the other newmac's are designed. My grandfather has the add on and it has a plate across the top of the firebox and halfway to the front and with just a few pieces of wood it will blow heat for hours. I think the furnace will work extremely well it just has some major design flaws, but with a few small add ons it will work well. The plates are very cheap to make and only lay in place. So there are no modifications.if you have any questions drop me a line.

 

[Owen1508]

Basically you added baffles to the unit. i know some of Newmac other multi fuel units have them in it. I am suprised this unit did not. Thanks for the info.

 

[Whateverworks]

This is not an uncommon problem with many wood furnaces and i have seen several wood furnaces get hot enough to get a thick steel pickup leaf spring red hot enough to bend straight while the plenum was barely warm.

What normally causes is the heat exchanger that normally has turbulators or baffles that spin or cyclone the hot gasses so that they contact the exchanger pipe and transfer the heat to the plenum. Most of the time the heat exchangers burn out their baffles or turbulators and you end up with bottle necks in the exhaust flow which slows down the fire and gets the firebox way too hot or puts the fire out. There does not seem to be a mid point where and fire will work correctly on these particular furnaces once the baffles go. They waste so much wood.

Yes having the wood higher up near the top of the furnace firebox will work as it is working like an old fashion hunting camp stove and it's why if you have enough room in your firebox to place several large rocks to make a reflector and a mass heater storage you will gain a significant amount of heat that was being wasted out the chimney as the rocks collect and slowly release the heat much better than firebrick. It works the same as the custom made metal reflectors mentioned in this thread.

Secondly some of the larger wood furnaces have a-lot of draft and you might need a make up air pipe in your home near the wood furnace. An air intake and replacement battle is not uncommon.

As for the Kuuma it's efficient on wood but you will need a mass storage rig to collect that heat as the kuuma is far from and all day long in freezing temperatures load capacity furnace at least for Canadian conditions.

I would look into the Yukon-Eagle Polar furnaces if you still need a combination furnace. They have built in reflectors and forge like air injection along with a stepped plenum/exchanger instead of baffles that allows the wood furnace to send heat to the home is the electricity goes off.

I got so tired of the wood furnaces i bought failing that i went and designed and built a proper large rocketstove/furnace that by design can only work if it can send the heat to the plenum being that rockets stoves are positive draft (aka they push the heat instead of the chimney draft pulling the air through. More difficult to start yes but so much more efficient for the home.

I use the hopsco airstove model 1500 (wood furnace) which is an outdoor forced air wood furnace (no water) for the shop and it's amazing even at -35c. It can also be installed indoors. Being that the hopsco airstove itself is the plenum and the exhaust is up front and goes back to the chimney most of the heat has to go to the plenum with or without the draft open or the blower running.

I tried several of the outdoor water jacket wood furnaces, and one air type and as usual they are highly dependent on location. Which makes them not worth the time to install if you are not 100% certain that it will work in that location. I've seen moving the water jacket furnace 5 feet in a heavily wooded or wind protected area increase it's efficiency by more than 50%. It's that crazy and unpredictable.

I tried the PSG Maxcady and Roy UHFT indoor wood furnaces and wasn't impressed. They didn't output anywhere near the rated BTU's. They burnt wood well i will give them that but the heat to the home wasn't good at all and i'l leave it at that.

I've migrated to furnaces that have more basic designs and don't rely on things such as internal heat exchanger baffles and they pollute less when you consider the problematic EPA approved furnaces consumed so much wood that there is no way they passed any environmental test with wood consumption numbers like that.

Safe Journey.

I am looking for any input concerning my 8yo Newmac oil wood comb furnace. When I use the oil, (which is rare) it heats the house fine. When I heat with wood, it struggles to get the house much over 60 if it is 20 or below outside.
It is a big rambling farmhouse(3500sqft) with r38 wall insulation and mostly newer insulated windows.
The fires that I burn are cranking hot hardwood fires. So hot that you cant get your face too close to the fire box.
That hot fire does not translate into a warm house. I also go through 10 full cords per year (oct to april)
I am pretty good with maintenance, dismantling and cleaning the angled steel chimney (6') that goes to the house chimney 2 to 3 times per year. I also scrape the soot that accumulates around the plenum, and change the air filters yearly. Any suggestions to improve this situation would be appreciated.

 

[Mark Ellsworth]

I got a bit tired of the furnace and we had quite a few blackouts last year, so I installed a new century 3000 wood stove in the rec room this fall. So far I am pleased with the wood stove but should have went a little bigger for longer burn times. The air does not circulate quite as well as the furnace so it is a small bit cooler upstairs than downstairs but it is normally 23 to 24 degrees C each morning when I come downstairs. This is afar cry from the 8 degree C mornings I experienced last year with just the furnace running. Still have the furnace but I have not used the wood part this year at all. I may use it sometime but in my opinion it will need a plate across the top so the heat will rise more and be forced towards the front of the firebox for it to work properly. So far this year I have hardly used any oil so the wood stove should have itself paid for by the end of this year or early next year, not even taking into account using only half the wood and half the work. I am still working at getting a little more heat upstairs but I'm sure I will find a few fans etc. with some picking around on this site.

 

[Whateverworks]

I've had the chance to work on a few of the Blazeking Princess stoves and they are quite good. The catalytic converter is my only worry as far as long term cost but adapting generic converters seems to work almost as good as the OEM converters. The heat transfer to the home of the princess is what makes me happy as it is very even. It won't run a Peltier tube stove fan as well as your century 3000 but it's not bad. I wouldn't say that the BK princess will heat 2000 sqft as they claim it will but it's not far off, it's the amount of time it will take to do so that be rather slow but it is consistent. We too have had several hydro outages here this year and usually at -30c and i have a rig i installed for the oil and wood furnaces to run them off a generator outside without opening a window but with the new custom wood furnace, it's only feeding power to the oil furnace.

Btw i did try your idea of the piece of steel on an angle to force the flames/heat of the fire up and forward of the firebox. It does work to a certain point, however you have to modify your draft to align the air to hit the wood at the right spot for the flow deflector to work.

Here is a video that shows a similar setup. My hopsco airstove is similar to this, just larger.

youtube video search ID: v=pHty-Fo8opc

 

[maple1]

I've seen moving the water jacket furnace 5 feet in a heavily wooded or wind protected area increase it's efficiency by more that 50%. It's that crazy and unpredictable.

Can you elaborate more on this?

 

[Whateverworks]

Distance from the home or which ever one or more buildings you are heating with the outdoor water jacket furnace, amount of wind , angle to the home, the list is rather long. Problems with sudden surges or sags of heat or no heat no matter how you adjust the rads inside the home. Same type or wood same climate conditions but burning 25+cords of wood per year then by moving the furnace the mentioned 5 feet brought the wood consumption to about 12-15 cords per year. Same problem with most outdoor water jacket wood furnaces around here and most other places. The problems get worse the more rads you have in series or parallel, and most opted to put a single large rad from the water jacket furnace in their old indoor wood furnace plenum and use forced air instead.

Some got hybrid in ground insulated plenums made to fix the problem without moving the actual furnace by changing the feed & return hose lengths. Same as the indoor wood furnace plenum rig but with the plenum outside underground with a similar in/out forced air blower system close to the home.

The production outdoor water jacket furnaces are still not as efficient on wood as the indoor types but what most people tell me is that it's the capacity to load for a whole day (8+ hours) is what interests them the most.

Still not all production water jacket furnaces are equal. I have a Polar Furnace G furnace testing now, however it will probably be the last i test as people around here have had far too many reliability issues with water jacket wood furnaces and no support from the manufacturers either. 200$ for a blower drive belt every couple years is one example of the water jacket furnace costs.

I have seen custom built outdoor water jacket wood furnaces that do work but they are in their own insulated shed, they have their own backup propane or electric heater for the water if the wood furnace goes out so that things don't freeze. It's a rather large investment to fix design flaws especially at -30c.

Many of the distance problems are a result of by laws and how far the furnace needs to be from the home and each regions has different laws which does not help matters and i have seen water jacket furnaces about 300 feet from a home and i couldn't believe it. There is no way that is going to work. I found out later that it was the insurance company that wanted that distance just in case the water in the furnace got out and caused flood damage in the home. Any how i helped out the home owner and managed to get close to breaking even and the insurance company off his back. Although no one should have to go through this.

I've seen moving the water jacket furnace 5 feet in a heavily wooded or wind protected area increase it's efficiency by more that 50%. It's that crazy and unpredictable.

Can you elaborate more on this?

 

[maple1]

Same type or wood same climate conditions but burning 25+cords of wood per year then by moving the furnace the mentioned 5 feet brought the wood consumption to about 12-15 cords per year.

So how about some specifics here? If that is true it should be easy to deduce the factors that would lead to a 50% reduction in wood consumption.

IMO unless the 5' move was to move it out from under a waterfall, then this is a highly suspect claim.

And who would put a plenum in the ground? Also the first I've heard of that highly questionable concept.

 

[rkusek]

I'm quite happy with my indoor downdraft gasser located in an insulated 30x60x14 pole barn. I have almost 700 feet (350 each way) of 1.5" pex spray formed in trench. Last week we were -10F with crazy windchills making it feel much colder than that. The boiler is rated at 130,000 btu but with my low quality wood and combustion fan at the lowest setting (50%) I would guess the output is more like 60-70k at best. Even so, the barn stayed above 60F and the home became too hot at night 69F that my wife got up and turned it down to 67. My boiler was still idling in these conditions heating both buildings with a load lasting about 7-8 hrs. If I ever get my storage tanks installed I should burn even less wood and not have to run my heat pump at all in the winter. I've done all my own work so upgrades take forever.

 

[Whateverworks]

Simple the thermostat read the heat from the flow at too low and ran the furnace combustion air blower constantly burnng the wood too quickly. The shorter feed pipes after the move kept the thermostat read constant and the blower off more often and not letting the water temp drop too much if you simply offset the thermostat. Its not that hard to understand and as for the in ground forced air plenums you certainly never researched geothermal energy, several local hospitals use a similar setup as well not to mention identical rigs in Iceland that i actually worked on. No matter if your not interested in listening then keep your comments to yourself.

Same type or wood same climate conditions but burning 25+cords of wood per year then by moving the furnace the mentioned 5 feet brought the wood consumption to about 12-15 cords per year.

So how about some specifics here? If that is true is should be easy to deduce the factors that would lead to a 50% reduction in wood consumption.

IMO unless the 5' move was to move it out from under a waterfall, then this is a highly suspect claim.

And who would put a plenum in the ground? Also the first I've heard of that highly questionable concept.

 

[Whateverworks]

Nice work with the mods.

I'm quite happy with my indoor downdraft gasser located in an insulated 30x60x14 pole barn. I have almost 700 feet (350 each way) of 1.5" pex spray formed in trench. Last week we were -10F with crazy windchills making it feel much colder than that. The boiler is rated at 130,000 btu but with my low quality wood and combustion fan at the lowest setting (50%) I would guess the output is more like 60-70k at best. Even so, the barn stayed above 60F and the home became too hot at night 69F that my wife got up and turned it down to 67. My boiler was still idling in these conditions heating both buildings with a load lasting about 7-8 hrs. If I ever get my storage tanks installed I should burn even less wood and not have to run my heat pump at all in the winter. I've done all my own work so upgrades take forever.

 

[maple1]

Simple the thermostat read the heat from the flow at too low and ran the furnace combustion air blower constantly burnng the wood too quickly. The shorter feed pipes after the move kept the thermostat read constant and the blower off more often and not letting the water temp drop too much if you simply offset the thermostat. Its not that hard to understand and as for the in ground forced air plenums you certainly never researched geothermal energy, several local hospitals use a similar setup as well not to mention identical rigs in Iceland that i actually worked on. No matter if your not interested in listening then keep your comments to yourself.

A 5 foot difference in pipe lengths would make no significant difference in the pipe temperatures. If anything made it burn more wood, it was improper sensor placement or aquastat adjustment and moving the furnace 5 feet would seem to be a waste of time & energy. But reducing wood consumption by half by simply reducing blower run time I would still regard as highly doubtful. I do agree that OWBs waste wood, generally speaking - but your other statement that there is no way 300' of separation will work is a function of the underground piping and not the furnace/boiler and it can indeed work, as has also been shown above.

I have indeed researched geothermal heating, as I was considering it for my house when I replaced my old heating unit. But in no case came across a solution that involved a plenum in the ground. Or a solution to poor OWB performance that involved the use of an underground plenum - which is the situation that you suggested an underground plenum was used for, and not industrial geothermal situations.

I am always interested in listening, and learning. Just as I always also welcome comments on any comments I might make on here - posting on a board is always open to responding comments, be they supportive or constructively critical or of contrary opinion. Links to supporting articles/documentation are also often quite useful as well....

EDIT: Sorry for the off-topic stuff, last from me...

 

[STIHLY DAN]

As for the Kuuma it's efficient on wood but you will need a mass storage rig to collect that heat as the kuuma is far from and all day long in freezing temperatures load capacity furnace at least for Canadian conditions.

I can tell you that at -25* c The Kuuma can heat a 3000 sq ft normal insulated house for more than 8 hrs.

 

[grammy]

I had a newmac wood oil combo and was continually frustrated with it... Very poor heat output and damper/combustion air blower system was a terrible way to control the fire. An open/closed damper system works much better.