Buying Advice for a Wood-Burning Furnace

[Jonathan Stroble]

Hello all,

I would appreciate any advice I can get about purchasing a new wood-burning furnace.

The background: I purchased this year a home, built 1973, in upstate New York. Two stories plus an unfinished attic and an unfinished basement with a concrete floor. About 2,150 square feet of living space to heat, split between the main level and the upstairs bedrooms.

The heating system is an oil-burning furnace in the basement providing forced air to the floors above, controlled by a digital thermostat on the main level. There is also a Brock wood-burning furnace tied into the HVAC ducting. I'm not certain but I believe it was manufactured in 1982. The oil-burning and wood-burning furnaces are each serviced by separate flues in a masonry chimney.

The Brock wood-burning furnace looks a bit decrepit. The electric motor controlling the metal flapper that regulates air inflow, just below the furnace door, is disconnected as evidenced by a bare wire dangling onto the basement floor. When I fired up the furnace, the side-mounted blower kicked on soon after the plenum became warm to the touch, but sounded sickly and produced exactly zero positive air pressure at every heating vent in the house. With a roaring fire, the oil furnace blower would kick on every 5-10 minutes for about 20-30 seconds, producing a brief flow of warm air throughout the house. But otherwise, the primary effect of the wood furnace seemed to be heating the basement from heat radiating off the plenum and chimney connector. There is no barometric damper installed on the Brock and even with the metal flapper open only about 1/4", there is a strong draft and 4-5 pieces of 16-18" wood are completely consumed within 2 hours.

I am strongly considering buying a new wood furnace to replace the Brock. I have a few choices among furnaces that are sold by local dealers. These include:

U.S. Stove 1602R
Harman SF-2500-A
Energy King 480EK
PSG Max Caddy

My budget is $3,000 - $4,000 for the furnace alone, not including the added expense of paying a HVAC company to modify the ducting in the basement to accommodate a differently-shaped setup.

If any of these models are clearly superior/inferior for my purposes, I would be glad to know that. I can find the various tech specs online but I don't have the knowledge or experience to know which one is best or worst.

Many thanks just for reading all of that!

 

[Gasifier]

Just a few things for you to think about.

I would not exclude looking at a Kuuma. (broken link removed) (Just click on Kuuma furnaces.)

I have no experience with them and am not affiliated with them in any way. I found them when researching wood gassification boilers. If I had been looking at a forced air unit I would have considered them. From what I have read, I have heard good about them. They are a little expensive, but you will save that money back in the efficiency of the unit, I would think. Gasification is an impressive burning technology.

A few questions for you. I don't know if you have burned wood in the past so, forgive me if you are an experienced wood burner who is knowledgeable about a few of these things.

Are you planning on adding the wood furnace for burning in this season?

Do you have a supply of seasoned wood ready for this season?
(Seasoned wood is something that is a decent moisture content of let's say 20% m.c. or less., this usually takes being split and stacked outside for a year or more depending on wood type. Some, like Ash can season quicker, but some like Oak take 2 years or more.)

If not. Can you get ahold of seasoned wood for this year. (Many who sell it say it is seasoned, but most of it really is not.)

You could also consider a gasification boiler and use some type of heat exchanger to convert to forced air heat and distribute the heat with your existing plenum and ductwork. I am no expert in this but there are many here who could help you through the process. (Even if you used a contractor to install it.)

But the simplest thing would probably be the route you are going. A forced air unit. I would shoot for the most efficient unit you can find. Even if it means waiting until next year to start burning in it while you get and wait for your wood supply to dry.

 

[lampmfg]

We stand behind our product and have undergone strict efficiency and emissions tests to prove our claims. It's hard to burn wood any cleaner or more efficiently!! Here is a review from a current Hearth.com member. https://www.hearth.com/talk/threads/kuuma-vapor-fire-100-wood-furnace-results.112796/
Proudly manufactured in small town of Tower, MN...

 

[laynes69]

Based on age and size of home, I would opt for the Max Caddy. The Usstove, Harman and Energy King contain no type of true secondary burn. For the most part, those wouldn't vary much from what you currently have. Based on your description of your current wood furnace, I wouldn't use it. If the blower isn't moving heat through the house, it sounds like the heat is moving backwards into the oil furnace. That heat is tripping the limit/control of the central furnace, which is the reason it runs for a few seconds till it drops in temp then shuts off the blower.

By far, the Max Caddy offers many options over a standard wood furnace. A self modulating blower based on plenum temps, a hot water option and the ability to add backup heating options. Also it's one of the largest furnace's with a clean burn capability. We have a Caddy, and it does well for us. The other furnaces listed would be wood eaters for sure. If I had the room, I would have the Max Caddy.

 

[brenndatomu]

The only half decent furnace (and I hear they are actually pretty good!) is the Caddy, delete the others from the running! From what I know about the Kuuma furnaces, that'd be my top pick unless you want/need one with a built in backup heat option, which the Caddy has. But if I had your budget to work with when I did my install, I'd likely have a Kuuma, give 'em a real good look, nothing else out there like 'em (that I know of) in forced air wood furnaces. Too bad Arboristsite is down, there are a number of REALLY happy Kuuma owners over there.

 

[georgia hillbilly]

I have experience with the usstove of the largest size available and also have experience with our
Charmaster. Hands down, one awesome heating machine. https://www.hearth.com/talk/threads/extremely-satisfied.115648/#post-1562959

 

[STIHLY DAN]

There is only 2 options. Max caddy and the Kuuma. Forget the rest, you want efficiency, safety, and ease of use. I chose the American made with American parts small family owned company of Kuuma for my furnace. Glad I did in more ways than one, they are great to deal with, real good people. There furnace is built awesome with no smoke and easer to use than the TV. From what I hear and read, PSG is also a good unit, I have no experience with them tho, There rep is an honest guy, very knowledgeable. But they are a LARGE Canadian Co. Good luck.

 

[brenndatomu]

(broken link removed)

 

[Jonathan Stroble]

Many thanks, all, for the thoughtful and helpful suggestions. I've been leaning toward US Stove but I'm now going to take a harder look at the other options. Thanks again!

 

[sloeffle]

I currently have a Caddy. I also looked at the Energy King 385ek ( EPA certified ) as they were roughly the same price. The Energy King is a little bit heavier but I did not really like how you would have to clean the secondary burn tubes. The dealer was also new selling them so he did not have anybody I could talk to about it.

My house is a little newer than yours but a little bigger. The Caddy heats it fine. IMHO I think the Max Caddy is too big for your sq footage. I would rather have a furnace that needs to run flat out vs lots of idling. Idling = creosote buildup and wasted wood. As laynes pointed out, it does have some features the others do not. A modulating blower and hot water would be a nice addition to have. I wish my Caddy had those options.

 

[Indiana_Guy84]

I m also looking but this will be my first wood furnace, I have a Older home and a 2.5 car Garage to heat. I was Looking into buying two of the Drolet Tundra's From Rural King for 1799.00 each, plus cold air/air filter kits and shipping total was about 2200.00 each. I found a local dealer for the Blaze king Apex but hasn't called me back yet for a Price. I Haven't been able to find any reviews or videos on youtube for the Drolet Furnace or the US Stove Company 8500 Pellet Furnace But I know Rural king has it for 2,299.99. I wanted a Pellet/Wood Furnace that was EPA rated but Don't have a Very large budget, I'm looking to spend around 2500.00 Max on each furnace but Only one furnace per year. Tax Time.
I'm currently heating with Natural Gas and want to add on to the Furnace in my House and have a stand alone in my garage. I was going to run a New natural gas lin to my garage since I don't pay very much for natural gas, but it would be expensive to run a new line with another meter. Currently I pay 0.57 Per Therm on natural gas. I have access to 20 acres of Black Walnut Trees Providing no termites, But there are people in my local area selling seasoned fire for 75.00 a truckload.


I called about the
Energy King 385Ek $3750.00
Blaze King Apex$ Waiting for Return Call
St.Croix $4400.00
Fahrenheit 50f $4000.00 New 2000.00 used.

Online/in Store
Drolet Tundra: Rural king Online 1799.99 Air Filter Kit and Cold air Return kits plus shipping $2122.34
Fire Chief 700E $2095 at Big R Stores.

 

[Jonathan Stroble]

I've got my eye now on a PSG Caddy that I can buy from local dealer for about $3,700 total, including the blower assembly and fan limit control (and tax). The only thing that concerns me now is whether a Caddy would supply sufficient heat for my house. I've read in a couple places that for my region (Upstate NY) I should need about 50-60 BTUs per square foot of heated space. With a 2,150 square foot house, that equals about 118,000 BTUs.

The Caddy (according to the PSG website) has a maximum output capacity of 106,000 BTUs; average output capacity of 69,000 BTUs. And it says "Maximum Output - EPA Test Wood: 52,000 BTUs."

Am I comparing apples to apples when I think about these numbers? I understand it's preferable not to get too big a furnace for the job, but I'm worried that the Caddy might not get the job done.

 

[STIHLY DAN]

That 118,000 is for fossil fuels. Heat on then off with many cycles. The wood furnace will be continuous heat output, You will be more than fine with it.

 

[brenndatomu]

Yeah, fossil fuel furnace is way oversized so that it only has to run 10 minutes or so, cuz when mamas cold, she wants heat NOW! Wood stove heat is constant, it's kinda like the ole tortoise and the hare, tortoise (wood heat) wins!
Caddy is rated for 2500 sq ft (or more) isn't it?

 

[wood butcher]

I have a Napoleon HMF 200 wood furnace. It can be wood/oil/electric if you want or any combination. I have the wood/ electric as I got rid of the old oil furnace. This is my second winter with it and no complaints. I would recommend the Caddy too. The Napoleon is a copy of the Caddy. I am heating an old school house and it does well in the middle of winter.

 

[Victorian Stove]

Have you checked out the Fire Chief wood furnace, American made and less expensive. It burns wood and coal and has several sizes. They are a baffled stove but make up for that with a thermostat and electric draft controller.

 

[Jonathan Stroble]

That 118,000 is for fossil fuels. Heat on then off with many cycles. The wood furnace will be continuous heat output, You will be more than fine with it.

Thanks, that's very helpful. I didn't understand the difference before your reply.

Does that mean also that the blower on a wood furnace will produce a more gentle airflow at the heating vents because it is designed to run for longer periods?

 

[brenndatomu]

I'd stick with a furnace that is meant to burn wood only if that is what you want to heat with. Combo furnaces (my Yukon included) sacrifice efficiency to be able to burn multiple fuels. Better to "specialize" ...JMO

 

[sloeffle]

Thanks, that's very helpful. I didn't understand the difference before your reply.

Does that mean also that the blower on a wood furnace will produce a more gentle airflow at the heating vents because it is designed to run for longer periods?

The Caddy has a four speed blower. You could set the blower to the lowest setting to allow for a more a heat pump type effect but you might end up loosing a lot of heat out of the flue. I have mine set at the medium-low speed and that seems to be a good mix of pushing air into the house, and keep my flue temps at a reasonable temperature. You can also change the off and on set point on the fan limit.

If you are interested in traveling to Ohio I might know of a dealer that might be able to beat the $3,700 price. Bringing cash to the table also helps. PM if you are interested in their info.

 

[brenndatomu]

Thanks, that's very helpful. I didn't understand the difference before your reply.

Does that mean also that the blower on a wood furnace will produce a more gentle airflow at the heating vents because it is designed to run for longer periods?

Basically, yes. Since a fossil fuel furnace has a high BTU output for a short time, that means that the blower has to run at a high speed to distribute that heat throughout the house. Conversely, a wood furnace normally has a lower BTU output over a long time, so the blower only has to run at a low speed to distribute the heat.
Ever notice that when a gas or oil furnace blower kicks on, that the first few seconds of the blast of air coming out of the vents is really cold? Even if a blower does cycle on and off, with a wood furnace, the first of the air will normally not be cold, because the blower needs to run often (due to the constant fire) so the ductwork never gets a chance to cool off. So yeah, gentle, even heat!

 

[Jonathan Stroble]

Purchased a PSG Caddy from Papa Bear Riverside Stove in Marathon, New York. Worked with Jim by phone, who was very friendly and helpful with purchase and delivery.

Total cost for my PSG Caddy (PF01010) was $4,215 USD which included the furnace, blower assembly, and fan limit control; sales tax; and, a $100 delivery fee to cover Jim's gas costs for hauling everything a couple hours north to my house.

Installation is set for Jan. 6 by a local HVAC outfit, Country Suburban. I will be replacing a Brock wood-burning furnace which I believe is about 30 years old. It shares ductwork with a Williamson Centennial Low Boy oil-burning furnace which just burned through $586 worth of #2 heating oil in about 35 days, thermostat set on 68. (Yikes.)

Will report back re: first burn.

 

[M1sterM]

Thanks for the update, Jonathan. Hope you keep posting good pics of the install and your impressions once it's up an running!

 

[Jonathan Stroble]

Here's the Caddy uncrated. Haven't yet uncrated the blower assembly.

Several of the firebricks inside the furnace collapsed during delivery, despite a wraparound cardboard insert apparently designed to prevent that. I stacked them back up to the best of my ability. One of the upper rear firebricks is precariously balanced and wants to fall forward into the firebox.

 

[laynes69]

That's one thing I would change is add some brick retainers in the firebox. When I clean our heat exchanger, I pull everything forward instead of inside the fire for removal. I love our Caddy, they are a nice looking furnace.

 

[Jonathan Stroble]

Finally got the PSG Caddy installed last night and it's up and running. Still figuring out the most efficient way to operate it... it's going to be a learning process. It's not too cold out this week, for January -- lows in the 20s, highs in the upper 30s -- so it's a good time to learn the furnace without feeling pressed to fight frigid temperatures.

I've installed a magnetic flue temperature gauge and I'm watching the relationship between various loads and the flue temperature. Highest I've let it go so far is about 500 F; from what I've been able to learn online, the safest operating zone is somewhere around 350 to 450 F. (One website suggested 400 to 900 F but that seems really high to me?) Fortunately, with the ceramic glass door it's easy to see what's going on inside the firebox.