Home heating with wood - Efficiency isn't the answer?

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medic

New Member
Aug 8, 2011
10
NY
Hi experts,

Like many folks I'm about to install a high efficiency ZC fireplace in an attempt to lower oil bills this season.
Having read every post on this forum I understand that my choices are Napoleon 6000, Lennox Montecito Estate (or BIS tradition), RSF Opel 3 (any others I should add to this list?) as I have 3500sqf to heat.

I see numbers for efficiency but that only tells me the energy conversion from the wood. Is there any data that would help me understand how much of that energy is directed into the house?
I'm thinking there must be differences in the heat exchanger designs, size of blowers etc that would help me choose between models and understand if I really will be able to heat my space effectively with any of these fireplaces.

Thanks for your time and help. I really appreciate any thoughts or suggestions on what to do to achieve warmth with wood this winter.

Mark
North East.
 
Are you wanting to decrease your heating costs with some additional heat from a wood-burning applicance or heat the entire place with a stove?? 3500 sq. ft!!!!!!!! You will need several stoves if you want to heat entirely with wood. What is your goal? Do you want both heat and a nice fire to watch? There are some options.
 
If you intend to heat your house with wood (sounds like you do), then read this article by The Chimney Sweep, Inc. It details why a ZC fireplace will probably not be the best solution for what you are looking to do. I think you would be much better served with a large wood stove insert such a Pacific Energy Summit.
 
medic said:
...really will be able to heat my space effectively with any of these fireplaces....
Mark
North East.

You are asking the right questions. My two cents based on what I read: these modern steel/cast iron wood stoves are hard to beat in the efficiency game.

This past June, we took out a zero clearance fireplace and installed a cast iron stove. In time, I will have some personal experience with one zc fireplace and one cast iron stove - among hundreds. I think I made the right decision, but who knows if it will be applicable to other homes, climates, wood, and burning techniques.

Good luck with your decision. Sounds like you are approaching it in the correct manner.
 
I am not familiar with any of the stoves listed, but just wanted to say good luck and hopefully you will be heating primarily with wood soon!
 
Welcome to the forums.

I'm a newbie myself. I told my install guy what we wanted, and he gave us some options. Based primarily on looks (though I understand it is pretty efficient as well), we picked the RSF Delta 2. So far I have been very impressed with how efficient it is... prior experience was all with older fireplaces.

Overall cost pushed us past 5 digits (i.e. >$10,000). So be prepared.

Sam
 
The Summit Insert will kick out more heat than anything you've mentioned and even it won't heat 3500 square feet in NY.

Figure 6000 btu per pound of wood.
 
One does need to be careful to see if a stove or ZC fireplace is EPA exempt or approved/certified. You don't want exempt. It's not true that all ZC fireplaces are exempt, however. The BIS/Lennox line is all EPA approved. It looks like the Opal is also when the catalytic combuster is installed. There are other big EPA-approved ZC fireplaces out there - Kozy Heat and Quadrafire get mentioned here a lot, offhand. I don't know that any single unit can heat 3500 sqft well, usually it's hard to get the heat distributed evenly. But many of the ZC units do offer remote duct options, both with blowers and passive (gravity vents).

With respect to the original question - there are indeed lots of different secondary-burn and heat-exchange designs out there. But I've never seen the data you're looking for - the heat-exchange efficiency or whatever it might be called. The EPA doesn't standardize it like combustion efficiency, so it doesn't get reported. Generally speaking, for EPA-approved units you'll get the most heat out of a freestanding stove with lots of exposed single-wall stovepipe and the least out of an insert or ZC fireplace because the latter two have no exposed pipe and thus less surface area. Typically inserts and ZC fireplaces have blowers to help compensate for this. I have an EPA-approved ZC fireplace (BIS Ultima), and while it's my workhorse for heating 2000+ sqft it's not quite as efficient as my free-standing stoves.
 
A WOOD STOVE IS NOT AS EFFICIENT TURNING WOOD TO HEAT AS OTHER SOURCES ARE....

Thats right, but infinitely misleading. about 70% of the heat generated burning wood is brought inside, the rest is waste. My ancient oil furnace gets about 80%.

But if you are talking about the whole system effiency, then include the oil refinery, and the tanker to ship it across the planet, then it isnt.

Wood is WAY cheaper ($/BTU) when compared to other sources, very few things beat it...

So the wood stove might not be efficient in certain terms of the wood. BUT its one of the cheapest ways to heat your home...unless you are an idiot and burn it down, or use an old stove, or green wood.
 
The simple answer is that the efficiency number DOES tell you how much heat is going into the house. That figure, just like the AFUE figure for fossil fuel appliances, tells you the percentage of heat that is not going up the stovepipe to the outside.

So for example if the stove is rated at 70%, then 70% is radiated into the house and 30% goes up the flue.


You are looking at a fireplace and you want to know what of that 70% goes into the room via the blower. Well I cant give you an exact figure but basically the only heat that doesn't go out that way is heat that radiates directly into the room via the face of the fireplace and heat that radiates into the walls and framing from the back and sides. If the fireplace is well insulated that heat loss should be minimal and some of it will eventually reach the room.
 
Welcome to the forum Mark.

So much for the talk of what stove or insert for your house. Now it is time to ask perhaps the question you should have been looking at first. What have you done about your fuel? You no doubt are prepared when it comes to your furnace but are you prepared BEFORE you install a wood burner?

Yes, it is important to consider the fuel even before you buy the box this wood will be burned in. Remember that buying fuel for the wood burner is not like buying fuel for your other furnace. You must buy your wood way, why ahead of when you will be burning it. Wood needs time to dry and those selling wood rarely have wood that is ready to burn no matter what they tell you.
 
Hi all,

Thanks for all the replies!!!

As a total newbie to this I've had an abrupt induction (by fire) into home heating.
We moved into the house in Jan 2011 and the oil truck started showing up twice a month till March. We averaged 300 gals/month with the thermostats set to 60!!! So you can understand my main interest is in lowering my oil bills...
The house is completely open plan with a centrally located 42" radiant heat ZC fireplace installed. Loading that up I can just about warm my hands at 6ft hence my motivation to put in something more efficiency. I've not looked too much at stoves as the fireplace I have is in the perfect location and I have little kids so consider all that exposed metal too much of a safety risk.

My plan is to install a large firebox high efficiency, load it up when I get home and before bedtime (heat needed eves through morning as house is empty during day) to supplement the oil heat. I was initially put off by the need to store/manage 3-4 cords of wood to cover each season but Irene downed 33 black locust in my yard so I have enough wood for a few seasons (neighbor offered to give me 3 cords of seasoned wood in exchange for 3 of my fresh to get me through this year).

So everything's coming together to make me a wood burner but before I spend 10 grand on equipment I gotta be sure I know what I'm doing (learning fast but still need as much help as possible).

All thoughts and comments very much appreciated.

Mark.
 
Hey Mark, welcome to the forum. If you're looking to supplement heating for you home and you're going to spend ten grand, it may take several years to make any returns. on that investment. Either way I wish you the best, but yowser that is a lot of money to invest in woodburning
 
I guess from one perspective, any solid fuel-burning appliance could be considered 100% efficient, in that all of the fuel is consumed and converted to heat energy. What's of concern to the owner/operator is the effectiveness of the whole system in heating the living space. In this respect, there is great variation across the spectrum of possible installations. The heat is produced by the fuel consumed...where that heat goes is the question. Some will always go straight up the flue to daylight and be lost, that's unavoidable...but how much, as compared to how much is transferred into the living space? Some appliances are more effective than others, some installations are more effective than others. In any case, frankly, I can't imagine effectively heating 3500 ft² with a single wood-burning appliance except for a ducted wood furnace. Every other appliance we talk about is a space heater. Rick
 
Thanks DaFattKidd,

An NZ6000 is around 5 grand, plus chimney, plus mantle, plus installation.... Oil bill was over a grand a month last year so if I can save half that it'll pay for itself in a few years. Besides the wife is pregnant and already moaning about the need to be extra warm this winter so I think it's time for (expensive) action.

Still learning....

DaFattKidd said:
Hey Mark, welcome to the forum. If you're looking to supplement heating for you home and you're going to spend ten grand, it may take several years to make any returns. on that investment. Either way I wish you the best, but yowser that is a lot of money to invest in woodburning
 
medic said:
Hi all,

Thanks for all the replies!!!

As a total newbie to this I've had an abrupt induction (by fire) into home heating.
We moved into the house in Jan 2011 and the oil truck started showing up twice a month till March. We averaged 300 gals/month with the thermostats set to 60!!! So you can understand my main interest is in lowering my oil bills...
The house is completely open plan with a centrally located 42" radiant heat ZC fireplace installed. Loading that up I can just about warm my hands at 6ft hence my motivation to put in something more efficiency. I've not looked too much at stoves as the fireplace I have is in the perfect location and I have little kids so consider all that exposed metal too much of a safety risk.

My plan is to install a large firebox high efficiency, load it up when I get home and before bedtime (heat needed eves through morning as house is empty during day) to supplement the oil heat. I was initially put off by the need to store/manage 3-4 cords of wood to cover each season but Irene downed 33 black locust in my yard so I have enough wood for a few seasons (neighbor offered to give me 3 cords of seasoned wood in exchange for 3 of my fresh to get me through this year).

So everything's coming together to make me a wood burner but before I spend 10 grand on equipment I gotta be sure I know what I'm doing (learning fast but still need as much help as possible).

All thoughts and comments very much appreciated.

Mark.


You're going to need a lot more than 3 cords with that fireplace.
 
Efficiency of the unit doesn't matter. They are all about the same. Really, you're splitting hairs to think otherwise. The fireplace will be the least efficient of the insert, stove, fireplace options but by only a tad.

Instead of worrying about efficiency, start choosing your stove based on specifications and reviews. You'll notice that almost nobody actually uses a fireplace for heat, not even a fancy EPA fireplace. They just aren't as effective as a freestanding stove.
 
I think there's more of us than that. I suspect it's the cost (especially for the install, although $10k seems very high) more than the efficiency/effectiveness that makes EPA fireplaces less popular. They should be the same efficiency as an insert, and tons of people use those for heat.
 
I was going to suggest a wood furnace also. It's one way to efficiently heat the whole home from a single firebox. The largest clean burning wood furnace that I know of on the market is the Max Caddy. It's firebox is around 4.5 cu ft. It contains the same secondary combustion setups as most stoves. There's also a modulating blower based on plenum temperatures, with other options. Something to check into and they are also reasonable.
 
Hey laynes69,

Good suggestion. I'd come across combo boilers whilst reading up on home heat. The oil boiler I have serves hot water, hot air downstairs and hot water baseboard heating upstairs so not sure how a Caddy could work as a replacement unit as I think it only provides hot air. Also my oil boiler is only a few years old...

I understand I'll still use oil even with the biggest wood burner I can install. Maybe I should focus on smaller units and think about closing off sections of the house around the fireplace.

Thanks again,

Mark.

laynes69 said:
I was going to suggest a wood furnace also. It's one way to efficiently heat the whole home from a single firebox. The largest clean burning wood furnace that I know of on the market is the Max Caddy. It's firebox is around 4.5 cu ft. It contains the same secondary combustion setups as most stoves. There's also a modulating blower based on plenum temperatures, with other options. Something to check into and they are also reasonable.
 
medic said:
Hey laynes69,

Good suggestion. I'd come across combo boilers whilst reading up on home heat. The oil boiler I have serves hot water, hot air downstairs and hot water baseboard heating upstairs so not sure how a Caddy could work as a replacement unit as I think it only provides hot air. Also my oil boiler is only a few years old...

I understand I'll still use oil even with the biggest wood burner I can install. Maybe I should focus on smaller units and think about closing off sections of the house around the fireplace.

Thanks again,

Mark.

laynes69 said:
I was going to suggest a wood furnace also. It's one way to efficiently heat the whole home from a single firebox. The largest clean burning wood furnace that I know of on the market is the Max Caddy. It's firebox is around 4.5 cu ft. It contains the same secondary combustion setups as most stoves. There's also a modulating blower based on plenum temperatures, with other options. Something to check into and they are also reasonable.

For the price you were willing to pay for the Napoleon plus installation you could buy a half a dozen Englander 30NC stoves installed.

If I was going to spend 10 grand in your situation, it would be on multiple large firebox stoves so the whole house is covered. 10 grand goes a long way. Put it to better use.
 
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