Wood Boilers vs. mod con

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Couderay80

Member
Hearth Supporter
Jan 14, 2008
52
South of the windy city
[Hearth.com] Wood Boilers vs. mod con Well after studying the situation for a few years about wood boilers I've come to the conclusion they are not for me.The house is 1400sq., ranch, on a full basement. I have a mod con I would not trade for the world and went with a wood stove for suppemental heating. For me I have the best of both worlds. The house is seven years old and tight. The envelope is by far the most important item in heating . I have the room and storage space(not in the house) for a wood boiler but the money and time for a wood boiler could not be justified. Call me crazy,Love boilers, but a wood fired one sorry. Love watching the fire in the wood stove from the comfort of my recliner.
 
94% Holy Hell! First I've heard of these-how much do they run?
 
I am leaning towards a pellet boiler for my old age. Oil is expensive and propane (here) is more, maybe tad better with less maintenance, greater efficiency, etc.
I buy wood, currently in log length so some savings there, but it's a fair amount of work. Pellets would cost more. I can see a modern (ie, Euro) self cleaning, efficient pellet boiler with a big hopper or bin to make it even more care free. No storage required.
 
Pellets....... Now you are thinking logically.

A good pellet boiler will require maintenance only 1-3 times per season and per btu pellets are about 1/2 the cost of propane and 1/3 of fuel oil. (at least in my neck of the woods) Just fill the hopper every 2-3 days and forget it. Automatic cleaning of the firebox and flue tubes + the same for the firebox make pellets very attractive in terms of labor involved and ease of use.
 
A condensing boiler will start around $3000.00 without trim. Double to triple that for trained installation. You do have to be careful of the cost per therm of fuel. The last condensing propane boiler I installed tested at 97.4% combustion efficiency on a radiant slab, but an 86% AFUE oil boiler may cost less to operate, depending on the cost of fuel per therm.

The high efficiency comes from the 100°F stack temperature.
 
Do your homework on the mod/con. Especially when using propane for fuel. Propane leaves more residue than natural gas and by their very nature most mod/con boilers have very small passage ways between the sections or tubes in the heat exchanger. These plug up in normal use and MUST be cleaned at least annually. We're talking remove the burner, apply chemical cleaner, soak, brush out, more than likely repeat if you let it go to long, then rinse out with clear water and reassemble.

Good ones are the Prestige series made by Triangle Tube, and the Vitodens from Viessmann to name a couple. Avoid anything with a heat exchanger made by a French company named Giannoni.....like the plague. A lot of the less expensive units/brands on the market use that heat exchanger.
Some manufacturers are using aluminum for their heat exchanger material and for me the jury is still out on that. Aluminum in contact with corrosive condensate, corrosive combustion byproducts and flame temps of 1700*+............Just doesn't "sit" good with me.
Expect to see the price for one of the two brands I mentioned in the $4-5,000 range for the boiler alone.

If you have a wood stove to take the edge off your fuel consumption I would want to do some math for you on payback for a mod/con vs standard boiler if you were my customer. The old cast iron type will outlast ANY M/C boiler by a 2-1 margin so when you factor that into the equation along with your wood stove I kinda scratch my head when I put myself in your shoes.

Of far more importance than the boiler itself is the skill and knowledge level of the installer. You and anyone else for that matter need to understand that efficient hydronic heating is influenced more by the piping, control and installation than by the boiler itself. This goes for wood or pellet fired boilers too.
Unfortunately, in a lot of areas, hydronic heating is a lost or dying art and finding someone who is a real live heating professional rather than just a plumber who puts piping together and a challenge. I would encourage anyone thinking about buying a boiler (of any fuel type) to buy John Sigenthalers book, Modern Hydronic Heating and hang around on the "Wall" at www.heatinghelp.com to become knowledgable enough to spot an installer who doesn't know jack about what he is doing.
 
Each condensing boiler manufacturer will have their own maintenance procedure.

Aluminum heat exchangers are the most common in the world. See Buderus/Bosch.

Cast iron boilers typically last 30 years...the jury is still out on condensing boiler serviceable life, but we have worked 20 year old condensing boilers with much lower technology...see Glowcore and Hydropulse.

System design and installation is the key and annual maintenance mandated by all Heating appliance manufacturers.
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The two condensing boilers with the most noble metal content are Viessmann & IBC but both are water-tube boilers like the Giannai if you are afraid of tight spaces. If you want easy cleaning, a condensing fire-tube boiler like Triangle Tube, the new NTI or Lochinvar may be the thing.

Propane will make maintenance more challenging but how much and how often depends on the fire time among other things.
 
A little more clarification on my post. I did install the boiler by myself, and yes it has its issues like maintaining once a year. But its nice to not have to do anything else for the last seven years. Pellets are 4$ a bag and a buddy has a similar house going thru a bag and a half a day.(pellet stove) I've done the math with propane and pellets still figure I'm a head of the game plus the convience of not having to load the boiler with fuel. I love wood heat wouldn't trade it for the world, but if I leave the house for the week I don't have to worry about feeding the boiler? That to me was worth the investment in the M/C boiler. In the face of efficiency a one hour cleaning once a year to the modcon. its a win win for me! Oh by the way the boiler is a munchkin (ducking ;) )
 
of course a woodstove makes the most economic sense for you. A small home and heating load means that you will almost certainly need thermal storage with a wood boiler - hard to justify a $20k investment to displace less than 500 gallons of LP per year.....I would guess that HearthStone cost you about $5000 installed? A very reasonable choice, I would agree. Of course there are other reasons to put in a wood boiler - top of the list: "because I want to" :)
 
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