Boilers, furnaces, gasifiers, indoor/outdoor - WHAT DOES IT ALL MEAN???

[deadtvs]

Ok, sorry for the not very helpful heading and sense of panic, but I am fairly overwhelmed. I'll try to state/stick to the facts:

1) We have a 3400SF house on the CO Western Slope, fairly well insulated, currently using propane central forced-air (downdraft). Heating (only) costs ran up to $800/month last winter - killing us.

2) We also have 23 heavily-wooded acres just begging to be thinned. I have heated with wood before (old Vermont Castings stove), not scare of working up a lot of wood. We have about 80/20 mix of Pinon Pine/Juniper - should be fairly good to burn, I think

3) I initially was looking for an efficient, see-through fireplace to replace our current POS gas insert; after finding almost nothing that would work, we came back down to earth and decided we need a wood-burning "something" to plug into our existing forced air plenum.

4) Was initially looking at various wood furnaces, starting with cheapo (but inefficient, apparently) Home Depot units, then looking at Drolet Heatmax (still pretty damn cheap) or Kuuma Vapor Fire units.

5) We have a strong preference for indoor unit, partially for logistical reasons (easier/closer to main plenum), partially for convenience (rather not have to always go outside to feed fire).

5) Trying to find local HVAC person who knows wood furnaces/boilers, but so far only found a Central Boiler dealer/installer - outdoor units only. He's coming up Friday just to give advice, but I'm not expecting much.

6) In researching Central Boiler, I discovered they are water heat only. Which led me to similar units, and a whole new world! I did discover another local dealer for Econoburn, and am going to call them as soon as I finish this post.

7) We intend to be in this house for the long-haul, not scared to sink some money into this, but want to make the "right" choice to begin with - not yank it out in a year or two because it didn't work.

So, my top questions at the moment are:

1) Apart from providing hot H2O, what are the advantages/disadvantages over water heat vs. forced air furnace units? I'm guessing the "boilers" (and does that always mean H2O-based?) are more expensive to install?
2) Is there something wonderful about outdoor units I'm missing? Other than the "safety" factor of having the fire outside, I don't see the attraction. For us, duct/pipe runs will be much shorter if we put it in the garage vs outside. I know I'll have to put in appropriate chimney, but it's straight up/out - not worried about that, except for cost.
3) Although I probably sound like an idiot in this post, I'm a fair handyman, not scared to get my hands dirty and figure stuff out. That said, I'm a neophyte at "advanced" wood heat. How much of this can I do myself? Where's the best place to go for advice (besides this great forum!)?

Oh, and what exactly is a "gasifier"? Seems to be simply a new term for catalytic/reburn process.

 

[bmblank]

Unless you're putting it right where the other furnace is your probably looking at getting a boiler and then running a water to air heat exchanger in your ducting system. It's a lot easier running hydronic lines then it is ducts. Less parasitic losses too, I suspect. Speaking of which, you may want to consider having somebody come in and seal up and insulate your ducting system to make sure the heat is going where you want it and not leaking out all over. $800 is a ton of money, I don't envy you there.

 

[deadtvs]

Unless you're putting it right where the other furnace is your probably looking at getting a boiler and then running a water to air heat exchanger in your ducting system. It's a lot easier running hydronic lines then it is ducts. Less parasitic losses too, I suspect. Speaking of which, you may want to consider having somebody come in and seal up and insulate your ducting system to make sure the heat is going where you want it and not leaking out all over. $800 is a ton of money, I don't envy you there.

I won't be replacing gas furnace, just hoped to run duct from wood furnace into FA plenum. Putting it in garage it's on the same level as our crawl space (where plenum is, of course). Duct would have to run @ 12-15' to reach plenum. Just seems like less muss/fuss than the water/heat exchanger. Although if we could get h2o heat from it, that would definitely be a plus! Current h2o heater/utility closet is directly above FA plenum, very accessible, so that might be feasible.

I've already looked over ductwork - it's pretty tight, and well-insulated where it should be, seems to me. Problem is, the bedrooms (especially master, where it's coldest), are a good 40-50' from existing furnace. Seems to be quite a bit of loss running through the crawl space, in spite of insulation.

 

[maple1]

You should work out a budget. There is a significant price difference between an add-on furnace [furnace = heats air] like say a Heatmax/Tundra, and an efficient boiler [boiler = heats water, but it doesn't really 'boil' it]. Depending on your layout and all kinds of other little factors, you could be looking at $5k furnace vs. $15k boiler system. Rough round numbers.

Most guys who add on a boiler to their hot air system use a heat exchanger in their plenum - if you are losing heat in your ductwork now to the far end of the house, that situation would likely still be there even if you went whole hog on a boiler system. Adding radiators & piping to them with well insulated piping would put the heat where you want it, but also likely put a lot of your money where you don't - retrofitting heat distribution systems is not much fun.

 

[deadtvs]

Your "rough round numbers" match exactly what I'm ball-parking. So the question becomes, is the boiler worth the extra 10K? Our water heater is propane as well, but using only ~15% of our total gas usage - the vast majority is for heat. I'm thinking boiler=not worth the extra $. However, I can't find a local HVAC/wood furnace guy to pick their brain (and potentially hire). The only ones I find do boilers exclusively.

And yes, I know the distribution will likely be a problem no matter what we end up with, but I'm hoping the cost savings of a wood unit will make it tolerable. Worst-case, I have thoughts of putting in a pellet unit down by bedrooms, if absolutely necessary.

For what it's worth, distribution is why I originally was looking at high-efficiency fireplace - our existing unit is about as central to the house as you can get, and sits right above plenum. Seems it should be doable to put in a fireplace that's ducted (with blowers, obviously) into that big central duct, but everything I read and all advice I got, was that we would be disappointed - wouldn't really heat house, etc.

Oh, and our budget is <$10K, could possibly stretch to $15K if I was convinced it was the perfect solution.

 

[Fred61]

A fireplace is " fire out f control" and by it's nature needs to allow a large flow of heated air out of the stack taking 70 to 85 percent of the heat generated by your fire with it. I got the impression that your present furnace plenum is directly in the center of your house below the fireplace. With that location being the most efficient, I'm wondering why you're loosing so much heat from the ductwork. How large footprint of the house? In other words, how long are your runs?

 

[brenndatomu]

A couple different comments here...
1. To answer your question, a gasifier is a firebox desined to burn in a more complete fashion, wood gas, smoke (most of it) and all. More efficient and cleaner burning. A lot of the gasifier boilers have the smoke traveling out the bottom of the firebox into a ceramic lined chamber where preheated oxygen is added resulting in a very high burn temp. The Kuuma furnace is a gasifier too, different design though, more similar to modern clean burn stoves. Kuuma is a top notch unit by the way
2. An outdoor unit, on top of the higher install cost, will use 2-3 times more wood then an indoor unit like the Kuuma
3. What about putting in a stove or two? (possibly two just because of the size of your house and where you are, heat load) No messing around with duct work then...and feeding even two stoves would probably use less wood than 1 OWB. Even if the stove route didn't supply all your heat, it sure would put a huge dent in your bill!
4, You are right, it is tough to find anybody that knows much about wood furnaces especially when it comes to doing installs. Best way I have found is to DIY as much as possible and then contract the rest out piece by piece to "specialist." Chimney to chimney sweep or a stove shop, duct work to a tin knocker, electric to a sparky, etc etc...

 

[STIHLY DAN]

Is this 3600 sq ft all a single story.

 

[deadtvs]

Is this 3600 sq ft all a single story.

Mostly. There is a large, finished attic over garage and kitchen that I can live without heating (much), and a "sun-room" that's basically closed of in winter, to main heated space is more like 2500.

 

[deadtvs]

@brenndatomu: I have thought about putting in at least one stove, but we're looking for a fairly convenient/no muss/no fuss solution. I have a time-consuming regular job, a semi-neat-freak wife who works full-time as well, and two growing girls. If it was just me, I'd be willing to try all kinds of things, but I think we need to focus on a "clean" install. I realize a furnace probably isn't all that clean, and of course there is the wood mess at a minimum, but that's why confining it to the garage is so appealing.

per the comments above (and thanks for all of them, by the way!), I've pretty much ruled out an outdoor unit, and leaning strongly toward a furnace rather than boiler - just don't see enough advantage to the boiler, and if we put it where I want to, ducting, say, the Kuuma into the plenum shouldn't be that hard. And as I said, chimney is straight up, standard ceiling/roof penetration, so not worried about that. Biggest issue is I can't find an installer! I do have a "traditional" HVAC guy coming out to inspect my gas furnace - I will try to pick his brain about the ducting, temp control, etc. - see if maybe they can work with me on installing the Kuuma or similar.I already have a contact at a stove dealer, will check on having them put in the chimney. Hoping I can do the rest.

Thanks again.

 

[bmblank]

Just as an FYI, most insurance co.s won't allow a furnace in a garage where vehicles are being stored. You may want to check if that was your plan.
Also, as far as ocd goes, is imagine pellets are pretty nice. It's easy for the wife or others to start it up if you're away, clean, easier to let it go for longer periods. With wood you will end up with some mess. In a garage it's not a big deal probably.

 

[deadtvs]

most insurance co.s won't allow a furnace in a garage where vehicles are being stored

That is bad news! But I should have thought of that. We're tenuous with them anyway, being in a high-risk area for wildfire - not sure I even want to ask.

 

[hobbyheater]

The PDF for our old Jetstream boiler gives the principles for gasification. The more modern gassers achieve the same end but most are down drafters. It also gives the principles and advantages achieved by using storage.

I have attached a PDF file for a Garn Junior. The Garn is efficient and simple in operation and is certified for operation with a horizontal flue. The chimney can go through a wall and does not have to go up through the roof. These boiler have been around for 30+ years with a good parts and service record.
The video is for the operation of a larger Garn but all work on the same principle.



The big problem when heating with a boiler is trying to match the load to the demand. Storage eliminates this problem. OWBs usually have an output of around 200,000 BTUs per hour and even if your house needs 50,000 BTUs per hour, this spells a lot of idling (no active fire) for an inefficient operation even for a Gasification Boiler. Lots of Idling also will mean the heat exchanger surfaces inside the boiler will plug with creosote requiring frequent cleanings and loss of efficiency.

Myself, I have heated with a gasification boiler with storage for more than 30 years and before that with pre-gasification boilers. Take your time in making your decision and if you are into looking at the long haul, the added expense for a small Garn down the road IMO will demand a serious look.