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[danicol12]

I'm going to be buying an OWB soon, but I'm trying to understand a few things a little better before I decide which boiler to purchase.  First of all, I'm looking to heat an 1800 sq. ft. house, a hot water heater, a hot tub, an insulated 25' x 32' workshop, and occasionally an uninsulated 45' x 50' pole barn (when I'm working out there, but not too often).  I've done a little research as well as some reading on this forum.  I've noticed that most boilers advertise that for that much I can use a boiler with 150-200 gallon capacity.  However, I like to play things safe, and I would like to get something with closer to a 300-gallon capacity.  What I'm wondering is, if I get something that will heat more water, it will take more energy to heat this water, but will it also hold it proportionately?  Just because I have a bigger boiler, will it burn more wood, or will I just have to fill it less often? 

Also, some boilers have 1/2" thick fire box, while most have around 1/4" thick fire box.  Which is better in your opinion?  Again, I know the 1/2" box will take more energy to heat, but have a feeling it will hold its heat better and possibly last longer.  Am I correct in my thinking? 

Also, what is the main difference between "gassers" and conventional boilers?  Are "gassers" just the OWBs with blowers in them to make them burn hotter?  I had a guy tell me that I don't need a blower if I dry my wood correctly and long enough.  How much does whether I get a "gasser" or not affect how tall I can make my exhaust pipe, and what lengths are good rule-of-thumbs for each style. 

Also, does the thermostat on the boiler control when the circulation pump kicks on, or does the circulation pump run continuously and the thermostat in the house control the temperature in the house?  I know this is worded weird, but I don't know how else to explain it. 

Thanks so much for the help, and I look forward to learning more about this process as well as reading some of your interesting posts! 

[buckgrunt]

I highly recommend a gassifier.  These are the new EPA approved units that have a secondary combustion chamber in which particulates in the smoke are burned at higher temps. This results in a cleaner smoke.  My outdoor wood boiler (Eclassic 2300) has 450 gallons of water and an air blower, as most OWBs do.  The blower only turns on when the house calls for hot water (either for heat or domestic hot water) and/or the water in the OWB goes below a pre-set temp. Once the water temp at the OWB reaches the set level (188 degrees for mine), the blower turns off (reducing the amount of air being forced into the fire box) and fire in fire box is reduced to a very small, almost smoldering fire.  My circulation pump on the OWB runs 24/7 during the heating season and transports the water to my heat exchanger, which heats up the water in my oil furnace heating system.  My thermostats in the house are usually kept at 70 to 72 degrees and my house stays nice and warm without burning a drop of oil. When I first installed my OWB, I did all the stupid/bull work and hired a plumber to install the heat exhanger and plumbing hook up to my oil furnace.   I burned 7 cord last winter (my 2nd season with my OWB), but it was a rather mild winter.  My first winter, I burned 10 cord, but my wood was not seasoned enough and it was a very cold winter.  The key to an gassifier OWB is burning seasoned/dry wood. 

[Scott7m]

1/2" fireboxes are about 25% less efficient than the 1/4" models....  When transferring heat, thickness is not your friend.  Properly maintained 1/4" thick is more than enough.

Gasification furnaces are highly efficient and will burn 1/2 the wood of a conventional.  However there are a lot of companies out there with gassers that just haven't proven themselves.  In gassifiers I love empyre and portage and main.  I'm currently burning an Elite 100XT from empyre, it's EPA phase 2 and can be sold in any state.

As far as chimney length, on gassers I keep em short, 18-36", it's not like your having to get rid of smoke as you do with a normal boiler, good gassers will rarely ever put out a puff of smoke, I was out in the yard all evening and mine was on and i never knew it lol

[boilerman]

That is a lot of buildings, do not undersize yourself! Also beware of trying to heat an uninsulated pole building of that size. You might as well throw an exchanger out in the snow and stand in front of it. You will be returning a lot of very cold water to the furnace, plus everything else you will be heating. Insulation is a must. A gasser is more than just a blower fan to make it burn hotter. Most push the smoke and gasses from the initial burn downward into a lower chamber where they are burned under intense temperatures rather than allowed the natural upward escape route up the chimney. This process leads to very little smoke and creates a much more efficient burn, meaning much less wood is burned. 1/4 inch firebox thicknesses are most common and give you the best performance and heat transfer. Having burned both Central Boiler's Classic and Eclassic models, I think both are great, but am burning 35-40 percent less wood in my Eclassic 2400 model. I went with and prefer Central Boiler's experience and models as they have led the way in both standard models and now EPA gasser models and technology.

[danicol12]

Thank you so much for all of your feedback!  This is a lot of help!  I'm sure I'll have more questions once I get my OWB!  Thanks again!

[woodman]

If you are serious about heating all that area you will need a boiler with multiple outlets. Don't believe the "rated" btu output advertised by the manufactures. Just remember you can only push so many btu's through a 1 inch pipe. Figure about 100,000 btu's per 1 inch port, and that may be a stretch. 

[Scott7m]

Most btu ratings are a joke, most show you a number that would be like if you were continually feeding it wood every few minutes

[willieG]

searching on the net provides me with this information about btu  (if it is all true)  180 degre F water can deliver to an "appliance" about 10,000 btu per hour per GPM of delivery as the temp goes down so will the delivered btu so what scott says about the furnace rating is true, as yoru owb slowly drops to your ON set temp you will be delivering less btu (how many i have no idea but not likley too many if your drop is not huge)

so if youwere pumping 10 gpm you would be able to supply to your home 100,000 btu per hour with 180 degree water. lets say (this is purely a guess) that at 170 you were delivering 80,000 btu per hour.

i am not sure what everyone feels they use in btu but  i can tell you this much. my OWB is set to off at 170 and on at 160, i also know that i am at best getting about 7 gpm, so i know i am delivering well below 100,000 btu per hour. i live in a two story brick farm house of about 1900 square feet that i would consider well insulated but still has room for improvment. I live 30 miles east of Port Huron michigan (so you can judge my climate) I have never, let me repeat NEVER not been able to heat my home becasue of not enough btu.

[Scott7m]

The whole total btu deal is a hoax of sorts.  The numbers look impressive, and that's what there interned to do is lure folks in. 

One thing I like about empyre is on there charts they show you a peak output, as well as how many btu your stove can deliver on a load at 6, 8, and 12 hour periods. 

Most homes require maybe 20-40k btu per hour to maintain 72 in the winter months, of course that changes based on a large number of factors.  One guy I know has a 5000 foot pole and beam house in Quebec, based on there average coldest winter day his house would only require 59k btu/hr to maintain 72.

Think about it and don't always fall for big numbers, understanding those numbers is far more important

[woodman]

I agree with both WillieG and Scott, but a uninsulated pole barn is a HUGE load! It will have a 140,000 btu hx running constant. 

[Scott7m]

Trying to heat an uninsulated pole barn will simply use how ever many btus that the appliance can put out that your trying to heat it with... 

[willieG]

un insulated pole barn? the only place you will feel warm is 3 feet in front of exchanger

[danicol12]

I may not have worded this correctly, but the uninsulated portion of the pole barn is of VERY minor importance to me.  Right now, I use a propane space heater (blower?) to just take the edge off when I have parties or am working on stuff out there.  This will be a separate heat exchanger that will not always run.  The hot-water supply lines will only extend past the insulated portion of the pole barn enough to fit the heat exchanger.  The primary heat with obviously be in my house (1,800 sq. ft.) and in the insulated portion of the poled barn (800 sq. ft.). 

One of my largest questions right now though is whether to go with gassification or not....  I keep hearing that it's easier to burn wood in a conventional OWB, because you don't need to have the wood as dry, or seasoned, as what you do in a gassification furnace.  I realize wetter wood will always smoke more, but will it really not burn in a gasser at all?  I plan to season my wood correctly, however, that may not ALWAYS work out as well as planned.  Besides that, I'm going to have to store the wood outside.  The main reason I want to go with a gasser is for less smoke......but if you need to have 2-year seasoned wood in order to have "no" smoke, I'm not going to waste the extra money, because that will never happen. 

Your thoughts and comments are greatly appreciated.  Thanks!

[Scott7m]

Some gassers are really picky....   

The empyre from my experience is pretty forgiving on wood quality.  We've burned wood of up to 35% moisture content. 

Folks who cut in the spring, cover, and burn in the fall are having great results.  None of this 2 year stuff. 

That's not like that with all gassers, some can't hold a fire at all and need propane to relite and silly stuff like that.

With the gassers ive messed with, the poorer the wood, the more cleaning you have to do.  Empyre is like wet wood, clean every 4-5 days. 10 min job. Average wood - 2-3 weeks, excellent wood.  3 weeks and up to as much as 6 with folks using pro former, an additive in the firebox

[jwrj78]

I have been looking for the last few months for an OWB. I have it narrowed down to a couple of different ones. Durning this  time, I noticed a neighbor of mine has an OWB that has been sitting in his shed. I stopped today and asked him if he wanted to sell it. His reply was yes. It is an Aqua 2 wood boiler, not Aqua Therm. It seems that it was manufactured around my area in Winston Salem, NC by Aqua Manufacturing. I guess the company has since went under. I have found one for sale on a site and on another site two individuals where seeking information on theirs with no replys. On one of the sites it said that theirs was a 500 gallon heater. I dont know about this one because it was bought from someone that has since passed and the current owner has developed health issues and cannot install it and wants to get rid of it. I did not measure it but it was abt 4 ft wide and taller than I am and I am 6-1. There are all kinds of pipes coming out of it and the smoke comes out the back. It has 2, 5 gallon buckets of stuff with it and 5 solar panels. He priced it to me for 900 dollars for all of it. Should I walk away or should I snatch it up? Can I still by parts for it? It was working when he bought it. The only reason the original owner sold it was because the solar panels caused his roof to leak. I plan on going later in the week to take pictures of it. Any help or advice woud be greatly appreciated.
By the way, GREAT SITE, it has been very informative in my search for an OWB.