need help with OWB selection

[ckarotka]

My brother-in-law has built himself a fine two story in the woods. We are all construction workers in the family and have done all the work ourselves. I burn in wood stoves and he wants to use a OWB for his primary heat source. He has one in mind, but to keep the post nuetral I would love to hear your recommondations for his set up. This site has offered myself a great wealth of knowledge for my needs and thought you all could help him before he makes his purchase. Here's his set up:

2700ft two story w/ 2300ft heated based and garage
2100ft out building for storage of tools and materials for future jobs.
all in floor pex tubing in the concrete, not sure how on first and second floor
the boiler will be about 150ft to the house and 175ft to the shop.

Any info on brand, make and model and why or why not would be very helpful

I'm not too familar with OWB but am trying to learn and help him out.

Thanks
Charlie

 

[Nofossil]

It's not technically an OWB, but given the amount of space that you want to heat and your presumed ability to create an outbuilding for it if needed, I'd look seriously at the Garn. It will burn a lot less wood and generate a lot less smoke than an OWB, and it has built-in storage to provide heat when the fire has gone out.

 

[Como]

Seconded

www.garn.com

 

[heaterman]

Thirded....................??? Is that a word?

A Garn is a perfect fit for a high mass radiant floor like you have. An OWB would be a poor choice unless you purchased a monster which would be drastically oversized for normal operation. The issue is that a slab like that can drain heat out of your boiler faster than it can be replaced in anything that one would consider to be normally sized for your actual load. It doesn't take much to maintain it once there but dragging a few dozen tons of concrete up even a few degrees can soak up unbelievable amounts of heat.
What happens in any boiler without massive storage capability is that the burner/heat exchanger cannot keep up with the rate the heat is being soaked out of the water. Unless, like I said, it is massively oversized. That being the case, you are left with one option and that is to put a lot of heat into thermal storage. That allows a draw that could be far in excess of the actual firing rate of the boiler for at least a few hours.
The problem you will have with an OWB or even a typical downdraft unit with little or no storage is that you will suck out all the heat and drop the water temp low enough to cause thermal shock, destruction of the boiler and/or creosote problems of ghastly proportion. With the downdraft unit this is less of a problem because most incorporate some kind of low water temp protection in their basic package.

A Garn, due to the fact that it contains 1500 gallons of water at minimum, is impervious to thermal shock. You can't change the temperature in it fast enough to cause problems. It will also run nicely at water temps down to the 115-120* range with no ill effect when using halfway decent wood.

Now. All that being said, A Garn is an indoor rated appliance and as such it must be installed in a building or at least under some kind of shelter and insulated in place. If it were my place, I would probably set it in the pole barn and pipe water to the house. Given the distance and load you describe, I have to think that you would be looking for 1-1/2" tubing to provide enough flow to the house. That will not be cheap to insulate properly.

Even if someone tells you their OWB will do it and you buy it, make sure you see their flow rate calculations if they recommend 1" Pex tube for either the house or shop. Ask them for a written guarantee that there will be sufficient heat for both places. I would walk away from any person or company that would not put it in writing.

I'll give you an extreme example of what I am talking about. We have a 4500 sq ft slab on a dairy farm which is kept ice free in the winter by a pair of WHS-2000 Garn wood heaters. This pair of stoves has a combined firing rate of well over 800,000 btu/hour. When that slab calls for heat and 35* water starts dumping back into the Garns, I have watched the water temp drop 50* inside of 30 minutes ..........with both units burning. That's a heat transfer rate of over 1.6 million btus/hour. Far far past what is needed to maintain the slab once up to temp and impossible to service without the energy stored in the 4,000 gallons held by the pair of Garns on site there. The load is however, handled quite nicely due to the storage capacity in the Garns..

 

[ckarotka]

Thanks guys,

I talked to BIL about this and his was definitely interested until I told him around 15k. If he was to use an other type of boiler how long do they last in real life with some protection from the weather. Also for an OWB about how much in making your own storage unit (old propane tank?) and other hidden costs that don't exist with the Garn? I have read posts that say "after all is said and done with storage and pumps and what not the Garn is not that much more than other heaters" When they say "close" I assume 2-3k?

If a Garn can go I'm guessing here, 20 years, how many OWB's would he go through in that amount of time, I understand the massive amount of firewood difference.

How about maintenance? Pumps, blowers etc. I assume the Garn is also less maintenance and after watching the video is also way less labor intensive. 3-4 hours a day opposed to "round the clock loading"

 

[Eric Johnson]

Another important consideration, at least for most people, is smoke output. You won't get any smoke from a Garn. From most--if not all--OWBs, you'll get plenty. The smoke is unused energy going up the stack and pissing off your neighbors in the process.

I suspect that when all is said and done, the Garn is going to be a significantly bigger investment than an OWB. But when you factor in the stuff that only you can know (less wood consumption, clean burn, longer service life, etc.) it's worth it, IMO.

 

[Jim K in PA]

Some of the GARN units that were set up as prototypes in the early 80s are STILL running, close to 30 years later. Depending on a lot of factors, I think a GARN will outlast an OWB at least 2:1, probably closer to 3:1. Even at 2:1, you are way ahead in terms of work and fuel usage as well as cost/time. A GARN is a decision made very much with long term planning in mind. It is dead simple to load and use by anyone able to lift a split. Just make sure you use seasoned (dry - 15-20% MC) wood. Yes, many will tell you an OWB will burn "anything", like that's a good thing. It is not a good thing.

Best of luck with your decision.

 

[heaterman]

I'm not sure what he's looking at in OWB's that are a lot cheaper than a Garn. A unit the size he would need is going to run 10-12K in a "good brand" like a HeatMor or a Central. A Garn 1500H is $12,400 so there's not a lot of difference in price compared to the difference in performance.

Granted you can get a less expensive OWB like a Fireking or Woodmaster but if he's going that way he might as well burn propane or Fuel oil. The stove will likely be shot before he gets any return on investment. Choose your poison.

If he goes with an OWB I'll guarantee that he will burn twice as much wood as with a Garn.

 

[ckarotka]

would it be too late for him to go with a Garn since he already has his underground done? Don't quote me but I thinks it's 1" pex buried around 4-5ft with 8" foam insulation below and above well all around i suppose. Wrapped in plastic to prevent the h2o carrying away the heat, on top of gravel as a drain and the ditch has fall to it. The utility room is also done manifold completed about 1.5 months ago. Does the Garn come complete, ready to install or is there extras after initial set up for his application? Other than the "Garn Cave".

 

[stee6043]

Regardless of the boiler there is no way your brother is going to be able to heat all of his loads with 1" pex supply/return lines. His demands are quite big by most normal measures and 1" pex is standard for most "smaller" loads. Most of us are running 1.25" lines on average loads. Above average (your brother) is going to need even more. I'd bet double 1" runs would be a minimum. I'm sure others will comment on this as well....

 

[heaterman]

would it be too late for him to go with a Garn since he already has his underground done? Don't quote me but I thinks it's 1" pex buried around 4-5ft with 8" foam insulation below and above well all around i suppose. Wrapped in plastic to prevent the h2o carrying away the heat, on top of gravel as a drain and the ditch has fall to it. The utility room is also done manifold completed about 1.5 months ago. Does the Garn come complete, ready to install or is there extras after initial set up for his application? Other than the "Garn Cave".

1" pex?? Which half of the house did he want to heat? Seriously, that is a really big mistake and unfortunately one of the most common. I'm placing a $10 bet right here and right now that a seller of OWB's told him 1" would do the trick.

 

[ckarotka]

You win $10! I don't know what his plans are now. He is looking into the Garn very seriously but he already has a deposit on a Hawken and thats what he budgeted for. All this info has really made him think long and hard about the rest of his install. He is on a very tight time frame now, kitchen is in, trim package and hard wood are being delivered with-in two weeks and he wants to live in it by Thanksgiving. I'm not sure if he has a secondary heat source planned and functioning right now.

Oh he plans on heating the 1st and 2nd floor of the house with a forced air heat exchanger from the boiler (I think that's right??). He wants A/C for the summer.

Had he know about the Garn from the beginning he would have made the garage bigger to house it. That would have made life real easy, park the truck start the Garn, eat dinner feed the Garn, take a shower Feed the Garn, relax, watch the tube and not worry about it until tomorrow without ever going outside, except to plow and restock the garage with fuel.

 

[HawkenGlobalYUK]

I purchased from Hawken Energy in 2005 and wish I had never met the owners of that company or ever heard of them for that matter. I am now involved in litigation with them. I would never do business with any company the owners of Hawken Energy were involved in. I have pages of detailed info. over at arboristsite as well. Be careful, I wish there had been this kind of resource back when I purchased this unit as I had to rely on their word. They have only been in business since late 2004 so be very weary of claims of longevity made on their website and in propaganda. Also, the "Independent" Industry comparison report by Energy Research and Analytics Group was formerly put out by The Pentwater Group, and who does this tie back too? The owners of Hawken Energy. I could go on for pages but already have on other forums and cannot keep up with all the information that is pouring in to keep up multiple threads. If interested do a search for Hawken Energy over at arboristsite dot com. Good luck with the decision, and if you don't go with the Gasser, at least do more OWB research and go with a longstanding manufacturer that has a clean track record. Also, stay away from Global Hydronics, Bio-Heat, or any of the other brand names Global Hydronics uses. These do not last, and Global Hydronics warranty is a joke. Seriously!! 100% for the first 5 years would be good if they would ever honor it. But......
I just hate to think of anyone having the kind of nightmare experience that I have with these OWB's. Measure twice, cut once. When it comes to OWB's research 100 times, buy once. Best to you and your project.
HawkenGlobalYUK.