Newbe needs a little advice.....

You have an ambitious project. You must have discussed your needs with Garn before deciding to purchase the Garn. What did it recommend? If cost isn't an issue, then consult with professionals in these areas who can not only select appropriate parts and supplies but also install to achieve "best" results would be the way to go. And as you are well aware, "best" is a matter of opinion, especially because installations vary, and what one user believes to be "best" in her installation may not be "best" in your installation. It will be of interest to see how your project develops.

Marshall,

Welcome, and Congrats on the GARN!

Sounds like you are going to have a pretty good load on your unit. Your distances and load might be at the upper end of the unit during those cold January days! You may have to fire more frequently! You will have to make certain in the design that you minimize the losses over those distances you will be pumping, so with that said make sure you don't skimp on the diameter of your distribution lines.

Question 1: I would think you have talked over with your rep the need for minimizing the loss from source to your loads, and the importance of insulating the PEX correctly. They most likely would recommend MICROFLEX, pretty pricey, but about the best pre-fab stuff around. My preference was DIY with closed-cell SPRAY FOAM, and I am very happy. Over my 120' run, I can measure no loss at all, so you may want to consider that as an option. If you chose to DIY, then UPONOR/WIRSBO HE-PEX is about the best out there.

Question 2: Pumps Taco and Grundfos both very good.

Question 3: Uponor/Wirsbo

Question 4: GEA

Controllers: TEKMAR, TACO, or nofossils homebrew controller found here.

You make want to take a look at the couple of GARN install blogs, Jim K from PA, sawyer's, Rick Stanley's, or mine found in the signature below. These may help answer some questions you have not thought of yet.

Good luck on your adventure, I'm sure we will be hearing more from you!

Welcome to the forum. Besides locating the Garn, getting your piping done will be a big job. With those distances make sure you get the pipe diameter and pump size correct the first time. Add to your trench an extra pull pipe(s) for control wires in the future. Black irrigation pipe works well for low voltage.
As your're progressing on the project start collecting and seasoning firewood. This is a second common problem that is seen on the forum.
At the top of the "Boiler Room" homepage there are yellow "Sticky Notes" a good read. The search bar will bring HOURS of good reading too.
Question ? Can't you place the Garn closer to, or, attached to, one of the three buildings and reducing some of the in-ground expense ?
If location of Garn isn't set in stone I would look at pipes diameter, required loads, and location of Garn as a cost vs. benefit problem. Add to that, do any of your buildings have existing heat for unusual cold snaps where you could take some load of Garn ?

Garn’s paperwork is saying that I should be using 140-deg water…....do you know why they like the 140 over the 180?

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A three part answer. 1) Garn integral storage tank functions similarly to another wood boiler with a storage tank of the same size. The quantity of useful hot water available depends on the temperature difference between the water in the tank and the temperature of the water your system needs to function. If your system needs 180F water, like some baseboard systems, then the Garn/wood boiler needs to be firing almost continuously to supply that hot water. Although the boiler might heat the tank up to 190 or somewhat higher, there aren't many "stored" btu's in the water from 180 - 190 to allows the boiler to burn out before it needs to be fired again, and loaded with wood, repeat infinitum. Therefore, a system which needs 180F water might be better served by a gasification wood boiler that does not have integral storage. The lower the temperature of useful water, the more a Garn/wood boiler with storage provides heat from stored btu's, the less often the boiler needs to be fired; thus the statement of 140F water. But even that is not optimal. For example, I supply my radiant in-floor with 100F water from my 1000 gal storage by a mixing valve. So far this winter, and with temps into the -20'sF, I've only had to fire the boiler every other day, with all heat being supplied from storage between firings. The main reason for this is that I get useful heat from only 100F water.

2) I suspect, but do not know for a fact, that the design of the Garn is most efficient in burning and transferring heat to the water up to about 140, and that over that temperature efficiency starts to drop off materially. I suspect that the Garn integral storage design does not allow efficient operation as supply water rises above 140F, and its ability to efficiently supply water above that temperature is impaired.

3) Other gasification wood boilers have a much different HX design than the Garn and heat much less water integral with the boiler -- storage is extra and not part of the boiler itself. The gasifiers operate very efficiently at supplying hot water of 180F because of their HX design and because they are only heating the water around their HX tubes (maybe 50 or so gallons of water) rather than trying to maintain 1800 gallons of 180F water, as in the Garn 2000. But even the gasifiers will need to fired almost continuously if the need is for continuous 180F water, and because storage is less useful in this operating range, a gasifer without storage, other than perhaps a buffer tank, may be more practical than a Garn with large integral storage.

Apart from your question, I think I will have the opportunity this winter to do weighed wood burns with a Garn 3200 and make a determination of efficiency in transferring heat to the integral storage. I've done this with my Tarm, and a comparison would be of interest.

I had real problems finding somebody I was comfortable with to do the design etc, I eventually found a guy who works as a consultant for a Distributor to the heating trade, he provides advise and guidance to Heating Contractors and had done a few wood based systems but a lot of solar etc systems.

So ask your plumber who the local guys go to when they need technical help.

Using a wood boiler of this type is very similar to Solar, except you use wood to re charge your system rather than sun. Or similar to an off grid PV system. Your tank is the equivalent of your battery back up. The longer you can draw down on your 'battery' the more practical your system is.

Most people have varying loads, I am guessing about yours but here goes.

Demand all the time but peaking morning and evening with a continuing load over night.

Shop, mainly during the day when you are in it.

Greenhouse, all the time but peaking at night when it is coldest and no solar gain.

A guy local to me only needs a few hours sleep so for him getting up at 4 am to load up is no problem, I am not like that. So my system would need enough energy to be able to get through the night and deal with the am load before I could get it going again.

Of course another solution is automatic feed systems, wood chip or pellets, they have their issues as well, the first one is cost, those systems and silo's are not cheap.

]Be aware that insulated pex gets expensive when dealing with large distances, and as it size increases. So at least think about keeping the large loads close.

1.) How do you like your Garn so far? Any problems or concerns?

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Marshall, I really like the garn. We are now in our second year of use with no problems. Let me back up a bit, and describe my situation before I outline concerns. My install is very similar to yours. Our house is modern construction 3800sf, we have a 500sf greenhouse addition, and my out building is 3000sf insulated steel w/ 20f ceilings. My plan was/is to heat it all. The outbuilding would only be heated to ~45-50F, the greenhouse we only heat in the late winter to start transplants. My heat emitters in the house are 80% radiant floor, and 20% slant fin baseboard. My domestic hot water is 2 indirect boiler mates, 1-100gal., 1-40gal. I found this for when I finish up the outbuilding heat.

Piping:
When I installed, my plan was to get the house/greenhouse up first, shake out the bugs, then install the barn. I am still in that mode, and have yet to finalize my outbuilding solution. I piped my existing boiler in series, and that is my first concern/issue. This coming spring, I plan to pipe my existing oil boiler and the garn HX in parallel to eliminate running the garn Hot water through the oil boiler. The drop across the oil boiler is just a waste of BTUs.

Domestic Hot Water:
Last year we stopped burning wood mid-april, and switched back to oil until Nov for domestic hot water. Operating the garn to heat your Domestic hot water only is a huge waste given the standby losses even with the best of insulation around the garn. Using it as a storage tank for solar hot water is also inefficient because the 2000 gallon size and the requirement to size your collector to heat that load. My biggest issue is heating domestic hot water indirectly with the garn. Basically, this type of hot water heater is designed to operate with a source temp of 180F provided by a boiler. Since the GARN, or any storage system for that matter, has temps that vary from 200F down to 120F, it becomes difficult to reach the "set-point" of the hot water tank when you are at the low end of storage temps. In fact, there is a cross-over point when the temp of the source water, after 2 heat exchangers, can fall below the set point, and you could actually begin to draw heat away from the domestic heater. This can be solved by wrapping some "logic" and "controls" around the domestic hot water heaters to control when you can heat by measuring the source temp.

2.) Did you talk to someone specific over at Garn that helped you with your install? If so, could you please provide their name?

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Yes I did, but I learned more here on this forum, and from my own background research. You provided a perfect example of why to search elsewhere when you mentioned they recommended a 1500, and not a 2000 for your application. Enough said. Heaterman on this forum has installed numerous garns, and I would not hesitate consulting with him. He has a web site, I just can't find it at this time. He also sells a very nice insulation blanket designed specifically for the garn. Any capable HVAC guy with should be able to do the actual work, but you want to have a plan laid out before you hire a contractor. Most HVAC guys know how to make things work when the water temps are always 180F. They aren't real sure how to deal with the range of temps you will find with storage.

3.) Everything I've read about OWF they talk about utilizing 180-deg water........Garn's paperwork is saying that I should be using 140-deg water.......do you know why they like the 140 over the 180? They state that is the accepted norm over in Europe.......but last time I checked we're in the USA.

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Jim covered this one pretty well. It boils down to your heat load, emitters, and worse case design day. If you have forced air emitters, then it is really tough to have a storage system. If your load is completely radiant with mixing temps of 120F, then storage is perfect. Ignoring Domestic hot water for the moment, you figure a 20F drop across the GARN to HOUSE HX, you could run your storage down to 140F, and still get 120F at the radiant. As jim mentioned, this is not drop dead by any means, radiant will still keep on delivering below that, infact right now my water is at 119F, and the house is at 70F. I will burn later this morning.

BTW, drop me a pm if you would like to talk further.

Hi Marshall.

Hmm... Garn plus lots of underground lines...sounds like you need to send a PM to "heaterman". Whatever you might end up paying him for design/consultation will be money very well spent. We are lucky here in the Boiler Room to get as much of his time as we do.

Good luck with your project and we loves us some pictures ;-) ,
Noah

Floydian said:

Hi Marshall.

Hmm... Garn plus lots of underground lines...sounds like you need to send a PM to "heaterman". Whatever you might end up paying him for design/consultation will be money very well spent. We are lucky here in the Boiler Room to get as much of his time as we do.

Good luck with your project and we loves us some pictures ;-) ,
Noah

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Ditto!

You will need to have heat loss calculations available in order to discuss the amount of flow needed over those distances.

I installed my own Garn a couple of months ago....as many folks here did as well. I think we all give Steve (heaterman) an enormous plug...... Not only will your system be designed right, I think he can supply you with the materials at a good rate. Indeed, he is an endless source of information from a true expert.