Hi everyone. I am new to the forum. We are considering a Garn 3200 unit to heat our workshop. The building is about 6000 square feet and is heated with baseboards. I did a heat loss calculation and I get about 180 000 Btu/hr for the coldest days. If I am not mistaking, the 3200 unit can store about 1548000 Btu for temperatures between 140F and 200F. This would mean 8.6 hrs between burns? All our wood is 32'' to 36'' long. Anyone have experience with burning 36'' logs in the 3200 unit? Can it take big diameter? Is it necessary to split the wood?

The WHS-3200 will store 2,064,000 Btu's in 120 degree to 200 degree water. The big question is whether you have enough baseboard radiation to take advantage of the lower temperature btu's. In other words will it heat your building on the coldest day with 120 degree water. Assuming it will or you add enough to acomplish that then you could heat your building on the coldest day with a WHS-2000 by firing every 6 to 7 hours. That's assuming your calculations are accurate. Keep in mind that the coldest days are a small piece of the heating season. If it were me I would consider improving the building efficiency if possible and I would install one WHS-2000 in a building big enough to accomodate a second one if needed and try it. You might be surprized? If it works out you are golden! If it does not you can install a second 2000 and you will have more storage for less than the cost of one 3200. When the weather is moderate you can alternate the firing and just fire on one. If you don't need the second unit you will have additional wood storage which is always a good idea. Don't forget to pipe the single 2000 as though you will someday add a second one but i suspect you won't need it.  

Thanks Kenny for responding. I don't really know for the baseboard calculation. They do cover all the exterior walls of the rooms but some sections are without fins on the tubing. I was looking at the WHS 3200 because of the bigger fire box and bigger water volume. We find it easier to prepare the wood when it is 32''- 36'' logs. We would like to have about 12 hrs between burns. Presently we have an OWB rated at 500000 Btu/hr. Lots of smoke and not very efficient. Is there a big price difference between the WHS-3200 and the WHS-2000? If you tell me that it is twice the price, then it would be better to have two WHS-2000. Is the WHS-3200 common? Most people seem to have WHS-1500 and WHS-2000. As for the heatloss, it should be Ok. We have lots of windows, doors, and ventilation in the workshop.

Luc,

      We generally sell the 3200 as a comercial/ industrial unit. They are often manifolded in multibles. That's not to say we won't build one for you but the cost is more than two 2000's. It's a monster! You can get a quote if you like from your dealer or rep. My territory is Wisconsin Mn, and Iowa. If you are in that territory you can contact me through the website. As for baseboard heaters you can figure that they will typically deliver about 450 to 550 Btu's per ft. @ 185 degrees if they are clean. At 130 degree water you can expect about 250 to 275 Btu's per ft. Often the best solution is to install more baseboard or a few flat panel radiators. You would have to do detailed heat loss calculations to determain your load, but you may not be far off on that 180,000 if you are in Minnesota or Wisconsin. Keep in mind that you can fire the Garn at higher temperatures when needed to get the BTu's you need but that is not the most convenient for some people and reduces your efficiency a little.

Kenny, any problems with flue condensating like in the oil boilers. In other words, what happens when the water falls bellow 120F? Will it condensate?

It can condense in the heat exchanger but not at those temperatures. The water would have to be well under 100 degree's. There are other posts in this forum about first fire start up condensation but the well water temp is typically less than 60 degree's. The heat exchanger is built with schedule 40 pipe. I don't think there is anything you could do to damage it.

Thanks Kenny for all the help. That answers my questions for now. I will contact a rep if we go ahead with the installation.

I could justify the 3200 in terms of load, but 2x2000 is cheaper. Is there something else that the 3200 has that justifies the significant price hike? Logic would suggest if it is just bigger than the price differential would be nearer plus25%.

The 3200 has a little bigger firebox and door which allows a little bigger wood if you are interested in lifting more weight. It has a little smaller footprint than two 2000's but also has less storage. It is a little easier to pipe a single unit but a little harder handle move and to set a 3200. Two 2000's will give you a little redundancy and you could alternately fire just one for much of the season. Of course then you could not say that you have the biggest GARN and anyone who understands GARN knows that size really does matter.

Size always matters! But it seems in this case 2 is better than 1.

In your case, I would say yes.

 I would echo what Kenny said on all points. If you have the space for it, 2- 2000's make more sense. I have an install running a pair of them on a really high load, well over 1MMbtu/hour under some circumstances. They handle it very nicely being that you can pull more btu's out of a Garn than you are putting into it for a short period of time. 

My max load would be about half that. I was thinking of 1 2000, but leaving space for a second if needed. I have an are of approx 16ft x 32ft. But need to allow for a back up system, water storage and electrical panels. Do you rely solely on the Garn? I appreciate you can add electrical elements. But otherwise I will need something elkse.

 If it were me, I would give a single 2000 a shot also. The firing rate will be more than sufficient but the big thing a second one would do is double the amount of time between firing. In the final analysis, the choice between on or two will prbably depend on you choice of heat emmitter for the shop. A low temp system, such as in floor radiant allows you to take full advantage of the temp swing between firing. If you use a system that requires high temp (150*+) such as typical forced air, you narrow up the temp band you can operate in by a substantial amount. That in turn demands more frequent firing.

The complicating issue is that the DoA has a grant, Vol 74 No 99. Apps in by end of July. So we have to be specific rather than suck it and see. But I am thinking that one plus back up will be the way to go.