# One Year Anniversary with Garn 1500...Reflections



## bpirger (Nov 21, 2011)

Nov. 17th was the first year anniversary with our Garn 1500.  I thought I'd throw together a few thoughts and observations, sort of a mini review.  It's been over a year since I burned a drop of oil.  I'm heating 2500 sq ft. R19/R38 insulation, all in-concrete radiant, outside Ithaca, NY.  DHW is provided with an indirect 52 gallon tank plumbed as a secondary loop.  The Garn is plumbed as a secondary system through a plate HX with the Garn water.  


We've used the Garn everyday, including all summer, for heat and/or DHW.   During the summer we burned every third or fourth day.   During the peak heating, we burn everyday.  In the peak coldest days, it can be a bit rough to make DHW early in the morning before a fire is started.  A 2000 gallon tank would likely have prevented this concern, and frankly, for the extra $2K, it would have been worth having the 2000.  I'd go bigger if doing it again.  Adding up all Garn, copper, HX, buried pipe (microflex 1.25"), pumps, controls, etc. I have well over $20K into the project.  10% more for 25% extra storage....I'd recommend it.  That said, my first year was using some less than ideal buried pex....not the microflex.  So hopefully things will improve with this switch over.

The Garn is extremely easy to operate.  Probably 80% of the fires were started by my wife.  Typically a bit of cardboard or paper and some kindling, turn on the blower, ignite the paper/cardboard (we use a propane benzomatic), close the door, and in a few minutes load on the wood...then walk away.  It really couldn't be easier.  One of our big concerns with the Garn and "all out burns" was having to start a fire every day.  It isn't a problem, as the forced air blower just sets it ablaze almost always without any fuss.  


Efficient?  I have not yet weighed my wood and measured my temperature differentials to determine an efficiency.  Last year we burned about 1.3 cords per month during the peak heating season.  All the mess is outside and this is the first year I haven't burned a woodstove in my home since 1991.  I thought I'd miss the fire, but I really didn't.  But warm radiant floors are extremely nice!  We certainly don't miss the mess!  I purchased one of the 32 channel USB temp sensor systems...but have yet to hook it all up.  It takes MANY, MANY hours to get everything setup and installed, especially when you are a plumbing newbie and doing everything alone.


Gasification.  One bummer about the Garn is not being able to see/hear the gassification flame.  Typically within 10-15 minutes of starting a fire, the smoke is gone.  There's some learning curve, how to place the wood, keeping a chunk at the front of the fire (or using a firebrick) to distribute some of the air coming in the bottom "port" around, etc.  Usually in my 1500, one load of wood will bring us up about 50-55 degrees.  Typically we will fire up to 190F.  It is best not to exceed 190 so as to minimize the breakdown of the water chemistry.

Chemistry.  The Garn is an open system and as such the water chemistry must be monitored and controlled. Part of the Garn package is lifetime water testing by Precision Chemical in WI.  Every 6 months a water sample is acquired from the Garn (dipping in the manhole) and sent off.  Initial water is tested, then initial chemical is supplied.  My second test was "fine", requiring no chemicals.  However, my Mg anode rod was completely consumed and had to be replaced.  I believe this is because of a stray ground related to my initial wiring, which has been modified when the second rod was installed, so time will tell.   Looking inside the tank after one year, I do not see signs of rusting of the pipes or Garn tank.  The water is crystal clear.  The HX pipes are coated with a white material, appearing somewhat uniform everywhere.  Far as I can tell, all is good.  Hopefully the anode rod will remain!


I added about 250 gallons after about 10 months of operation.  Water will evaporate through the manhole.  Presumably I should have added 150 gallons after 6 months.  I assume this is normal.


Besides for the anode rod, I have not had to do any work or replace anything on the Garn.  It is built like a tank, simple, and no fancy control electronics.  The new controller from Garn is a digital controller which operates very nicely I'm told, mine is still sitting on the workbench waiting it's place in the queue.  I had a touch of "smoke" exiting between the rear horizontal chimney ring and the garn tank wall.  I sealed this with high temp silicon and aluminium tape and have seen nothing further.  


I did clean the HX today after 1 year of burning.  The first tube on the left (4") produced about 1 cup of fine soot.  There was no significant build up that I could see.   The second 4" pipe (bottom right) produced about 3/4 cup of fine soot.  The 4" pipe with the blower motor attached produced more material, approximately 2 cups of "flakier" soot.  I wouldn't call it creosote looking, but I suspect it is, though it was more like "corn flakes" of soot as it came out of the pipe.  the final 5" pipe out the flu produced about 1.5cups of similar stuff.  It took about 1.5 hours to clean and was quite simple.  I did have to start by running to the hardware store to purchase the "smaller" fiberglass cleaning rods used with the smaller 4" and 5" brushes, compared to the 6" brush/rods I had for my woodstove.  There are two sizes of these cleaning rods?  Yep.

One has to insulate the Garn.  I set the unit on 2" of extruded polystyrene and placed fiberglass underneath the Garn between the skids.  I wrapped the unit in two layers of R-30, then built a box around the entire thing, enclosing it in approximately R-100 of fiberglass on the sides.  The rear is in about R-50 and the front is much less, more like R-13.  It is not trivial to frame in and insulated the front face of the Garn.  Doing it again, I'd place more polystyrene on the bottom.  Spray foam would be great, but Dectra (who builds the Garn) doesn't give the A-OK as they have no long term experience with it.    

So all in all, we are pleased.  I wish we had the 2000, but this isn't a big deal, just would be a touch more convienient for DHW first thing in the morning.  No problems, no complaints.  Great for those with radiant who need low temps.  Probably not as great for those requiring high temp all the time, i.e. baseboard or water to air.

Hope this helps someone considering a Garn.


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## Retired Engineer (Nov 21, 2011)

Hi bpirger, 

Thanks for sharing.

We are also coming up on the 1 year anniversary at the end of Dec. Our 2000 is supplying heat and hot water at my son's house next door (H2O to air) and our 2000 sq ft shop ( in floor) and soon (I hope) our house.  No oil at the son's house or propane at the shop this year. Still working on the staple up and pluming in my house. It will be a primary secondary system with combo of home grown and Tekmar controls.

Still need to clean, check water chemistry and anodes and finish adding sheetrock on front of garn.

So far we are quite satisfied with the 2000 as it does more the the old OWB with much less wood.  Still need to get further ahead with dryer wood.

Tom


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## Kemer (Nov 21, 2011)

Hey Bruce

Can you tell me how much wood you put in a load? I don't seem to get a 50-55* rise like you.Mine is more like 25-30*.I don't cram in the wood. It's more like about 60-70% full.Have you ever measured your stack temp yet? 

Harry


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## Gasifier (Nov 21, 2011)

Glad to hear the Garn is working out well for you bpirger! Nothing like heating everything with wood. What type of outbuilding do you have it in? Is it a garage or a building specifically for the Garn? What type of wood do you generally burn? How long is the wood you burn season for? Thanks for sharing. Had a cooler night up here on the St. Lawrence river last night. 22 Degrees on the back porch. I still have the same amount of oil I had October 1st. Cool.  :coolsmile:


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## bpirger (Nov 21, 2011)

Hi Harry:  A 50-55 degree load would be essentially a full firebox with hardwood.  My wood was split this past spring...so it is probably borderline dry enough.  Mostly ash and soft maple, though some oak, cherry, etc.

Nope, I haven't hooked up the new controller, so I haven't measured my stack temp yet at all....Ah, too many projects.  About 75% of the way towards getting the old poorly insulated pex out of the system too boot!

Seems to consistenly get a 50-55 degree rise with that full load.  My pieces are abour 23" long....but lately I've been stacking them until I can fit no more.  I think that is NOT what we did last heating season, but we did do this all summer when burning the spruce for DHW.  Will have to watch the smoke in the exhaust and make sure there isn't any....might have to back off the load size.

But it sounds like I'm putting in 40% more wood, so that's likely the difference....


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## bpirger (Nov 21, 2011)

I had built a 24x16 shed a few years earlier that was mostly storage/junk....had to get the stuff out of the house when we moved in.  The never ending saga when you do everything youself.  I cut out the floor and dug down a little and backfilled with stone and then poured a lot of concrete to make a solid floor for the Garn, as well as a real foundation.  The shed was just sitting on blocks, sitting on the shale rock around here.  I put an overhead door on the thing so I have easy access to get wood in...I think it will work out nicely.  I can stack about 1.5 cord of wood, enough for over a month, along the 24' wall of the building.  I don't have it insulated or sealed yet...another project.  BUt I buried the Garn in fiberglass inside it's box.

I'm in the middle of 44 acres of woods, so there's lots of wood.  Mostly red maple, ash, red oak, some cherry, pine, beech etc.  This weekend I brought in maybe two cords of beech and a red maple that had broken about 30' up.  Everything just takes time!  This wood is for next year.  The majority of the wood for this season I brought in during the Spring, so it is dry enough, but not as dry as I'd like it to be.  There's a lot of work in getting ahead, and with the addition and all the other projects, and life, only so much gets done.  But I've been focusing on trying to get in wood for next year and letting the addition sit...waiting for insulation and rock.  Also getting the plumbing set up so I can heat that floor too!  

I too have the tekmar controls in the house...I really like them.


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## Kemer (Nov 21, 2011)

Bruce
How long are your burns when you pack it full? I usually go about 3.5 hrs.on two loads and then I get the 50-60*.I wonder if I would do better with one burn (less electric).I to am getting wood for next year.I have a lot of standing dead and cut them up in 10' lengths.Then I use my grapple bucket on my cat rubber track skid steer to bring them to my staging area I made three sided boxes out of pallet's and use my forks to get them to the Garn.I try not to handle them anymore then I have to.


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## bpirger (Nov 21, 2011)

I'd say the "full load" is gone in 2.5-3 hours...time for fan to be turned off....with just a handful of coals left.  The last half hour will reduce a huge bed of coals to just a few, typically gaining about 5-8 more degrees it seeems....


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