For all you Garn owners, what range do you like to keep your tank temperature in? For me the sweet spot seems to be a low of 140 and a high of 180. With the temperature tipping below zero lately I have been keeping it on the high side of that but otherwise that seems to work. I am burning one and a half to two full loads per day to keep my 3500 square-foot well insulated house and 800 square-foot shop at 70 to 72°. What works for you?
Garn 2000 Tank temperature range
- Thread starter mynx
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eauzonedan
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I shoot for the 180 area at the top. I don’t think you would break anything if you went another 5 or 10 however. I’m just conservative. Bottom is driven by whatever the emitters need. I cook dhw and that needs 140+ so that’s where I recharge. I also have some panel rads and they like similar temps to really perform. If I only had the Warmboard and in slab I would be happy to run it down another 25 degrees. There is a lot of stratification in the tank so be sure to consider that and don’t assume the controler is any kind of average. Dan
Thanks Dan. It sounds like we have similar systems. I heat my DHW and have euro radiators, a large panel, and some in floor radiant. Probably similar climate as well…
My tank temperature depends a lot on the weather. In the summer I run down to 120 and up to 180 when I recharge. I have exchanger's in LP furnaces so when it gets real cold like last week it would take two loads a day to keep the house at 74 degree's and I would run the water temp 150-190. This week we have been usually warm for Jan and one load a day and 140-180 has been the range. Back when I was still working in town we normally worked 12-14 hours a day so when it was real cold I would have the burns end closer to 200 so I had more time between the next burn. When we get extended cold period and I am working in the shop a lot it takes three full loads a day to stay warm.
It would kill me to have to burn three loads a day! I had to spend all my life cutting firewood! By the way, what length logs do you all burn? I burn the 16 inch logs last year Add it was a pain handling those small logs so frequently. This year I cut to 20 inches and that seems like a nice balance of efficiency but not too heavy
I don't do a lot of the bucking after a couple shoulder surgery's I don't run the saws much. I have a couple buddy's that we exchange some hunting rights for some wood cutting time. I usually burn 10-15 cord a year of good hard wood mostly hedge and locust. I am burning load right now that has some mulberry, elm and ash mixed in. My splitter and processor is set up to do 24 inch and under. I would say average is around 18-20 inch . We come right off the processor or splitter right into trailers that mostly hold three to four cord. Wood seasons in the trailer in sheds. Cuts down on handling . Trailer gets backed up to Garn barn in a pole shed and then unloaded right into the Garn. I have six trailers so I have more than a years supply on trailers. Probably have three years supply of hedge logs on the ground brushed out right now. We did a lot of logging and cleaning up the pasture last summer after spraying and then later after harvest.
Temps can vary a lot from top of the tank to the bottom. TCaldwell, used 4 probes to measure temp down the front of the unit. I think its made by Johnson controls, it takes an average. I installed a Mcmaster Carr 1142k31 oil level sight where the mechanical thermometer used to be in the front of the garn above the door. I marked it with with a sharpie when the boiler was full of water heated to 120 degrees. My controller might read 170-180 top of the tank but If I see the water level is close to the "cold" mark I fire the boiler.
My filter circulator only runs when the garn is burning so my tank stratifies considerably. I try to stay in the 140-185 range unless we are going down to single digits. I only heat house with two zones of baseboard. DHW is on Heat Pump water tank.
My filter circulator only runs when the garn is burning so my tank stratifies considerably. I try to stay in the 140-185 range unless we are going down to single digits. I only heat house with two zones of baseboard. DHW is on Heat Pump water tank.
I am curious what made you decide to only run the circulator on the filter when you are burning. I have been running mine 24/7 since I put the filter on after the first cracked weld leak. I guess I should redo that statement to say 24/7 when it wasn't down for the second leak repair. I do think it helps stratifies the tank temp. I do have my circulator switch mounted on the control panel for the timer so I could change it to burn only very easy.
I to run it continuously. The current draw is so small on the pump that I don’t see a downside. After shoveling out several buckets of crap out of the bottom of the tank, I am taking every precaution I can…
I bought my Garn 2000 used (9 years ). I heated the unit up to 130 (on the controller) to check for leaks (before finishing enclosure), I used an infrared thermometer to see the temperature variation from the bottom of the tank. bottom of unit was 80 or 90 degrees when top of tank is 130.
Since I don't heat domestic hot water, and I run my system completely open (no heat exchanger) I can run lower temp water through my baseboard utilizing Tekmar 256 outdoor reset. It really helps get more mileage out of a fire in the shoulder seasons. If air temp is 45, Tekmar may only call for mixing temp 110-115 degrees. I can go 2 or 2.5 days between full load of wood. My circulators run almost continuously and the house is more comfortable because you don't get those temp spikes with 180 or 190 degree water running through baseboard. The whole house just feels warm, not hot/cold as system cycles on and off.
Since heat rises, it just made sense not to continuously mix the cold water (bottom of tank) to the top 1/3 where my system pulls the heat from. (I piped mine with the supply from the top of tank. )
Depending on how complex the filter piping circuit is, the pump probably does 10-15 gpm through the filter, If you have a 2 hour burn time, that is 1200 of the 2000 gallon tank. Every other day the entire system goes through the filter. My system inside is piped with close t's so the oil boiler sits cold. I also have BoilerMag magnetic filter installed on the heating circut, so if either zone is calling it passes through it. After a year of running there was just a little residue in the BoilerMag.
I think eliminating the adnode rods, following the new installation manual with electrical isolation, dielectric unions, etc and biannual water testing eliminates the corrosion factor. (I'm only 3 years in with a 13 year old garn. )
I do run the filter circuit for a week before I fire the boiler for the season, just so I can get a good water sample for Precision Chem.
After first heating season I had to open manway cover to add more chemicals I looked inside with a LED spotlight and everything looked the same as it did since I filled it.
I can understand that. Its not the electrical draw I worry about. Its the heat loss from constantly mixing the cold water from the bottom of the unit to the top (where the supply is piped). less heat loss = less time cutting wood
I bought my unit used and had to deal with a similar problem cleaning up the mess the junk annode rods left behind.
I run through a heat exchanger at the house so I do need higher temps. I have hydronic radiators and each radiator has a thermostatically controlled valve so my house stays very evenly heated. I range from a low of 70 on cold windy days to 74 or 75 when it’s sunny. People might ask why I keep it so warm and that’s to maintain the thermal mass in the house for when it does get really cold. There are days when the wind blows a steady 40 miles an hour with the air temperature in the single digits. If I kept the house at 70 it would dip into the mid 60s and take a long time to come back up. I am on track to burn about 12 cords of wood – real cords - this season. I am heating about 5000 ft.² of space. As a nice bonus, while I do have a dedicated heat circuit into my shop, since it is adjacent to the room where my garden is, just by leaving the door open my shop stairs a study 64° with no supplemental heat. When I had the shop done last winter, I had our 30 foam put in the walls and are 60 in the ceiling. Even with an 8 ft insulated door Garage door and an uninsulated unheated slab that stays nice and toasty. My unit is semi electrically isolated. I still need to do dielectric unions on the pot plumbing
