Fuel oil been Garn for a year. attn Garn owners

[Ice Cold]

I love not burning fuel oil, cutting wood, and shooting and eating Moose. Haven't burn a drop of oil in a year except when gone for vacation. Wife loves it too, she gets to buys more knock-knocks........

Here is the dilemma........... Efficiency

I've been fine tuning my timer to shut off while there is still a bed of hot charcoal in the firebox. Reason, why warm cold air with the induction fan when all the creosote is already out of the wood. It is just charcoal.

First question; Is my assumption correct? let loose boys, fire at will. Is there a risk of creosote buildup after you let all the smoke out of your wood?

It is a Garn 2000 and we try to keep it around 170 degrees during the winter because we have baseboard heat. When My wife fires the thing typically we get about a 20 degree rise out of each burn, a bit more if the themp is down farther. We are burning dry seasoned birch, no snakes in my wood. Some of it is a little punky from sitting around too long but it is dry. I know Im not getting full BTU's out of it but I would say it is about 75-80 percent good wood. To give you guys something to chew on. White birch 23.6mil btus per chord gross, I'm burning about half chord per week give or take. 5000 ft house walkout basement with 2.5 car garage. figuring about somewhere between 50k-60k btu/hr heat loss. Calculated to about roughly vaguely maybe a guess..... 1.3 mil Btu/day give or take.

Second question; What temp rise are you other Garn guys getting out of a full burn? My numbers don't seem too far out of wack but wanted to run it by you experts. I'm wondering about my efficiency and system setup.

It seems that the Garn does a great job of extracting the heat out of wood but like other storage systems the standby loss can rob efficiency if allowed to sit around. I'm trying to find the balance between burning the wood and getting the heat into my house.

I'm not the greatest about getting online but i'll try to check back in couple of days. Meanwhile I wanted to pose a couple of specific questions and get you guys started on a general discussion about extracting more efficiency out of the Garn.

Say ye?

 

[TCaldwell]

as a fellow garn owner, you have to remember that this is 25 year old technology, and respectfully still has other manufacturers cursing at its simplicity and reliability. most of your concerns are able to be isolated and controlled, its just that due to a garns size they appear as large ineffiencies. i have mostly all ci baseboard and rads, you should comfortably be able to run the supply temp to 135degf, the benefits include firing at a lower water temp, this is where the greatest effiency is attained, the most heat is extracted into storage, and you would have less stand-by loss and less waiting for the coals to die out, because you would not be firing as often.You are correct that the last 1/4 of the burn is not all that productive, due to the lack of independant primary/secondary air control you end up with too little primary air to reduce the coals fast enough,and all the secondary air is removing heat from the firebox. again less firing by running supply down will help the heatloss, also you could try reducing the timer length a little bit. standby heat loss is all about insulation or the lack of it, at the garn, trench and house piping. do you have inline thermometers at different points along the way to detect heat loss, or a ir gun. i have about the same heatload as you indicate, do you run the supply temp to 200. you could use a type k thermocouple input into a basic pid temperature controller that would shut the inducer off at a preset fluegas temp,and also close a damper on the combustion air inlet to stop the idle air convection.

 

[heaterman]

I love not burning fuel oil, cutting wood, and shooting and eating Moose. Haven't burn a drop of oil in a year except when gone for vacation. Wife loves it too, she gets to buys more knock-knocks........

Here is the dilemma........... Efficiency

I've been fine tuning my timer to shut off while there is still a bed of hot charcoal in the firebox. Reason, why warm cold air with the induction fan when all the creosote is already out of the wood. It is just charcoal.

First question; Is my assumption correct? let loose boys, fire at will. Is there a risk of creosote buildup after you let all the smoke out of your wood?

It is a Garn 2000 and we try to keep it around 170 degrees during the winter because we have baseboard heat. When My wife fires the thing typically we get about a 20 degree rise out of each burn, a bit more if the themp is down farther. We are burning dry seasoned birch, no snakes in my wood. Some of it is a little punky from sitting around too long but it is dry. I know Im not getting full BTU's out of it but I would say it is about 75-80 percent good wood. To give you guys something to chew on. White birch 23.6mil btus per chord gross, I'm burning about half chord per week give or take. 5000 ft house walkout basement with 2.5 car garage. figuring about somewhere between 50k-60k btu/hr heat loss. Calculated to about roughly vaguely maybe a guess..... 1.3 mil Btu/day give or take.

Second question; What temp rise are you other Garn guys getting out of a full burn? My numbers don't seem too far out of wack but wanted to run it by you experts. I'm wondering about my efficiency and system setup.

It seems that the Garn does a great job of extracting the heat out of wood but like other storage systems the standby loss can rob efficiency if allowed to sit around. I'm trying to find the balance between burning the wood and getting the heat into my house.

I'm not the greatest about getting online but i'll try to check back in couple of days. Meanwhile I wanted to pose a couple of specific questions and get you guys started on a general discussion about extracting more efficiency out of the Garn.

Say ye?

I encourage my customers to play with load size and timer settings to achieve and end of fire result where you will have a small bed of coals a maybe a couple larger hunks of charcoal at shut off. No harm in that as pretty much all the creosote and moisture has been extracted from the wood. You just want to avoid larger pieces of unburned wood smoldering.
I agree with what Tom said and would advise you to experiment with water temps to find the range you need to actually heat your house. Lot's of times 170-180+ is not necessary.

 

[Ice Cold]

thanks for the info Tcaldwell.

Sounds like you have your Garn dialed in. I bought the Garn for its simplicity. I previously thought about dampers, thermocouples, fine tuning the heat exchanger, etc, etc. I travel a lot for my job and my wife is chief engineer of the Garn. It has to be very user friendly and simple. Because they don't like complicated unless it is a relationship... God bless them! She has been terrific with the Garn. We upgraded from two Blaze kings (still have them and use them) and the oil boiler. Our workload has decreased about 90 percent comparing the Garn with the woodstoves. Offset of course by the need for more wood. I was under the asumption that older baseboard systems were designed for a 180 degree input and length of baseboards determined required heat delivery.

Right now it is -20 outside. I want the house warm 70 degrees warm, so we burn what it takes to keep the Garn at about 180, basing that on my previous statement about design. Maybe I'm wrong but just not sure if lower temps will get me through the night when it is this cold outside. My pumps would be running a lot more for sure.

You say you have the same heat load. what temps do you shoot for after firing? You said you have radiators, are they retrofit or were they designed into the system? and where are you located? I'm in alaska and even though it is cold we rarely get wind where I live, only when it is warmer outside

thanks heaterman

sounds like i'm barking up the right tree. Again considering the btus in the tank and how cold it is outside those values will change. if colder outside need more heat in the tank to get trough the night. We are not unlike other temperate climes, we have up and down temps from -40 to 50, those being the extremes.

thanks again guys.

another note:
I designed the plumbing in my system and wanted some rough numbers from other Garn guys to see if I'm close. Basically I just bought another pump and plumbed it into a parallel leg around the existing boiler. ran power from the honeywell do-hicky (call for heat) to a double pole aquastat on the Garn that tells which pump to kick in and isolates other side (oil boiler). Obviously, one side just sits and waits for electricity from the aquastat. used an off the shelf $15 DPDT relay to throw the thermostats to the according system. Really very simple and I'm thinking it is working out well. the boiler temp is around room temp when isolated. Used a 50 plate flat HX and 1-1/4 to move water from Garn 40feet away. I'm glad I went big on the HX and piping. Just wanting to see if my thought process was not out to lunch by asking around and getting general number from other Garn guys and girls.

Thanks again and other please chime in

 

[TCaldwell]

ice, my 80 yr old farmhouse came with ci rads, when we expanded i added ci baseboard, yes the design temps for rated effiency are high, however you can still extract sufficient heat output down to 140 deg, you might give it a try. my heatloss is comprised of 2600 sqft house, thermostats over 70deg, indirect fired hwh, 750gal gunite hot tub at 102degf, 900sqft shop with radiant in the slab, over the heating season my load averages 45/65kbtu/hr. in the summer i heat a 22kgal gunite pool with a 250kbtu/hr shell and tube, and tme dwh, i actually burn more in the summer, i live in n/w connecticut with 5500-7000 degree days

 

[Jim K in PA]

Ice - as to your first question, I shoot for the same thing as far as end of burn timing. A bed of coals is just fine after fan off. However, sometimes I (or my wife/kids) over estimate how much time is needed to finish the burn, and the fan will keep running longer than needed, heating the backyard. Next year I intend to put in a temp controller or PID to do exactly as TC stated. It will override the mechanical timer and shut off the fan. The intake damper is going in also to help reduce standby airflow, especially in windy conditions.

As to your second question, I get anywhere from a 15-30+ degree temp rise in an hour. I have repeatedly seen burn cycles where I meet or exceed the GARNs 400k+ Btuh rating. It is incredibly good at getting the most heat out of the wood. I am burning a lot of pine this year, and it works great. I load more frequently with the pine due to its lower density, but it makes good heat.

I will also concur with TC on the temp range you are working with. Granted, you are MUCH colder than where I am, but I have been experimenting with water temps and find that I can readily drop to the mid-130s and get plenty of heat out of my finned tube BB convectors. That is, when the temps are not too much below freezing. When it is really cold (single digits) and windy, I'll see how it goes this year, but I generally kept the GARN above 145-150 for those brief periods of extremes. The longer you can go between burns, the more efficient you are. Lower GARN temps also means less standby loss. Insulate that beast some more if you can.

Keep on burnin'!

 

[heaterman]

Just a tidbit of info regarding Garn controls..........I know that a new control is in the works that will take the guesswork out of cycle length. It will probably come into production mid year 2010 and will retrofit to older units. I can't say any more than that right now as there are too many details being worked out as of yet. We did some brainstorming on it at last years meeting and Martin and crew have been working on it since then. It will be sweet.

Regarding the water temp needed to heat ones home........It's all about heat loss and the emitter capacity. The outdoor temp doesn't really dictate your water temp, it's the ability of your emitters to crank out btu's at a given temp that makes the difference. Lot's of radiant floor homes in Alaska being heated with 100-110* water while the outdoor temp hovers at -40*. Heat transfer is not a function of the Garn or any other type of heating source.

 

[Jim K in PA]

Just a tidbit of info regarding Garn controls..........I know that a new control is in the works that will take the guesswork out of cycle length. It will probably come into production mid year 2010 and will retrofit to older units. I can't say any more than that right now as there are too many details being worked out as of yet. We did some brainstorming on it at last years meeting and Martin and crew have been working on it since then. It will be sweet.

:coolsmile: I will probably still modify my unit, but I look forward to seeing what they came up with. I was going to go to the annual meeting last year, but couldn't swing the time (had a conflict).

Regarding the water temp needed to heat ones home........It's all about heat loss and the emitter capacity. The outdoor temp doesn't really dictate your water temp, it's the ability of your emitters to crank out btu's at a given temp that makes the difference.

Really? Then why are outdoor reset controllers like the Tekmar products integrated into low mass condensing boilers, oil furnaces, etc.? In fact, when I was speaking with Dectra before I bought my WHS2000, it was suggested that I incorporate a mixing valve and outdoor reset control to maximize my use of storage.

Lot's of radiant floor homes in Alaska being heated with 100-110* water while the outdoor temp hovers at -40*. Heat transfer is not a function of the Garn or any other type of heating source.

Steve/Ice - if I posted something confusing, I apologize. I do agree that transfer of heat into the space is independant of the means of producing the heat. However, control of the heat source based on RATE of transfer is desirable, depending on the MEANS of transfer. Outside temps DO affect heat loss from the structure, and if you are NOT using radiant floor heating, BB emitters will have varying output based on the water temperature. My drafty farmhouse will not stay comfortable with 135 degree water in the BBs when the outside temp is 5° F and the wind is blowing, no matter how long the pump runs. For example, depending on the heat loss overnight, and the temperature of the GARN, when the setback T-stats kick back to day temps in the AM the need for output capacity from the emitters increases substantially. I need to have supply temps high enough to meet the demand, and my emitters may meet that demand with 160 degree water, but not with 140 degree water. When it is mild out obviously I can run temps much lower than when it is cold and windy. I understand that with RF you do not use setback T-stats, and the water will circulate constantly during colder periods. However, it is my understanding that the RF design temp RANGE is rather small (110-140° F ???) compared to what I can get out of my BBs. There is also substantial lag (inertia) with RF in response to rapidly changing conditions. To me, that is a great disadvantage radiant floor has relative to other emitters with the capacity for more rapid rates of heat transfer.

So, with respect to what I said in my last post, essentially what I am doing is a poor man's outside temp reset (modulation) of the GARN. Hope I did not make things more confusing, or poke anyone in the eye . . .

 

[Ice Cold]

Jim,
I agree with you. The emitters do matter. I don't have a setback thermostat, thought about it but have not made a decision yet. when its cold up here, its cold! So instead of trying to get more heat out of my emitters (BB-baseboards) to "catch up" in the morning I just leave the t-stat at 70 all the time. Because its my thought when the temp has been drawn down through the night, and the system is designed for 180 water, trying to play catch up in the morning would take a while longer with the lower temps available. I feel the way you do about infloor (IR?), its not a cure-all best solution for every situation. I think a lot of people have been told and believe it is always the best solution. I disagree because I believe it isn't optimum with setback thermometers. It takes a longer time to transfer the heat when the temp differential is lower, 180+/- vs 110+/-. Maybe with the setback t-stat I would draw slower and more temp diff would be available in the morning when the family rises.....I guess i would have to buy all the junk and find out. Not willing to do that right now because things are working quite well as is.

As far as "warmer" periods we also let the temp in the Garn decrease a bit. But we also need to keep the temps up when it is cold outside. This current cold snap started over a week ago. lows of -20 for a week are not uncommon. therefore we keep the temps up to have a higher differential. there is no substitute for raw horsepower. that is why I am a proponent of the baseboards, they deliver the heat quickly if it is available.

TCaldwell,
I just don't think I would have the horses to keep the house warm down at those low temps when it is so cold outside. I could be wrong but..... My Garn is in the garage and during the summer I get a sunburn while in the garage, but when we hit -20 even the garage gets cold. I'm speaking to the standby loss, I know I'm getting it but even it is not enough to keep the garage warm. just ask the dog (he is a wimp but I like him).

heaterman,
can't wait to see the new controls the Garn guys are coming up with. thanks for the tip, I'll be looking into it. Meanwhile what is this PID and temp controller you guys are talking about? Can someone explain it.....

All The Garn delivers as promised! I rave to all my friends and should return my investment in about a year from now. I have had it installed since Oct '08. A 2-1/2 year return would make any business man drool. Especially when these things can last longer than my back will hold out. but the exercise with gathering wood may just make my back stronger.

Now I'm going to call my senators and tell him I'm not interested. It is just too much money...........

 

[Ice Cold]

TCaldwell,
how do you figure degree days???

 

[TCaldwell]

ice, the easiest way is to google heating degree days for your area,basically using a baseline temp of 65 , and subtracting it from your average daily temp, if your average daily temp was 60 deg that would represent 5 degree days, energy companys use to calculate the next delivery date for a example.

 

[heaterman]

Regarding the water temp needed to heat ones home….....It’s all about heat loss and the emitter capacity. The outdoor temp doesn’t really dictate your water temp, it’s the ability of your emitters to crank out btu’s at a given temp that makes the difference.

Really? Then why are outdoor reset controllers like the Tekmar products integrated into low mass condensing boilers, oil furnaces, etc.? In fact, when I was speaking with Dectra before I bought my WHS2000, it was suggested that I incorporate a mixing valve and outdoor reset control to maximize my use of storage.

I see where you are going Jim and I agree with it but the point I was making is that you can have 200* water available and still not be able to heat a structure if the emitters are undersized. Heat loss does of course enter into the equation but again, if the emitters are not up to the task water temp and heat loss become secondary. Adequately sized emitters of whatever type make it possible to utilize a mixing device and outdoor reset.

BTW........poke all you want. It says in Proverbs that, "As iron sharpens iron, so one man sharpens another". I get a little "dull" once in a while and need a "stimulus package" now and again

 

[Ice Cold]

Wow, I'm over 12,000 HDD's where I live. Wish I could heat the lake next summer........ I wonder if the ga.........nah better not go there

 

[Gooserider]

My understanding of the outdoor reset theory is that while we calculate our heating loads for sizing purposes based on the coldest anticipated temps, in actual practice the REAL heating load varies with the temperature - it takes fewer BTU's from the emitters to keep the house at a given temp when it's 40 out than when it is -40... The idea of outdoor reset is that it lowers the water temp and thus the amount of heat put out by the emitters as the outside temps go up, so you continue to run the pumps the same amount, but put out fewer BTUs/hr and still balance the heat load vs. the emitter output... The other option is to cycle the pumps on and off varying amounts of time so that the emitters are always putting out the same amount of heat when emitting, but spend less time doing it...

IOW - you always want to have the heat emitters putting out the same number of BTUs/hr as the load is losing - and there are two methods of doing it -
1. Run the emitters all the time, and vary their operating temperature
2. Run the emitters at a constant temperature, and vary the operating time
One can combine the two approaches, but that just confuses the discussion so I'll keep with the purist approach and say either / or.... Outdoor reset assumes that it costs less to do option one.

Since a mod-con boiler is most efficient when it has the coldest water going through it, this helps keep the boiler temps low and allows one to burn less fuel. W/ our wood burning and storage systems, the lower the temps we can get away with at the emitters, the lower we can pull our storage temps, which increases time between burns, and again improves the efficiency when we build the next fire because of the increased benefit of charging from a lower starting temperature...

While BB does in theory need 180°F on design day, it might not in practice - Heating contractors are a lazy bunch, and would far rather do a conservative guess at the heat load and put in more emitter than is really needed as opposed to figuring an exact load and putting in just enough, then getting griped at by customers if they underestimate and have to come back later and install more... (Not that I blame them for this...) In practice, this means you can often set up for a lower emitter temp and get away with it, but only experimentation will tell you how much lower.... This is also one of the ways you can benefit if you've upgraded insulation or weathersealing since the heating system was put in - the heating load has dropped, but the heating system still has the same potential output....

Another option to consider is adding more emitter - Maybe add more BB to the existing loops if possible, or add more loops w/ Radiant floor or flat panels - thus allowing you to put out the same BTUs/hr w/ lower temperature water...

I'm not a Garn expert, but from all that I've read, it sounds to me like one the biggest efficiency boosts you have available to you right now is to figure out how to increase the storage temperature range you can use...

Gooserider

 

[Rick Stanley]

W/ our wood burning and storage systems, the lower the temps we can get away with at the emitters, the lower we can pull our storage temps, which increases time between burns, and again improves the efficiency when we build the next fire because of the increased benefit of charging from a lower starting temperature…

This is probably a dumb question, but I've asked a lot of them in here....................... If it takes twice as much wood to raise storage temps twice as far, and it will, I would think; have you really saved anything by drawing storage down twice as low? Maybe not worded the best, but see what I'm asking?

Plus, by not drawing down storage as far, you'll get hotter water to the emitters which will satisfy the thermostat quicker. It seems like from a convienience standpoint it would be best to go as long as you can between burns, but from a pure efficiancy standpoint, I don't know................

 

[heaterman]

W/ our wood burning and storage systems, the lower the temps we can get away with at the emitters, the lower we can pull our storage temps, which increases time between burns, and again improves the efficiency when we build the next fire because of the increased benefit of charging from a lower starting temperature…

This is probably a dumb question, but I've asked a lot of them in here....................... If it takes twice as much wood to raise storage temps twice as far, and it will, I would think; have you really saved anything by drawing storage down twice as low? Maybe not worded the best, but see what I'm asking?

Plus, by not drawing down storage as far, you'll get hotter water to the emitters which will satisfy the thermostat quicker. It seems like from a convienience standpoint it would be best to go as long as you can between burns, but from a pure efficiancy standpoint, I don't know................

Time spent firing plays a big part in that equation for a lot of people. Nice to have only one burn per day for all involved. There's also another side of the low water temp scenario. With your Garn, you will absolutely pick up about 4 points of efficiency firing at 110 compared to 140+. If you run water temps from say 110 to 180, the first 30* of rise will but at 87-89% efficiency.

Viessmann studied the increased rate of heat transfer at low water temps extensively and determined that you pick up 1% efficiency for every 4* below 140 during firing.

 

[Rick Stanley]

Ok, asked and answered. Even if it was dumb. I love this place

 

[loggie]

Hello,my 1250 gal switzer uses a timer for the fan,but it also has a low limit in the flue that will shut down the fan below a set flue temp. It is a little tricky to get set right but it works well. It is just a standard honeywell furnace switch.It seems it would be simple to incorporate this into a garn.I have also found the lowest water temp you can get away with the more efficient you will be.I am in the process of adding heat emission plates to my staple up radiant to get the same heat at a lower water temp.I have taken the boiler up to 220 deg but the amount of heat loss even with my well insulated boiler is much greater than at 180.

 

[Ice Cold]

Heaterman,
Who is Viessmann? Is his stuff published? Sounds interesting and I would like to take a look. I had a hunch the efficiency was better when firing at lower temps, based strictly on my observations while using the Garn.

 

[Gooserider]

Heaterman,
Who is Viessmann? Is his stuff published? Sounds interesting and I would like to take a look. I had a hunch the efficiency was better when firing at lower temps, based strictly on my observations while using the Garn.

Viessman is an EU based boiler and heating equipment maker, mostly fossil based, but also has some very slick looking gasifiers that aren't available in the US... High end stuff, w/ excellent quality and reputation... Heaterman would have to provide pointers to any of their published docs that might talk about this.

Gooserider

 

[heaterman]

Heaterman,
Who is Viessmann? Is his stuff published? Sounds interesting and I would like to take a look. I had a hunch the efficiency was better when firing at lower temps, based strictly on my observations while using the Garn.

Viessmann is a family owned boiler manufacturer from Germany that pretty much sets the standard in whatever type of boiler you would want to discuss. The reference I made to the efficiency was something I was told at a training session in WaterLoo Ontario a long time ago. One of their engineers was discussing the merits and finer point of heating systems that are designed to work with low water temps. It is probably published somewhere in their tech archives but I haven't a clue as to where.

I make a conscious effort to avoid their website as the drool always seems to short out my keyboard.

 

[Jim K in PA]

I see where you are going Jim and I agree with it but the point I was making is that you can have 200* water available and still not be able to heat a structure if the emitters are undersized. Heat loss does of course enter into the equation but again, if the emitters are not up to the task water temp and heat loss become secondary. Adequately sized emitters of whatever type make it possible to utilize a mixing device and outdoor reset.

Aha! Gotcha. You were talking about the other end of the spectrum. I have significant OVER-capacity with respect to my BB emitters, and that is what allows me to run lower temps than "designed". You are 100% correct that, within reason, an undersized emitter installation will have a hard time keeping up regardless of input water temps. I have not come across that, since most homes are piped with way more emitter capacity than necessary, at least here in the NE/Mid-Atlantic region. Plumbers usually don't like to do calculations . . .

BTW........poke all you want. It says in Proverbs that, "As iron sharpens iron, so one man sharpens another". I get a little "dull" once in a while and need a "stimulus package" now and again

:lol: Amen brother, Amen.