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Posted By gfirkus,
Aug 8, 2016 at 8:36 PM
I'm hoping to fire mine up this weekend for the first time. I can't wait!
So, how'd it go??!!
Actually was a week late firing it up. So just did it this past weekend. First burn took about the same as you; 5 hours and 3 wheelbarrow loads of wood to get to 220. Heating my house and all my DHW using wood is awesome! This thing really works.
My second burn I did last night. The water temp was down to 170°F, so I only needed a half load of wood. It came up to temp quickly (even quicker than the first burn). And heated up to 215°F nicely. I did have to adjust the water level in the expansion tank a little as the pressure was creeping up and weeping some out the blow off valve. But a little bit drained out and we were good to go.
I am also impressed at the smoothness of his setup. I know Gary was reluctant to go to the electronic controls at first. But just like his stoves, he seems to have things worked out quite well. My brother bought a boiler from him about 2 years ago and has the old mechanical controls. While they work, the electronic controls seem much smoother.
I was also impressed how well the boiler held the heat over the night. Even 12 hours after the burn was finished, the temp of the water never budged. The coals left from the burn must keep heating the water overnight. Even 24 hours later, I had a few coals to start the next fire with. Throw in a couple pieces of cardboard, load it up with wood, hit the start button and the thing takes off. You don't have to touch a thing! I can't wait to get home tonight to do it again!
Good to hear another successful wood burning story.
What's your minimum temperature before you need to fire? 170°F seems really high to need a fire.
With my Garn I top out and 170° and go down to 110° ish.
The Garn is unpressurised so maybe that's the difference in temp ranges.
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220°F is the highest I want to see it. It can be pushed to 230°F max, but aiming for 220°F allows for some overshoot. This is a pressurized system. So that 220°F is at 25psi.
I could probably go another day and let it drop down to 110°F, but then I would need a longer burn time on my next burn. I am a creature of habit and like get into a system of doing a small burn everyday. That is my plan anyway.
My minimum temp is around 115°F as that is where the aquastat shuts off the wood boiler and switches over to my backup propane boiler. My radiant floor heat uses water at 90-110°F temps.
Does your efficiency go down as temperature goes up? On my unit after 160 the last 10 degrees takes forever to achieve 170. I can go from 110 to 160 in about 2hr 15 minutes.
I totally understand habits. We had a warm week and I can home and made fire....Well it was almost 80° in the barn(where we are living during our remodel....The wife was not haply.
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I would drop those temps some. Sounds like you're working with a 50° swing (170-220), I would put that swing down to more like 140-190. Or even lower if your low end is 115. I started out charging my storage fairly high - now I don't usually go much past 180. Don't fire until I need to - usually 130-140 on top. Would also depend on your emitters - I have Slantfin baseboard, oversized a bit. The higher the boiler temps, the lower the efficiency - although I don't know if it's enough of a difference to worry about. I also like more of an overshoot cushion to the overheat zone.
The written rule in the world of energy efficiency is to work with the lowest temperatures your system can tolerate whether it is wood, fossil, solar or any other way of making heat. The lower the temperature the lower the loss. Not only that, the last 20 degrees come at a huge expense in that the boiler has more trouble absorbing the BTUs being made. To raise the temperature from 200 to 220 it takes a much larger amount of wood percentage wise than it does to raise the temperature from 180 to 200.
Over the course of the winter it could cost you a cord +.
Gary told me to take temp up to 205 to 210 on every fire and wait till temp gets down to 140 ish with 120 being the lowest. I agree it seems to take longer above 170 to raise temp. I like to run the temp up because I get more time out of storage. I've been going 2 days between fires most of the winter . With temps in the 30's now I can stretch it to 3 days.
With the garn I like the 145/175 routine, 90 lbs wood 2000gal 30 deg rise
Did he give a reason as to why? If running it up that extra 20° or so will get you another day before having to burn again, I could certainly understand that, I think. Otherwise, getting that extra amount of heat in the tank will cost on the wood consumption end. I would love to have more storage to be able to skip more days.
That's what I seemed to observe after a year or two here, supported by what I had also read - but everyones setups & preferences are different, so it still comes down to doing how you prefer.
Sure sounds like a good unit though.
I'm sure I asked and he told me but I can't remember the reason for sure. I think it has to do with stack temp and not leaving any unburned wood at shutdown. Everything (except high temp shutoff - aquastat) is controlled by the stack temp through the control box. Fan speed, primary-secondary- side air doors. When stack temp hits 210 fan and all air doors shut down. If water temp is at 180 it it absorbs more btus thus lower stack temps as it burns down and could leave some wood unburned. At least I think that's how it works?? I've only been online with this unit for 3 months. I'm sure there is a bit more to learn about it.
So I decided to keep track of temp and time tonight. Top of boiler temp was at 130 when I started a fire. 1-1/2 hrs in it was up to 175. I reloaded (a little too much) and 2-1/2 more hrs it was up to 220 and shut down. When I fire I usually turn on my bsmt floor loop and it will take another 1 or so. Tonight I left it off. 1400 gal was raised 90 deg in 4 hrs. How does that compare to other systems?
Based on your numbers, 1400x8.34=11,676btu/degree raised.
11676x90 deg raised=1,050,840 total btu into storage.
1050840/4hrs= a firing rate 262,700 btu/hr.
Next time weigh your wood so we can determine in the future how many lbs you will need to load to get to a desired storage temp.
thats the overall firing rate from start to finish, does gary offer a firing rate for this boiler, 350kbtu?
It would still make me very nervous to run the water temps up to 220 with pex pipe in your system. Could be disastrous if it fails.
Yes, I think I'll stick with my earlier thoughts on the high temps.
Do I dare ask what such a machine costs? His shop is within driving distance to me, maybe 2 hrs.
Give Gary a call and he can go over pricing with you for different sizes. Even if it is to much, you should still go to his shop and see the one he has running. You might change your mind.
Or make a feeble attempt to build one. Thanks
I was thinking they were priced comparable to a Garn, but don't really know. Think Garns start at around $11k for the Jr?
When I checked in 15' it was a tick over $13,000 for a garn from my local dealer. Mine was under that but I had to get it to wisco. To build a similar boiler is do-able, but the controls is the ticket to get right. I'm 5 days between burns right now for heating DHW. 5 person house hold. I absolutely love it. FYI - this was a 3-4 year research and $ save for me, but I wanted the best. I also added a boiler room before I bought. I plan on staying at this house for a great while. ( as long as I keep the wife happy, that's the key)
I don't know if the Switzer uses refractory or not but from my experience refractory will wear a lot more at 200+F than it does running at 185F max.