Jeff Watt

No winter got busy and I never ended up building anything. Maybe next year

Anne Miller wrote:So the patio will help cool the concrete slab aka thermal mass?

My house has a small front patio about 50 feet by 5 ft.  I have not noticed it changing the temperature of the slab much.I have an unheated room at the back half of the house and the slab will keep the room at 60 degrees no matter how cold the temps get.

Not quite, the slab should be charged up to probably no more than 70 degrees to keep the house 68 or so. So if its a sunny day and the house is already warm and the slab is already at temp the hot water solar panels cant send any more heat to the slab without just overheating the house. The house will likely already be gaining heat due to the solar gain from the south glass without the floor in the equation.

This is where the secondary thermal mass comes in aka a big water tank in the basement how big, I am not sure? 500 gallons maybe? Not really sure how to size that. But for examples sake lets say the tank is 500 gallons. If that tank is already at whatever maximum design temp is lets say 140-160 degrees and the sun is still shining and the hot water solar collectors are still collecting heat this is where you would "dump" heat to the outdoor patio slab just to bleed some off and not overheat the system. Heat may also need to be dumped in the summer when the only load is domestic hot water and there are a lot more sunny days. Probably some of the collectors might be able to be shut down in the summer to avoid this problem some. In the winter the issue I forsee is in sizing the system big enough to take advantage of the minimal sun there may be times where there is too much heat. I believe a dump zone is common in these types of systems.

Anne Miller wrote:My first though is that you have not mentioned passive solar for cooling.

Jeff said, There will be a poured patio outside so that could become a dump zone if I needed to get rid of excess heat.

How does this get rid of excess heat?

Sorry miscommunication I didn't mean to cool the house but rather to cool the thermal battery. By this I mean, if I oversize a hydronic solar array, on a sunny day I can not overcharge the floor slab as the house will overheat, I want to build an extra large water storage tank as a secondary thermal battery to store the excess heat, in the event of many warm sunny days in a row where the water battery is also "full" ie as hot as I would want to let it get I could "dump" excess heat to the outdoor concrete slab.

I am in the planning stages of a small(ish) well insulated home build. The house will basically be a modified A-frame, technically it will be an extra tall gambrel on 4 foot knee walls so that I can have counters and furniture up against walls that are 90 degrees. Footprint of 24×36′ Full ICF basement as well as the two long 4′ knee walls and the rear 24′ knee wall. Building will be south facing and the south gable wall will be primarily glass. The first floor deck I believe I am going to do with an ICF decking system so it will be poured concrete with a ton of thermal mass I believe around 14 yards of concrete or roughly 56,000lbs. There will be an open loft in the back with half wall front (south) half will be open cathedral ceiling. Open floor plan, I believe I will do a spiral staircase roughly centered that goes from basement to loft continuous.  Insulation will be r-49 Minimum in walls and (hot) roof.
Ok now that you have the gist of the build a couple questions.

Am I crazy to do radiant heat with 20′ high cathedral ceilings? I will have some ceiling fans of course to circulate heat down but will I be making heat at the floor and losing it to the ceiling or will this work out fine?

I would really like to add hydronic solar for the radiant but house is already going to be passive solar, so on days where the sun is shining in winter (I am in Vermont and there are less of those sunny days than we would like but its always cold) Anyway, on days the sun is out I really should not be heating the slab at all, the house with all the glass should really heat well on its own. Could I way oversize a basement water storage tank to use as additional thermal battery? There will be a poured patio outside so that could become a dump zone if I needed to get rid of excess heat.

If this is a solid plan how would you size the solar array?

craig howard wrote:If you add some mass to it, there is less chance of burning the syrup.
The most critical time is right near when it's done.

I don’t finish in the pan. I get it close as I dare and then let it cool down and drain the pan and bring it inside where I finish on the stovetop with full control. This is one advantage to the current non rocket stove set up. I can let the level in the pan get a little high and load the stove up and call it a night about an hour early knowing it will continue to boil down some while I sleep. Then in the morning I drain it into a bucket and bring it into the stove. I have gotten pretty good at knowing just where to leave it to find it where I want it in the morning. As I am generally only ever doing batches of 1-2 gallons (finished) at a time this works fine for me.

The J and L hybrid idea is interesting. I’ll have to give that some thought.

The clapboards do have a tendency to collapse into a huge pile of coals even in the normal stove this can be an issue. But they burn fast and hot and I can get them free and dry. I think a dual stove set up might allow me to clean one out while keeping the boil going. I don’t really see feeding two stoves as that big of a challenge as they will be literally feet from each other. If one end of the pan is boiling more vigorously than the other that’s not an issue for me as I don’t have baffles in the pan and I don’t do a continuous finish process like some of the bigger operations do where they are pulling syrup from one end and adding sap to the other. I do batches.

A few years back I had my sugaring setup using a first gen prototype of a rocket stove. I actually went through a couple prototypes of this a few different seasons and then moved to a non rocket stove set up. I want to go back to a rocket stove next year and while I watch the sap steam off this year I am doing some planning in my head.

My pan is 16”x41” long. Previously I put a rocket stove at one end and a long narrow passage under it with the chimney at the far end. This caused the flames to have to move along the bottom of the pan to get to the chimney. It worked ok but I really only got a vigorous boil right above the stove and a lazy boil about 1/2 of the way down to barely a simmer if anything at the back of the pan.

I want to build the next one with two stoves. And a similar passageway under them to a chimney at the back.

Previously I used an L shaped stove, I like the idea of a J stove because it’s self feeding. However the problem is unlike a normal cook stove or rocket mass heater, this thing can run continuously for 6-8 hours or more to get through all the sap. This creates a lot of ash. I think it’s a lot easier to clean out an L stove than a J stove and I’m pretty sure that’s why I went with this design last time.

Other than having to keep poking the wood forward, is there any other real disadvantage to sticking with L stoves?

Alternatively anyone ever build or see a J stove designed with some kind of ash pit with a cleaning door? Would love to see pictures of this as that might be the best of both worlds.

I can get a nearly unlimited supply of kiln dried pine/spruce clapboards from a local mill with really high standards and plenty of cull. These make almost the perfect fuel for a large rocket stove I think.

I didn’t really know where this should fit I don’t think there’s a heating forum. Anyhow I want to create a hybrid water heating system I have a pile of old solar hot water panels, I would also like to do a wood stove hot water loop. I like the idea of thermo-siphons for their simplicity and lack of fail points especially in an outage situation. The problem obviously is that the tank needs to be up high. Practically speaking I can only put a tank so big on the second story of my house. The ideal place for a large storage tank is my basement. I had the idea of a hybrid system. What if I had a smallish tank maybe 25 gallons upstairs with a thermosiphon when this reached a specified temp say 130 degrees it could dump the the basement tank being refilled with cooler fluid from that tank. The upstairs tank can be vented to atmosphere in the event of an extended power outage or pump failure that tank can overheat all it wants. There’s many more details I could discuss but that’s the gist of the basics. Anyone ever see anything like this?

I’m in the early planning stages now but plans can be found online for basic digesters I likely won’t reinvent the wheel I’ll just use someone’s proven idea and adapt it to the materials I have on hand. I do have a couple 500 gallon poly water tanks i am currently not using, I could salvage one of those for this project. You are correct some way to stir it is essential in most designs.

Just a standard wet style methane digester. Some sort of a large chamber probably with a floating drum style storage tank.

I’ve read sawdust gums up the works in digesters as it has too much fiber. I have a pair of working steers (term for young oxen in training up to 4 years of age) they weigh about 1000lbs each right now, they make a lot of manure. I have always wanted to make a methane digesters. The problem is I bed their barn in pine/spruce sawdust I get from a local clapboard mill. It’s smaller dust than the planer shavings type stuff you get at the feed store but not tiny like what you’d get off a table saw it’s more like what you’d get off a chainsaw. Anyway it’s always mixed in with the manure. Does this make it unusable? I was thinking perhaps if added with water and stirred up before pouring in the sawdust may mostly rise to the top and could be skimmed off, but I haven’t really experimented with this at all yet. I think making this “slurry” is part of the process anyway right? What about hay as a feed stock? The area around there hay feeder gets pretty thick with a mat of manure and wasted hay. Lots of stuff talks about grass clippings but I haven’t seen hay mentioned. Hay is really just dried grass clippings…