Are you using the water directly or running a copper coil through the tank? This is something I’ve seen debated for safety vs effectiveness, and I’m not decided either way.
I am glad to hear 50 gal is plenty of storage, the tank as drawn holds around 200 gal but it may need to shrink as I draw things to scale.
Are you referring to the heat exchanger in my drawing? It’s meant to thermosyphon to the tank above it. So essentially it’s just an extension of the storage tank, but the pipe grid arrangement increases the surface area significantly.
Leaks are a concern. However I’ve been around water heaters and plumbing all my life, I’ve never seen a bucket-dump type event, just broken pipes, loose fittings, or rusted out tanks with pinhole leaks. A 700 gallon tank leaking is no different than a burst pipe, either way you will have 700 gallons on the floor within hours, but not instantly.
I need to ensure a) that all leaks are detectable and b) that I provide a drain path that won’t ruin the house. Something like a water heater pan with a drain hole - I use these on all my water heaters and they do work, if you plumb them correctly. I will probably pony up for a stainless water tank inside the masonry heater, since it will be difficult to service. That should eliminate corrosion issues.
I’m more concerned with the additional weight. I will need a very solid foundation for the masonry already, and adding 1500+ pounds of water to that calls for special considerations.
Chris the tarm boiler would raise 700 gallons of water from 160 to 180 with a single full burn of the fire box about two armloads of wood. That was enough heat to heat the 30x30 saltbox open concept house with 2 full floors of space for about 12 hours here in NH. When it got about -15f i would probably have to fill the boiler a 3rd time. But the water was the only thermal mass in my system.
As the the hours comment you are correct but it has been my luck that such events happen when no one is home for hours and you return to a big mess. Not saying it is inevitable it was just a risk i didn’t want to take when i had an easy alternative. If i had a full basement that wasn’t finished i wouldn’t worry about the tank there. Just my two cents.
The point i wanted to share is the thermal mass needs to equal the burn load energy of the fire box. This is the ultimate goal to burn fast and store the heat. In your case the water and stone combination will require some knowledge to size the fire box. Also is that your hot water for the summer? If so it would probably heat the house.
On i forgot to say i saw a design for a masonry heater with the water coil and a regular stone thermal mass but you could choose which way the smoke went to heat. I really liked that design as you could heat the hot water in the summer without heating the mass of the heater. They said the only down fall was you burned 2 loads of the fire box if you needed to heat both the storage tank and the room with the mass heater. But both where sized to the same burn volume of wood.
For hot water I’m planning to use PV electric to run a regular water heater, with preheat from the masonry system in winter time. I feel like during summer it’s an easy load-shed for excessive solar once batteries are charged. In winter, it won’t have as much work to do because of the preheat.
I did consider thermal solar panels, but the cost is high vs the equivalent PV panels, and electricity is more versatile once the water’s hot. Plus the necessary drainback systems and additional storage tanks etc, just too complex for me at this point with no clear advantage.
Hi ChrisKY
I linked back to your post #54 Nov 1 post.
Something there like fingernails on a chalk board to me.
I’ve slept on it.
Gone back and reviewed my four comments on this topic back in Febuary so’s not to repeat cautions, pictures, my own life stories.
You are combining too many needs to be fulfilled into one system.
And basing too much of that system on the one-concept of “rocketing” turbulence combustion.
as a do-all, for-all superior. It is not.
Here is a good Life’s rule-of-thumb to develop.
A Rule of Threes.
If a tool is made that will have more than three primary uses it will then compromise too much all needs.
There are reasons a fellow like WayneK has three different farm tractors.
I have evolved to three different primary use chainsaws.
Having a wife people hauler car/vehicle. A work commuter/light hauler rig. A hauling-towing real truck-truck. Like many fess up to having here.
Wood fueled for heat energy is the same.
You will benefit best by having three dedicated, using wood-for-fuel; use-seasonally systems.
A wood fueled dedicated cooking stove that can heat water too.
A whole house wood fueled heating system that can heat water too.
An outside summer BBQ/oven/smoker/slow cooker/pleasure fire system. It does not have to heat water directly.
Regards
Steve Unruh
I like the plan of solar PV using a storage tank as an opportunity load. I would just make both thermal loads use the same tank. If you have a mass of water you can have a heating zone thermal coil and a separate DHW coil. The last time i checked was about 15 years ago but code here was two copper walls of isolation between antifreeze and drinking water. So if the tank was full of just water you could run antifreeze in the heating loop if you wanted. I ran water in everything figuring if it got cold enough to freeze i would have long since adressed the cold house or would have much bigger problems.
But if you do solar PV in the same tank even in winter if the batteries are charged there will be days you get free heat from the panels in a common thermal mass.
Steve, I appreciate the wisdom here. I also have multiples of nearly everything… three tractors (plus the walkbehind BCS), three vehicles, two (working) chainsaws, etc. My running joke is I have to have two of everything - except a wife! She’s as good two of me, anyhow.
You’re assuming this is my do-all system but it is not. This is why I removed the cooktop function, I really don’t want to fire this thing up every time I need to cook all summer. I will probably install a separate metal wood cookstove at some point, but until then (and even then) I will have a boring propane range, like normal people. Water heating will not be reliant on this, only for preheat. Even home heating will not fully rely on this system, I will also have a mini-split for A/C which can do some supplemental heating in the spring/fall if needed.
This heater has one purpose - heating the entire house through the winter. Pizza making is a distant second, fun byproduct (and yes I’ll build a real pizza oven outdoors for summertime. Along with a grill / smoker / outdoor kitchen area).
Yes but in summer the tank would shed heat into the cold masonry. I am counting on that staying cold for passive cooling purposes.
I have a better idea, why not put a heating element straight in the masonry storage tank? then I can control it separately, still do the load-shedding in winter if I want to. Keeping a standard electric water heater (with a warranty!) is too simple to ignore. Like Steve said, we should avoid combining too many things in one system.
This morning: just started house heating fire.
Started on thumb-sized forest floor picked up dry sticks. A bit of consumer paper. With two old covers removed books on the side walls. A single chunk of corrugated box cardboard on top.
“Rocket” velosity, turbulence zoom-zoomed up to be as smoke-less as possible heating ASAP.
Get the chimney updraft flowing good.
Then the fire transitioned over to slow, slow long duration combustion with cut up furniture woods boned out of box-springs mattresses; upholstered chairs and some old tables. Screws, nails, hanging springs and hog-ringed bits of fabrics still attached.
Last night it was big solid cottonwood dry chunks/splits.
I’ve previously pictured double craft paper bagged heating with hand compacted cubes of wood shed floor chips, sawdusts and wood debris in my bulk wood stoves.
Rocket stoving is quick-use; sticks-woods; one-shots does it all. One dimensional like the Drizzer fellow. Like a Wankle engine as a do-all. Not. Never be a do-alls, for all uses.
Stupid to idealize around one dimensional fuel type/forms dependencies.
Leaving you vulnerable to manipulations, and beyond your control “market-forces”.
Grow and use your own woods. ALL forms of woods.
S.U.
Chris there are many ways to solve the same problem. If you want 2 separate tanks you would probably be better off to use coils to exchange heat between them. Seems to me getting electricity into the masonry heater would be problematic. You already have a heating coil in there. I was just saying with the tarm boiler i had a separate tank that had a separate coil for DHW and it worked very well. I was able to heat the tank with either my oil or wood boiler and today i want to build a tank that can be heated with either a boiler or electric elements but provides both hot water and heating.
To me one common tank is just easier outside of the thermal mass of the masonry heater. That is what i like about the coil in the heating path it keeps the impacts of the thermal mass out of the smoke path and separate from the Mansony heater. This is probably me having struggled with the headache of cold starting a tarm boiler. When the water jacket was below 140f that boiler was so bad i would burn the oil furnace to heat the wood boiler. In the end that made me love the idea of separate water thermal mass from the fire box. I don’t think the tank will be a problem in the heater you want i just am guessing a single larger tank outside would be more useful year around.
Did you think about solar hot air panels, aka solar furnace? You can make them yourself, so low cost. They won’t leak and ruin your shingles or anything like that. If used with a thermal mass system, like you propose, I suspect they will make a low cost, low labor, safe and efficient system.
Rindert
My plan is to use the south facing window wall to heat up the masonry directly. I can control the solar gains using curtains in the summer or overnight in winter.
Solar air panels heat up air, which is great for convection heating. However I’m trying to maximize radiant heat, and trying to heat the masonry using hot air is difficult.
Using the warm air directly could be a good supplement, maybe down the road a bit. For now I’m focusing on the core.
Chris you can get the seasonal benefits by having a roof line that will shade the windows from the high angle sunlight of summer but allow the low angle winter sunlight in. I don’t remember the equation used in passive solar design but it is based on your latitude. I am sure if you google passive solar you can quickly find it or i can look and see if i have any of those design books left. What you describe is very classic 70s passive solar with the south facing windows and the thermal mass the over heating in the summer is a well researched problem with the early designs most everything i read said the correct roof overhang is the best solution. Kind of like why old farm houses have south facing porches to keep the first floor cool in the summer
Unfortunately when i was moving back here to the farm i gave up my dream of building my own home and gave most of my books on home design to a friend who had just bought land and wanted ideas on how to build.
I would pass the hot air through a box of rocks. The rocks would have a lot of surface area to absorb and release heat from. A box of rocks can be very low cost and easy to make. Maybe black basalt road base rocks that are used by railroads.
Rindert
Ha! I know well that I come across as the moods-killer asshole.
My needs are wood stove driven whole house dehumidify ventilation.
Me; the three dogs; and at times the two foster girls will go out side in the rain walking and come back wet-wet. This morning accompanied by the three, 5 months old cats too.
Never any talk about the befits of inside house wood heating dehumidifying. Experiencing this it is the real bonus.
I figure we brought in at least 10 pounds of rain water from this morning walk about:
Mine and the girls stuff is not left outside. But brought inside to dry and warm up for the next time going outside. No cold and clammy boots, coats and hats for us!!
Wet dogs and the drying off toweling too needs to dry:
None knows, can smell, our in-house critters. High flow wood stove negative pressurizing ventilation. The wife’s scented candles (count five on the mantel - one lit):
Referring back to your question #68. There are two serpentine pipe grids in the back of my firebox. That box is two foot by two foot by two foot and is built from welded together 6 inch channel with the flanges turned out. Those flanges are boxed in and I pump air through them with a box fan. That is enough to heat most of the winter living sections of the house without the water if necessary. The steel pipe grid feeds water directly into the two storage tanks and then into the Pex. The whole system was made from obtanium so nothings tech about it. One tank is a full size Oxy bottle and the other is a hundred pound propane tank. I had a metering valve in when I first built it but that proved unnecessary so I deleted it. My water has a high calcium content and every couple of years I have to pull all the piping apart and clean it out. Not a fun job. Had to do it this year. In all these years I have never had a problem with tanks leaking or even deteriorating as far as I can tell. I keep the valve on top of the oxy tank cracked to vent in case I forget to power up the pumps and the water in the tanks gets to boiling temp. Once, years ago, I forgot to open that valve and blew one of the PEX return lines out. That was the only semi-disaster I’ve ever experienced. I guess I should mention that the hot water from the grids thermosyphons into the tanks and I pump the water from there through the floors and it returns colder to the top of the tanks. The main thing about my system is that it must be run hot. I have to refuel it about every three to four hours depending on outside temps. The smoke from the system is generally burned by secondary air into the firebox so much of the volatiles are burned that way but even very hot in the firebox, by the time the heat runs through the convoluted ducting of the smoke path, most of the heat is absorbed in the mass and the heat at the flue seldom exceeds 200f and that flue is 25 foot of 6" sch 40. It had to be brushed out two or three times in the winter or it will clog with creosote. Probably more than you needed to know.
thermal solar is really only cheaper if you DIY or design it into the house design.
honestly since you are building a new house, I would look at passive solar designs. Not joking.
App State has info including house plans. The planbook goes through some of the design aspects which will help when you go to look at other plans or talk to builders, etc. It is the first 20 pages of the ‘view the entire planbook in pdf’ link from this page (which loaded really slow for me.)
Every BTU pumped out into the open air is a waste. I have put a lot of effort into circumventing that loss. The thing about heating systems and particularly wood fired systems is that a certain amount of heat differential is required between ambient air and the flue of the heater, otherwise the smoke or other gases will not be evacuated. On the Rocket Mass heater in my greenhouse I read over 500f on the surface of the barrel. There is very little if any smoke because it is burned in the tunnel between the fuel feed port and the heat riser. Leave the heat riser at perhaps 800f, travels though ducts inside a heat storage bed filled with cob and exists the flue stack around 80f. If outside ambient gets above 50f then it will require a booster fan to pull the mostly water vapor up the stack. The colder the ambient the better it will work. Closest I have found to a zero waste system. A batch rocket would presumably perform the same but I have not run one to prove that. Under certain circumstances it is also necessary to block off some of the feed port to maintain a good draw plus the fuel has to be refed every half hour or so. Not something a person wants to have to babysit on a daily basis to heat a house.
One of these days I will show the other heater I have built for the greenhouse but it is so far untested. A brief description is a 25 gallon air compressor tank suspended inside a 44 gallon well pressure tank. Inside the compressor tank is a copper coil and between the two tanks is a water jacket. The fuel is fed though the top of the inner tank and heats the water in the jacket and thermosyphon’s up the coil into a 500 gallon open storage tank. I don’t have pictures on this computer or this description would make more sense. The only downside is that the hot smoke and gasses in the burn chamber must be directly vented outside. That’s a lot of lost BTU’s. That upsets me. Because of space limitations, capturing a least a portion of that heat is difficult. With some pictures I’m sure the braniacs here could come up with some solutions. I have to get some taken.
I think what you are ultimately looking for is called a ‘net-zero’ home. There are a few in NC. But I would also peruse what appears in Northern California that is roughly the same latitude since they changed a bunch of laws recently for new house codes that now actually require like solar and battery storage in their houses which means they will be appearing in house plans that you can buy. There may be some plans that are relatively inexpensive, but in 5 years there will be more which is probably outside your timeline, but it has been worked on for quite a while and the whole net-zero concept has been reappearing for a decade so there are plans that incorporate newer technologies and research. I personally would start there.
