Phil Holbrook

F Styles wrote:

this is amazing information. do you think my water tank diagram design will work then? how much copper do you have in the "firebox" how hot does you firebox get and is your system open or closed system? my diagram to heat water is a concept i would like to add and the copper will be about 10' long inside the exhaust duct 220 degrees at one end and 180 at the other end and circulating up inside a tank outside of a mass bench. should i keep the copper line there or should i move it closer to the heat?

I can't tell just how your tank is situated but I think as long as it is higher than the heat source it will circulate by itself, hot water rise and cooler water sink back to the stove. But I'm just sure that 10' of copper tube is not enough nor the temp hot enough where it is. I think you're enough of a do it your self guy to put that tubing where it's way hotter and test it to see what it does. I've got 20' right in the fire, but like I said, I'm going to change it next summer to an open system to be safer, thanks to the warnings on this forum. Last winter I did for the first time have the temp/pressure relief valve spit a little when it got too hot, so I would run some hot water down the drain to cool it off. This winter I'm watching it closer to make sure the water tank doesn't get that hot. I've got to check out this 'flashing to steam' talked about here. I'm pretty sure that is what is causing the snapping and popping I hear when getting the stove too hot too fast, but it never hurt anything, so I would welcome anyone explaining it better.

I have never made a diagram here. I'll have to have someone show me how. But my system is simple. The 20' of 1/2" copper tubing in the fire in the stove and then piped up stairs to the electric hot water heater, which never comes on in the winter, and returns from the water heater to the other end of the tubing at the stove, one line to the top and and one to the bottom of the water heater. At my hangar I've got an open system. I think 50' of 1/2" OD copper tubing in the fire of the stove circulating to a 30 gal. tank sitting on the stove, the top cut off of the water tank. Then 60' of tubing coiled in the hot water and circulating through the slab floor. I use pumps here for faster water flow. A couple times we've had the whole tank boiling away and splashing overboard. Usually the water in that tank is about 140 f while the heat is being sent to the floor. So I'm pretty happy with that setup.

But I'm a little jealous of your stove, which is like what i've got in mind to make next using firebrick. I like the long burns you're getting and it sounds like it is burning pretty clean and using the heat for the house instead of the great outdoors like most stoves. I'd love to cut my wood use in half too. Or better than that? Haha.

I live in Alaska with temps in winter usually down to minus 50 or 60. I've been heating water with a wood stove in my house for 40 years now and usually have plenty of free hot water all winter. I have about 20 feet of 1/2" OD copper tubing right in the fire box and it circulates to the hot water heater upstairs. No pump, it circulates by itself, but if I start the fire from cold I have to not get it hot real fast or it pops and snaps till it gets to circulating, then it doesn't matter how hot the stove gets, it just makes the water go faster and heat the tank sooner. So I am sure you need more copper tubing and in a hotter place to get enough hot water. I know about all the warnings about the dangers and plan to change things nest summer, but don't consider it an emergency now after 40 years.
That brings me to my other system I have in my airplane repair shop which is a stove made of a 30" x 42" pipe with if I remember right 50 feet of tubing and it circulates to an open 30 gal. tank sitting on top of the stove. Another 60 feet of tubing is in that tank and circulates to the tubing in the concrete floor. I'm out of time now, have to leave. But want to say a little more about it later.

I know, one more guy butting in with an opinion. But I believe that compressing 3" down to 1" will lower the R value but will be more than 1" puffed up. So if you stuff insulation in a 3" gap like inside a pipe around your heat riser it will be more insulated compared with 3" puffed up even though it will be less than the if the whole amount stuffed in was left loose. And your wire I'd say you either have the wrong kind or are winding it too tight. Some soft iron wire will be easy to wind on and not break.

Anyway Bacon, you're doing a very good job and i've been closely following this whole thread with interest. Keep up the good work.

Aryln, thanks for the update. I always wish more people would give results of their new builds after using them a while such as how much wood and amount of heat put out compared with the old stove. I want to build an 8" batch stove next spring or summer and it's good to hear that they put out more heat than a regular metal stove. I am in interior Alaska and can't afford to mess around when it comes to heating the house.

Thanks Mike, that would have been my best guess but it always bugged me cuz I wasn't sure, so now I know.

I've got a simple question, I'm not sure what a face cord is. 4x4xstove length or 4x8xstove length. Or something else?

I would love to cut down my firewood by 50%. I live in interior Alaska and burn about 7-8 full cords (4x4x8) per winter in a steel Earth stove.