12 hr burn cycles

[SolarAndWood]

We have found that 12 hour burn cycles work best for us during mid winter. Is this possible to do with a small boiler and still burn clean? Or are the fire boxes too small relative to the lowest clean burn rate to make a quick rake/reload possible after 12 hours?

I am thinking an 85K or even smaller unit would get rid of the LP water heater, heat the entire house in milder temps and then even out the heat in the house when both the boiler and stove are required. 1000 gallons pressurized storage, ci radiators and a superstor or similar is the current system plan.

 

[Nofossil]

One of the problems with boilers that have smaller outputs is that they have smaller fireboxes. My EKO 25 will burn about 4 or 5 hours on a full load (less if it's softwood). On the average winter day, I need 7 hours of burn time per day. That works out to the following daily routine:

1) Start the fire with a small amount of wood.
2) About 30 minutes later, refill with a partial load, depending on the temperature and the state of the storage tank
3) Return 1 to 4 hours later (depending on the wood loaded in step 2) and fill it to the gills.

I usually plan it so that step 3 happens right at bed time.

On warmish days, I'll run it longer and then skip the next day.

 

[SolarAndWood]

So, it sounds like there is no way out of starting a fire at the beginning of every burn cycle and have it eventually go out unless you fill it every 4 hours if you want to burn clean? I assume that happens with the bigger boilers as well, you just load more wood and get more heat out in the process?

 

[henfruit]

I can get 12 hour burns from my green wood 100 with the temps in the 20 to 30 range. idont storage as of yet but it would help in the shoulder seasons. i burn very clean just soot on my heat exchanger pipes. i like the load and and walk away style of it. no fans blowers to deal with.

 

[WoodNotOil]

With the storage you don't need a long burn time because once the fire is out the heat is drawn form storage. Burn time becomes less of an issue. The real issue is to figure out how many btus you need to heat your house and then size the boiler and storage accordingly. If you only want to load it once, size the output and storage so that one firebox would produce enough btus for the whole day. That would mean a larger boiler size with a bigger firebox. For instance, if NoFo had an Eko 40 137k btu as opposed to the Eko 25 85k btu, it sounds like one firebox might do it for the whole day in cold weather and allow him to skip a day in slightly warmer weather. With gassers and storage, you have to change your whole way of thinking about burn time...

 

[SolarAndWood]

I suppose I have been spoiled by the cat with the big firebox this year. I didn't know that you could do so little fire tending and get so much heat out of it. I like the small boiler strategy because of the lower initial cost and spending more time putting heat directly into the space. It would seem that I will just have to get used to the idea of having kindling around.

 

[DaveBP]

WoodNotOil

With the storage you don’t need a long burn time because once the fire is out the heat is drawn form storage. Burn time becomes less of an issue. The real issue is to figure out how many btus you need to heat your house and then size the boiler and storage accordingly. If you only want to load it once, size the output and storage so that one firebox would produce enough btus for the whole day. That would mean a larger boiler size with a bigger firebox. For instance, if NoFo had an Eko 40 137k btu as opposed to the Eko 25 85k btu, it sounds like one firebox might do it for the whole day in cold weather and allow him to skip a day in slightly warmer weather. With gassers and storage, you have to change your whole way of thinking about burn time…

This concept has been stated many times on this forum. But this particular paragraph states is about as clearly as I can imagine.

Could be its own sticky.

 

[SolarAndWood]

In an ideal world, I would prefer to burn 24/7 and just use storage to smooth out the bumps and for off season dhw. However, I have no interest in loading a firebox 6 times a day especially in the middle of the night.

 

[ISeeDeadBTUs]

But, to be fair, if you (or someone of gentler constitution) have to start a fire twice a day, that could easily be a factor in deciding to not go the gasser/storage route. I know my wife is comfortable adding wood the the GW if she needs to on occasion. But would she routinely want to come home and start a fire? Nope! Nor would I for that matter. I like the convience of reload and walk away.

 

[SolarAndWood]

Is the cost of that convenience a gunked up stack? What percentage of the time are you idling?

 

[ISeeDeadBTUs]

My stack (8" all the way) does not 'gunk up'. Iget some very fine fly ash in there, but no creosote in the insulated part. I get minor creosote in the uninsulated.

No question in my mind that, if you are not going to do storage, you need to be obsessive about how you load. But it's still gonna idle some, which makes it less efficient than storage. It's a trade-off.

 

[ihookem]

I need to fill my Eko 25 four times per day in most days. I get up and reload at 6:30, leave for work and my son gets home at 3:30 and puts a few logs in. I get home at 5:00 and put some more in. Then at 9:30PM I load it for the night, set it at 160 degrees and in the morning there is enough coals that I don't have to relight. I can get away with 3 loads if it's about 30 degrees and calm for a high. If it's low of 20 and high of 40 I can set it at 160 degrees and load it twice a day. I don't see too much of a problem but wish I would have spent the extra 500 dollars and get an Eko 40 for somewhat longer burn times for when we are all gone all day.

 

[Fred61]

My burn cycle is similar to Nofossil's. My 500 gallon un-pressurized storage came on-line at the beginning of this heating season. Now, after doing extensive rework and insulating on my 1000 sq. ft. ranch My burn schedule is a dream come true.

I have one fire per day which lasts about six hours. In the afternoon about three or four o:clock I start the fire with about six or eight small splits (4 or 5 inch- about 1/4 to 1/3 full) start the fire with a propane torch, when stack temp. is about 400 °F I close the by-pass damper and let her go for about 45 minutes at which point I go down and add wood. If the outside temps are cold or if the radiant floors are calling for heat, I fill it up. If outside temps. are about normal (15 to 20 degrees) I'll put in a little less wood.

By bed time the fire is burned out, top of tank is about 182 to 185 degrees and I shut off the master switch on the boiler control. I've not had an overnight fire in the boiler this heating season.

 

[SolarAndWood]

Thanks guys. I have no illusions that a small boiler is going to keep up with demand when its cold out. Maybe the 12 hour burn cycles in the stove that my wife is happy to participate in given how easy it is combined with a boiler burn whenever I get home in the evening is the right compromise. It achieves my goals of ridding ourselves completely of propane, evening out the heat in the house, reducing the amount of wood moving through the living room and most importantly only processing one wood size. Unless I can special order an 300K btu boiler sized firebox with the clean burn rate of a 60K...

 

[ihookem]

Fred, that is a dream. I don't think you will burn 2 cords of wood that way. I don't have storage but you are making me think twice. I have somewhat of a different appoach since I have no storage. I run the boiler hard after work for 5 hours or so it gets the house temp up to about 70 and before bed I load the boiler, lower the thermostat to 66. Around 2o am the house calls for heat. I know this is 4 hrs of idling but when I load up at 6:30 am there is usually wood left if it's 10 degrees or so. Last week it was low of 30 and I didn't load the boiler at 9:30 Pm. My point is I kind of use my house as storage. I sometimes let the house get up to 72. The wife like it too. This is the only thing I can do to keep the efficiency of the boiler up. How much is 500 gal. of storage? My stove is outside 120' from the house and want the storage inside.

 

[Fred61]

Fred, that is a dream. I don't think you will burn 2 cords of wood that way. I don't have storage but you are making me think twice. I have somewhat of a different appoach since I have no storage. I run the boiler hard after work for 5 hours or so it gets the house temp up to about 70 and before bed I load the boiler, lower the thermostat to 66. Around 2o am the house calls for heat. I know this is 4 hrs of idling but when I load up at 6:30 am there is usually wood left if it's 10 degrees or so. Last week it was low of 30 and I didn't load the boiler at 9:30 Pm. My point is I kind of use my house as storage. I sometimes let the house get up to 72. The wife like it too. This is the only thing I can do to keep the efficiency of the boiler up. How much is 500 gal. of storage? My stove is outside 120' from the house and want the storage inside.

I know what you're saying about using the house for storage. I also do! After rework on this place, the floors ended up about 2 1/4 inches thick so you can guess that my response time is slow. Luckily the house is insulated well enough so that when the thermostats call for heat at 69 °F the air temp. in the house doesn't drop any further before the floor heats up. I think I could have a problem if the house leaked more. Anyway, once the house temp is satisfied at 70 °F the zones won't call for heat for another two or three hours. So if my zones are calling in the afternoon, which they usually are on the typically dark (not sunny) days we've been having this year, my thermostats will be satisfied and won't call for heat 'till some time in the wee hours of the morning. They will live on the residual heat stored in the plywood, ceramic tile and brazilian cherry which have a high enough spscific heat to sustain the space for that long.

Cost? I didn't keep good records! Probably 1600 bucks. You may or may not recall from postings last spring that I'm the guy that is bucking the conventional way of constructing a non pressurized storage tank by using a 500 gallon oil tank with one end cut off and coating the inside with high temperature epoxy. After this heating season is over I plan on opening it up to see how well it did. I did see some foreign stuff suspended in the sight glass but when I drained it into a small container there wasn't enough of it to determine what it was. I am loosing about a half inch off the water level per month but I assume it is escaping as vapor out through the snorkel that is vented through the sill to the outside.

 

[henfruit]

Fred you are only heating a1000 sq. feet. what is your heat loss load?

 

[Como]

Every Boiler manufactuer bar one recommends storage, if for no other reason that stratification.

If you want small constant burn then wood chip or pellets would be the way to go, otherwise batch burn and store.

There was a guy who had a house pupose designed for Passive Solar near where I used to live, he had a large trumbell? wall south facing that abosrbed the suns heat duing the day and released it at night

He had a thermostat affixed as a joke, a joke which he had not shared with then GF.

He was away and she could not get it to turn up so called a plumber....

 

[Fred61]

Fred you are only heating a1000 sq. feet. what is your heat loss load?

Dunno! What ever it was when I bought the place, it about half that now.

This was supposed to be my retirement home. You know, little place, low maintenence but I've been working on it since I moved here 6 years ago. Since it's a ranch you can do anything with it. I've pulled out walls re-done the kitchen and bathroom as well a replaced all the windows.I must have too much time on my hands. Keep thinking of all these wild things. When I re-built the rooms, I added 1 1/2 inch isocyanurate to the outside walls under the sheetrock and this past summer I tore off the roof, I mean trusses and all and changed the pitch to accomodate the addition of a full length front porch and mud room. While I was there I blew in 16 inches of cellulose insulation. I installed the staple-up radiant a couple years ago but in my little mudroom addition, I installed in-floor tubing immediately below the cement board and ceramic tile. Boy is that nice!

 

[SolarAndWood]

Every Boiler manufactuer bar one recommends storage, if for no other reason that stratification.

If you want small constant burn then wood chip or pellets would be the way to go, otherwise batch burn and store.

There was a guy who had a house pupose designed for Passive Solar near where I used to live, he had a large trumbell? wall south facing that abosrbed the suns heat duing the day and released it at night

He had a thermostat affixed as a joke, a joke which he had not shared with then GF.

He was away and she could not get it to turn up so called a plumber....

That's pretty funny. While I did put the vast majority of the windows on the south/ssw walls and designed the overhangs to shade during the summer, I eliminated the trombe wall deciding that firewood is a lot more reliable than the sun on any given day here.

I have no problem with storage and accept the burn cycle of a load of wood. I would just prefer for the fire to never go out and put the heat directly into the living space whenever possible without having to load 6 times a day.

 

[pybyr]

I find that my EBW 150 Econonoburn is pretty easy to start as long as I simply take one of my firewood logs and whack it into about half a dozen pieces for kindling. That and the NoFossil starting method almost always get it to go in one try, in under 10 minutes (often under 5) in anything other than warm rainy weather, when my chimney is much less enthusiastic. In the warm rainy weather, if I toss some pinecones or small pine scarp over the nozzle, it's still usually a quick sure bet.

Have you given up your prior thoughts of a Garn? With one of those, you might not get a 12 hour burn, but I'll bet you can get more than 12 hours between burns.

 

[pybyr]

Every Boiler manufactuer bar one recommends storage, if for no other reason that stratification.

If you want small constant burn then wood chip or pellets would be the way to go, otherwise batch burn and store.

There was a guy who had a house pupose designed for Passive Solar near where I used to live, he had a large trumbell? wall south facing that abosrbed the suns heat duing the day and released it at night

He had a thermostat affixed as a joke, a joke which he had not shared with then GF.

He was away and she could not get it to turn up so called a plumber....

I know a fellow who is an assistant City Engineer who has had his crews install placebo thermostats for fussy employees, and has had them thank him for how much more comfortable their offices are afterwards....

 

[SolarAndWood]

Have you given up your prior thoughts of a Garn? With one of those, you might not get a 12 hour burn, but I'll bet you can get more than 12 hours between burns.

I would have to cut a good size hole in the house to get it in and replace an interior load bearing block wall with a piece of steel to make it work. Not sure it is worth it over a small boiler and some used propane tanks that will fit through the windows on the lower level.

 

[henfruit]

If leave my greenwood alone and let it burn out,i can open the door 2 days later and dig up coals enough to get a fire going in no time. If i had storage iwould maybe need one good fire a day. Now to get storage.

 

[ISeeDeadBTUs]

Every Boiler manufactuer bar one recommends storage, if for no other reason that stratification.

If you want small constant burn then wood chip or pellets would be the way to go, otherwise batch burn and store.

There was a guy who had a house pupose designed for Passive Solar near where I used to live, he had a large trumbell? wall south facing that abosrbed the suns heat duing the day and released it at night

He had a thermostat affixed as a joke, a joke which he had not shared with then GF.

He was away and she could not get it to turn up so called a plumber....

Let us guess . . . the plumber came and laid pipe and the GF no longer lives in the house with the toy 'stat?? :coolhmm:

I think I know the answer to this, but . .who's the manufacturer that doesn't recommend storage?