Picking a wood stove for a 30x36' hoop house.

[EatenByLimestone]

What's the downside/consequence if this doesn't work out as suspected?

It doesn't sound like fire code is going to be followed, so what happens if the plywood catches on fire while you're 1/4 mile away?

 

[DancingWolf]

What's the downside/consequence if this doesn't work out as suspected?

It doesn't sound like fire code is going to be followed, so what happens if the plywood catches on fire while you're 1/4 mile away?

If it catches fire? well, stuff happens. Its also unincorporated land and fire code doesn't apply. The gases shouldn't be hotter than 250F and even if they are, its got an air gap and will have some form of thin metal to cover the gap. That or I'll just use double walled pipe.

Greenhouse plastic doesn't melt easily. The wood I'm burning is actual wood, mostly cedar, some oak. The only green wood is bird berry trunk pieces and its just going to sit in its own pile until next year. Cedar is split if its large, the oak is too old and hard to split with an axe and has to be burned as rounds.

The downside is if it doesn't work as intended and doesn't keep my GH 45-55+ or even just above freezing, some plants may have freeze damage to them or die, but I'll know if its going to work / no work before then. Pereskiopsis will die just from frost, dragonfruit and plumerias don't like it either.

In the worst case scenario, I'll order a 220V electric heater ($200) and make a mini-greenhouse inside the larger one out of scrap wood and plastic. The downside to electric heating is cost, and that we have lost power in the past. The electric co-op need only screw up but one cold night to kill a lot of plants, hence why I keep my patio heater as a backup for my small greenhouse.

Attached is some of the cedar I collected up today. My only concern with cedar is that it burns really hot.

 

[bholler]

If it catches fire? well, stuff happens. Its also unincorporated land and fire code doesn't apply. The gases shouldn't be hotter than 250F and even if they are, its got an air gap and will have some form of thin metal to cover the gap. That or I'll just use double walled pipe.

Greenhouse plastic doesn't melt easily. The wood I'm burning is actual wood, mostly cedar, some oak. The only green wood is bird berry trunk pieces and its just going to sit in its own pile until next year. Cedar is split if its large, the oak is too old and hard to split with an axe and has to be burned as rounds.

The downside is if it doesn't work as intended and doesn't keep my GH 45-55+ or even just above freezing, some plants may have freeze damage to them or die, but I'll know if its going to work / no work before then. Pereskiopsis will die just from frost, dragonfruit and plumerias don't like it either.

In the worst case scenario, I'll order a 220V electric heater ($200) and make a mini-greenhouse inside the larger one out of scrap wood and plastic. The downside to electric heating is cost, and that we have lost power in the past. The electric co-op need only screw up but one cold night to kill a lot of plants, hence why I keep my patio heater as a backup for my small greenhouse.

Attached is some of the cedar I collected up today. My only concern with cedar is that it burns really hot.

Ok first off fire code applies Incorporated or not. And if you are running your exhaust at less than 250 you will have massive creosote buildup which will lead to s fire in your "chimney". That means 2000 degrees. You need to learn a whole lot more about this or you are going to burn your greenhouse down.

 

[Highbeam]

I just assumed this was a marijuana grow!

 

[SpaceBus]

I just assumed this was a marijuana grow!

Heh, you would not need nearly the heat load. Most cannabis is cold hardy, but it really needs tons of sun. Full disclosure, Afghanistan is covered in fields of the stuff, at least where adequate amounts of water exist.

 

[SpaceBus]

If I were heating a greenhouse a DIY boiler and storage would be my go to. Especially since uninsulated water storage tanks would make great radiant heaters. It's probably not too difficult to make a non pressurized water heater out of a wood stove.

 

[Ashful]

If I were heating a greenhouse a DIY boiler and storage would be my go to. Especially since uninsulated water storage tanks would make great radiant heaters. It's probably not too difficult to make a non pressurized water heater out of a wood stove.

Yeah, even an OWB could be put inside the greenhouse, eliminating most of the losses associated with OWB’s. Any boiler with storage would turn that 3x/day trip down to 1x every day or three.

 

[Seasoned Oak]

If I were heating a greenhouse a DIY boiler and storage would be my go to. Especially since uninsulated water storage tanks would make great radiant heaters. It's probably not too difficult to make a non pressurized water heater out of a wood stove.

Provided a good supply of seasoned hardwood is available. Remember he is using brush cuttings for fuel. Not exactly a treasure trove of BTUs.

 

[DancingWolf]

I don't know where every one keeps getting the idea I'm using little sticks for burning. Most of what I plan to burn is 6+ year old cedar and oak wood, larger cedar gets split as I get it and oak is too rock hard to split with an axe. I'll burn brush during the day though while I'm working.

This is just trimming from a fence I've been clearing out. My options are to burn it in brush piles, or pay to have it dumped, so it makes sense to just get a wood burner and get some useful heat from it.

 

[Ashful]

I don't know where every one keeps getting the idea I'm using little sticks for burning.

I think it was your multiple uses of the word “brush”, as in “brush piles”, in your original post. Going back and re-reading it now, I see it was just a misinterpretation of a vague statement, but you can see how that happens. No biggie.

 

[Seasoned Oak]

There is useful heat is this stuff but possibly not what an EPA stove works well with ,which is why i suggested a barrel stove. They are not too particular about the wood or if it is unsplit and has a bit too much moisture . OWB with their huge fire boxes can use it more effectively as well. Friend of mine burns stumps in his,doesn't get much heat ,but it burns. (eventually)

 

[bholler]

I don't know where every one keeps getting the idea I'm using little sticks for burning. Most of what I plan to burn is 6+ year old cedar and oak wood, larger cedar gets split as I get it and oak is too rock hard to split with an axe. I'll burn brush during the day though while I'm working.

This is just trimming from a fence I've been clearing out. My options are to burn it in brush piles, or pay to have it dumped, so it makes sense to just get a wood burner and get some useful heat from it.

What you are burning doesn't concern me that much. What worries me is the lack of concern about proper clearances

 

[SpaceBus]

Yeah, even an OWB could be put inside the greenhouse, eliminating most of the losses associated with OWB’s. Any boiler with storage would turn that 3x/day trip down to 1x every day or three.

Even just a barrel stove with a stainless steel loop with unpressurized tanks above would be great. You could naturally thermosiphon the water and then you don't need elextri

 

[DancingWolf]

Well, what clearances should I have for a straight pipe up through the ceiling then? Because I was going to just stick a piece of plywood on the top of the greenhouse, rather than the back wall, one of those ceiling chimney guards on and a piece of triple wall through it. That IS what the chimney guards are for right? To keep things from burning, not much of a guard if it doesn't.

I doubt I could afford an outdoor water boiler even if I wanted one.

 

[bholler]

Well, what clearances should I have for a straight pipe up through the ceiling then? Because I was going to just stick a piece of plywood on the top of the greenhouse, rather than the back wall, one of those ceiling chimney guards on and a piece of triple wall through it. That IS what the chimney guards are for right? To keep things from burning, not much of a guard if it doesn't.

I doubt I could afford an outdoor water boiler even if I wanted one.

Well if you are talking about using a price of chimney pipe through the roof with the required 2" clearance from it that is just fine. I was under the impression you were going to be using single wall for all of it. If going with a barrel stove that will need 36" of clearance and any single wall pipe needs 18". I don't know what guard you are referring to but if you install the chimney pip correctly that is fine

 

[Seasoned Oak]

Definitely the barrel stove, you cant get cheaper wood heat than that. Only problem is going to be short burn times. Seal it up good so you can regulate the air to get maximum fire control. I prefer the double barrel so your sending less heat up the pipe. Let us know how it works.

 

[DancingWolf]

Definitely the barrel stove, you cant get cheaper wood heat than that. Only problem is going to be short burn times. Seal it up good so you can regulate the air to get maximum fire control. I prefer the double barrel so your sending less heat up the pipe. Let us know how it works.

I had planned to make it completely air tight, gaskets, sealants, cement, line the bottom with sand and bricks, etc, cost a bit extra but I do want it to look and feel nice when its assembled. I may use a 1-2" pipe with valve to control the air flow, rather than the included vent. I can starve it out if need be.

The only thing left to get is the barrels, (80+ mile drive to Houston for those), and the stove piping. I have six feet of cheap single wall, galvanized stuff, used lightly, but I may pick up some nicer black steel stove pipe from ace hardware. The galvanized stuff apparently "doesn't last".

 

[bholler]

I had planned to make it completely air tight, gaskets, sealants, cement, line the bottom with sand and bricks, etc, cost a bit extra but I do want it to look and feel nice when its assembled. I may use a 1-2" pipe with valve to control the air flow, rather than the included vent. I can starve it out if need be.

The only thing left to get is the barrels, (80+ mile drive to Houston for those), and the stove piping. I have six feet of cheap single wall, galvanized stuff, used lightly, but I may pick up some nicer black steel stove pipe from ace hardware. The galvanized stuff apparently "doesn't last".

It can also give off really nasty fumes

 

[jetsam]

When I was in Holland, a common household appliance was a "portable" electric heaters that had brick jackets on it. You run it during the night when rates are lower, and let the hot bricks and solar gain take over during the day. Something like that would be pretty cheap to build (presumably out of a modified space heater and a pile of bricks).

The galvanized stuff apparently "doesn't last".

I put a 2' extension on the top of my flue with painted galvanized pipe, and after just 1 year the end was already rotting off. It really doesn't last.

I think if I was in your shoes I'd be building a masonry stove, but the barrel stove should work until the barrel goes. (The barrels suffer from the same problems as galvanized pipe, plus they suffer from the high temperatures.)

If this is only going to burn for a week per year, you may get years and years out of one barrel, though.

 

[Seasoned Oak]

I have a wood stove i built out of a 275 gallon oil tank. Thats a barrel stove on steroids. Too much for anything but a pole barn or a large greenhouse . I only used it a few times as it just overwhelms a smaller space quickly. Seemed to be super efficient though, didnt take a lot of wood to heat up the whole tank to high temps.

 

[Seasoned Oak]

The only thing left to get is the barrels, (80+ mile drive to Houston for those), and the stove piping.

I get mine from a lumber co . They get hydraulic fluid in em. Most places are just glad to get rid of em and give em away.

 

[Trey1979]

I just assumed this was a marijuana grow!

Me to ha ha

 

[Rickb]

It's all fun and games till your she shed burns down.

 

[SpaceBus]

I would also do my best to get as much mass as possible inside the greenhouse. I've read about several folks who just put hundreds of gallons of water in a greenhouse just to act as a thermal mass. In midler climates this is usually enough to keep it from getting too cold for the plants.

 

[DancingWolf]

Passive solutions also cost money but can be great if you have level ground to build on. A foot black granite will soak up a lot of heat but that much granite is very expensive. You can see by the picture of the greenhouse that its a strong slope at around 18" per 16' and I can't use granite unless I box it in and terrace it. The floor will be terraced into two sections due the slope. I did get the side supports on today. I need some clamps for the ends, its a used greenhouse so some parts need replacing.