OK good! I'd rather spend money on something else. Anyone know of. Place to buy large heat exchangers? I am burning 3 pallets right now with some green wood and am almost able to watch the temp rise. Feeling like the wood is a major factor.
I was thinking like a 250 gallon propane tank sized tank to circulate hot water into to add an extra 250 gallons of hot water to heat. Once you had it warm it wouldn't circulate the water as much to cool it slower. May not work but it could help if you can get it hot enough at first.
I don't have to heat any green houses thru the entire winter but I do have 1 that is 25x 100 that we start roses in that needs heat in the early spring till warm weather. When I recover a green house I always use double 6 mil with air inflation. Not sure the extra thickness is any difference but who knows? It looks from your pic that you have a concrete floor in your GH? All out GH's are gravel floors which seem to act better as a heat sink when using forced air for heating. One suggestion I would make is to looking into putting pex on your existing floor and a skim coat of gyp crete over that and use your boiler to heat that water to get better heat down low where you need it. I would want to talk to a person with some real time experience before I did so just to justify the cost but there has to be a large commercial grower who has tried it. I,m sure you know as well as I do that blowing hot air into an uninsulated plastic tube is an exercise in futility when in a cold climate.
the heat exchangers are good, you are dumping all the heat that the thing is making. perhaps too much and it cools the system down to where it loses efficiency. IF you are getting down to 110 going back into the boiler then there is no problem dumping the heat. if anything you may be underpumped, but i cant imagine that with 44gpm, even with 1" lines. are you sure that is correct? (that is a small line and will be hard on the pump, btw) can you slow the heat exchanger fans down? this will allow you to maintain a higher system temp which may be where your sweet spot is. storage wont help you if you are currently burning full out and not getting enough heat. i havent crunched any numbers, just throwing out ideas that may or may not help. how is the insulation on the lines between boiler and greenhouse? you can lose incredible ammounts of heat to the ground. the buble wrap stuff most OWB dealers push is chit. so where are you measuring your temps? compare boiler temp to heat exchanger in and out temps. splitting green wood isnt going to make much of a difference if you cant give it time to dry. need seasoned! when we are not splitting around here we like to beat that dead horse to keep in shape! did you compare portage and main boilers at all when you researching before settling on the CB? the downdraft P&M's are quite nice. CB dealers blow enough smoke before thier boilers are even lit...
Just be sure if you have the time in the summer too buy a semi load and have it all cut split and stacked out in the sun and wind to dry at the very least a whole summer. Try to get a couple years ahead if at all possible. Otherwise buying dried wood inn the winter is expensive and can be very sketchy with people not being honest our just not knowing that seasoned wood doesn't mean it's been drying for a week. And now that i have a splitter i split anything over 6inches inn half abd bigger pieces i split even more its all about the surface area to dry faster. Spitting wood for it to only dry for a week especially in the winter is a waste of time.
Yeah I plan on being seasons ahead on wood. This is my setup. Wood in barn south end of barn (roughly 30x60 feet) to the ceiling with truck path left open down center lane after it seasons first summer outside. I will probably buy split seasoned this summer to add to what I am cutting myself. I know it's best left in the sun and wind but if I put the seasoned dry stuff in the barn right away and then have an outside pile I move in to the barn before winter. It will be nice doing all the loading and unloading out of the wind and snow. All that junk in the corner is going to the dump.
Hydro - I feel you pain. I have 4 - 30 x 100' greenhouses. Can't offer you much advice about the boiler heating thing, but we saved a lot of money in heating bills by heavily insulating the north side of the greenhouse with rigid foam boards and the south sides with clear bubble wrap material. How tall are your sidewalls? We only heat our houses minimally in the winter - just above freezing, but we have totally different crops...
I might have missed it but how well are your PEX lines insulated between the boiler and the heat exchangers? To me it sounds like you've got a major wood problem, i.e. you're using just as many BTU's (trying to burn) burning the green wood as it is putting into the water.
I have zero experience with boilers or greenhouses, but I'm wondering whether you've got the water circulating too fast. The wet wood is unquestionably a big problem, but part of the reason it's a problem is that the water in the wood depresses combustion temperatures so that much of the combustible stuff that wood is made of goes out the stack as unburnt smoke instead of burning inside the firebox and heating the water. Burning wet wood is going to suck no matter what, but if you've got the water circulating through so quickly that the boiler can't maintain a healthy water temperature then you're cooling the firebox and depressing combustion temps even further, so that even less of the fuel actually burns. What I'm suggesting is that slowing down the water circulation to the point that the boiler can maintain a healthy water temp might improve combustion and decrease waste.
The HTX's are doubled up on one squirrel cage blower - any reason for this? Are both htx's plumbed on their own circuits? or are they series? When you had the propane furnaces running (I assume they were forced air) did you use poly tubes to distribute the heat from the furnaces? I'm wondering if you aren't losing a bunch of heat in the distribution hoses and moving them closer to the furnace with poly tubes to distribute the heat wouldn't help.
Pex lines are insulated and dry from boiler. I am going to insulate north and south walls of greenhouse when next winter comes. Didn't have funds for much past what i have invested already for this year. (Divorce sucks lol.) Greenhouse is 144x30 with 16 foot peak and 6 foot sidewalls. It's not a standard hoop. It's peaked. So the total cubic is 7713. I have fans that even out the air from top to bottom. I would poly the trusses but I have light movers and halides in the entire thing so that is out of the question.
Heat exchangers are each on own supply and return. Propane furnaces are modine forced air. But I have no propane because I gave all that money to lawyers lol. I have things happening that are catching me back up now but it is the "now" that I am in this issue. The future I will have 650k btu propane as backup
No I have 6 6500cfm circulation fans that evened the air out and helped predate the moisture problems
I honestly think it's wood coupled with small diameter coiling in the exchangers now after hashing it out with you guys. It's 3/8 Id. I want to get something along the lines of 3/4 Id coil in a 36 x24 configuration in front of 1hp blower. Something like an airplane cabin exchanger. Just go overkill. On paper this boiler should be able to keep up (per the engineer I talked to who seemed to know his stuff at steibel). He said if I can keep the water hot the more volume and faster the flow the better. It keeps the coils at temp. Doesn't cool off too much and is therefore minimal draw on boiler. Main focus this summer is better wood source and stash, better insulation and bigger exchangers / blowers. Should be good to go I would hope. I mean at a certain point it should be total overkill on parts and have no choice but to stay warm not to mention the extra 650k btus of propane as backup.
I understand budget constraints, but by doubling the htx's with the same temp water running through them your not going to heat the air any more effectively. By running poly tubes off the ductwork at varying lengths through the greenhouse you'll be able to distribute hot air more effectively and not have recirculation of air at the units you've built already(which are pretty clever). This an idea of what I'm talking about. http://www.uline.com/Product/Detail...ujziPYZG0_2wk-WyqutZMaAm6x8P8HAQ&gclsrc=aw.ds You could run one larger htx unit or use the existing units built into a duct distribution near the boiler end and then use dampers to regulate flow on each poly tube.
Heat exchangers / coolers are a funny thing. Bigger does not always transfer more heat. Faster flow does not always transfer more heat either. It's just that the heat exchange is governed by a bunch of differential equations such that the optimal answer is never obvious. I'd look into it with a bit more nuance than a "bigger is better" mentality - you might spend a lot of money without any payback if you make too many sizing assumptions.
The chart that came with my boiler suggest that wet wood has 40% the heat output of wood that has 20% moisture content. 60% of the energy in the wood is being used to boil off all that water in the wood instead of heating the water in your boiler.
