Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: hondaracer2oo4 on November 14, 2013, 07:50:05 PM
-
I have a Hardy H4 which is 120 gallons. I was thinking of adding a 50 gallon hot water tank in the loop to add extra capacity to the system. Anyone think it is worth it?
-
Nope, wastimng time and money
That stove was designed for the capacity it already has
If you start adding capacities your system wasn't designed for, complications can quickly arise
For example if you take a boiler designed to operate on 80 gallon and then triple it, it's idle times will increase and could result in a nasty firebox if it doesn't get hot enough to clean itself, there is many reasons not to
-
Scott,
I respect your opinion but I differ in my thought process. Yes the stove is designed to heat so much water around the firebox, thats why the firebox differs in size with different water capacities in boilers. If you have a 300 gallon boiler the firebox will be much larger than on the 100 gallon version. Also you said that longer idle times will lead to more creosote build up but with a larger water store it will take longer to reheat the water which means longer burn times which means hotter more efficient burns. Just like how you guys don't set the differential on the aquastat at 5, you set it at 15-20 to get longer, hotter, more efficient burns. What do you think?
-
Scott,
I respect your opinion but I differ in my thought process. Yes the stove is designed to heat so much water around the firebox, thats why the firebox differs in size with different water capacities in boilers. If you have a 300 gallon boiler the firebox will be much larger than on the 100 gallon version. Also you said that longer idle times will lead to more creosote build up but with a larger water store it will take longer to reheat the water which means longer burn times which means hotter more efficient burns. Just like how you guys don't set the differential on the aquastat at 5, you set it at 15-20 to get longer, hotter, more efficient burns. What do you think?
thats why I said id it doesnt get hot enough to clean itself, due to various other factors like wood quality or moisture content
adding more water etc doesnt change your personal btu requirements, in batch burn units where they have huge capacities of water all wood is consumed in one maybe 2 fires per day
ive heated my home on stoves that held as little as 30 gallons of water and some that held 265, if simply adding more water was the answer they'd be doing it from the manufscturer because that would be cheap to do
look at emyre gasser units, a stove rated at 400k btu and 8000 sq ft holds 115 gallons
there commercial boilers are 2.5 million btu per hour and yet only hold 3-400 gallon.
Ive been meaning to ask you about your spray foam pipes? How I s that woekkng so far and are you concerned with gas depletion in the foam and water logging??
-
I understand that my btu needs would not change, but my available btus would change dramatically because it would take much longer to bring the water down to the point that the boiler would have to refire again to bring the temp back up. Longer, hotter fires are more efficient right? The way that I see it is that the boiler manufacturers can't just make a larger water tank because the water tank has to be proportional to the size of the fire box to work correctly right? Can't put 1000 gallons of water around a 25 cubic foot firebox, not enough heat transfer area to gallons of water.
As far as the spray foam goes I have no complaints. The spray foam is closed cell spray foam, not open so it can't become water logged. No way for water to get into it. Not sure what you mean by gas depletion, do you mean breaking down over time? I will let you know it 10 years how it worked out. On year 3 now.
-
I understand that my btu needs would not change, but my available btus would change dramatically because it would take much longer to bring the water down to the point that the boiler would have to refire again to bring the temp back up. Longer, hotter fires are more efficient right? The way that I see it is that the boiler manufacturers can't just make a larger water tank because the water tank has to be proportional to the size of the fire box to work correctly right? Can't put 1000 gallons of water around a 25 cubic foot firebox, not enough heat transfer area to gallons of water.
As far as the spray foam goes I have no complaints. The spray foam is closed cell spray foam, not open so it can't become water logged. No way for water to get into it. Not sure what you mean by gas depletion, do you mean breaking down over time? I will let you know it 10 years how it worked out. On year 3 now.
yea by all means try it and see how it does, u may potentially gain something with a cleaner burn, whether its enough to notice I dont know
reason I asked about pipe was ive seen folks do it with closed cell spray foamand ovrr time performance declined, the gas in the bubbles themselves were breaking doown and allowing it to take water. Logstor has a gas membrane in there pipe because they experienced it too. Ive posted pics a few times of thermopex taking on water like crazy when it wasn't supposed to be able to
I was curious how long u have had yours andnif you've noticed any decline in efficiency
-
Scott,
Only time will tell on the spray foam. Right now I lose 1-2 degrees over the 200 foot run and this is year 3. I found it to be more only viable option because I needed to run 2 one inch feed lines each way to keep my Delta T where it needed to be. If I can find a 50 gallon water heater for cheap to free I will give it a try and report back.
-
Sounds good
-
Less water is more efficient..Less burn time, quicker recovery..My boiler holds 59 gallons of water and rated for up to 5000sq ft..I guess I don't understand why would you want that extra capacity when i assume your boiler itself can clearly heat your house and what ever..Do what you what ever want..But I think your wasting your time and dollars
-
im not sure about gassers but these onld conventionals there may (i say may cause i dont know) be something said for more water? more water would mean a longer burn to re heat it, this means less ON/OFF of the blower and this means less smoldering (when heat is leaving the stack as smoke ((unburnt gas)) so lets say you have 20 stops and starts with less water and only 15 stops and starts with more water with teh exact same amount of wood....would this in fact mean you captured more of the usable btus in the larger water tank or not?
jsut a question that maybe some one in the know could answer?
-
In my experiance the only times that extra water capacity is needed is when you have a huge BTU draw all of a sudden after a long period of dormancy such as a greenhouse that sits idle all day because the sun is out and then when the sun goes down you need everything that the boiler can give you and more, this is a good time to have a couple thousand gallons of storage on the system #1 to put a load on the boiler during the day to keep the boiler hot and then when you have that huge demand you can draw from it until the boiler is up to temp.
-
slim i was not saying it is a good thing (or bad) i was just pondering if less stops and starts would mean more btu' captured as we all know that when the blower quits there is a lot of unburnt gas goes out the stack and also when the blower first starts there is a lot of btu go out the stack before the fire is hot enough to burn those first gasses that were created?
perhaps lessstos and starts are not as good for the furnace, i dont know it was just a point to maybe get foks thinking and post their own take on it
-
I have an additional 330 gallons hooked to my P and M 250. Why, because it was already there.
There is no benefit as far as I can see, my boiler runs for a little in the morning and a little in the afternoon at 40 outside. I suppose it might run a more often if I take it offline and I will try it this weekend and let you know.
-
Yea Willie, there are so many variables there and it's up to those much smarter than I to figure out which direction is better, I can tell you that like in the greenhouse situation that I am describing,water storage definately helps, on a home that has a fairly steady heat load, i'm not sure if the cost of storage is worthwhile, 50 gallons aint gonna make a hill of beans
-
Coolidge, I would love to find out if you bypassed the storage system if you saw a difference? Slim I know as far as mass storage goes that 50 gallons really isn't much. I was looking at the angle of the fact my current system has 120. If I increase that to 170 it is a 45% increase in capacity. But maybe it wouldn't make a difference. I just think that every time my boiler fires it takes 5 minutes or so to get it back to a roaring fire, before that the fan just pushes smoldering gasses and heat out of the boiler.
-
Hondaracer, I'm not saying that the extra 50 gallons wont help at all but I doubt that you will see a difference, what I do think would make a difference is adding thermal mass inside the firebox in the form of firebrick, it will help to insulate the fire from the water jacket to keep the coal bed hot, does this not sound more like what you want to accomplish? For those on here that don't like firebrick, all you have to do is look at our chip boiler with brick added and then without, it is auger fed at variable speed with a measured amount of fuel, the brick added keeps the pot hot enough to relight the chips far longer and it burns much cleaner with added brick.
-
Hondaracer, I'm not saying that the extra 50 gallons wont help at all but I doubt that you will see a difference, what I do think would make a difference is adding thermal mass inside the firebox in the form of firebrick, it will help to insulate the fire from the water jacket to keep the coal bed hot, does this not sound more like what you want to accomplish? For those on here that don't like firebrick, all you have to do is look at our chip boiler with brick added and then without, it is auger fed at variable speed with a measured amount of fuel, the brick added keeps the pot hot enough to relight the chips far longer and it burns much cleaner with added brick.
Slim if you add firebrick to most of these conventional boilers and it insulates the fire from water jacket where is it supposed to pull its heat from? I understand fully how it works but without heat fire tubes it could actually hurt the performance
-
I have never understood the fascination by some with extra water storage. On 99% of systems it is not needed or desirable. Maybe if you had a huge load kick in at one time it would help but in all other cases its a waste of time. Why store a bunch of heat when it isn't needed? I keep me heat stored in wood because any stove worth its salt should be able to heat water faster than it can be pulled off. If your system uses heat faster than the furnace can produce it you would most likely need to get a furnace with a bigger firebox anyway.
-
Yoder,
It isn't about the fact that a stove could be able to keep up with the demand load. It is the fact that a longer hotter fire is more efficient than a short burst of fire that spends the first few minutes getting the fire back up to temp, then puts out some good heat for a few minutes and then shuts off the damper and slows back down. If you had a larger mass of water the fire wouldn't have to do these cycles as often and the fires would be more efficient. For me, I have a 24x24 water to air hx. My Delta T is about right on at 22* across the hx but I am also moving alot of water as well. My stove works pretty hard for me when its cold meaning it cycles often. When it gets real cold out, the time between firings is usually pretty short so the extra water probably wouldn't help in those circumstances but this time of year when the temps are in the 40s during the day and 20s at night I believe it would help to get a longer, more efficient burn. I am hoping coolidge will report back on what he found, his water mass is much larger than mine would be.
-
If I may chime in, I think there is a point at which a "long burn" is long enough. When my stove fires for a 15 degree drop, by the time the temp starts walking back up, that fire is raging! I think that there is a point at which the fire reaches a maximum temp or intensity and it stays that temp for the remainder of the burn. Therefore, I would think that a burn that lasts 15 degrees of water temp swing for 200 gallons is the same amount of clean as a 15 degree swing for 500 gallons. I would argue that a 30 minute burn is just as clean as a 60 minute burn. I think based on the discussions that I've read on here, that we can all agree that the fire box doesn't reach this max until longer than a 5 degree burn, but less than 20. Otherwise, we'd all be shooting for a 30 degree swing or something like that. I'm just swinging by the seat of my pants here, but that's what I was thinking.
-
I have a Hardy H4 which is 120 gallons. I was thinking of adding a 50 gallon hot water tank in the loop to add extra capacity to the system. Anyone think it is worth it?
Hondaracer, I am curious about the extra capacity idea. First off how would you go about doing it, where would you put the tank, would it require an extra pump or maybe a larger capacity pump? Oh by the way the H-4 holds 130 gallons according to the online manual, but that may be the newer ones.
-
I think your right about the 130, 120 was a typo. I planned to just place it in series with the heat exchanger. I would put the supply line in through the bottom drain and continue it out through the hot supply if the hot water tank. I would plug the cold in to the tank
-
Ok Taking the tank of the system didn't make much of a difference at all. Saturday and Sunday the boiler had a cycle 1 extra time,230 ish. I did not time it Saturday but Sunday it ran for 13 minutes, 2 minutes to full gasification, so actual "burn" time was only 11 minutes. It did not cycle again until 830 at night. I don't see the benefit. Mine was because I only had to buy two valves to hook it up and it also helps when I forget to turn the blower on.
-
Not sure how the temps were where you are but they were mild here in New Hampshire. I would be interested to know if it made a difference when the average temps were in the 30s. Interestingly enough maybe it wouldn't be worth putting in the extra capacity.
-
It was warm, I am just over the border from you in Maine.Where abouts in NH?
-
Canterbury, about 10 minutes away from the Nascar track. Where are you?
-
Canterbury, about 10 minutes away from the Nascar track. Where are you?
Im right next to you..Alton here..
-
Matty, Yeah short ride over to Alton from here.
-
About three hours from you in Maine, been through your area more than once.
-
You must be far north up the border?
-
Matty, Yeah short ride over to Alton from here.
Yup it is!