Print

[hondaracer2oo4]

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?

[Scott7m]

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

[hondaracer2oo4]

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?

[Scott7m]

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??

[hondaracer2oo4]

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.

[Scott7m]

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

[hondaracer2oo4]

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.

[Scott7m]

Sounds good

[MattyNH]

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

[willieG]

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?

[slimjim]

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.

[willieG]

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

[coolidge]

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.

[slimjim]

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

[hondaracer2oo4]

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.