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[Mr. Maple]

 Had a salesman in this morning, took me around to  existing customers of his. He told me my problem with the present boiler(Empyre 450) is too small a water jacket to keep up with demand. We are feeding heat to two farmhouses, running two different directions from the boiler. He likened it to a family function, big pot of stew on the stove , running low, just add a bit of water, and some scraps and you can continue serving, versus small pot of stew, run out and have to start from scratch. It makes sense to me, not sure how much our Taco pumps pump through per hour, he said the damper would cycle a lot less, burning less fuel with a larger water jacket. On the flip side of the coin,from what I have read a smaller water jacket heats up faster, but will it be able to keep up as well once the demand is put there from two houses?
Thanks for your help

[Jwood]

That does sound like a salesman, a boiler compared to a pot of stew is one I've never heard till now 

[slimjim]

Sounds like somebody has been partaking before 4:20 to me, more water does not create more heat period.

[1ELVIS]

Maybe he was talking about more water for his 4:20 instrument.

[slimjim]

Seriously guys, think of extra water storage like a larger battery on your old truck, if the alternator does not put out enough amperage to carry the load, then the larger battery does no good, the extra water is for when you have more heat than you can presently use and it is stored in the battery/tank

[MattyNH]

Less water is more efficient. Quicker recovery time, less burn time..No brainer..It takes less energy to heat  50 gallons of water than heating 100 gallons..As long at the boiler is sized up to heat whatever you desire..Should not be a problem..

[mlappin]

Less water is more efficient. Quicker recovery time, less burn time..No brainer..It takes less energy to heat  50 gallons of water than heating 100 gallons..As long at the boiler is sized up to heat whatever you desire..Should not be a problem..

Don't tell Garn that.

You'll have shorter burn times with less water but more of them. With less water you also don't have near as much leeway to refill the with wood either if you should be detained by overtime at work or whatever.

[MattyNH]

Less water is more efficient. Quicker recovery time, less burn time..No brainer..It takes less energy to heat  50 gallons of water than heating 100 gallons..As long at the boiler is sized up to heat whatever you desire..Should not be a problem..

Don't tell Garn that.

You'll have shorter burn times with less water but more of them. With less water you also don't have near as much leeway to refill the with wood either if you should be detained by overtime at work or whatever.

That fine..Ill call my neighbor to fill it... ..I think everyone that owns a OWB, when running has a plan or who to call to fill the boiler....People call me..

[ijon]

I am curious about not having the bigger water storage. Seems like I will have to watch how much wood there is in the stove so it won't go out.

[yoderheating]

Slim is so right on the money, more water doesn't equal more heat output.
 More water will help with
-less burn cycles (if for some reason you want that).
-the ability to have multiple heating systems come on at once without "shocking" the system and causing water temps to drop quickly.
What more water capacity will not help with is
-more total heat output.
-more efficiency ( unless you are using a system like Garn that uses a different burn time concept then traditional outdoor furnaces).
 If your problem is that the furnace can not keep up with demand increased water capacity does little to help. What would do you a lot more good is a furnace with a larger firebox. This would do two things, increase the amount of BTU's the furnace could generate and also increase the amount of BTU's that could be absorbed into the water jacket.
 In other words a firebox has a certain amount of sq inches of space to exchange heat into a water jacket. Increasing the amount of water around the same size of firebox doesn't increase that exchange rate. Adding water doesn't make the fire burn hotter or the heat to move more quickly from the firebox to the water jacket. A bigger firebox does both. Of course a bigger firebox would need a larger water jacket to work properly.
 In the example given by the salesman he says its like a pot of stew. Add water and serve more people? But in the end you are serving a poorer product because there is less actual nutrition. Its actually a fairly good analogy of why his theory is wrong. More water doesn't make better stew or a better furnace.
 I would seriously consider not buying anything from a salesman who knows so little about how a furnace operates. There is no possible way water can increase BTU's, storage just doesn't do that (unless we are talking huge amounts that is heated during the day when demand is low). I would highly recommend finding a local dealer who understands how these systems work. If you don't I'm afraid you may waste more money. Good luck 

[dukethebeagle]

what do you think about thermal storage tanks then.
some places on the net rave at the benifits of stoage tank saying it adds bulk to your system
you still need so many gallons to heat a certain amount of space.
if not,wouldn`t the boiler yoyo when heat is required.
i always thought more water meant less up and down and a more even running system

[slimjim]

You are right Duke! Thermal storage is more like a big buffering tank, it stabilizes the load but it still takes lots of heat to get the tank hot and then there is the added load of heat loss at the tank. Storage tanks work well for batch burning or where there is a very large load all of a sudden like in a greenhouse application where the stove is dormant all day and as soon as the sun goes down you need everything that the stove can provide, this is where the tank can be used to store heat during day allowing the stove to stay hot by dumping the heat into the tank

[yoderheating]

I completely agree with Slim (as always)! There is a time and place for large storage. The problems that a normal situation involving an outdoor furnace is the heat loss and the refiring of the furnace after all the stored heat is used. On a normal outdoor furnace hooked to a home the large storage isn't necessary and would just be a nuisance. Greenhouses, dairy barns, some commercial buildings ect are examples where heat load may fluctuate greatly and heat storage may be beneficial.

[woodbutcher]

All I can tell you is that my system has 400 gal. of water. I'm heating house and basement and a 1500 sq.ft. shop. When the house calls for heat, I loose 12 degrees in temperature as the heat is pulled out of the water on the way back to the boiler. Now if the water in the boiler is running at 175 degrees it don't pull the boiler water down 12 degrees. I watched the boiler temp. and only lost 2 degrees after about 5 minutes of heat being pulled out of the water. It takes a lot of a long time to cool down before the boiler kicks in. Everybody has there onion on more or less water in the boiler jacket. I have a buddy who believes less is better, but he is always refilling with more wood because he is using up the smaller amount of water. He does have a quicker recovery time but is refilling more often. Let's try this. Put 2 identical pots on the stove, one with 1 qt. of water and the other with 3 qt. of water heat to almost a boil. Turn off the burner and leave pot on hot burner. Which one will cool down quicker. The air temp. pulling the heat out of the water, and the burner being the heat source. It takes longer for the 3 qt. pot to cool down than the 1 qt. Everybody has there onion on which is better. Small water jacket or large. I prefer the larger jacket.     

[slimjim]

But the part you are missing is the added fuel it takes to heat the 3 quart pan vs the one quart pan and the added heat loss from the surface area of the larger pan, believe me there are places where extra thermal storage is a good idea, huge amounts of water surrounding a wood fire is not one of those