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Post in 'The Boiler Room - Wood Boilers and Furnaces' started by chewy, Apr 24, 2013.
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Good luck on your boiler choice. It was not hard for me. My first boiler was a gassifier that was used. It seemed like such a bargain. After burning large amounts of wood the first season and listening to the performance by the regular contributors to this site, I realized my used boiler was bogus. As a building contractor I have always liked the saying "that everybody has penty of money to do it right the second time around." After much searching on this forum, I too chose the frohling 50. It was best move I ever made. The whole conversion to boiler heat with radiant floors and forced air heat exchanger and pressurized storage is alot of work and expense. When you look at the cost of a high quality heating system over the life of the appliance,it is not a lot of extra money.The frohling is easy lighting and sure does not lack any horsepower to heat water.
Ty for the response. Would you mind telling me what gasser you had before the frohling?
I have my Effecta up and running, it does both wood and pellets.
I am thuroughly impressed so far. I have been running pellets for hot water and will switch to wood in Nov time frame
The pellet gun I have is capable of 138K and wood is 205K BTU.
The have smaller units as well.
I too looked hard at Froling P4 but was unhappy with the cost. After some research I deicded the ability to switch from one fuel to the other was a great option.
So I went with it.
Good luck in your research and decision.
From a standpoint of best stratification a vertical 1000 gallon tank would be the holy grail. Practically speaking........you'll have to make that decision based on your circumstances. I would not do it unless I poured a substantial footing under the tank and bolted it down with some serious anchors. In most installations I see using multiple tanks, that actual storage volume is not equal to the total capacity of the tanks due to the vagaries of piping and flow between the two tanks. Figure 70-75% of total volume unless you use a single tank.
On another note......in all your posts about the boiler/storage and what not, you are basically describing a Garn as it incorporates both storage and excellent burn characteristics in one package. Just slide it in place and hook it up. No additional piping, no additional controls or pumps. Very simple.
My storage tank is 1000 gal horizontal. The Tarm supplies directly to top of tank at one end aabout 6" from the top and returns from the tank at the same end about 6" up from the bottom; the tank in effect operates like a large hydraulic separator. The supply has a 24" extension into the tank. Stratification is excellent in the entire tank, supply is at about 12-14 gpm. System draws from top of tank near the middle and returns to bottom of tank by a diptube, also near the middle.
The benefit of stratification on charging is better supply of cool water to the boiler, greater delta-T, and improved efficiency in heat transfer. The benefit of stratification on system supply is realized depending on your need for hot water. If you need 160F+ water, then stratification will be especially important. If you only are supplying low temp radiant, then stratification is not very important at all, as you will need to mix down to radiant supply temperature. I supply only in-floor pex, and I supply at 100F = no need for much stratification at all in supplying the system. In addition, because I mix down, relatively hot water is being returned to the bottom of the tank, which results in mixing.
Maintaining stratification during system supply will depend on flow rate and temp of system return water. If you supply system at 180F and return is 160F, then hot water being returned to the bottom of tank will quite quickly mix the entire tank up towards 160F. On the other hand, if return is 120F, much less up mixing will occur. Similarly, if system return flow is high, more mixing will occur vs low flow system return.
The Garn is a good system, especially where it excels in my opinion: need for relatively moderate maximum supply temperature (approximately 140F or less) and batch burn operation, that is, burn to charge tank, let fire go out, draw from tank to supply system, remove accumulated ashes from Garn to prepare for next burn, repeat, etc. On the physical side, availability of space for the Garn is a consideration. On the hydronics side, the Garn is unpressurized and a heat exchanger likely will be needed to supply a pressurized system, and use of a heat exchanger adds cost plus reduces maximum supply temp to roughly 5-10F less than water temp in the Garn storage. On the chemistry side, the Garn requires annual water testing and treatment as needed. With regard to my statement on need for relatively moderate maximum supply temperature, this is because the Garn will supply from storage from its maximum tank temperature (about 185F) and then draw down to 140F before another burn will be needed, that is, a batch burn operation. Of course, the lower the supply temperature needed, the longer between batch burns. The Garn is not designed to burn more or less continuously because of the need to remove ash, which also may contain a quantity of hot coals, depending on the time between batch burns. So, if supply water needs to be 160F+ or so, the Garn would need to be burned nearly continuously, depending on the btuH of the Garn you would choose, which also relates to the size of the integral Garn storage.
Gasification boiler systems using many of the boilers mentioned by others, with storage, also are good systems. They equally excel in the areas where the Garn excels, as well as better offering more or less a continuous supply of very hot water (approximately 140F and up and also 160F+ water) because most can be burned more or less continuously, if needed. At the same time, in my opinion, these also excel in a batch burn operation, like the Garn, while usually not requiring removal of ash and coals between burns, except on an occasional basis. Due to their small firebox size and design of operation, usually only fine ash and some cool charred coals remain. I empty ash from my Tarm about once other week, and the ash volume is very small.
Most if not all of these other gasification boilers also are pressurized, thus eliminating the need for a heat exchanger to supply the heating system, as well as not requiring water testing and treatment, except on the initial system setup. I haven't touched the water system in my Tarm + 1000 gallons of storage in the last three years. I do take a few drops of water from the system annually to check pH and total alkalinity, which so far hasn't change from setup. Physical install of one of these boilers plus a storage tank may be easier and offer more options on placement.
The volume of storage you will want or need will relate to space available, the btuH output capacity of your boiler, system btuH demand, and how long you want the system to be supplied from storage before the next burn. In my case with the Tarm Solo 40 (140,000 btuH rating) and 1000 gallons of storage, my system typical load is around 12-15,000 btuH average, maximum is about 20,000 btuH. I can heat the storage to 193F maximum, top to bottom, although my usual target is 185F; I can use storage water temp down to as low as 100F, so I can heat solely from storage 185 to 100F before I need to burn again, although I usually will burn when storage drops to about 110-120F. At storage 110F, I have 1000 x 8.34 x 75 = 625,500 btu's available, which at a draw of 14,000 btuH = 45 hours of heat from storage. My typical burn then is every other day, and burn time is about 6 hours, during which the boiler is supplying the system plus charging the storage tank back up to 185F.
If I've been repetitive of others, I apologize. I hope this helps you make a decision.
Hello guys!! Sorry for the delay, I fell off the grid for a while. I think my a d d kicked in!
Ty for the responses. Hole everybody is having a great summer.
I'm still thinking about how I want to do it. My main problem is deciding where I'm going to place the boiler shop.
I've got an outlet for 1000gal anhydrous tanks at scrap price so I'm going to do that and probably go with one horizontal.
So youve got nothing done in four months? Welcome back. Now get to work!
Ya, I know, I'm a scatter brain!! It's looking like its going to be next year before I get a gasser. Time is running out for me. I've been working on my sons nursery/room and converting a back porch into a laundry room. The stork should be dropping him off in the next couple weeks. But, this is a good thing since ill be able to bug and annoy you guys for another year as I drag my feet!!